JP2010209993A - Backlash removing control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To generate offset torque of an optimal value while positively preventing generation of backlash or lost motion. <P>SOLUTION: If an actual rotation deviation angle Δθ<SB>m</SB>being a rotation deviation angle between a first rotation angle θ<SB>1</SB>and a second rotation angle θ<SB>2</SB>during actual operation becomes small with respect to a set rotation deviation angle Δθ<SB>mo</SB>being a rotation deviation angle between the rotation angle θ<SB>1</SB>of a motor side gear G<SB>M1</SB>and the rotation angle θ<SB>2</SB>of a motor side gear G<SB>M2</SB>when there is no backlash, it is determined that backlash occurs, and an offset torque setting part 40 automatically increases a value of offset torque τ<SB>O</SB>output from an offset torque command value 31. By this, if an operating weight of a movable member is increased, the offset torque automatically becomes larger, and occurrence of backlash or lost motion is prevented. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a backlash removal control apparatus, which is configured to optimally set an offset torque value to prevent occurrence of backlash and lost motion without waste.

In a machine tool, the rotational force (driving force) of a motor is transmitted to a table and a main shaft, which are movable members, via a power transmission mechanism, and the movable member (table and main shaft) is moved.
When the movable member is heavy, such as a table, the movable member is driven via a speed reducer between the motor and the movable member. In the case of a feed mechanism, it is driven via a mechanism such as a ball screw or a rack and pinion.

Since a gear is incorporated in such a power transmission mechanism, backlash becomes a problem when performing accurate position control, and hence accurate machining.
That is, if backlash exists, it becomes difficult to drive the movable member stably with high positional accuracy, which adversely affects machining accuracy.

Furthermore, if backlash is present, when the acceleration of the movable member reverses, the meshing between the gear teeth on the input side (motor side) and the gear teeth on the output side (movable member side) changes, so the lost motion That is, a state occurs in which the input side gear teeth and the output side gear teeth are not engaged with each other during the period from when the engagement is released until the engagement is performed again.
While the lost motion is occurring, the torque of the motor is not transmitted to the movable member, so that an uncontrolled state occurs temporarily and the positioning accuracy deteriorates.

Here, the lost motion generated between the gear connected to the motor side and the gear connected to the movable member side (for example, a ball screw shaft coupled to the table) is described with reference to FIGS. explain. 6A to 6D show only a part of the teeth provided on the gear.
The gear connected to the motor side will be described as “motor side gear G _M ”, and the gear connected to the movable member side will be described as “movable member side gear G _L ”.

Lost motion by backlash, which in the moving direction of the movable member (acceleration) is inverted, occurs because the float with the teeth of the movable member side gear G _L, apart engagement with the teeth of the motor side gear G _M It is.

Figure 6A is in contact tooth surfaces of the motor side gear G _M and the tooth surface of the movable member side gear G _L is, by the motor side gear G _M is rotated in the clockwise direction, the movable member side gear G _L are anti A state of rotating clockwise is shown.

When the motor is decelerated, the movable member (e.g., a table) continues to move due to its own inertia, as shown in FIG. 6B, the engagement of the teeth of the movable member side gear G _L of the motor side gear G _M starts away.

Thereafter, as shown in FIG. 6C, although the motor side gear G _M in the rotating direction of the motor is inverted starts to rotate in the counterclockwise direction, the movable member side gear G _L movable member (e.g., a table) is stopped to stationary, the teeth of the motor side gear G _M and the teeth of the movable member side gear G _L becomes completely separated state, lost motion will occur.

It lost motion, as shown in FIG. 6D, until the teeth of the motor side gear G _M and the teeth of the movable member side gear G _L meshes again.

  In this way, lost motion occurs, which is the main cause of positioning error.

  In order to transmit power from the motor side gear to the movable member side gear while preventing the occurrence of backlash and lost motion as described above, conventionally, a configuration in which the movable member is driven by two motors has been adopted. However, a method for optimally controlling the driving of both motors has been developed.

Here, an example of such a prior art will be described with reference to FIG.
As shown in FIG. 7, in this example, the first motor side gear G _M1 and the second motor side gear G _M2 are engaged with the movable member side gear _GL connected to the movable member.

The first motor side gear G _M1 is connected to the first motor 11, and the motor side gear G _M1 rotates when the motor 11 rotates. The second motor side gear G _M2 is connected to the second motor 21, and the motor side gear G _M2 rotates when the motor 21 rotates.

Explaining the control system, the drive torque command unit 30 outputs a drive torque command τ _d , and the offset torque command unit 31 outputs an offset torque command τ _o .

The value (absolute value) of the drive torque command τ _d is a torque value necessary for moving the movable member via the movable gear _GL , and is set according to the machining program or the like. The polarity of the drive torque command τ _d may be positive or negative depending on the machining situation or the like.
The value of the offset torque command tau _o (absolute value) is set in consideration of the weight and friction of the movable member, the value of the offset torque command tau _o (absolute value), the driving torque command tau value of _d ( It is smaller than the absolute value. The polarity of this offset torque command τ _o is always positive.

When the drive torque command τ _d is input, the zero torque limiter 12 outputs the drive torque command τ _d only when the polarity is positive. When the driving torque command τ _d is input, the zero torque limiter 22 outputs the driving torque command τ _d only when the polarity is negative.

The adder 13 adds the offset torque command τ _o to the drive torque command τ _d output from the zero torque limiter 12 to obtain a total torque command τ _t1, and sends the total torque command τ _t1 to the servo amplifier 14.
The subtracting unit 23 subtracts the offset torque command τ _o from the drive torque command τ _d output from the zero torque limiter 22 to obtain a total torque command τ _{t 2,} and sends the total torque command τ _{t 2} to the servo amplifier 24.

The servo amplifier (current control unit) 14 supplies a current corresponding to the total torque command τ _t1 to the motor 11, and the motor 11 outputs a torque corresponding to the total torque command τ _t1 to rotate the motor side gear _GM1 . To drive.

