JPH09128031A - Servo controller, its method, robot controller, and its method using the servo controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control a controlled target so that an effective current value related to the target becomes almost equal to a rated current without exceeding it and an acceleration/deceleration curve causing operation exceeding the limit performance of the target is never generated. SOLUTION: A servo controller 1 is provided with an effective value calculating means 8 to calculate the effective value of acceleration (or current) related to operation up to a current point and the effective value of acceleration (or current) related to future operation. A TP and α value determining means 5A determines a peak speed arrival time value TP and a time base extending/ reducing parameter a defined by dividing the value TP by a reference value (peak speed arrival time related to a reference function of an acceleration/ deceleration curve) based upon a condition equation that the sum of the effective values is almost equal to a value corresponding to the rated current value of the controlled target and sends the determined values TP, α to an acceleration/deceleration pattern generating means 3. Then an acceleration/deceleration curve regulated by the limit performance of the target is generated and sent to the target.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is designed to generate an acceleration / deceleration pattern that never exceeds the characteristic limit of a controlled object and can make the effective current value of the controlled object as close as possible to the rated current value. The present invention relates to a servo control device, a servo control method, a robot control device, and a robot control method.

[0002]

2. Description of the Related Art In general, control is performed such that acceleration control is performed on a speed or angular velocity to be controlled and then deceleration control is performed, or deceleration control is performed after constant speed control for a predetermined period after acceleration / deceleration control. When performing, control related to the shape of the acceleration / deceleration curve is necessary.

When the control target is specified as a system including the motor and its drive circuit (hereinafter referred to as "motor system"), for example, a triangular shape as shown in FIG. 33 is obtained according to the rotation angle of the motor shaft. It is possible to generate an acceleration / deceleration curve (the speed reaches a peak at the apex position) and use this as a control signal to perform acceleration / deceleration control of the motor system. Note that FIG.
Represents the time t on the horizontal axis and the velocity Ω = θ ⁽¹⁾ on the vertical axis ⁽ subscript “(n)” at the upper right of the position function θ (n is a natural number).
Means the nth derivative with respect to time t, and this abbreviation will be used hereafter. ), An example of the shape of a triangular acceleration / deceleration curve is shown. The acceleration / deceleration curve a at which the speed reaches the peak value at the time t = T _P is inclined to the upper right in the range of 0 ≦ t ≦ T _P. The linear acceleration part b and T _P <t ≦ 2 ·
In the range of T _P , the linear deceleration portion c is inclined downward to the right.

By the way, the controlled object has some limitation on its performance, and it is not possible to generate a control signal according to an acceleration / deceleration curve corresponding to an operation deviating from the controlled object as it is. When generating,
The condition that the limit performance of the controlled object is not exceeded is always imposed.

That is, if the control target is constantly controlled so as to achieve its limit performance, damage or performance of the control target is impaired when the performance limit of the control target is exceeded due to temperature rise of the control target or the like. However, if the control has too much margin, the ability of the controlled object cannot be fully utilized, so a design compromise is sought while considering such conflicting circumstances.

[0006]

In the conventional control, when the limit performance of the controlled object is known,
It is difficult to give a clear answer as to what kind of guideline can be used to generate the acceleration / deceleration curve so that the effective current value of the controlled object can be brought close to the rated current value without exceeding the limit performance of the controlled object. Met.

As a result, there is a tendency to select a slightly larger capacity for the controlled object (for example, in a motor system, there is a tendency to use a large motor with a higher output), which increases the cost and the apparatus. There is a problem that it leads to a cause such as an increase in size.

Therefore, the present invention controls so that the effective current value of the controlled object does not exceed the rated current and becomes substantially equal to this value, and causes an operation that deviates from the limit performance of the controlled object. An object is to control so that an acceleration / deceleration curve is never generated.

[0009]

In order to solve the above problems, the present invention provides the following (1) to (4).
It has the structure shown in FIG.

(1) After specifying a limit characteristic line relating to the characteristics of acceleration (or force or torque) with respect to the speed (or speed, angular velocity or rotation speed) of the controlled object, the acceleration (or force or torque) and speed ( Alternatively, the shape of the acceleration / deceleration curve and its reference function and the peak speed related to the reference function under the condition that the operating point defined by the speed, angular velocity, or rotational speed) is on the limit characteristic line related to the controlled object. Define the arrival time. For that purpose, the acceleration / deceleration pattern generating means for holding the reference function and its peak speed arrival time is provided, and the outer frame of the control is controlled so that the operation according to the acceleration / deceleration curve generated by this does not deviate from the limit performance of the controlled object. Stipulate.

(2) The first effective current (or effective acceleration) related to the operation to be performed is calculated based on the acceleration / deceleration curve related to the operation, and based on the acceleration / deceleration curve related to the operation already performed. Alternatively, the second effective current (or effective acceleration) relating to the operation up to the present time is calculated based on the actual current or acceleration sent from the controlled object. This calculation is performed by the effective value calculation means.

(3) Squared value of the first effective current (or effective acceleration) and 2 of the second effective current (or effective acceleration)
The peak value arrival time of the acceleration / deceleration curve and the peak speed arrival time are related to the reference function of the acceleration / deceleration curve so that the sum of the power value and the predetermined value corresponding to the rated current of the controlled object is almost equal. Determine the value of the time axis stretch parameter defined by dividing by the velocity arrival time. This determination is made by the peak velocity arrival time value determining means.

(4) The acceleration / deceleration curve is obtained by performing the expansion / contraction operation in the time axis direction on the reference function based on the time axis expansion / contraction parameter value and the scaling operation on the reference function value based on the designated value of the servo control variable. Is generated and sent as a control signal to the controlled object. That is,
The acceleration / deceleration pattern generation means of (1) generates an acceleration / deceleration curve by performing a scaling operation of the function value or a time axis expansion / contraction operation on the reference function.

Therefore, according to the present invention, the shape of the acceleration / deceleration curve, that is, the reference function is defined by the limit performance of the controlled object, and the acceleration / deceleration curve is changed by the scaling operation of the function value or the time axis expansion / contraction operation with this as the upper limit. Is generated, the operation corresponding to the acceleration / deceleration curve does not deviate from the limit performance of the controlled object, and the second effective value related to the operation up to the present time and the first effective value related to these operations are generated. The value of the peak speed arrival time related to the acceleration / deceleration curve can be obtained by the relational expression that the sum of the above is substantially equal to the rated current value of the controlled object or the value corresponding thereto.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The servo control device and servo control method of the present invention will be described below.

Before describing the apparatus and method according to the present invention, the basic configuration and functions thereof will be described.

In the control according to the present invention, it is necessary to understand the following two basic matters.

A) The shape of the acceleration / deceleration curve is determined depending on the limit performance of the controlled object. In other words, the controlled object is always constrained to be used within the range of its limit performance, and therefore the shape of the acceleration / deceleration curve cannot be freely selected. Also, if the shape of the acceleration / deceleration curve is influenced by the ability and experience of the designer, the design will be inefficient because thinking and error will be forced each time.

Therefore, it is necessary to clarify how the shape of the acceleration / deceleration curve is defined based on the limit performance of the controlled object.

B) The acceleration / deceleration curve is generated by performing some kind of scaling operation on the reference function of the shape.

Even if the shape of the acceleration / deceleration curve is defined by the above a), it is troublesome that the generation algorithm is different for each acceleration / deceleration curve. This is because, in the case of a robot that is composed of a large number of arms and its drive system, the algorithm for generating the acceleration / deceleration curve when controlling each arm requires as many arms as the extreme example. Therefore, it is necessary for the control device of the arm drive system to be provided with a means for generating an acceleration / deceleration curve for each algorithm, which is complicated and uneconomical.

Therefore, no matter what the shape of the acceleration / deceleration curve obtained in a) is, only the reference function of the shape of the acceleration / deceleration curve is prepared and scaled in order to unify the generated algorithms. (Variation and expansion / contraction of time axis)
It is necessary to handle the acceleration / deceleration curve freely by performing an operation.

In the following, description will be given while always keeping the above two matters in mind.

First, the controlled object in the present invention must have its limit performance characterized by acceleration (or force, torque, etc.)-Velocity (or speed, angular velocity, rotational speed, etc.) characteristics. That is, as long as there is no limit constraint on the performance of the controlled object, the performance of the controlled object will not be exceeded regardless of the shape of the acceleration / deceleration curve used.
Since it is not possible to specify a criterion for determining the value of the shape of the acceleration / deceleration curve, it is removed from the controlled object according to the present invention. Therefore, as long as this condition is met, the controlled object according to the present invention may have any configuration,
A system including various actuators and driving circuits thereof is included in the controlled object.

Next, the acceleration (or force, torque, etc.)-Speed (or speed, angular velocity, rotational speed, etc.) characteristic that defines the limit performance of the controlled object is the position or angle of time such as acceleration or torque. Taking the second derivative or the amount containing it on one axis,
When the first-order derivative of a position or angle with time, such as velocity or angular velocity, or a quantity including this is expressed on the other axis with respect to the relationship between them, the limit performance of the controlled object is specified on the diagram. Characterized by a curve (limit line).
That is, the performance and quality of the controlled object are guaranteed on the curved line and in the inner area surrounded by the curve and the two axes, but when stepping into the outer area, the performance and quality of the controlled object are guaranteed. Disappear.

For example, when the control target is specified to the motor system, the characteristics as shown in FIG. 1 can be exemplified.

FIG. 1 shows the torque-speed (rotational speed) characteristic of an AC (alternating current) motor system (only the first quadrant is shown), where the horizontal axis represents the torque T and the vertical axis represents the speed N. This shows several examples of the limit TN line and the rated TN line.

In the example shown in FIG. 1A, the rated TN line g
1 is composed of a line segment of N = Nm, a line segment of T = T1 (rated torque), and a line segment descending to the right connecting both line segments,
Further, the limit TN line g2 inclines downward to the right in succession to the line segment N = Nm and T = T2 (instantaneous maximum torque)
And a line segment that intersects the T-axis.

In the example shown in FIG. 1B, the rating T-
The N line h1 has the same shape as the rated T-N line g1, but the limit T-N line h2 is a line segment of N = Nm, and a line segment that slopes to the lower right and intersects the T axis at T = T2. , And a line segment descending to the right that connects both line segments.

In the example shown in FIG. 1C, the rating T
The −N line i1 has the same shape as the rated TN line g1, and the limit TN line i2 is a line segment of N = Nm, a line segment of T = T2, and a right-downward line connecting both line segments. It is composed of line segments and.

The limit T-N line and the rated T-N line composed of a plurality of line segments as described above are expressions for convenience to make the characteristics of the motor system easy to understand, and the actual limit T The −N line and the rated TN line are generally curved lines having a complicated shape.

