JPH1039916A - Acceleration and deceleration control method for articulated robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an acceleration/deceleration control method for articulated robot with which the allowable maximum angular velocity of every driving shaft can be easily derived without pressing the arithmetic part of a controller. SOLUTION: A minimum torque tolerance ξmin is calculated by an unbalance torque Pi and a maximum allowable torque Tsplyi of a motor and a decelerator and while considering inertia Ji for it, allowable maximum angular acceleration αmaxi is calculated. Besides, after estimated maximum angular velocity Vmaxi at an intermediate position θi <half> among plural teaching points set by teaching is calculated based on the recording information of teaching points, an estimated maximum value Cmaxi of centrifugal force and Coriolis force at the intermediate position θi <half> is calculated. In this case, when the estimated maximum value of centrifugal force and Coriolis force is higher than a critical value (Tsplyi -Pi ), the estimated maximum angular velocity Vmaxi is corrected and this value is defined as the allowable maximum angular velocity Vmaxi . Based on the calculated allowable maximum angular acceleration maxi and allowable maximum angular velocity Vmaxi of respective driving shafts, the acceleration/deceleration of articulated robot is controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method for accelerating and decelerating an articulated robot having a plurality of drive axes, and more particularly, to controlling the angle, angular velocity, and angular acceleration of each drive axis during operation from the operation of other drive axes. The present invention relates to an acceleration / deceleration control method for an articulated robot configured to be affected by a received force, that is, a reaction force.

[0002]

2. Description of the Related Art In an articulated robot having a plurality of drive shafts, an allowable maximum angular acceleration α _maxi of each drive shaft is calculated from the characteristics of the drive shaft motor, the form of an arm, and the like. the angular acceleration alpha _i of so as to control so as not to exceed the allowable maximum angular acceleration alpha _maxi. The allowable maximum angular acceleration α _maxi is limited so that the generated torque τ _i of the drive shaft does not exceed the maximum allowable torque T _splyi of the drive shaft. Here, the maximum allowable torque T _splyi of each drive shaft is given by the smaller one of the generated torque limit T _mi of the drive shaft motor driving each drive shaft and the allowable torque T _gi of the speed reducer. .

Generally, the generated torque τ _{i on} the i-th drive axis (i is the drive axis number) of an articulated robot having n degrees of freedom has an inertia J _i (θ
_{1, θ 2, ···, θ} n), the angular acceleration alpha _i, the torque due to the centrifugal force and the Coriolis force _{C i (ω 1, ω 2} , ···, ω n,
θ _1, θ _2, ..., θ _n )
_{i (θ 1, θ 2,} ···, θ n) When, given by equation (1).

[0004]

(Equation 1)

In equation (1), (θ _1, θ _2, ..., Θ
_n ) are the angles of the first to nth drive shafts, and (ω1 _, ω2 _, ...)
., Ω _n ) are the angular velocities of the first to n-th drive shafts. Substituting the maximum allowable torque T _splyi of the i-th drive shaft into the left side of Expression (1), the allowable maximum angular acceleration α _{maxi on} the i-th drive shaft becomes as shown in Expression (2).

[0006]

(Equation 2)

In the actual acceleration / deceleration control of the articulated robot,
In all the drive shafts, control is performed so that the angular acceleration α _i of each drive shaft does not exceed the allowable maximum angular acceleration α _maxi . Since the postures and angular velocities of all the drive shafts are taken into account in the equation (2), when the robot arm is operated at a relatively low speed, the allowable maximum angular acceleration of each drive shaft calculated by the equation (2) is used. By controlling each drive shaft based on α _maxi , it is possible to prevent the reduction gear from being damaged and the life thereof being shortened.

However, since equation (2) does not take into account the force received from the operation of the other drive shafts, that is, the reaction force, the case where a plurality of drive shafts operate simultaneously at a high speed, or the case where rapid acceleration / deceleration is performed, etc. In an operation mode in which the effect of the reaction force received from another drive shaft cannot be ignored, the expression (2)
When the angular acceleration α _i of each drive shaft is controlled based on the maximum allowable angular acceleration α _maxi of each drive shaft calculated according to the above, the maximum allowable acceleration of each drive shaft is affected by the reaction force received from other drive shafts. There is a problem that the torque T _splyi may be exceeded. In an extreme case, even when the angular acceleration α _i of the i-th drive shaft during operation is 0, the torque τ _i generated by the i-th drive shaft is affected by the reaction force received from the drive shafts other than the i-th drive shaft. _May exceed the maximum allowable torque T _splyi of the drive shaft.

Therefore, the applicant has filed a Japanese Patent Application No. Hei 8-
In No. 30120, even when a plurality of drive shafts operate simultaneously at a high speed or sudden acceleration / deceleration is performed, even when the reaction force received from the operation of another drive shaft cannot be ignored, the generation of each drive shaft An acceleration / deceleration control method for an articulated robot has been provided that can prevent damage and reduction in life of a reducer without _{causing the} torque τ _i to exceed the maximum allowable torque T _splyi of the drive shaft.