The servo amplifier (current control unit) 24 supplies a current corresponding to the total torque command τ _t2 to the motor 21, and the motor 21 outputs a torque corresponding to the total torque command τ _t2 to rotate the motor side gear _GM2 . To drive.

The operation of the prior art having such a configuration will be described.
For example, the value of the driving torque command tau _d output from the driving torque command section 30 (absolute value) is a polar positive 10 (i.e. command value is +10 in the drive torque command tau _d), from the offset torque command section 31 The case where the value (absolute value) of the output offset torque command τ _o is 1 and the polarity is positive (that is, the command value of the offset torque command τ _o is +1) will be described.

In this example, the drive torque command τ _d output from the drive torque command unit 30 passes through the zero torque limiter 12 and is output from the zero torque limiter 12, but is blocked by the zero torque limiter 22 and zeroed. It is not output from the torque limiter 22.

The adder 13 adds the drive torque command τ _d having a command value of +10 and the offset torque command τ _o having a command value of +1, and outputs a total torque command τ _t1 having a command value of +11.
The servo amplifier (current control unit) 14 supplies a current corresponding to the total torque command τ _t1 to the motor 11, and the motor 11 rotates in the positive rotation direction (clockwise) according to the total torque command τ _t1 whose command value is +11. Direction) to output a torque corresponding to “11”, rotationally drive the motor side gear _GM1 in the forward rotation direction (clockwise direction), and move the movable side gear _GL in the negative rotation direction (counterclockwise direction). Rotating drive.

The subtracting unit 23 subtracts the offset torque command τ _o having a command value of +1 from the drive torque command τ _d having a command value of 0, and outputs a total torque command τ _t2 having a command value of −1.
The servo amplifier (current control unit) 24 supplies a current corresponding to the total torque command τ _t2 to the motor 21, and the motor 21 responds to the total torque command τ _t2 whose command value is −1 in the negative rotation direction (reverse direction). The torque corresponding to “1” is output in the clockwise direction), the torque in the negative rotation direction (counterclockwise direction) is applied to the motor side gear _GM2, and the positive rotation direction (clockwise rotation) is applied to the movable side gear _GL. Direction) torque. This torque becomes the preload torque (offset torque).

As a result, a torque corresponding to “11” acts on the movable member side gear _GL in the negative rotation direction (counterclockwise direction), and a torque corresponding to “1” in the positive rotation direction (clockwise direction). Works. For this reason, the movable member side gear _GL rotates with a torque corresponding to “10” along the negative rotation direction (counterclockwise direction).

The difference between the torque in the negative rotation direction (counterclockwise direction) and the torque in the positive rotation direction (clockwise direction) is an internal force having a value of “1” (ie, offset torque). This internal force “1” meshes the teeth of the motor side gear _{GM1 and} the teeth of the movable member side gear _GL , and also meshes the teeth of the motor side gear _{GM2 and} the teeth of the movable member side gear _GL. It demonstrates the function of preventing the occurrence of backlash and lost motion.

Further, for example, the value (absolute value) of the drive torque command τ _d output from the drive torque command unit 30 is 10 and the polarity is negative (that is, the command value of the drive torque command τ _d is −10), and the offset torque command When the value (absolute value) of the offset torque command τ _o output from the unit 31 is 1 and the polarity is positive (that is, the command value of the offset torque command τ _o is +1), the adding unit 13 determines that the command value is The +1 total torque command τ _t1 is output, and the subtracting unit 23 outputs the total torque command τ _t2 having a command value of -11.

Therefore, the motor 11 outputs a torque corresponding to “1” in the forward rotation direction (clockwise direction) in response to the total torque command τ _t1 having a command value of +1, and the motor 21 has a command value of −11. depending on the overall torque command tau _t2, and outputs the torque corresponding to "11" in the negative direction of rotation (counterclockwise direction).

As a result, the torque corresponding to “1” acts on the movable member side gear _GL in the negative rotation direction (counterclockwise direction) and the torque corresponding to “11” in the positive rotation direction (clockwise direction). Acting, the movable member side gear _GL rotates with a torque corresponding to “10” along the forward rotation direction (clockwise direction).

The difference between the torque in the negative rotation direction (counterclockwise direction) and the torque in the positive rotation direction (clockwise direction) is an internal force having a value of “1” (ie, offset torque). This internal force “1” meshes the teeth of the motor side gear _{GM1 and} the teeth of the movable member side gear _GL , and also meshes the teeth of the motor side gear _{GM2 and} the teeth of the movable member side gear _GL. It demonstrates the function of preventing the occurrence of backlash and lost motion.

JP-A-4-109890

Incidentally, the prior art as shown in FIG. 7 has the following problems.
That is, the offset torque (preload torque) is an internal force as described above, and is not a torque for moving the movable member, and even when the acceleration of the movable member is reversed, the offset of the tooth of the movable member side gear _GL This is for ensuring the meshing state with the teeth of the motor side gears G _M1 and G _M2 and preventing the occurrence of backlash and lost motion.
Therefore, the offset torque is ideally a little larger than the Coulomb friction force generated when the movable member is moved, and may be of a magnitude that allows the movable member to move slightly with only the offset torque.

However, since the weight of the movable member and the Coulomb friction force change depending on the state, the value of the offset torque command τ _o is set so that the actually generated offset torque value is larger than the ideal value described above. Based on experience, it was set slightly larger.
Thus because it was slightly larger set the value of the offset torque command tau _o, it has been a waste of internal force increases and the energy which the motor 11 and 21 is generated.
Further, since the value of the offset torque command τ _o was set based on experience, the value could not be set clearly.

Conventionally, when the value of the offset torque command τ _o is set, the value is fixed. On the other hand, the weight and frictional force of the movable member may fluctuate (increase) depending on the use situation.
For example, when the movable member is a table, the substantial weight of the table is the weight of the table itself plus the weight of the work placed on the table. In this case, the substantial weight of the movable member increases.
When such a substantial weight of the movable member is increased, in accordance with the offset torque offset torque command tau _o the value is fixed, the lack of offset torque, the lost motion can not be sufficiently removed backlash May occur.