Since the motor system has been taken up as the control target, the effective values of the mechanical power (power) and electric power (power consumption) of the motor will be described.

[0033] FIG. 2 shows a simplified equivalent circuit of the servo motor, the resistance to the variable voltage source Vccm showing a control voltage (resistance value and "R _M".) And the electromotive force (motor torque The constant is “K _t ” and the angular velocity of the motor is “Ω”
Then, −K _t · Ω. ) Is connected in series with the voltage source shown in FIG.

For simplification of explanation, a triangular acceleration / deceleration curve as shown in FIG. 33 (the peak speed arrival time is "T _P ", the peak speed value is "Ω _p ", The area enclosed between the deceleration curve and the time axis, that is, the total movement (rotation) amount of the motor is “Δθ”. However, the result obtained here will be generalized later. Be careful.

Table 1 below shows symbols and meanings of various physical quantities used in a tabular form.

[0036]

[Table 1]

First, when the motor is operating, the motor resistance R _M
It is consumed when the power to be thermally and _"I P", which is as the following equation by.

[0038]

(Equation 1)

[0039] Thus, the effective value in the period 2 · T _{P "I}
P _RMS ", this becomes as shown in the following equation.

[0040]

(Equation 2)

Note that " _I P _RMS " is determined only by the current I _M , that is, the acceleration, and is not related to the total movement amount Δθ of the motor.

Next, the mechanical power supplied from the power source to the mechanical portion via the motor during the operation of the motor is represented by " _K P
(T) ”and the effective value in the period 2 · T _P is“ _K P _RMS ”, this becomes the following formula.

[0043]

(Equation 3)

In the case of a triangular acceleration / deceleration curve, _K P
(T) is proportional to the time t as shown in the following equation [Equation 4],
Substituting the equation 4 into the equation 3 above to obtain the effective value _K P _RMS , the total movement amount Δθ of the motor can be obtained as shown in the following equation 5.
It is a function of the peak velocity Ω _p in proportion to the square of.

[0045]

(Equation 4)

[0046]

(Equation 5)

FIG. 3 shows the peak velocity Ω _p and the peak velocity arrival time T _P when the triangular acceleration / deceleration curve is continuously used.
FIG. 4 is a t-Ω diagram showing the state of one cycle when the value is changed. FIG. 4 shows the locus of the operating point corresponding to each acceleration / deceleration curve and the effective value of the mechanical power and the effective value of the electrical power. It is shown.

In FIG. 3, the acceleration / deceleration curve j _i (i = 1 to 4) has the respective peak speed arrival times T _Pi (i = 1).
To 4) and the peak speed is Ω _pi (i = 1 to 4).

The horizontal axis of FIG. 4 is K _t · I _M, and
The vertical axis forming the quadrant is the speed Ω, and the vertical axis forming the fourth quadrant is R _M · I _M / K _t , and the acceleration / deceleration curve j
The effective value of the mechanical power corresponding to _i (i = 1 to 4) is “ _K P _RMSi ” (i = 1 to 4).

As shown in the figure, the effective value _I P _RMS of the electric power consumed by the resistor R _M is constant regardless of the acceleration / deceleration curve, and is equal to the area of the shaded portion. In addition, the effective value of mechanical power _K P _RMSi (i = 1 to 4)
Corresponds to the area of each quadrangle, as can be seen from the fact that the operating point moves on the side of the quadrangle as shown by the arrow, and differs for each operation.

Since the ability of the controlled object depends on its temperature, the algorithm for generating the acceleration / deceleration curve is _I P _RMS
It is preferable to include the value in the evaluation value for control.

When the controlled object is operated continuously,
The values of _I P _RMS and _K P _RMS are determined as described above, but it can be shown that the relationship between the total movement amount Δθ and the peak speed arrival time T _P is defined from the condition that these are always constant. it can.

That is, when _I P _RMS is controlled to be constant,
The following expression [expression 6] is obtained from expression [expression 2], and T _P is 2 of Δθ.
A relationship that is proportional to the 1st power is derived.

[0054]

(Equation 6)

That is, when Δθ is taken on the horizontal axis and T _P is taken on the vertical axis as shown in FIG. 5, if the relationship between the two is defined as shown by a parabola pr connecting points A and B, The temperature of the controlled object can be kept constant even when the continuous operation of the controlled object is performed at any Δθ. The point A in FIG. 5 is the minimum value T _{PMI of} T _P determined by the limit of the frequency characteristics of the controlled object.
A point corresponding to _N, and a point B indicates a point corresponding to the maximum value of the peak velocity Ω _p .

When _K P _RMS is controlled to be constant, a relational expression that T _P is proportional to the third power of Δθ is derived, and when _I P _RMS + _K P _RMS is controlled to be constant. Is Δθ of 2
Since the fourth-order equation of T _P including the power is derived, the Δθ-T _P characteristic can be defined based on these, as in the case of FIG.

Next, regarding b), the scaling operation for the reference function and the expression of the acceleration / deceleration pattern obtained by the scaling operation will be described.

The "acceleration / deceleration pattern" referred to here is
The state quantity (that is, the velocity and the angular velocity) directly described by the acceleration / deceleration curve is, of course, a broad concept including the time derivative of the state amount, the integral amount, and the like.

The acceleration / deceleration curve relating to the controlled object needs to be generated according to the unified algorithm regardless of the shape.

Therefore, by imposing as few constraints as possible on the shape of the acceleration / deceleration curve, a unified expression of the acceleration / deceleration curve including the conventional acceleration / deceleration curve having a triangular shape or a sine wave shape is given. .

This new acceleration / deceleration pattern is characterized by the introduction of a reference function that determines the shape of the acceleration / deceleration curve and the scaling operation for the reference function.
Hereinafter, this will be referred to as a “scalable pattern”.

The standard function of the scalable pattern is referred to as a "normalization function", which will be referred to as "θ _N (τ / T)". However, “τ” represents a time axis parameter, T represents a time constant of the control system, and is a constant necessary for making dimensionless to τ / T.

Then, the position function related to the scalable pattern is ".THETA. (T)" (where t is real time), and the time axis expansion / contraction parameter defined by the relationship "t = .alpha..tau.". Introduce “α”.

The amount of movement related to Θ (t) (that is, Θ ⁽¹⁾
Total amount of movement obtained by integrating (t) over the entire movement time. ) Is defined as “Δθ”, and the first-order time derivative of the normalization function θ _N θ _N ⁽¹⁾
Is referred to as "normalized speed", and the time until the peak value is reached, that is, the peak speed arrival time related to the normalized speed θ _N ⁽¹⁾ is defined as " _TPn ". Further, if the peak velocity arrival time for velocity, which is the first-order time derivative of the position function Θ (t), is “T _P ”, then T _P has a lower limit value (this is referred to as “T _PMIN ”) and an upper limit. Since there is a value (denoted as “T _PMAX ”), T _Pn can be chosen to be some value within the range T _PMIN ≦ T _P ≦ T _PMAX .

The definitions of the above various quantities are summarized in Table 2 below.

[0066]

[Table 2]

FIG. 6 is a graph showing the normalized speed θ _N ⁽¹⁾ , where the horizontal axis is “τ” and the vertical axis is “θ _N (τ /
T) ”, and“ T _all ”indicates the total travel time. The normalized speed θ _N ⁽¹⁾ is 0 ≦ τ ≦ T _Pnu (= T
_Pn ), the acceleration part and T _{P nu ≤τ≤T all} -T _Pnd
Constant speed portion during the period (hereinafter, referred to as "T _c "),
T _{al l} serves and a speed reduction unit in the period -T _Pnd ≦ τ ≦ T _all, the area of the area surrounded by these parts and tau shaft, i.e. constant integral value has the property that is equal to 1. In other words, “normalization” in the normalization function θ _N means θ _N
It means that the total movement amount related to is always adjusted to 1. It should be noted that this may not always be included in the constant speed part (period T _c = 0).

The relational expression showing the property of the normalization function θ _N is shown below.

[0069]

(Equation 7)

[0070]

(Equation 8)

[0071]

(Equation 9)

[0072]

(Equation 10)

The expression [7] means the existence of a peak speed value of the standardized speed, and the expression [10] implicitly assumes that the deceleration portion does not include a vibration component. When the component is included, it is generally “θ _N (∞ / T) = 1”.

Next, for the sake of convenience of description, an assumption will be made for the standardization function θ _N that does not impair generality.

The first reason is that the acceleration time is considered in consideration of the fact that the limit characteristic line that determines the performance of the controlled object has symmetry between the portion belonging to the first quadrant and the portion belonging to the second quadrant on the characteristic diagram. T _Pnu is set equal to the deceleration time T _Pnd , and the second is to set T _Pn to the minimum value T _PMIN of T _P , and when these are expressed by a mathematical expression, the following expression is obtained. .

[0076]

[Equation 11]

[0077]

(Equation 12)

It should be noted that these assumptions are merely for the sake of convenience, and the assumptions are intended to give concreteness to the explanation by reducing the arbitrariness of the setting of T _Pn and the shape of the acceleration / deceleration curve as much as possible. Be careful not to pass too much.

Specific examples of the standardization function θ _N include the following functions.

I) In the case of a triangular acceleration / deceleration curve.

[0081]

(Equation 13)

Ii) In the case of an acceleration / deceleration curve obtained when the position command is given to the third-order filter as a ramp signal.

In controlling the servo system to be controlled, a system corresponding to the actual servo system is simulated by software processing and prepared in the control device (such a servo system will be described below. By introducing a "virtual servo system") and using it as a calculation means, it can be used for generation of acceleration / deceleration curves and calculation of various estimated quantities. For example, in the control circuit of the motor system,
A circuit part directly related to motor control and a part related to dynamic compensation for stabilizing control are provided in the servo system, but a virtual motor system (hereinafter, referred to as a virtual motor system having a filter configuration corresponding to these is provided. "Virtual motor system") is prepared as an internal model by software processing in the control device, the output when a command is given to the virtual motor system is used as it is for the control signal to the actual servo system. be able to.

For example, the virtual servo system is constituted by a third-order low-pass filter, and the output when the position command of the ramp signal as shown in FIG. 7 (this is referred to as “Δθ _REF ”) is used is used. By doing so, it becomes unnecessary to explicitly perform the calculation related to the normalization function. That is, in general, the response characteristic of the servo system is not always expressed by an analytical expression, and therefore it is useful from a practical point of view to introduce a virtual servo system that imitates the actual servo system.

In the case of the third-order filter, the function expression can be easily obtained, and the following expression is obtained.

[0086]

[Equation 14]

In the above equation, "T _i " (i = 1, 2, 3)
Is the time constant of the servo loop, " _Tf " is the break time of the ramp signal (see FIG. 7), and "exp ()" is an exponential function. Further, in deriving the above equation, the inverse Laplace transform may be performed on the output obtained from the product of the Laplace expression of the ramp signal and the loop transfer function of the filter, but the process is directly related to the gist of the present invention. Since it does not exist, the explanation is omitted.