That is, in Japanese Patent Application No. 8-30120,
The angle θ _i , the angular velocity ω _i , and the angular acceleration α _i of each drive axis of the operating multi-joint robot are affected by the force received from the operation of the other drive axes, that is, the reaction force. in deceleration control method for the drive shaft, torque C _i due to centrifugal force and the Coriolis force, unbalanced torque P _i, and smaller Izure whether the value of the allowable torque T _gi of a motor generator torque limit T _mi a speed reducer Of the drive shaft, i.e., the maximum allowable torque T _splyi , the torque margin ratio _{ト ル ク i} of each drive shaft is calculated, and the calculated torque margin ratio of all the drive shafts having the minimum value is determined as the minimum torque margin ratio ξ _{i. min} and the maximum allowable torque T
_The maximum allowable angular acceleration α _{maxi of} each drive shaft is _{obtained from splyi} , the minimum torque margin ratio ξ _min , and the inertia J _i of the drive shaft.
By controlling the angular acceleration α _i so that it does not exceed the allowable maximum angular acceleration α _maxi for all the driving axes of the operating articulated robot, it is possible to prevent the reduction gear from being damaged and shortening its life. I made it possible.

The above-mentioned acceleration / deceleration control method will be specifically described with reference to a flowchart shown in FIG. First, to obtain (step 31) from the command position generating apparatus this command position theta _i for outputting a command position theta _i as the arm angles of the drive shaft for the robot to operate properly, and the command position theta _i, memory Then, the angular velocity ω _i of each drive shaft is calculated from the command position θ _i ′ one calculation cycle (one scan time earlier) before θ _i stored in step 32 (step 32). From command position theta _i and the angular velocity omega _i of each drive shaft, the torque margin rate xi] _i of each drive shaft is calculated by the equation (3) (Step 33).

[0012]

(Equation 3)

In the equation (3), C _i (ω _1, ω _2, ...
, Ω _n , θ _1, θ _2, ..., Θ _n ) are the torques due to the centrifugal force and Coriolis force on the i-th drive shaft, and P _i (θ
_1, θ _2, ..., Θ _n ) is the unbalanced torque on the i-th drive shaft. T _splyi is the maximum allowable torque on the i-th drive shaft. This value is given by the smaller of the generated torque limit T _mi of the motor of this drive shaft and the allowable torque T _gi of the speed reducer. Can be

Next, as shown in the equation (4), the one having the minimum value among the torque margins ξ _i of each drive shaft calculated from the equation (3) is extracted as the minimum torque margin ξ _min . (Step 34).

[0015]

(Equation 4)

Next, the minimum torque margin ratio ξ _min calculated from the equation (4), the maximum allowable torque T _splyi of each drive shaft and the inertia J _i (θ _1, θ _2, ..., Θ _n ). Then, the allowable maximum angular acceleration α _maxi of each drive shaft is calculated by equation (5) (step 35).

[0017]

(Equation 5)

Finally, the allowable maximum angular acceleration α _maxi of each drive shaft calculated by the equation (5) is outputted to the above-mentioned command position generator for outputting the command position θ _i of each drive shaft (step). 36).

[0019]

However, in the above-described process for deriving the allowable maximum angular acceleration α _maxi of each drive shaft, the torque C _i due to the centrifugal force and the Coriolis force,
The values of the unbalance torque P _i and the inertia J _i must be accurately obtained. In the case of an articulated robot, these calculations require a complicated coordinate conversion process. In order to cope with the pressure on the processing capacity, it has been necessary to take measures such as extending the operation cycle (scan time). Therefore, Japanese Patent Application No. 8-3012
The method of No. 0 has the advantage that the accuracy of the trajectory of the robot can be improved by guaranteeing the acceleration / deceleration control within the torque that can be produced by the drive shaft motor, but the calculation cycle of the control device is extended, This has caused side effects such as a decrease in short-pitch movement performance and a decrease in tracking performance of a real-time tracking system.

Here, the short-pitch movement performance refers to the movement performance when moving on a short pitch, that is, a short distance.
When the calculation cycle is extended, the time required for outputting the movement command is extended, and as a result, the short-pitch movement performance is reduced. The tracking performance of the real-time tracking system refers to, for example, the conveyor synchronization function of a robot when a handling robot and a conveyor device are combined to convey articles, in accordance with a conveyor position signal input from the conveyor device in real time. The follow-up performance when shifting the position.If the operation cycle of the control device is extended, the calculation interval for calculating the reproduction position of the robot will be extended, and as a result, the pulsating phenomenon will occur to the operating robot. Occurs,
The tracking performance will be reduced.