  An object of the present invention is to provide a backlash removal control device that can optimally set the value of an offset torque command while reliably preventing the occurrence of backlash and lost motion in view of the above-described conventional technology. To do.

The configuration of the present invention for solving the above problems is as follows.
A movable member side gear connected to the movable member;
A first motor side gear that meshes with the movable member side gear and is driven to rotate by a first motor;
A second motor side gear that meshes with the movable member side gear and is rotationally driven by a second motor;
A first zero torque limiter that passes a drive torque command having a positive polarity but blocks a drive torque command having a negative polarity;
A second zero torque limiter that passes a drive torque command having a negative polarity but blocks a drive torque command having a positive polarity;
An offset torque command unit that outputs an offset torque command in which an initial set torque value (T ₀ ) is preset as an offset torque value (T) and the offset torque value (T) can be updated before actual operation. When,
Torque is generated according to the value of the total torque command obtained by adding the offset torque command to the drive torque command that has passed through the first zero torque limiter, and the rotation direction is in accordance with the polarity of the total torque command. A first current controller for supplying a current to the first motor,
Torque is generated according to the value of the total torque command obtained by subtracting the offset torque command from the drive torque command that has passed through the second zero torque limiter, and the rotational direction is in accordance with the polarity of the total torque command. A second current controller for supplying a current to the second motor,
In a backlash removal control device having
A rotation angle detecting means for detecting a first rotation angle (θ ₁ ) that is the rotation angle of the first motor side gear and a second rotation angle (θ ₂ ) that is the rotation angle of the second motor side gear;
A preset rotation deviation angle (Δθ _mo ), which is a rotation deviation angle between the _first rotation angle (θ ₁ ) and the second rotation angle (θ ₂ ) when no backlash occurs, is preset, and An actual rotation deviation angle (Δθ _m ) that is a rotation deviation angle between the first rotation angle (θ ₁ ) and the second rotation angle (θ ₂ ) during actual operation is calculated, and further an offset torque value (T) to the calculated actual rotational difference angle ([Delta] [theta] _m) and the set rotational deviation angle ([Delta] [theta] _mo) and updates the torque value by adding a value corresponding to the difference (T _K), updating the torque value (T _K) is An offset torque value setting unit that resets the updated torque value (T _K ) at that time as the offset torque value (T) after that time when the offset torque value (T) at that time becomes larger It is characterized by that.

The configuration of the present invention is as follows.
A movable member side gear connected to the movable member;
A first motor side gear that meshes with the movable member side gear and is driven to rotate by a first motor;
A second motor side gear that meshes with the movable member side gear and is rotationally driven by a second motor;
A first zero torque limiter that passes a drive torque command having a positive polarity but blocks a drive torque command having a negative polarity;
A second zero torque limiter that passes a drive torque command having a negative polarity but blocks a drive torque command having a positive polarity;
An offset torque command unit that outputs an offset torque command in which the offset torque value (T) can be updated;
Torque is generated according to the value of the total torque command obtained by adding the offset torque command to the drive torque command that has passed through the first zero torque limiter, and the rotation direction is in accordance with the polarity of the total torque command. A first current controller for supplying a current to the first motor,
Torque is generated according to the value of the total torque command obtained by subtracting the offset torque command from the drive torque command that has passed through the second zero torque limiter, and the rotational direction is in accordance with the polarity of the total torque command. A second current controller for supplying a current to the second motor,
In a backlash removal control device having
A rotation angle detecting means for detecting a first rotation angle (θ ₁ ) that is the rotation angle of the first motor side gear and a second rotation angle (θ ₂ ) that is the rotation angle of the second motor side gear;
Together with the first rotation angle (theta ₁₎ and the second rotation angle (theta ₂₎ and the rotation deviation is the angle setting rotational deviation angle ([Delta] [theta] _mo) is preset when a backlash does not occur, An actual rotation deviation angle (Δθ _m ) that is a rotation deviation angle between the first rotation angle (θ ₁ ) and the second rotation angle (θ ₂ ) during actual operation is calculated, and the actual rotation deviation angle ( An updated torque value (T _K ) having a value corresponding to the difference between Δθ _m ) and the set rotation deviation angle (Δθ _mo ) is calculated, and the updated torque value (T _K ) is the offset torque value (T) at that time. The offset torque value setting unit resets the updated torque value (T _K ) at that time as the offset torque value (T) after that time.

The configuration of the present invention is as follows.
A movable member side gear connected to the movable member;
A first motor side gear that meshes with the movable member side gear and is driven to rotate by a first motor;
A second motor side gear that meshes with the movable member side gear and is rotationally driven by a second motor;
A first zero torque limiter that passes a drive torque command having a positive polarity but blocks a drive torque command having a negative polarity;
A second zero torque limiter that passes a drive torque command having a negative polarity but blocks a drive torque command having a positive polarity;
An offset torque command unit that outputs an offset torque command in which the offset torque value (T) can be updated;
Torque is generated according to the value of the total torque command obtained by adding the offset torque command to the drive torque command that has passed through the first zero torque limiter, and the rotation direction is in accordance with the polarity of the total torque command. A first current controller for supplying a current to the first motor,
Torque is generated according to the value of the total torque command obtained by subtracting the offset torque command from the drive torque command that has passed through the second zero torque limiter, and the rotational direction is in accordance with the polarity of the total torque command. A second current controller for supplying a current to the second motor,
In a backlash removal control device having
A rotation angle detecting means for detecting a first rotation angle (θ ₁ ) that is the rotation angle of the first motor side gear and a second rotation angle (θ ₂ ) that is the rotation angle of the second motor side gear;
The first offset torque value (T ₁ ) generated by the first motor is estimated and calculated based on the motor current value (i ₁ ) flowing through the first motor and the first rotation angle (θ ₁ ). An offset torque value estimation unit;
Motor current value to be supplied to the second motor (i ₂₎ and the second rotation angle (theta ₂₎ a second offset torque value second motor is generated based on (T ₂₎ the second for estimating An offset torque value estimation unit;
The first offset torque value (T ₁ ) is compared with the _second offset torque value (T ₂ ), and the first offset torque value (T ₁ ) and the second offset torque value (T ₂ ) are different. An offset torque value setting unit that resets a value obtained by adding a predetermined additional torque value (ΔT) to the offset torque value (T) at that time as an offset torque value (T) after that time. It is characterized by that.