Iii) In the case of an acceleration / deceleration curve having a shape including a sine function.

[0089]

(Equation 15)

Now, when the standardization function θ _N is defined as described above, the scalable pattern can be defined as follows based on this.

[0091]

(Equation 16)

First, the position function Θ (t) is obtained by multiplying the normalizing function θ _N by Δθ and multiplying the time axis τ and the time constant T by α, as shown in the following equation.

[0093]

[Equation 17]

The velocity function Θ ⁽¹⁾ (t) is obtained by multiplying Δθ by 1 / α and multiplying it by the normalized velocity θ _N ⁽¹⁾ as shown in the following equation.

[0095]

(Equation 18)

The acceleration function Θ ⁽²⁾ (t) is obtained by dividing Δθ by the square of α as shown in the following equation, and the acceleration function θ _N ⁽²⁾ (hereinafter referred to as “normalized acceleration”). .).

[0097]

[Equation 19]

From these equations, it becomes clear that the function related to the scalable pattern is obtained by independently performing the expansion / contraction operation in the time axis direction for the normalization function and the like and the scaling operation for the function value itself.

FIG. 8 is a diagram for explaining the scaling operation with respect to the standardized speed with τ on the horizontal axis and the speed Ω on the vertical axis. FIG. 8A shows the standardized speed with Δθ = 2. The operation of doubling the value of θ _N ⁽¹⁾ is shown in FIG.
FIG. 8B shows an operation in which α = 2 and the normalized speed θ _N ⁽¹⁾ is doubled in the time axis direction. FIG. 8C shows the operation in FIG. 8A and the operation in FIG. 8B. It shows an operation that is a combination of operations.

As described above, if the standardized speed (or the standardized function) is given in advance, the standardized speed (or the function value scaling direction) or the horizontal axis (time axis) direction is independent of this. By adopting the rule of performing expansion / contraction operation (scaling), the normalized function θ _N or the normalized speed θ _N ⁽¹⁾
The acceleration / deceleration pattern can be freely controlled regardless of the shape of the. In other words, all the acceleration / deceleration patterns generated by such a method are included in the scalable pattern.

It should be noted that a specific example of the scalable pattern can be easily obtained by substituting the expressions of the standardization functions shown in the equations [13] to [15] into the equations [16] to [18]. Since the generation algorithm does not depend on the specific shape of the acceleration / deceleration curve with respect to the concept of the scalable pattern, the description thereof will be omitted.

As described above, it becomes clear that the position, velocity, and acceleration related to the scalable pattern can be derived based on the normalization function. More generally, the physical quantities relating to the motion of the controlled object are _N ), the amount of change (total amount of movement Δθ), and the time axis expansion / contraction parameter (α).

For example, in the case of the effective current value related to the controlled object, in the control such that the effective value _I P _RMS of the electric power is kept constant when the controlled object is specified to the motor system (see FIG. 5). ), It is possible to discuss the magnitude of _I P _RMS by the effective current value of the motor, and the effective current value is often more convenient when referring to the specifications of the motor.

Therefore, the effective current value of the motor is set to " _IRMS ".
Then, this can be defined by the following formula [Formula 20], and by using the formula [Formula 19] and the relation of “t = α · τ”, the following formula [Formula 21] can be obtained.

[0105]

(Equation 20)

[0106]

(Equation 21)

[Equation 21] shows that the effective current value of the motor when the motion control is performed according to the scalable pattern is
It shows that it can be calculated from the effective value of the normalized acceleration (θ _RMS ⁽²⁾ ), Δθ and α.

In the above description, when calculating the value of the standardization function, the amount of calculation is not considered and the value to be calculated is obtained immediately. However, when the shape of the standardization function is complicated. Since it is expected that the calculation of the function value will take time, in such a case, it is practical to prepare a data table relating to the standardization function in advance and to make a database of the function value.

From the above description, it is clear that the item b), that is, the introduction of the scalable pattern, realizes the unification of the acceleration / deceleration pattern generation algorithm, but the control target in the item a). Since the description of the relationship between the limit performance and the shape of the acceleration / deceleration curve remains, this point will be described in detail below.

As described above, the limit performance of the controlled object is defined by the limit characteristic line in the acceleration-speed characteristic diagram or the like, and it is easily understood that this serves as a design guideline for the acceleration / deceleration pattern. This is because the motion of the controlled object corresponds to the operating point or the locus of the operating point on the characteristic diagram in a one-to-one manner, and the acceleration / deceleration is such that the operating point deviates from the guaranteed operating range bounded by the limit characteristic line. This is because the generation of the pattern is not permitted or dangerous in terms of control.

Therefore, in the following, first, the behavior of the operating point corresponding to the motion according to the scalable pattern on the characteristic diagram will be described.

FIG. 9A shows an operating point Q (θ _N on the normalized acceleration (θ _N ⁽²⁾ )-normalized velocity (θ _N ⁽¹⁾ ) diagram for the normalizing function of the scalable pattern. ⁽²⁾ , θ _N
⁽¹⁾ ) about the trajectory M, where the horizontal axis is the standardized acceleration and the vertical axis is the standardized speed. For comparison, temporal changes in the standardized speed and the standardized acceleration are shown in FIGS. 9B and 9C, and the subscript "" attached to the physical quantity in these figures is shown. "P" means the peak value of each amount.

In the locus M shown in FIG. 9A, the portion M1 shown in the first quadrant of the figure corresponds to the acceleration portion in the acceleration / deceleration curve, and the portion M2 shown in the second quadrant of the figure shows the acceleration / deceleration curve. It corresponds to the deceleration part, and the operating point Q is the locus M.
Move up in the direction indicated by the arrow.

Here, note that θ _N ⁽²⁾ is θ _N
^This means that it is a monovalent function for ⁽¹⁾ . For example, as shown in FIG. 10A, there are a plurality of acceleration values corresponding to one value of θ _N ⁽¹⁾ , or as shown in FIG. 10B, a locus including a loop is not drawn. That is.

When the acceleration / deceleration curve relating to the normalization function includes the constant velocity portion, the operating point Q is (0, θ
_NP ⁽¹⁾ ).

If the behavior of the trajectory related to the normalization function is clarified, the behavior of the scalable pattern obtained by performing the scaling operation on it is also clarified. At that time, the scaling operation is performed on the characteristic diagram. Figure 1 shows how it affects the trajectory of the normalization function.
1 will be described.

In FIG. 11, the horizontal axis represents the acceleration (Θ ⁽²⁾ (t)), and the vertical axis represents the velocity (Θ ⁽¹⁾ (t)).
FIG. 10 shows the locus of (Θ ⁽²⁾ , Θ ⁽¹⁾ ) and also shows the locus M related to the normalization function shown in FIG. 9.
It should be noted that, for simplification of description, only loci belonging to the first quadrant are shown in the figure.

As described with reference to FIG. 9, in the scaling operation related to the scalable pattern, the scaling operation of the function value itself and the expansion / contraction operation in the time axis direction are independent of each other.

FIG. 11A is for explaining the scaling operation (scaling by Δθ) of the function value itself, and as can be seen from the formulas [18] and [19], Θ
^{Since (2)} and Θ ^{( 1)} are proportional to Δθ, when the time axis expansion / contraction parameter is fixed to α = 1, this operation shows the trajectory M related to the normalization function as it is for both axes. It is nothing but to obtain a trajectory Ma similar to the trajectory M by multiplying by Δθ.

FIG. 11B is for explaining the expansion / contraction operation (magnification by α) in the time axis direction. If Δθ = 1 in the formulas [18] and [19], As shown in the formula [Equation 22], the speed is 1 / α of the standardized speed, and the acceleration is the standardized acceleration α.
Since it is converted to a value obtained by dividing by a square of, the operation is performed with respect to the locus M related to the normalization function as shown in the figure, where α is 1 / square for the acceleration axis and α is for the velocity axis.
It is nothing but to obtain the locus Mb by reducing the number by one.

[0121]

(Equation 22)

In the figure, 0 ≦ α ≦ 1 is set for the sake of easy understanding, but this is T _Pn = T _PMAX , considering the arbitrariness of the selection of the peak velocity arrival time T _Pn related to the normalization function. Corresponds to the case you choose.

FIG. 11C shows the operation of FIG. 11A and FIG.
1 shows a locus Ma * b obtained from a locus M relating to a normalization function by combining with the operation 1 (b), and shows a general behavior of an operating point U relating to a scalable pattern. .

As described above, also with respect to the locus of the operating point U related to the scalable pattern, the locus M of the operating point P related to the standardizing function has an important role, and both are closely related through the scaling operation. It becomes clear.

Next, regarding the normalizing function and the function relating to the scalable pattern, the physical meaning of the area surrounded by the loci of the operating points will be described.

As described with reference to FIG. 4, when the motor shaft is rotated at a constant speed with a constant torque load applied to the motor, the effective value of the mechanical power is the torque-speed characteristic diagram. It is represented by the area of the quadrangle region surrounded by the locus drawn by the operating point and the acceleration axis and the velocity axis in the following. .

In FIG. 12, the horizontal axis shows θ _N ⁽²⁾ and Θ ⁽²⁾ together, and the vertical axis shows θ ⁽¹⁾ and Θ ⁽¹⁾ together. * b is shown together.

First, regarding the normalization function θ _N , FIG.
If the area in the locus M in the θ _N ⁽²⁾ −θ _N ⁽¹⁾ characteristic diagram of (indicated by the slanting line descending to the left in the figure) is “s”, the following formula is obtained.

[0129]

(Equation 23)

Therefore, the effective current value of the controlled object when operating according to the acceleration / deceleration curve related to the standardization function is “i _RMS ”.
Then, this can be obtained by the following equation.

[0131]

(Equation 24)

That is, it can be seen that the effective current value i _RMS is proportional to the square root of the area s in the locus M.

Further, the same calculation as described above can be performed for the locus associated with the scalable pattern.
The area within the locus Ma * b (shown by the slanting line in the lower right of the figure ^{) in} the Θ ^{(2) −} Θ ^{( 1)} characteristic diagram of is as “S”, and the effective current value related to the controlled object is as “ _IRMS ”. Then, S becomes like the following formula.

[0134]

(Equation 25)

[Equation 20], [Equation 21], [Equation 2]
4] and [Equation 25], the effective current values I _RMS and i _RMS
The following relationship is found between and.

[0136]

(Equation 26)

That is, if the effective current value i _RMS related to the normalization function, that is, θ _RMS ⁽²⁾ is known, the effective current value I _RMS during actual operation can be known (that is, the squared value of I _RMS can be obtained). It can be known from the squared value of i _RMS .).