According to the present invention, when the substantial weight of the movable member increases and the offset torque becomes insufficient, the offset torque can be automatically increased, the optimum offset torque can be reset, and excessively There is no waste without setting a large offset torque.
Further, the value of the offset torque command can be set to an optimum value of the offset torque command without calculating and empirically setting the value of the offset torque command.
In the end, the value of the offset torque can be set optimally, and the occurrence of backlash and lost motion can be reliably prevented without waste.

The block diagram which shows the backlash removal control apparatus which concerns on Example 1 of this invention. The characteristic view which shows the relationship between the rotation angle of a motor side gear, and the rotation angle of a movable member side gear. The state diagram which shows the relationship between the rotation angle of a motor side gear, and the rotation angle of a movable member side gear. The state diagram which shows the relationship between the rotation angle of a motor side gear, and the rotation angle of a movable member side gear. The state diagram which shows the relationship between the rotation angle of a motor side gear, and the rotation angle of a movable member side gear. The state diagram which shows the relationship between the rotation angle of a motor side gear, and the rotation angle of a movable member side gear. The block diagram which shows the backlash removal control apparatus which concerns on Example 2 of this invention. The block diagram which shows the backlash removal control apparatus which concerns on Example 3 of this invention. Explanatory drawing which shows the generation | occurrence | production state of a lost motion. Explanatory drawing which shows the generation | occurrence | production state of a lost motion. Explanatory drawing which shows the generation | occurrence | production state of a lost motion. Explanatory drawing which shows the generation | occurrence | production state of a lost motion. The block diagram which shows the conventional backlash removal control apparatus.

  Hereinafter, the form for implementing this invention is demonstrated in detail based on an Example.

  A backlash removal control apparatus according to a first embodiment of the present invention will be described with reference to FIG. Note that parts having the same functions as those of the prior art shown in FIG.

<Configuration>
As shown in FIG. 1, the encoder 11 a is built in the motor 11, and the encoder 11 a outputs a rotation angle θ ₁ that indicates the rotation angle of the rotating portion of the motor 11. Since the rotating portion of the motor 11 is connected to the motor side gear G _M1 , the rotation angle θ ₁ also indicates the rotation angle of the motor side gear G _M1 .
The motor 21 has a built-in encoder 21 a, and the encoder 21 a outputs a rotation angle θ ₂ that indicates the rotation angle of the rotating portion of the motor 21. Since the rotating part of the motor 21 is connected to the motor side gear G _M2 , the rotation angle θ ₂ also indicates the rotation angle of the motor side gear G _M2 .

Here, the rotation angle θ ₁ indicating the rotation angle of the motor side gear G _M1, the rotation angle θ ₂ indicating the rotation angle of the motor side gear G _M2 , and the rotation angle θ _L indicating the rotation angle of the movable member side gear G _L. The relationship will be described first with reference to FIGS. 2 and 3A-3D.
3A to 3D are schematic views showing the gears developed linearly.

In FIG. 2, the vertical axis represents the rotation angle, and the horizontal axis represents time.
Definitive when set to a predetermined reference rotation angle rotation angle of the movable member side gear G _L, the rotation angle theta _L of the movable member side gear G _L, is defined as 0 ° of the rotation angle theta _L.
Definitive when setting the motor side gear G _M1 as backlash is most larger rotational angle relative to the teeth of the movable member side gear G _L set at the reference rotation angle, the rotation angle theta ₁ of the motor side gear G _M1 Is 0 ° of the rotation angle θ ₁ .
The rotation angle θ ₂ of the motor-side gear G _M2 when the motor-side gear G _M2 is set so that the backlash becomes the maximum rotation angle with respect to the teeth of the movable member-side gear _GL set at the reference rotation angle. Is 0 ° of the rotation angle θ ₂ .
The rotation angle θ _L is positive in the counterclockwise direction, and the rotation angle θ ₁ and rotation angle θ ₂ are positive in the clockwise direction.
FIG. 3A shows a state where the rotation angle θ _L , the rotation angle θ ₁ , and the rotation angle θ ₂ are all 0 °.

At time t0 in FIG. 2, the rotation of the movable member side gear G _L , the motor side gear G _M1, and the motor side gear G _M2 so that the rotation angle θ _L , the rotation angle θ ₁ , and the rotation angle θ ₂ are all 0 °. The position is set (see FIG. 3A).

From this state, for example, by driving the motor 11, the motor side gear G _M1 is rotated in the forward rotation direction with a torque corresponding to “11” (moved to the left in FIG. 3A), and by driving the motor 21, the motor side gear G _M2 Is rotated in the negative rotation direction with a torque corresponding to “1” (moved to the right in FIG. 3A), the rotation angle θ _L remains 0 ° from time t0 to time t1, and the rotation angle θ ₁ increases in the positive direction, and the rotation angle θ ₂ increases in the negative direction.

Then, at time t1, with teeth meshing of the movable member side gear G _L teeth and the motor side gear G _M1, the teeth of the motor side gear G _M2 of the movable member side gear G _L meshes.
FIG. 3B shows the state at this time.

From time t1 to time t2, when the movable member side gear G _L is rotated with a torque corresponding to “10”, the movable member side gear G _L and the motor side gears G _M1 and G _M2 are generated without backlash. Rotate while meshing with each other, the rotation angle θ _L , the rotation angle θ ₁ , and the rotation angle θ ₂ increase at the same rate.
At this time, the rotation deviation angle between the rotation angle θ ₁ and the rotation angle θ ₂ is a constant angle, and the rotation deviation angle when the backlash does not occur is set as the set rotation deviation angle Δθ _mo (FIG. 3C). reference).

When backlash occurs when rotating the movable member side gear _GL from the time t2 to the time t3, the increasing rate of the rotation angle θ ₁ and the rotation angle θ ₂ varies.
At this time, the actual rotation deviation angle Δθ _m that is the rotation deviation angle between the rotation angle θ ₁ and the rotation angle θ ₂ becomes smaller than the set rotation deviation angle Δθ _mo due to the occurrence of backlash (see FIG. 3D).

Therefore, the actual rotation deviation angle Δθ _m that is the rotation deviation angle between the rotation angle θ ₁ and the rotation angle θ ₂ is detected over time, and the actual rotation deviation angle Δθ _m becomes smaller than the set rotation deviation angle Δθ _mo. Then, it can be determined that a backlash has occurred.
In the present embodiment, the offset torque value is defined based on such knowledge.

The offset torque value setting unit 40 sets and updates the value of the offset torque command τ _o (offset torque value T) output from the offset torque command unit 31.
A method for setting the offset torque value T by the offset torque value setting unit 40 will be described later.

<Backlash removal operation>
Of the operations of the present embodiment having such a configuration, the backlash removal operation will be described first.

For example, the value (absolute value) of the drive torque command τ _d output from the drive torque command unit 30 is 10 and the polarity is positive (that is, the command value of the drive torque command τ _d is +10). The case where the value (absolute value) of the output offset torque command τ _o is 1 and the polarity is positive (that is, the command value of the offset torque command τ _o is +1) will be described.

In this example, the drive torque command τ _d output from the drive torque command unit 30 passes through the zero torque limiter 12 and is output from the zero torque limiter 12, but is blocked by the zero torque limiter 22 and zeroed. It is not output from the torque limiter 22.

Addition unit 13, a drive torque command tau _d command value is +10, command value by adding the offset torque command tau _o +1, command value to output the total torque command tau _t1 of +11.
The servo amplifier (current control unit) 14 supplies a current corresponding to the total torque command τ _t1 to the motor 11, and the motor 11 rotates in the positive rotation direction (clockwise) according to the total torque command τ _t1 whose command value is +11. Direction) to output a torque corresponding to “11”, rotationally drive the motor side gear _GM1 in the forward rotation direction (clockwise direction), and move the movable member side gear _GL in the negative rotation direction (counterclockwise direction). To rotate.

The subtracting unit 23 subtracts the offset torque command τ _o having a command value of +1 from the drive torque command τ _d having a command value of 0, and outputs a total torque command τ _t2 having a command value of −1.
The servo amplifier (current control unit) 24 supplies a current corresponding to the total torque command τ _t2 to the motor 21, and the motor 21 responds to the total torque command τ _t2 whose command value is −1 in the negative rotation direction (reverse direction). The torque corresponding to “1” is output in the clockwise direction), the torque in the negative rotation direction (counterclockwise direction) is applied to the motor side gear _GM2, and the positive rotation direction (clockwise) is applied to the movable member side gear _GL. (Turning direction) torque is applied. This torque becomes the preload torque (offset torque).

As a result, a torque corresponding to “11” acts on the movable member side gear _GL in the negative rotation direction (counterclockwise direction), and a torque corresponding to “1” in the positive rotation direction (clockwise direction). Works. For this reason, the movable member side gear _GL rotates with a torque corresponding to “10” along the negative rotation direction (counterclockwise direction).

The difference between the torque in the negative rotation direction (counterclockwise direction) and the torque in the positive rotation direction (clockwise direction) is an internal force having a value of “1”. This internal force “1” meshes the teeth of the motor side gear _{GM1 and} the teeth of the movable member side gear _GL , and also meshes the teeth of the motor side gear _{GM2 and} the teeth of the movable member side gear _GL. It demonstrates the function of preventing the occurrence of backlash and lost motion.

Further, for example, the value (absolute value) of the drive torque command τ _d output from the drive torque command unit 30 is 10 and the polarity is negative (that is, the command value of the drive torque command τ _d is −10), and the offset torque command When the value (absolute value) of the offset torque command τ _o output from the unit 31 is 1 and the polarity is positive (that is, the command value of the offset torque command τ _o is +1), the adding unit 13 determines that the command value is The +1 total torque command τ _t1 is output, and the subtracting unit 23 outputs the total torque command τ _t2 having a command value of -11.

Therefore, the motor 11 outputs a torque corresponding to “1” in the forward rotation direction (clockwise direction) in response to the total torque command τ _t1 having a command value of +1, and the motor 21 has a command value of −11. depending on the overall torque command tau _t2, and outputs the torque corresponding to "11" in the negative direction of rotation (counterclockwise direction).

As a result, the torque corresponding to “1” acts on the movable member side gear _GL in the negative rotation direction (counterclockwise direction) and the torque corresponding to “11” in the positive rotation direction (clockwise direction). Acting, the movable member side gear _GL rotates with a torque corresponding to “10” along the forward rotation direction (clockwise direction).

The difference between the torque in the negative rotation direction (counterclockwise direction) and the torque in the positive rotation direction (clockwise direction) is an internal force having a value of “1”. This internal force “1” meshes the teeth of the motor side gear _{GM1 and} the teeth of the movable member side gear _GL , and also meshes the teeth of the motor side gear _{GM2 and} the teeth of the movable member side gear _GL. It demonstrates the function of preventing the occurrence of backlash and lost motion.

<Offset torque value setting / updating operation>
Next, an operation of setting / updating the offset torque value T of the offset torque command τ _o output from the offset torque command unit 31 by the offset torque value setting unit 40 will be described.

The offset torque value setting unit 40 sets an initial set torque value To as the offset torque value T of the offset torque command τ _o before the backlash removal control device is first operated. For example, the initial set torque value To is set to “+1”.
The initial set torque value To is, for example, slightly larger than the Coulomb friction force generated when the movable member is moved, and is set to such a magnitude that the movable member slightly moves with only the offset torque.
The offset torque value T is updated according to the situation as will be described later.