Based on the relationship between the function related to the scalable pattern and the normalization function, various physical quantities related to the property of the acceleration / deceleration curve are set to the normalization function regardless of the shape of the acceleration / deceleration curve. It can be reduced to such an amount.

Based on the above results, a method of generating a scalable pattern in consideration of the limit characteristic of the controlled object will be described.

FIG. 13A shows the acceleration function Θ on the horizontal axis.
⁽²⁾ Taking (t) and taking the velocity function Θ ⁽¹⁾ (t) on the vertical axis, the locus Mt of the operating point U (Θ ⁽²⁾ , Θ ⁽¹⁾ ) relating to the motion of the controlled object is shown. In the figure, “Θ _P ⁽²⁾ ” indicates the peak value of acceleration, and “Θ _P ⁽¹⁾ ” indicates the peak value of velocity. These include information on T _P and Δθ. ing. Now, the question is how to determine the shape of the acceleration / deceleration curve when the controlled object is moved along the locus Mt. For the sake of simplification of description, it is assumed that the acceleration / deceleration curve does not include a constant velocity portion, and the locus Mt is in the first quadrant and the second quadrant of the Θ ⁽²⁾ -Θ ⁽¹⁾ diagram. The portion having the symmetry, that is, the portion of the trajectory Mt belonging to the first quadrant is represented by Θ
^{(1) When} it is folded back about the axis, it can be overlapped with the part of the trajectory Mt belonging to the second quadrant. Even if such an assumption is made, the generality of the following discussion will not be impaired.

Since the velocity function Θ ⁽¹⁾ (t) is a function of the acceleration function Θ ⁽²⁾ (t), the locus Mt in the figure can be expressed by the following equation.

[0142]

[Equation 27]

[Θ _F ⁽¹⁾ ] in the above equation is a functional.

If the above equation is written in a more understandable form, the following equation is obtained.

[0145]

[Equation 28]

The above equation is obviously a differential equation, and by solving this equation, a solution like the following equation can be obtained.

[0147]

(Equation 29)

The integration constant (constant in C or Ω (t)) in the above equation is determined by considering initial conditions and boundary conditions (related to Δθ, T _P, etc.). For example, from the initial condition Ω (t = 0) = 0, C = 0, and finally, the solution shown in the following equation is obtained, and when this is conceptually illustrated in FIG.
(B).

[0149]

[Equation 30]

From the above discussion, it becomes clear that the locus Mt defines the shape of the acceleration / deceleration curve.
We will supplement that understanding by presenting some concrete examples.

FIG. 14 is a Θ ⁽²⁾ -Θ ⁽¹⁾ diagram showing an example of the characteristic line showing the limit performance of the controlled object (see the limit TN line i2 in FIG. 1C). , The limit characteristic line L is Θ ⁽¹⁾ =
Θ _MAX ⁽¹⁾ line segment Lb, Θ ⁽²⁾ = Θ _MAX ⁽²⁾ line segment La,
These line segments are connected at points A and B, and include a line segment Lab inclined downward to the right. That is, the point A is the line segment L
It is the connection point between a and the line segment Lab, and its coordinate value is (Θ _MAX
⁽²⁾ , Θ _ap ⁽¹⁾ ), and the time when the operating point passes through this point A is t = T _a . Further, the point B is a line segment Lab and a line segment Lb.
And the coordinate value is (Θ ⁽²⁾ _b , Θ ⁽¹⁾ _MAX ).
And the time when the operating point passes through this point B is t = T _b .

The line segment Lab has its inclination (this is "-T _m "
And ) Or the intercept on the Θ ⁽¹⁾ axis (this is referred to as “Θ _c ⁽¹⁾ ”) is determined by giving the coordinate values of points A and B, so the limit characteristic line L is expressed by the following equation. be able to.

[0153]

(Equation 31)

The above equation corresponds to the equation [27], and the following equation is obtained from the integration operation of the first equation in the equation [31].

[0155]

(Equation 32)

Further, the solution of the differential equation utilizing the Laplace transform can be used for the second equation in the equation [31], and the following equation is obtained after the transformation.

[0157]

[Equation 33]

The Laplace expression of each quantity is specified by adding (s) to the function using the parameter s (independent of the area s described above).

From the equation [32], Θ ⁽¹⁾ (s) can be obtained by the following equation.

[0160]

(Equation 34)

By applying the inverse Laplace transform to the above equation, Θ ⁽¹⁾ (t) can be obtained as the following equation.

[0162]

(Equation 35)

This formula corresponds to the above [Formula 29], and by imposing the initial condition of the following formula [Formula 36], as a result, [Formula 37] is obtained as a solution corresponding to the formula [30].
You can get the formula.

[0164]

[Equation 36]

[0165]

(37)

Next, _letting T _{PMAX be the} time for the speed Θ ⁽¹⁾ to reach its maximum value Θ _MAX ⁽¹⁾ , t =
By substituting T _PMAX , the following formula [Formula 38] is obtained, and from this, T _PMAX is obtained as shown in the formula [Formula 39].

[0167]

(38)

[0168]

[Equation 39]

Summarizing the results so far, the speed function is expressed by the following equation.

[0170]

(Equation 40)

Therefore, to obtain the position function from this,
The following expression [expression 41] is obtained by integrating the first expression of the expression [40] (however, the integration constant is set to zero from the initial condition), and the second expression of the expression [40] is integrated. (However, the integration constant is set as “C”.) By the following expression [Formula 42] is obtained.

[0172]

[Equation 41]

[0173]

(Equation 42)

In determining the integration constant C, the following equation [Equation 4]
3], the boundary condition at t = T _a may be used.

[0175]

[Equation 43]

By summarizing the above results, the formula [44] is obtained for the velocity and the formula [45] is obtained for the position, which is shown in FIG.

[0177]

[Equation 44]

[0178]

[Equation 45]

In this example, since it is assumed that the locus L has symmetry between the first quadrant and the second quadrant, the acceleration part and the deceleration part of the acceleration / deceleration curve have symmetrical shapes. Of course, if the assumption is not satisfied, the solution for the speed reducer can be obtained by the same procedure as described above. It is also easy to generalize the above discussion to the case where the acceleration / deceleration curve includes the constant velocity part (since the operating point of the constant velocity part is only at the Θ ⁽¹⁾ axis).

FIG. 16 is a Θ ⁽²⁾ -Θ ^{( 1)} diagram showing another example of the characteristic line showing the limit performance of the controlled object, and the limit characteristic line L'is a straight line inclined downward to the right. It consists of line segments only. That is, in the limit characteristic line L shown in FIG. 14, a point A (Θ _MAX ⁽²⁾ , 0) is set and a point B (0, Θ _MAX ⁽¹⁾ ) is set.
Is the limit characteristic line L '.

Therefore, the condition shown in the following equation [Equation 46] is
By substituting into the equations [44] and [45], the solutions shown in the equations [47] and [48] can be obtained without resolving the differential equations.

[0182]

[Equation 46]

[0183]

[Equation 47]

[0184]

[Equation 48]

FIG. 17 is a Θ ^{(2 )} -Θ ⁽¹⁾ diagram showing another example of the characteristic line showing the limit performance of the controlled object, and the limit characteristic line L ″ is Θ ⁽²⁾ = θ. Line segment of _MAX ⁽²⁾ and Θ ⁽¹⁾
= Theta consists of a segment of _{MA X} ^(1), a trace corresponding to the triangular acceleration and deceleration curve, as described in FIG. 4, Equation 49]
It is expressed by an equation.

[0186]

[Equation 49]

Therefore, if this is solved, the solutions shown in [Equation 50] and [Equation 51] can be obtained, but the intermediate calculation is not important (the acceleration / deceleration curve and T in FIG. 4 are omitted). -This supplements the explanation of the correspondence with the loci on the N diagram.)

[0188]

[Equation 50]

[0189]

(Equation 51)

From the above, it is understood that the shape of the acceleration / deceleration curve is defined by the characteristic line (that is, the locus) that defines the performance of the controlled object.

Therefore, with respect to the motion of the controlled object, since it is not allowed or dangerous to exceed the limit performance of the controlled object, the acceleration / deceleration curve is defined by the limit performance characteristic line of the controlled object, that is, If the standardization function related to the scalable pattern is specified from the limit performance characteristic line of the control target, it is possible to control so that the operating point or locus corresponding to the acceleration / deceleration pattern is always located within the range of the limit performance characteristic line. it can.

That is, T _PMAX (maximum peak velocity arrival time) and Δθ _MAX (= Θ (T _PMAX )) always exist for the controlled object, and these are bounded by the boundary as shown in the equation [39]. Since it is uniquely determined by the condition, the acceleration / deceleration pattern corresponding to the operation when the controlled object is drawn to the limit of its capability may be used as the reference of the scalable pattern.

Specifically, when the position function related to such an acceleration / deceleration pattern is set to "Θ _MAX (t)", the normalization function θ _N related to the scalable pattern is defined as the following equation.

[Equation 52]

Therefore, if T _P for Δθ (≦ Δθ _MAX ) is determined, the time axis expansion / contraction parameter α is determined as shown in the following equation [53], and a function related to the scalable pattern, for example, the position function Θ (T) is determined as shown in the following equation [Equation 54].

[0195]

(Equation 53)

[0196]

(Equation 54)

Now, recall the arbitrariness of the selection of the peak velocity arrival time T _Pn related to the normalization function.

FIG. 18 shows a scalable pattern in which the limit performance of the controlled object is taken into consideration. The change of the acceleration / deceleration curve and the corresponding Θ ⁽²⁾ −Θ ⁽¹⁾
It is a conceptual illustration of a correspondence relationship between a change in the locus of the operating point on the diagram.

The acceleration / deceleration curve AL shown in the figure corresponds to the limit characteristic line L of the controlled object, and the acceleration / deceleration curve al has a certain Δθ (<
_Acceleration / deceleration curves for Δθ _MAX ) and T _P (<ΔT _PMAX ), that is, obtained by performing a scaling operation on the normalization function of [Equation 52],
The characteristic line corresponding to this is l. In the drawing, the correspondence between each part of the acceleration / deceleration curve and each part of the characteristic line is indicated by the symbols.

Therefore, it is concluded that the acceleration / deceleration curve generated as the scalable pattern does not deviate from the range defined by the limit characteristic line L of the controlled object for the corresponding operating point.

[0201] Incidentally, as can be seen from the number 44] where the acceleration and deceleration curve t = 0, T _a, or no longer be guaranteed continuity of acceleration in T _{PMA X,} or the control target limit characteristic line shape It is necessary to take some measures to deal with the case where is not as simple as the above example, and the following two methods will be described.