The offset torque value setting unit 40 is preset with a set rotation deviation angle Δθ _mo .
Setting the rotational deviation angle [Delta] [theta] _mo, as described above, definitive when backlash occurs without movable member side gear G _L and the motor side gear G _M1, G _M2 is rotating while meshing, the motor side gear G _M1 This is a rotation deviation angle between the rotation angle θ ₁ and the rotation angle θ ₂ of the motor side gear _GM2 .

Further, the rotation angle θ ₁ detected by the encoder 11 a and the rotation angle θ ₂ detected by the encoder 21 a are input to the offset torque value setting unit 40.
Offset torque value setting unit 40 is detected over time the actual rotational difference angle [Delta] [theta] _m, which is the rotational deviation angle between the rotational angle theta ₁ and the rotation angle theta ₂ during production.
Then, T + K (Δθ _mo −Δθ _m ) is obtained over time as the update torque value T _{K with K} as a positive constant (predetermined constant). Here, the offset torque value T is a value set as the value of the offset torque command τ _o at that time.

When the backlash does not occur, since a Δθ _mo = Δθ _m, updating the torque value T _K is equal to the offset torque value T at that time.
When backlash occurs, Δθ _mo > Δθ _m is satisfied, and therefore the updated torque value T _K is larger than the offset torque value T at that time.

The offset torque value setting unit 40 compares the initial set torque value To with the update torque value T _K every predetermined time from when the backlash removal control device is first activated, and the update torque value T _K is the initial set torque. When larger than the value to, is updated to a value indicating an offset torque value T with the updated torque value T _K.

Also in the subsequent period, the offset torque value setting unit 40, at every predetermined time, compares the offset torque value T above the value has been updated, an update torque value T _K at each time point, the update of the time When the torque value T _K becomes larger than the offset torque value T whose value has been updated previously, the offset torque value T is updated to a value indicated by the updated torque value T _K at that time.

Thus, every time backlash occurs, the value of the offset torque command τ _o (set torque value T) is updated to a value indicated by the updated torque value T _K at that time and becomes larger.

Therefore, when the state change such as a work weight placed on the movable member is increased is insufficient offset torque generated, the value of the offset torque command tau _o (set torque value T) is automatically increased The generated offset torque can be automatically increased.
For this reason, the offset torque value can be increased to an optimum value in response to a situation change such as an increase in weight, and an offset torque without excess or deficiency can be generated.

  As a result, even if there is a change in the situation such as a substantial increase in the weight of the movable member, the offset torque value automatically increases accordingly, preventing subsequent backlash and lost motion. The offset torque value can be set to an optimum value without waste.

A backlash removal control apparatus according to a second embodiment of the present invention will be described with reference to FIG.
The second embodiment employs an offset torque value setting unit 41 instead of the offset torque value setting unit 40 used in the first embodiment.
Since the other parts are the same as those in the first embodiment, the description will focus on the function / operation of the offset torque value setting unit 41, and the explanation of the other parts will be omitted.

The offset torque value setting unit 41 sets and updates the value of the offset torque command τ _o (offset torque value T) output from the offset torque command unit 31.

The offset torque value setting unit 41 is preset with a set rotation deviation angle Δθ _mo .
Setting the rotational deviation angle [Delta] [theta] _mo, as described above, definitive when backlash occurs without movable member side gear G _L and the motor side gear G _M1, G _M2 is rotating while meshing, the motor side gear G _M1 This is a rotation deviation angle between the rotation angle θ ₁ and the rotation angle θ ₂ of the motor side gear _GM2 .

Further, the offset torque value setting unit 41, the rotation angle theta ₁ which is detected by the encoder 11a, the rotation angle theta ₂ is input detected by the encoder 21a.
The offset torque value setting unit 41 detects an actual rotation deviation angle Δθ _m that is a rotation deviation angle between the rotation angle θ ₁ and the rotation angle θ ₂ during actual operation over time.
Then, the K ₁ as positive constant (predetermined constant), and over time calculated K ₁ for (Δθ _mo -Δθ _m) as an updated torque value T _K.

The offset torque value setting unit 41 sets an initial set torque value To as the offset torque value T of the offset torque command τ _o when the backlash removal control device is first activated. The initial set torque value To is, for example, “+1” in the first embodiment, but is “0” in the second embodiment.

The offset torque value setting unit 41 obtains an updated torque value T _K when the movable member is moved (for example, moved along a typical trajectory pattern) when the backlash removal control device is first activated, and the offset torque value T Is updated to a value indicated by the updated torque value T _K.

Also in the subsequent period, the offset torque value setting unit 41, at every predetermined time, compares the offset torque value T above the value has been updated, an update torque value T _K at each time point, the update of the time When the torque value T _K becomes larger than the offset torque value T whose value has been updated previously, the offset torque value T is updated to a value indicated by the updated torque value T _K at that time.

  As a result, when the backlash removal control device is first activated and the movable member is moved, the offset torque is set to the minimum offset torque necessary to prevent backlash at that time. The value can be set optimally.

In addition, every time a backlash occurs due to a change in state such as an increase in the weight of the workpiece placed on the movable member in actual operation thereafter, the value of the offset torque command τ _o (set torque value T) is It is updated to the value indicated by the updated torque value T _K at that time and increases.

Therefore, at the time of initial startup, the optimum offset torque value can be automatically set, and if the change in state such as the weight of the work placed on the movable member increases and the offset torque is insufficient The value of the offset torque command τ _o (set torque value T) is automatically increased, and the generated offset torque can be automatically increased.

As described above, the optimum initial offset torque can be automatically set, so that it is not necessary to obtain the initial offset torque value by manual calculation or experience.
Even if a change in state such as a change in workpiece weight occurs, the optimum offset torque can be obtained.

  A backlash removal control apparatus according to a third embodiment of the present invention will be described with reference to FIG.