The first is the "low-pass filter method",
For example, as shown in FIG. 19, the acceleration / deceleration curve corresponding to the equation [44] is passed through a low-pass filter LPF having a predetermined cutoff frequency, and its output (in FIG.
_o ⁽¹⁾ (t) ”, and the peak velocity arrival time is“ T
_P ′ ”and the maximum speed is“ Θ _MAX ⁽¹⁾ ′ ”. ) Is given to the controlled object as a control signal. That is, since a point in the acceleration / deceleration curve having a problem of continuity of acceleration or a portion near the connection point corresponds to a portion including a high frequency component, the low-pass filter LPF facilitates the connection of the components of the acceleration / deceleration curve. can do. By this, Θ ⁽²⁾ corresponding to the output of the low pass filter LPF
The locus Lo on the −Θ ⁽¹⁾ diagram is located inside the limit characteristic line L as shown by the broken line in FIG. Note that the filter configuration can be generally an n-th (n is a natural number) low-pass filter, and its order and frequency characteristics (pole arrangement) can be determined so as to match the frequency characteristics of the control target. . For example, when the virtual servo system as described above is built in the control device, the servo parameters and time constants related to the virtual servo system are fixed according to the parameters and time constants related to the actual servo system. Thus, the virtual servo system can be used for the low-pass filter, and in this case, control can be performed so that T _P ′ ≧ T _PMIN .

The second method is the "inscribed method", which is shown in FIG.
As shown in FIG. 1, when the limit characteristic line L of the controlled object is a complicated curve, it is approximated by a polygon (a side of a polygon) LL inscribed in the curve, as shown by a chain double-dashed line. Is the way to do it. That is, if the function Θ _F ^{(1) of the} equation [27] is simple, the differential equation can be solved by the above procedure, but if the function is complicated, some approximation is required. . Therefore, the accuracy of the approximation can be improved by increasing the n value of the n-sided polygon inscribed in the limit characteristic line L as an approximate function of the target function.

If there is no corner in the limit characteristic line L, a smooth acceleration / deceleration curve can be obtained, the low-pass filter method is unnecessary, and the shape of the limit characteristic line L should be simple. For example, even if it is a curve, it is sufficient if it can be expressed easily by an analytical expression. Since these methods are complementary, there is no practical problem due to the combination of these methods. An acceleration / deceleration curve can be obtained. That is, when the limit characteristic line L is complicated, the inscribed method is required to obtain the approximate expression, and the low-pass filter method is required to smoothly connect the approximate characteristic lines.

From the above discussion, however, the shape of the acceleration / deceleration curve is determined by the items a) and b) above, that is, the limit performance of the controlled object. It is clarified that it is generated by a unified algorithm that performs a scaling operation on the digitized function, and based on these, the basic configuration of the servo control device according to the present invention is understood.

FIG. 22 shows the basic configuration of the servo control device. The servo control device 1 includes a command means 2, an acceleration / deceleration pattern generation means 3, a T _P (peak speed arrival time) value determination means 4, α ( The time axis expansion / contraction parameter) value determining means 5 and the low-pass filter 6 are included.

That is, the signal (position command, etc.) generated by the command means 2 is sent to the acceleration / deceleration pattern generation means 3 and the T _P value determination means 4
Sent to

[0208] T _P value determining means 4 is intended to define the relationship between the position command [Delta] [theta] and T _P value, corresponding to their [Delta] [theta] T _P
The value is determined, and this value is sent to the α value determining means 5 in the subsequent stage.

[0209] For example, as shown in FIG. 23 (a), taking the [Delta] [theta] on the horizontal axis, taking the T _P on the vertical axis, points corresponding respectively to the lower limit and the upper limit of the T _P value MIN ([Delta] [theta] _MIN,
T _PMIN ) and the point MAX (Δθ _MAX , T _PMAX ) are determined as points unique to the controlled object.

Therefore, for example, considering the characteristic in which the points MIN and MIN are connected by a straight line as shown in the figure, 0 is obtained.
In the range of ≦ Δθ ≦ Δθ _MIN , T _P = T _PMIN , Δθ _MIN ≦ Δ
In the range of θ ≦ Δθ _MAX , the T _P value (where T _PMIN ≦ T _P ≦ T _PMAX ) according to the inclination of the straight line is obtained, and in the range of Δθ ≧ Δθ _MAX , T _P = T _PMAX is obtained.

The shape of the line connecting the point MIN and the point MAX depends on what is used as the evaluation function. For example, as shown in FIG. 5, when the effective value _I P _RMS of electric power is targeted for evaluation and control is performed to keep it constant, as shown in the formula [6], T _P is proportional to the square root of Δθ. At that time, the acceleration / deceleration curve has been described as having a triangular shape, but if the effective value _I P _RMS is associated with the effective current value, the effective current value becomes constant.
When the effective current value I _RMS is made constant in the formula [26] and the effective current value i _RMS is determined by the normalization function, a general result that α = T _P / T _Pn is proportional to the square root of Δθ Leads to.

Further, when FIG. 23 (a) is generalized to the case where the acceleration / deceleration curve includes a constant speed portion, it becomes as shown in FIG. 23 (b). That is, FIG. 23B shows Δθ on the horizontal axis and T _all (= 2 · T _P + T _c ) on the vertical axis, and the characteristics are as shown by the solid line, and 0 ≦ Δθ ≦ In the range of Δθ _MIN , T _all = 2 · T _PMIN , and in the range of Δθ _MIN ≦ Δθ ≦ Δθ _MAX , the T _all value (however, 2 · T
_{In the range of PMIN} ≦ T _all ≦ 2 · T _PMAX ), Δθ ≧ Δθ _MAX , the T _P value according to the straight line having the slope of 1 / Θ _MAX ⁽¹⁾ is determined. Note that for the slope value 1 / Θ _MAX ⁽¹⁾ , the amount of movement of the constant velocity part of the acceleration / deceleration curve is Θ _MAX ⁽¹⁾ · T _c .

In FIG. 23 (b), when the dynamic range of the controlled object is large, the characteristic line is extremely close to the point MIN and the point MAX as shown by the alternate long and short dash line in FIG. In some cases, the two points coincide as shown by the chain double-dashed line (that is, T _P until this point is reached)
Is constant, but if it exceeds this, the T _P value becomes the maximum speed Θ _MAX.
^It depends on ^{( 1)} . ) It will be.

In this way, the T _P value determining means 4 sets Δ
When the T _P value corresponding to θ is determined, the α value determining means 5 determines the value of the time axis expansion / contraction parameter α based on this. However, as can be seen from “α = T _P / T _Pn ”, the division is performed only once. In addition, [Equation 52],
As shown in the formula [53], the standardizing function determined by the limit characteristic line is set to "T _Pn = T _PMAX ", but the selection of T _Pn is generally arbitrary.

The acceleration / deceleration pattern generation means 3 is the command means 2
The acceleration / deceleration pattern is generated based on the command signal from the .alpha. As described with reference to FIG. 8, the operation here is nothing but a scaling operation with Δθ or α with respect to the normalization function. That is, the acceleration / deceleration pattern generation means 3 has a standardization function corresponding to the limit performance of the controlled object (see [Equation 52], [Equation 54], etc.).
The scaling operation can generate a scalable pattern, and the motion according to the pattern never deviates from the limit performance of the controlled object.

When the low-pass filter method is used, the output of the acceleration / deceleration pattern generating means 3 is sent to the servo system 7 to be controlled after passing through the low-pass filter 6. In some cases, the output is 1 in FIG. As shown by the dotted line,
It is sent to the servo system 7 as it is. The “servo system” here means a wide system including a servo circuit and the like in addition to a drive source and / or a drive mechanism to be controlled. Further, in FIG. 22, the portion excluding the servo system 7 is a portion that can be realized by software processing in the control device.

The basic procedure of the servo control method is summarized in FIG.

First, in step S1, the limit performance of the controlled object is specified. For example, in the case of a motor, the limit T-N line as shown in FIG. 1 is specified from the specifications provided by the manufacturer, but in some cases, an experiment or theoretical calculation for determining the limit performance of the controlled object. Can be specified from.

In the next step S2, the shape of the acceleration / deceleration curve is determined based on the limit characteristic line of the controlled object. That is,
As shown in [Equation 27] to [Equation 30], this is nothing but solving the differential equation corresponding to the limit characteristic line. As a result, the normalization function related to the scalable pattern is determined from the limit performance characteristic line of the controlled object.

Then, in step S3, the Δθ-T _P characteristic is defined. As a result, T corresponding to the command value Δθ
The values of _P and α can be determined (see FIG. 23).

At the next step S4, a scalingable pattern is generated by performing a scaling operation on Δθ and α for the standardization function. That is, step S
In the acceleration / deceleration pattern obtained by the scaling operation (see FIG. 8) for the standardization function determined in 2, the locus of the operating point that moves on the characteristic diagram accordingly is limited by the limit performance characteristic line of the control target. It will always be located within the range without departing from it. It should be noted that, although it is a stumbling block, with respect to the scaling law for α, the time dimension such as T _P is the α multiplication rule, the velocity dimension is the α times multiplication rule, and the acceleration and current dimensions are the square of α. Obey the 1x rule of.

Then, in step S5, the control signal related to the acceleration / deceleration pattern is sent to the controlled object as it is or through the low-pass filter 6.

In the actual control operation of the servo control device 1, steps S1 and S2 and part of step S3 are already determined at the design stage.
It should be noted that the motion control of the controlled object is performed by repeating steps S3 to S5 according to the command from the command means 2.

Further, in order to generate the scalable pattern in step S4, it is necessary to prepare various amounts including the standardizing function as a database in advance. For example, taking the acceleration / deceleration patterns shown in [Equation 44] and [Equation 45] as examples, the standardization function has a shape as shown in the upper part of FIG. 15, and T _aMAX , T _PMAX or T
_PMAX - _TaMAX , θ _NP ⁽¹⁾ (peak value of normalized speed) is required. Further, the calculation of the current effective value I _RMS is, theta _NRMS
⁽²⁾ (This is T _{PMIN in} the fourth equation of [Equation 21].
_Replaced by _PMAX . ), The moment of inertia J, the torque coefficient K _t, etc., are required. The expression of the normalized function (Equation 45] where reference.) Various amounts of contained (theta _c and T _m, etc.) is required of course. The acceleration / deceleration pattern generation means 3 in the servo control device 1 holds data relating to these amounts.

Based on the basic matters and the configuration described above, the explanation of the present article will be started.

FIG. 25 shows the acceleration Θ ⁽²⁾ on the horizontal axis and the speed Θ on the vertical axis when the control target is the motor system.
By taking ⁽¹⁾ , an example of the limit characteristic line ib and the rated characteristic line ia of the motor system is illustrated.