The third embodiment includes an offset torque value setting unit 42 and offset torque value estimation units 51 and 52.
Since other parts are the same as those in the first embodiment, the description will focus on the functions and operations of the offset torque value setting unit 42 and the offset torque value estimation units 51 and 52, and the description of the other parts will be omitted.

  Specifically, the offset torque value estimation units 51 and 52 are configured by a torque estimation observer.

The offset torque value estimation unit 51 includes a torque coefficient multiplication unit 51a, a second-order differentiation circuit 51b, a subtraction unit 51c, and a filter 51d.
The offset torque value estimator 51 receives a motor current value i ₁ indicating a current value flowing through the motor 11 from the servo amplifier 14 and a rotation angle θ ₁ indicating a rotation angle of the motor side gear G _M1 from the encoder 11a. Entered.
The torque coefficient is set as _KT in the torque coefficient multiplier 51a, and the moment of inertia of the movable member is set as J in the second-order differentiation circuit 51b.

The offset torque value estimation unit 52 includes a torque coefficient multiplication unit 52a, a second-order differentiation circuit 52b, a subtraction unit 52c, and a filter 52d.
The offset torque value estimation unit 52, the motor current i ₂ that indicates the value of the current flowing in the motor 21 is inputted from the servo amplifier 24, the rotation angle theta ₂ encoder 21a indicating the rotation angle of the motor side gear G _M2 Entered.
The torque coefficient is set as _KT in the torque coefficient multiplier 52a, and the moment of inertia of the movable member is set as J in the second-order differentiation circuit 52b.

By rotating the motor side gear G _M1 in the clockwise direction, while rotating the movable member side gear G _L in the counterclockwise direction, the offset torque imparted to the movable member side gear G _L by the motor-side gear G _M2 The offset torque value estimator 51 estimates and calculates the offset torque value T ₁ using the following equation (1), and outputs the estimated and calculated offset torque value T ₁ via the filter 51d that is a low-pass filter. To do.
The offset torque value estimating unit 52 estimates and calculates the offset torque value T ₂ using the following expression (2), and outputs the estimated and calculated offset torque value T ₂ via the filter 52d that is a low-pass filter.
T ₁ = K _T · i ₁ −J · d ² θ ₁ / dt ² ... (1)
T ₂ = K _T · i ₂ (2)
As can be seen from Equation (2), at this time, the offset torque value estimation unit 52 does not perform the calculation by the second-order differentiation circuit 52b.
In equation (1), “J · d ² θ ₁ / dt ² ” is a generated torque for actually moving the object (movable member).

By rotating the motor side gear G _M2 in the counterclockwise direction, the movable member side gear G _L while rotating in the clockwise direction, the offset torque imparted to the movable member side gear G _L by the motor-side gear G _M1 The offset torque value estimator 51 estimates and calculates the offset torque value T ₁ using the following equation (3), and outputs the estimated and calculated offset torque value T ₁ via the filter 51d that is a low-pass filter. To do.
The offset torque value estimating unit 52 estimates and calculates the offset torque value T ₂ using the following equation (4), and outputs the estimated and calculated offset torque value T ₂ through the filter 52d that is a low-pass filter.
T ₁ = K _T · i ₁ (3)
T ₂ = K _T · i ₂ −J · d ² θ ₂ / dt ² ... (4)
As can be seen from the equation (3), at this time, the offset torque value estimation unit 51 does not perform the calculation by the second-order differentiation circuit 51b.
In Expression (4), “J · d ² θ ₂ / dt ² ” is a generated torque for actually moving the object (movable member).

When the backlash does not occur, the offset torque value T ₁ and the offset torque value T ₂ are equal, but when the backlash occurs, the offset torque value T ₁ and the offset torque value T ₂ Will be different.

The offset torque value setting unit 42 sets an initial set torque value To as the offset torque value T of the offset torque command τ _o when the backlash removal control device is first activated.
The initial set torque value To is, for example, slightly larger than the Coulomb friction force generated when the movable member is moved, and is set to such a magnitude that the movable member slightly moves with only the offset torque.

The offset torque value setting unit 42 compares the offset torque value T ₁ with the offset torque value T ₂ every predetermined time from when the backlash removal control device is first activated, and compares the offset torque value T ₁ with the offset torque value T _1. When the torque value T ₂ matches, the offset torque value T is held at the initial set torque value To, and when the offset torque value T ₁ and the offset torque value T ₂ do not match, The offset torque value T is updated so as to increase to a value obtained by adding a predetermined additional torque value ΔT to the initial set torque value To.

Also in the subsequent period, the offset torque value setting unit 40, at every predetermined time, compares the offset torque value T ₁ and the offset torque value T _2, the offset torque value T ₁ of the value and the offset torque value T ₂ of the value Are not matched, the offset torque value T is updated so as to increase to a value obtained by adding a predetermined additional torque value ΔT to the offset torque value T whose value has been updated previously.

That is, every time a situation occurs in which the value of the offset torque value T _{1 and} the value of the offset torque value T ₂ do not match, the offset torque value T is increased stepwise by the added torque value ΔT.

Accordingly, when a change in state such as an increase in the weight of the workpiece placed on the movable member occurs and the offset torque becomes insufficient, the value of the offset torque command τ _o (set torque value T) automatically increases. The generated offset torque can be automatically increased.
For this reason, the offset torque value can be increased to an optimum value in response to a situation change such as an increase in weight, and an offset torque without excess or deficiency can be generated.

  As a result, even if there is a change in the situation such as a substantial increase in the weight of the movable member, the offset torque value automatically increases accordingly, preventing subsequent backlash and lost motion. The offset torque value can be set to an optimum value without waste.