In the figure, the ratio between the rated value Θ ⁽²⁾ _a of the acceleration (that is, corresponding to the current ⁾ and the instantaneous value Θ ⁽²⁾ _b is 1: 3, which is an electric value that determines the temperature of the controlled object. As is clear from the formula [1], the dynamic power is proportional to the square of the motor current. Therefore, when the motor system is operated along the limit characteristic line ib and when the motor system is operated along the rated characteristic line ia. It can be seen that the former requires 9 times more power than the latter when operated.

That is, if the operation is in accordance with the rated characteristic line ia, continuous operation of the motor system is possible, but the limit characteristic line i
It is impossible to perform the continuous operation of the motor system by the operation according to b, and such an operation is allowed only in a short time.

By the way, when the controlled object is continuously operated, the Δθ-T _P characteristic may be defined so that the effective current value of the controlled object does not exceed the rated current value. In general, the operation and the non-operation are repeated.

For example, as shown in FIG. 26, when the motor system is repeatedly operated and stopped for each period T along the time axis t, the current value I during the operation period is a constant value (less than the rated current value). This is referred to as “I _o ”), and assuming that the current value in the inoperative period is I = 0, the effective current value I _RMS is as shown by the broken line. In this case, the period n
· T (n is a natural number.) Is the effective current value over the "I _RMS = I _o
-(N- [n / 2]) / n "(where [m] is a Gaussian symbol indicating a maximum integer that does not exceed m), and when viewed over a long period of time, _IRMS is almost equal to the current _Io . Half the value,
It can be seen that the operation is quite affordable.

Therefore, when the controlled object is operated including the inoperative period (generally, the operating period and the inactive period are rare, these periods are variable in length). In addition, if the controlled object can be operated more efficiently according to the length of the non-operation period, the effective current value _IRMS can be brought close to the rated current value. In other words, if the controlled object was resting for a certain period,
Since the effective current value over the period up to that point is low, the controlled object should be able to operate with a larger current during the next operation. However, the condition that such an operation must not exceed the limit performance of the controlled object is always imposed.

The above items are summarized as follows.

(A) Operations that deviate from the limit performance of the controlled object are prohibited.

(B) The effective current value of the controlled object accompanying the operation does not exceed the rated current value.

(C) When the effective current value of the controlled object has a margin, an operation for making the effective current value as close as possible to the rated current value within the range satisfying the condition (A) is realized. It is desirable to automatically generate the acceleration / deceleration pattern.

A method of determining the peak velocity arrival time T _P or the time axis expansion / contraction parameter α for satisfying the above matters will be described below. The definitions of various quantities used thereafter are shown in the table below.

[0237]

[Table 3]

Now, as shown in FIG. 27, the horizontal axis is set to the time axis t starting from the start time of the operation of the controlled object, and the vertical axis is set to the speed Θ ⁽¹⁾ (t) related to the acceleration / deceleration pattern. If so, the operation of the controlled object up to the present time t = T _TOT can be represented by some acceleration / deceleration curves as shown by the solid line. That is, each operation related to the controlled object is described by the scalable pattern generated corresponding to the limit performance of the controlled object as described above, and the operation and the non-operation are repeated many times in the figure ( Acceleration / deceleration curves a1, a2,
See ... ).

Acceleration / deceleration curve a'shown by a two-dot chain line in FIG.
Indicates an operation to be performed on the controlled object, and the acceleration / deceleration curve a ′ does not have a constant velocity part, and
Under the assumption that the acceleration part and the deceleration part have symmetry, the time required for the operation is 2 · T _P , and the time t = T _TOT +
The operation ends at 2 · T _P.

[0240] The effective acceleration at the present time is "Θ
_RMS ⁽²⁾ (T _TOT ) ”and the effective acceleration“ Θ _RMS ⁽²⁾ (T _TOT + 2 · T _P ) ”at the end of the next operation.

Effective acceleration Θ _RMS ⁽²⁾ shown in the following equation [Equation 55]
When the square value of Θ _RMS ⁽²⁾ (T _{TO T} + 2 · T _P ) is calculated based on the definition formula of, the following formula [Equation 56] is obtained.

[0242]

[Equation 55]

[0243]

[Equation 56]

However, “Θ _RMS ⁽²⁾ (2 ·
T _P ) ”is the effective acceleration for the next movement.

The condition (B) above is that when the acceleration corresponding to the rated current value of the controlled object is "Θ _R ⁽²⁾ ", the effective acceleration is "Θ _RMS ⁽²⁾ (T _TOT + 2 · T _P ). Is the square value of "Θ _R
⁽²⁾ ”is equal to or less than the squared value, and the following inequality is obtained from this.

[0246]

[Equation 57]

In the above equation, T _TOT is known by measuring how much time has elapsed from the starting point of the time axis t, and the effective acceleration “Θ
_The squared value of “ _RMS ⁽²⁾ (T _TOT )” is known by accumulating the calculated values of the effective accelerations related to the respective motions since the motions performed so far are known. Therefore, the effective acceleration “Θ _RMS ⁽²⁾ (2 ・
If the squared value of “T _P )” can be calculated in advance,
The peak speed arrival time T _P related to the acceleration / deceleration curve a ′ can be obtained.

That is, the acceleration / deceleration pattern relating to the next operation is nothing but a scaling pattern (see the formulas [17] to [19]) according to the limit performance of the controlled object, which is already familiar. Therefore, the effective acceleration can be calculated in advance from the acceleration / deceleration pattern as shown in the following equation.

[0249]

[Equation 58]

Therefore, the following expression [expression 59] is obtained from the expressions [expression 57] and [expression 58].

[0251]

[Equation 59]

The equation for the equal sign in the above equation is a quartic equation with respect to α as shown in the following equation.

[0253]

[Equation 60]

By solving this equation by a known method (Newton's method, iterative method, etc.), α satisfying the above conditions (B) and (C) can be defined.

In order to obtain an approximate value of α, instead of obtaining the exact solution of the equation [60], the time required for the next operation is 2.
It is sufficient to utilize that T _P is sufficiently smaller than the time T _TOT thus far. That is, the equation [60] is replaced by the following equation [61]
If it is transformed as follows, “2 · α · T _PMAX / T _{TOT ≈0} ”, then the following equation [Equation 62] is obtained.

[0256]

[Equation 61]

[0257]

(Equation 62)

Therefore, the inequality to be satisfied by α is as follows.

[0259]

[Equation 63]

When α in the above equation where the equal sign is satisfied is set as “α _RMS ”, the value of α _RMS is adopted, and thus the square value of the effective acceleration at the end of the operation corresponds to the rated current “θ _RMS ”. ⁽²⁾ It turns out that it becomes equal to _R ”. In addition, [Equation 6
When the denominator of the expression 3] becomes zero, a temporary stop time may be provided for the controlled object.

Therefore, the position function Θ relating to the final acceleration / deceleration pattern is given by the following equation by setting “α = α _RMS ” in the equation [17].

[0262]

[Equation 64]

Θ _RMS ⁽²⁾ (T
_TOT ) can be calculated based on the acceleration / deceleration pattern generated for each operation, but if the actual acceleration Θ _M ⁽²⁾ related to the controlled object can be known,
Since Θ _RMS ⁽²⁾ (T _{TO T} ) can be calculated using this, α _RMS can be obtained with high accuracy. Furthermore, if the actual current value I _M can be known, the value of α _RMS can be calculated from the following equation more practically and with high accuracy.

[0264]

[Equation 65]

"I _RMS " in the above equation is an effective current value related to the normalization function, and is as shown in the equation [24].

As described above, the condition (A) is satisfied by the generation of the scalable pattern considering the limit performance of the controlled object as described above, and the condition (B) is effective up to the present time. The sum of the squared value of the acceleration and the squared value of the effective acceleration relating to the next operation is satisfied by the inequality that is equal to or less than the squared value of the acceleration corresponding to the rated current value of the controlled object, and the equal sign of the inequality is satisfied. The time-axis expansion and contraction parameter α _RMS
Further, it becomes clear that the condition (C) is satisfied.

In the above description, it is assumed that the performance of the controlled object is not affected by the influence of the outside air temperature or the like. However, the performance of the actual controlled object is generally affected by the temperature or the outside air temperature. Is. In other words, the rated current value of the controlled object regulates the amount of heat generated, which causes the temperature of the controlled object to rise, and the sum of the temperature increase and the outside air temperature becomes the temperature of the controlled object and its capacity is increased. Because it affects.

For example, when the motor system is specified as the control target, the limit TN line D (C1) and the rated TN line E (C1) on the torque (T) -speed (N) diagram of FIG. ) Shows the characteristics when the temperature is C1, and when the temperature rises, C
When 2 (> C1), the limit TN line deteriorates as indicated by D (C2) and the rated TN line indicates E (C2).

As described above, in order to cope with the change in the characteristic due to the temperature, the temperature of the controlled object and the outside air temperature are constantly detected and generated in accordance with the detected temperature when the scalable pattern corresponding to the limit performance of the controlled object is generated. The limit characteristic line and the rated characteristic line may be specified and an acceleration / deceleration pattern corresponding to them may be generated.

Thus, the servo controller 1 according to the present invention.
The configuration of A is as shown in FIG. 29, and comprises command means 2, acceleration / deceleration pattern generation means 3, T _P and α value determination means 5A, effective value calculation means 8, and low-pass filter 6.
Since the means other than the T _P and α value determining means 5A and the effective value calculating means 8 have already been described, these will be mainly described below.

The effective value calculating means 8 is provided to calculate the effective value of the acceleration or current based on the acceleration related to the acceleration / deceleration pattern or the actual acceleration or current value from the servo system. That is, as described above, the square value of the effective acceleration “Θ _RMS ⁽²⁾ (T _TOT )” for the operation performed up to now is calculated, or the effective acceleration “Θ _RMS ^{(2 )} for the next operation is calculated.
(2 · T _P ) ”is calculated. For that purpose, the effective value calculating means 8 has a first effective value calculating section 8a as shown in the drawing.
And a second effective value calculation unit 8b.

The first effective value calculation unit 8a calculates the square value of the effective acceleration or the effective current for the operation to be performed, and the parameter α (the α value is undetermined at this point). The effective value (hereinafter, referred to as “first effective value”, Θ _RMS ⁽²⁾ (2 ^{) of the} acceleration / deceleration pattern assumed to be generated by the acceleration / deceleration pattern generation means 3 based on・ T _P ).)
Is calculated.

The second effective value calculating section 8b is for calculating the effective acceleration or the square value of the effective current for the operation performed up to the present time. For example, it is generated by the acceleration / deceleration pattern generating means 3 and the servo is generated. Based on the acceleration / deceleration pattern already sent to the system 7 directly or via the low-pass filter 6, or based on the information on the actual acceleration and current obtained by the detection means included in the servo system 7, the effective value (hereinafter, referred to as “the 2 rms value, Θ _RMS ⁽²⁾ (T _TOT )
Is equivalent to ) Is calculated.

The T _P and α value determining means 5A determines the α value based on the information indicating the effective value from the effective value calculating means 8. That is, the square of the first effective value and the second effective value of 2
A relational expression that the sum of the product and the power is equal to or almost equal to a predetermined value (corresponding to the rated current value of the controlled object)
See the equal sign in equation 3]. ) And the T _P value and α
The value is determined and sent to the acceleration / deceleration pattern generation means 3.

The acceleration / deceleration pattern generation means 3 is the command means 2
From the command value Δθ and T _P and the α value from the α value determining means 5A, an acceleration / deceleration pattern corrected by the α value is generated and sent to the servo system 7 directly or via the low-pass filter 6. To do.

By constructing a feedback system including the T _P and α value determining means 5A and the effective value calculating means 8, the acceleration / deceleration pattern relating to the operation control for bringing the effective current value close to the rated current value is automatically generated. Can be generated dynamically.

In order to generate an acceleration / deceleration pattern suitable for the characteristic line of the servo system 7 according to the outside air temperature or the like, the temperature detecting means 9 is provided to detect the temperature of the servo system 7 and its surroundings ( 29)), by sending the detection information to the acceleration / deceleration pattern generation means 3, it is possible to generate an acceleration / deceleration pattern corresponding to the limit characteristic line of the controlled object having the temperature characteristic.

The procedure of the servo control method according to the present invention can be summarized as shown in FIG. First, step Sa
After the limit performance of the control target is specified in, the shape of the acceleration / deceleration curve is determined based on the limit characteristic line of the control target in the next step Sb. When the influence of the outside air temperature or the like is taken into consideration, the shape of the acceleration / deceleration curve is determined based on the limit characteristic line of the controlled object according to the temperature change.

Then, in step Sc, based on the first effective value relating to the operation to be performed, the acceleration / deceleration curve from the acceleration / deceleration pattern generating means 3, or the actual current or acceleration sent from the controlled object. The second effective value for the operation up to the present time is calculated based on

In the next step Sd, the relation that the sum of the square value of the first effective value and the square value of the second effective value is equal to or substantially equal to the rated current of the controlled object or a predetermined value corresponding thereto. Α is defined by dividing T _P (peak speed arrival time) related to the acceleration / deceleration curve and the T _P value by its reference value (T _P value related to normalized speed) based on the equation.
The value of (parameter for time axis expansion / contraction) is determined.

Then, in the next step Se, a scaling operation based on Δθ or α is performed on the standardization function to generate a desired acceleration / deceleration pattern, and step Sf
The control signal according to the acceleration / deceleration pattern is sent to the control target as it is or through the low-pass filter 6. It should be noted that the point to be noted here is that the controlled object needs to satisfy the condition that the current consumption in the inactive period is zero or very small. This is because the large current consumption during the non-operation period means that the control target consumes electrical power regardless of the non-operation period. This is the same as the above, which is not in line with the gist of the present invention focused on the effective current (or acceleration).

[0282]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example in which the present invention is applied to a robot controller will be described below with reference to FIGS. 31 and 32.

FIG. 31 schematically shows a main part of the hardware configuration of the robot controller 10.

The robot controller 10 has a CPU (central processing unit) 11 as a core, and a storage unit 13 directly or indirectly connected to a bus 12 thereof.

In the storage unit 13, for example, a robot program relating to the description of the operation procedure of the robot, a system program relating to the description of the robot system (for example, the description such as coordinate conversion for determining the movement of each axis of the robot), and the like. Will be remembered.

The servo units 14, 14, ... Are independent for each drive axis forming the robot 15,
It is provided to control an actuator (motor, cylinder, etc.) that drives the axis of the robot 15 in accordance with a command issued from 11. The teaching pendant 16 according to the operation instruction of the robot 15 is a T.P. P. (Abbreviation of teaching pendant) It is connected to the bus 12 via an interface 17.

FIG. 32 shows a horizontal multi-joint type robot having four axes as an example of the configuration of the robot 15 to be controlled.

That is, the robot 15 is provided with a base shaft portion 18, a first arm 19 and a second arm 20, and the first arm 1
9 is attached to the base shaft portion 18 in a state in which one end portion of 9 can rotate. Then, one end of the second arm 20 is rotatably attached to the other end of the first arm 19, and a tool mounting shaft 21 is provided to the other end of the second arm 20. .

A motor 22 for rotating the first arm 19 is provided on the base shaft portion 18, and the driving force of the motor 22 is transmitted via the harmonic speed reducer 23 to the first arm 1.
It is adapted to be transmitted as the turning force of 9.

The first arm 19 is provided with a mechanism for rotating the second arm 20. That is, the motor 25 and the harmonic reducer 26 are attached to the support portion 24 fixed to one end of the first arm 19, and the pulley 27 is attached to the output shaft of the harmonic reducer 26. The pulley 28 forming a pair with the pulley 27 is the second
The pulley 2 is fixed to the rotary shaft 20a of the arm 20.
A belt 29 is stretched between 7 and the pulley 28. That is, the driving force of the motor 25 becomes the rotational force of the pulley 27 via the harmonic speed reducer 26, and this is transmitted to the pulley 27 by the belt 29 and becomes the rotational force of the second arm 18.

The tool mounting shaft 21 is slid in the vertical direction by an actuator 30 provided on the upper surface of the rotating end of the second arm 20, and at the end of the second arm 20 near the rotating shaft 20a. The rotational force of the provided motor 31 is transmitted to the tool mounting shaft 21 by a belt or the like, whereby the motor 31 is rotated around the shaft. And
A tool mounting portion 32 is fixed to the lower end of the tool mounting shaft 21 so that an effector such as a hand or a tool can be attached.

[0292] As described above, the robot 15, the rotary shaft of the first arm 19 (theta ₁ axis), pivot axis of the second arm 20 (theta _2-axis), the rotary shaft of the tool mounting portion 32 (R.theta Shafts and sliding shafts (Rz axes) as drive shafts, and are configured by servo systems related to each.

Therefore, when applied to the robot controller 10, it is necessary to construct the configuration of the servo controller 1A shown in FIG. 29 for each drive axis of the robot. That is,
It can be considered that the servo system 7 shown in FIG. 22 corresponds to one of the drive axes of the robot, and the servo control means for controlling the robot is functionally the CPU 11, the storage unit 13, the servo unit 14, the teaching pendant 16 and the like. It is realized by combining.

However, in the case of a multi-axis configuration such as the robot 15, PTP (Point Toe) for each drive axis is used.
Point) The maximum value of the α values of the drive axes is selected in consideration of the necessity of synchronizing the start and stop of the operation. That is, the robot is composed of M drive axes, and the α value associated with the i-th (i = 1, 2, ..., M) drive axis is “α _i ” (i = 1, 2, ...
M), α _i is represented by the following formula [Formula 66], and therefore the α value common to all drive axes (this is referred to as “α _RMS ”) is represented by the following formula [Formula 67]. Just decide.

[0295]

[Equation 66]

[0296]

[Equation 67]

The function max (X1, X2, ...
..) is a function for extracting the maximum value of the variables X1, X2, ...

In this case, the position function (eg, phase angle in the case of a motor) of the acceleration / deceleration pattern related to the i-th drive shaft is set to "Θ _i " (i = 1, 2, ..., M). , Their normalization function is “θ _Ni ” (i = 1, 2, ..., M)
Then, the following formula will be obtained.

[0299]

[Equation 68]

The standardizing function is generally different for each drive axis, but if the standardizing function for each drive axis can be unified into one function, the device configuration is It will be easy. This is because, in this case, the standardization functions for each drive axis are in a proportional relationship with each other, and the acceleration / deceleration pattern for all drive axes can be generated by the scaling operation for one standardization function.

However, since the relationship between Δθ and T _P generally differs for each drive axis, such a robot has the largest value of α _RMSi · T _PMAXi for each drive axis, as shown in the following equation. Just choose one.

[0302]

[Equation 69]

Therefore, when the servo control device according to the present invention is applied to a robot control device, each servo control device according to the acceleration / deceleration pattern that does not deviate from the limit performance of the servo system related to each drive axis forming the robot is used. Not only the drive axes can be controlled, but also a robot operation without waste can be realized by generating an acceleration / deceleration pattern for making the effective values of acceleration and current related to the operation control of each drive axis close to the rated current value. .

That is, when the robot is performing work by repeating the operation and the stop, the stop period of the robot is the rest time of the robot, and the amount of the rest of the robot during the period is equivalent to the rest period of the robot. Since there is a margin, the robot can be made to perform a slightly tight movement in terms of its power at the next movement. In this way, by regaining the amount of work that is about to be lost due to the stoppage period of the robot during the operation period of the robot,
Looking at the effective current value of the robot per day, this value is close to the rated current value, and therefore, the amount of work per day of the robot increases.

[0305]

As is apparent from the above description, according to the inventions of claims 1 and 2, it is possible to generate an acceleration / deceleration pattern without deviating from the limit performance of the controlled object. , This guarantees the performance and quality of the controlled object, and by making the effective current value related to the controlled object close to the rated current value of the controlled object, the controlled object can be utilized to its full capacity. It is no longer necessary to select the one with more performance than necessary. Then, based on the conditional expression that the sum of the second effective value related to the operation up to the present time and the first effective value related to the future operation is substantially equal to the rated current value of the control target or a value corresponding to it, Since the value of the peak velocity arrival time related to the acceleration / deceleration curve is determined, the determination algorithm is clarified, and the experiment or the like for determining the peak velocity arrival time is unnecessary.

Further, according to the inventions of claims 3 and 4,
It is possible to maximize the capacity of the servo system including the drive source and the drive circuit related to the arm and tool mounting part of the robot, increase the work amount of the robot for a long period of time, and improve the work efficiency and speed. Then, regardless of the structure of the robot, a unified control algorithm can be used for each servo system.

[Brief description of the drawings]

FIG. 1 is a schematic graph showing several examples of characteristic lines indicating a limit performance and a rated performance related to a motor system.

FIG. 2 is a diagram showing an example of an equivalent circuit of a servo motor.

FIG. 3 is a diagram showing several triangular acceleration / deceleration curves.

FIG. 4 is a diagram showing an effective value of mechanical power and an effective value of electrical power corresponding to the acceleration / deceleration curve of FIG.

FIG. 5 is a diagram showing Δθ-T _P characteristics in control in which the effective value of electric power is constant.

FIG. 6 is an explanatory diagram of a shape of normalized speed.

FIG. 7 is a graph showing a ramp signal.