11, 21 Motor 12, 22 Zero torque limiter 13 Adder 23 Subtractor 14, 24 Servo amplifier (current control unit)
30 Drive torque command unit 40, 41, 42 Offset torque value setting unit 51, 52 Offset torque value estimation unit

Claims (3)

A movable member side gear connected to the movable member;
A first motor side gear that meshes with the movable member side gear and is driven to rotate by a first motor;
A second motor side gear that meshes with the movable member side gear and is rotationally driven by a second motor;
A first zero torque limiter that passes a drive torque command having a positive polarity but blocks a drive torque command having a negative polarity;
A second zero torque limiter that passes a drive torque command having a negative polarity but blocks a drive torque command having a positive polarity;
An offset torque command unit that outputs an offset torque command in which an initial set torque value (T ₀ ) is preset as an offset torque value (T) and the offset torque value (T) can be updated before actual operation. When,
Torque is generated according to the value of the total torque command obtained by adding the offset torque command to the drive torque command that has passed through the first zero torque limiter, and the rotation direction is in accordance with the polarity of the total torque command. A first current controller for supplying a current to the first motor,
Torque is generated according to the value of the total torque command obtained by subtracting the offset torque command from the drive torque command that has passed through the second zero torque limiter, and the rotational direction is in accordance with the polarity of the total torque command. A second current controller for supplying a current to the second motor,
In a backlash removal control device having
A rotation angle detecting means for detecting a first rotation angle (θ ₁ ) that is the rotation angle of the first motor side gear and a second rotation angle (θ ₂ ) that is the rotation angle of the second motor side gear;
A preset rotation deviation angle (Δθ _mo ), which is a rotation deviation angle between the _first rotation angle (θ ₁ ) and the second rotation angle (θ ₂ ) when no backlash occurs, is preset, and An actual rotation deviation angle (Δθ _m ) that is a rotation deviation angle between the first rotation angle (θ ₁ ) and the second rotation angle (θ ₂ ) during actual operation is calculated, and further an offset torque value (T) to the calculated actual rotational difference angle ([Delta] [theta] _m) and the set rotational deviation angle ([Delta] [theta] _mo) and updates the torque value by adding a value corresponding to the difference (T _K), updating the torque value (T _K) is An offset torque value setting unit that resets the updated torque value (T _K ) at that time as the offset torque value (T) after that time when the offset torque value (T) at that time becomes larger than the offset torque value (T);
A backlash removal control device comprising: A movable member side gear connected to the movable member;
A first motor side gear that meshes with the movable member side gear and is driven to rotate by a first motor;
A second motor side gear that meshes with the movable member side gear and is rotationally driven by a second motor;
A first zero torque limiter that passes a drive torque command having a positive polarity but blocks a drive torque command having a negative polarity;
A second zero torque limiter that passes a drive torque command having a negative polarity but blocks a drive torque command having a positive polarity;
An offset torque command unit that outputs an offset torque command in which the offset torque value (T) can be updated;
Torque is generated according to the value of the total torque command obtained by adding the offset torque command to the drive torque command that has passed through the first zero torque limiter, and the rotation direction is in accordance with the polarity of the total torque command. A first current controller for supplying a current to the first motor,
Torque is generated according to the value of the total torque command obtained by subtracting the offset torque command from the drive torque command that has passed through the second zero torque limiter, and the rotational direction is in accordance with the polarity of the total torque command. A second current controller for supplying a current to the second motor,
In a backlash removal control device having
A rotation angle detecting means for detecting a first rotation angle (θ ₁ ) that is the rotation angle of the first motor side gear and a second rotation angle (θ ₂ ) that is the rotation angle of the second motor side gear;
A preset rotation deviation angle (Δθ _mo ), which is a rotation deviation angle between the _first rotation angle (θ ₁ ) and the second rotation angle (θ ₂ ) when no backlash occurs, is preset, and An actual rotation deviation angle (Δθ _m ) that is a rotation deviation angle between the first rotation angle (θ ₁ ) and the second rotation angle (θ ₂ ) during actual operation is calculated, and the actual rotation deviation angle ( An updated torque value (T _K ) having a value corresponding to the difference between Δθ _m ) and the set rotation deviation angle (Δθ _mo ) is calculated, and the updated torque value (T _K ) is the offset torque value (T) at that time. An offset torque value setting unit that resets the updated torque value (T _K ) at that time as an offset torque value (T) after that point;
A backlash removal control device comprising: A movable member side gear connected to the movable member;
A first motor side gear that meshes with the movable member side gear and is driven to rotate by a first motor;
A second motor side gear that meshes with the movable member side gear and is rotationally driven by a second motor;
A first zero torque limiter that passes a drive torque command having a positive polarity but blocks a drive torque command having a negative polarity;
A second zero torque limiter that allows a drive torque command having a negative polarity to pass but blocks a drive torque command having a positive polarity;
An offset torque command unit that outputs an offset torque command in which the offset torque value (T) can be updated;
Torque is generated according to the value of the total torque command obtained by adding the offset torque command to the drive torque command that has passed through the first zero torque limiter, and the rotation direction is in accordance with the polarity of the total torque command. A first current controller for supplying a current to the first motor,
Torque is generated according to the value of the total torque command obtained by subtracting the offset torque command from the drive torque command that has passed through the second zero torque limiter, and the rotational direction is in accordance with the polarity of the total torque command. A second current controller for supplying a current to the second motor,
In a backlash removal control device having
A rotation angle detecting means for detecting a first rotation angle (θ ₁ ) that is the rotation angle of the first motor side gear and a second rotation angle (θ ₂ ) that is the rotation angle of the second motor side gear;
Motor current value to be supplied to the first motor (i ₁₎ and the first rotation angle (theta ₁₎ the first offset torque value first motor generates based (T ₁₎ the first for estimating An offset torque value estimation unit;
A second offset torque value (T ₂ ) generated by the second motor based on the motor current value (i ₂ ) flowing through the second motor and the second rotation angle (θ ₂ ). An offset torque value estimation unit;
The first offset torque value (T ₁ ) is compared with the _second offset torque value (T ₂ ), and the first offset torque value (T ₁ ) and the second offset torque value (T ₂ ) are different. An offset torque value setting unit that resets a value obtained by adding a predetermined additional torque value (ΔT) to the offset torque value (T) at that time, as an offset torque value (T) after that point;
A backlash removal control device comprising:

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