FIG. 8 is an explanatory diagram of a scaling operation related to a normalized speed, where (a) performs only a scaling operation related to a function value, and (b) performs only a time-axis expansion operation with respect to the normalized speed. In the above case, (c) shows the case where the combined operation of (a) and (b) is performed.

FIG. 9 is a diagram for explaining a locus on a θ _N ⁽²⁾ −θ _N ⁽¹⁾ diagram related to a normalization function, and (a) is θ _N ⁽²⁾
-Θ _N ⁽¹⁾ diagram, (b) t-θ _N ⁽¹⁾ diagram, (c) t-
It is a θ _N ⁽²⁾ diagram.

FIG. 10 shows an example in which the functional relationship between θ _N ⁽²⁾ and θ _N ⁽¹⁾ is not univalent with respect to the trajectory on the θ _N ⁽²⁾ −θ _N ⁽¹⁾ diagram regarding the normalized function. It is a figure.

FIG. 11 is a diagram for explaining the relationship between the trajectory on the θ _N ⁽²⁾ −θ _N ⁽¹⁾ diagram regarding the normalization function and the scaling operation regarding the normalization speed, and (a) is a function value. When only the scaling operation related to is performed, (b) is a time axis extension operation with respect to the normalized speed, (c) is (a)
The respective cases where the operations of (1) and (b) are combined are shown.

[Figure 12] θ _N ⁽²⁾ relating to the normalized function - [theta] _N ⁽¹⁾ line and the area of the region surrounded by the trajectory in diagram, theta according to variable scaling pattern ^{(2) -Θ (1)} diagram It is a figure which also shows the area in the area | region enclosed by the above locus.

13A is a diagram for explaining a trajectory on a Θ ⁽²⁾ -Θ ⁽¹⁾ diagram relating to a controlled object, and FIG. 13B is an acceleration / deceleration defined by the trajectory of FIG. 13A. It is a graph figure for demonstrating a curve.

FIG. 14 is a Θ ⁽²⁾ -Θ ⁽¹⁾ diagram showing an example of a characteristic line showing the limit performance of the controlled object.

15 is a diagram for explaining an acceleration / deceleration pattern defined by the characteristic line of FIG.

16 is a Θ ⁽²⁾ -Θ ⁽¹⁾ diagram showing a characteristic line different from that in FIG. 14;

FIG. 17 is a Θ ⁽²⁾ -Θ ⁽¹⁾ diagram showing yet another characteristic line.

FIG. 18 is a diagram for explaining a correspondence relationship between an acceleration / deceleration curve and a locus on a Θ ⁽²⁾ −Θ ⁽¹⁾ diagram.

FIG. 19 is an explanatory diagram of a low pass filter method.

FIG. 20 shows Θ ⁽²⁾ − when the low-pass filter method is used.
FIG. 3 is a schematic diagram for explaining a trajectory on a Θ ⁽¹⁾ diagram.

FIG. 21 is an explanatory diagram of an inscribed method.

FIG. 22 is a block diagram showing a basic configuration of a servo control device according to the present invention.

FIG. 23 (a) shows an example of a Δθ-T _P diagram,
(B) shows an example of a Δθ-T _all diagram.

FIG. 24 is a flow chart diagram showing a basic processing flow of a servo control method according to the present invention.

FIG. 25 is a graph showing an example of a limit characteristic line and a rated characteristic line of a controlled object.

FIG. 26 is a diagram for explaining an effective current value when the control target repeats operation and non-operation.

FIG. 27 is a t-Θ ⁽¹⁾ diagram for explaining past operations and future operations related to the control target.

FIG. 28 is a graph showing an example of a limit characteristic line and a rated characteristic line of a controlled object caused by a temperature change.

FIG. 29 is a block diagram showing a configuration of a servo control device according to the present invention.

FIG. 30 is a flow chart diagram for explaining a servo control method according to the present invention.

31 shows an example of application to a robot controller together with FIG. 32, and this figure is a diagram showing an example of a hardware configuration of the robot controller.

[Fig. 32] Fig. 32 is a schematic side view showing a robot with a four-axis configuration by cutting out a part thereof.

FIG. 33 is a diagram showing a triangular acceleration / deceleration curve.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Servo control device 2 Command means 3 Acceleration / deceleration pattern generation means 5A Peak speed arrival time and time axis expansion / contraction parameter value determination means 8 Effective value calculation means 10 Robot control device 15 Robots 19, 20 Arms 32 Tool mounting part

Claims (4)

[Claims] 1. A servo control device for performing acceleration / deceleration control corresponding to a marginal performance of a controlled object, comprising a command means for issuing a command value for a servo control variable, and a first operation related to an operation to be performed. The effective current (or effective acceleration) is calculated based on the acceleration / deceleration curve related to the operation, and based on the acceleration / deceleration curve related to the operation already performed or based on the actual current or acceleration sent from the control target. An effective value calculating means for calculating the second effective current (or effective acceleration) relating to the operation up to the present time, and a square value of the first effective current (or effective acceleration) from the effective current (or effective acceleration) calculating means The acceleration / deceleration curve is set so that the sum of the squared value of the second effective current (or effective acceleration) is equal to or substantially equal to the rated current of the controlled object or a predetermined value corresponding thereto. The peak that determines the time until the velocity reaches the peak value (hereinafter referred to as "peak velocity arrival time") and the value of the time axis expansion / contraction parameter defined by dividing the peak velocity arrival time by the reference value. The speed arrival time and the parameter value for time axis expansion / contraction, the operating point defined by the acceleration (or force or torque) and the speed (or speed, angular velocity or rotation speed) is the acceleration (or force or torque) of the controlled object. ) Speed (or speed,
The shape of the acceleration / deceleration curve is specified under the condition that it is on the limit characteristic line on the characteristic diagram for the angular velocity or the number of revolutions), and the value of the peak velocity arrival time related to the reference function of the acceleration / deceleration curve is expanded / contracted on the time axis. As the reference value of the parameter for control, the acceleration / deceleration curve is generated by the expansion / contraction operation in the time axis direction for the reference function based on the parameter value for time axis expansion / contraction and the scaling operation for the reference function value based on the command value from the command means. And a acceleration / deceleration pattern generation means for transmitting the servo control device to the servo control device. 2. A servo control method for performing acceleration / deceleration control corresponding to the limit performance of a controlled object, wherein the speed (or speed, angular velocity or rotation) of acceleration (or force or torque) is first controlled for the controlled object. Number) is specified, the operating point defined by acceleration (or force or torque) and speed (or speed, angular velocity or rotation speed) is placed on the limit characteristic line related to the controlled object. The shape of the acceleration / deceleration curve, its reference function and the peak velocity arrival time related to the reference function are defined under the condition that the first effective current (or effective acceleration) related to the operation to be performed is It is calculated based on the acceleration / deceleration curve related to the motion, and based on the acceleration / deceleration curve related to the motion already performed or based on the actual current or acceleration sent from the control target. After calculating the second effective current (or effective acceleration) related to the operation up to the present time, the second effective current (or effective acceleration) squared value and the second effective current (or effective acceleration) are calculated.
The peak value arrival time and the peak speed arrival time of the acceleration / deceleration curve such that the sum of the effective current (or the effective acceleration) and the squared value becomes substantially equal to the rated current of the controlled object or a predetermined value corresponding thereto. Determine the value of the time axis extension / contraction parameter defined by dividing by the peak velocity arrival time of the reference function of the acceleration / deceleration curve, and based on the time axis extension / contraction parameter value, the extension / contraction operation in the time axis direction for the reference function is performed. Servo control characterized in that an acceleration / deceleration curve is generated by performing a scaling operation on the reference function value based on the specified value of the servo control variable and is sent as a control signal to the controlled object. Method. 3. A robot control device for controlling the operation of a robot, which comprises a plurality of arms and / or tool mounting parts and a plurality of servo systems including drive sources for the arms or tool mounting parts and their drive circuits, Servo control means for controlling each servo system issues a command value for a servo control variable and a first effective current (or effective acceleration) related to the operation to be performed, to the acceleration / deceleration related to the operation. The second effective current (or effective acceleration) related to the operation up to the present time based on the acceleration / deceleration curve related to the already performed operation or based on the actual current or acceleration sent from the controlled object, as well as based on the curve. And an effective value calculating means for calculating, and a square value of the first effective current (or effective acceleration) from the effective current (or effective acceleration) calculating means and the second value. The peak value arrival time and the peak speed arrival time related to the acceleration / deceleration curve are set so that the sum of the effective current (or the effective acceleration) and the square value becomes substantially equal to the rated current of the controlled object or a predetermined value corresponding thereto. Peak speed arrival time value determining means for determining the value of the time axis expansion / contraction parameter defined by dividing by the reference value, and is defined by acceleration (or force or torque) and speed (or speed, angular velocity or rotation speed) The operating point is the speed (or speed,) of the acceleration (or force or torque) to be controlled.
The shape of the acceleration / deceleration curve is defined under the condition that the acceleration / deceleration curve is on the limit characteristic line on the characteristic diagram for the angular velocity or the number of revolutions. As a reference value of, the acceleration / deceleration curve is generated and sent to the controlled object by the expansion / contraction operation in the time axis direction for the reference function based on the time axis expansion / contraction parameter value and the scaling operation for the reference function value based on the command value from the command means An acceleration / deceleration pattern generating means for controlling the robot. 4. A robot control method relating to motion control of a robot, comprising: a plurality of arms and / or tool mounting parts; and a plurality of servo systems including drive sources for the arms or tool mounting parts and drive circuits thereof, When controlling each servo system, first specify the limit characteristic line related to the speed (or speed, angular velocity or rotation speed) of acceleration (or force or torque) of the controlled object, and then accelerate (or force or torque) And the speed (or speed, angular velocity or number of revolutions), the operating point defined by the acceleration / deceleration curve shape, its reference function and the reference function The peak speed arrival time is defined, and the first effective current (or effective acceleration) related to the operation to be performed is calculated based on the acceleration / deceleration curve related to the operation. After calculating and calculating the second effective current (or effective acceleration) related to the operation up to the present time based on the acceleration / deceleration curve regarding the already performed operation or based on the actual current or acceleration sent from the controlled object , The square value of the first effective current (or effective acceleration) and the second value
The peak value arrival time and the peak speed arrival time of the acceleration / deceleration curve such that the sum of the effective current (or the effective acceleration) and the squared value becomes substantially equal to the rated current of the controlled object or a predetermined value corresponding thereto. Determine the value of the time axis extension / contraction parameter defined by dividing by the peak velocity arrival time of the reference function of the acceleration / deceleration curve, and based on the time axis extension / contraction parameter value, the extension / contraction operation in the time axis direction for the reference function is performed. Robot control characterized in that an acceleration / deceleration curve is generated by performing a scaling operation on the reference function value based on the specified value of the servo control variable and is sent as a control signal to the controlled object. Method.