The present invention has been made to solve such a problem of the prior art, and simply and easily allows the maximum allowable angular acceleration α of each drive shaft without squeezing the processing capability of the arithmetic unit of the control device. It is an object of the present invention to provide an acceleration / deceleration control method for an articulated robot that can derive _maxi .

[0022]

Means for Solving the Problems] torque C _i due to centrifugal force and Coriolis force described above, unbalance torque P _i, and each time the ratio required for the calculation of the inertia J _i is
Applicant has learned that it is approximately 4: 1: 1. Therefore, in the present invention is to provide a processing method of dealing by calculating the torque C _i due to centrifugal force and Coriolis force requires the longest calculation time among these, the pressure on the processing capacity of the arithmetic unit of the control device Thus, the above problem has been solved. That is, in the calculation processing method according to the present invention, the torque C _i due to the centrifugal force and the Coriolis force is obtained from the calculation process of the allowable maximum angular acceleration α _maxi of the related art shown in FIG.
The calculation process of the maximum allowable angular velocity V _maxi at the intermediate position between the teaching points is newly set for a plurality of teaching points given by the teaching instead of the calculation process of the two teaching points. The maximum allowable angular acceleration α _maxi and maximum allowable angular velocity V _maxi of each drive shaft calculated in the process are output to a command position generator that outputs a command position θ _i of each drive shaft, and these values are set as upper limit values. The angular acceleration and angular velocity of the drive shaft are regulated.

As a specific configuration, in the process of calculating the allowable maximum angular acceleration α _maxi , the unbalance torque defined by the command position θ _i with respect to the drive shaft is calculated for each drive shaft. P _i, and calculates a torque margin rate xi] _i by a torque value or maximum permissible torque T _Splyi the smaller among Izure whether the value of the allowable torque T _gi of a motor generator torque limit T _mi speed reducer (step 12), Among the calculated torque margins of all the drive shafts, the one having the minimum value is extracted as the minimum torque margin ratio ξ _min (step 13), and the maximum allowable torque T _splyi and the minimum torque margin ratio ξ for each drive shaft are extracted. _{Based on min} and inertia J _i , an allowable maximum angular acceleration α _maxi is calculated (step 14). Here, the command position θ with respect to the drive shaft
_i indicates the angle data of the drive shaft output from the command position generating device of the control device to the servo motor that operates each drive shaft.

On the other hand, in the process of calculating the allowable maximum angular velocity V _maxi , for a plurality of teaching points set by teaching, the angular velocity at the intermediate position θ _i ^half between the teaching points is calculated from the recorded information of the teaching points, and this is calculated. Expected maximum angular velocity V
_maxi (step 15), and the intermediate position θ _i ^half
And the expected maximum angular velocity V _maxi , the intermediate position θ
calculating a predicted maximum value C _maxi centrifugal force and Coriolis force at _i ^half (step 16), the maximum permissible torque T _Splyi and centrifugal force from the unbalance torque P _i and the Coriolis force limits _(T splyi -P _i) Is calculated, and this limit value (T
_splyi− P _i ) and the expected maximum value C _maxi ((T _splyi
−P _i ) / C _maxi ) is set as the ratio ρ _i of the two (step 17). When the ratio ρ _i is less than 1, the expected maximum angular velocity V _maxi is multiplied by the square root of the ratio ρ _i (√ρ _i ). The obtained value is replaced with the allowable maximum angular velocity V _maxi , while when the ratio ρ _i is 1 or more, the value of the expected maximum angular velocity V _maxi is directly used as the allowable maximum angular velocity V _maxi (steps 18 to 1).
9).

Here, the recorded information of the teaching point is various parameters that are set when the teaching point is designated by teaching, and specifically, the position data of the teaching point, the moving speed data to the teaching point, the teaching data, and the like. Positioning accuracy data at points,
The data includes movement form data such as interpolation for movement to the teaching point. In the present invention, the predicted maximum angular velocity V _{maxi at} the intermediate position θ _i ^half between the teaching points is calculated based on these pieces of recorded information. In addition, regarding the point where the expected maximum angular velocity V _maxi is set as the angular velocity at the intermediate position θ _i ^half between the teaching points, it is generally at the intermediate position between the teaching points that the angular velocity becomes largest in the movement between the teaching points. It depends.

Finally, based on the allowable maximum angular acceleration α _maxi and the allowable maximum angular velocity V _maxi of each drive shaft calculated by these two calculation processes, the angular acceleration α _i of each drive shaft is changed to the allowable maximum angular acceleration α _maxi And the angular velocity ω _i of each drive shaft is controlled not to exceed the allowable maximum angular velocity V _maxi , thereby preventing the reduction gear from being damaged and having a reduced life.

Here, in the configuration according to the first aspect, when the ratio ρ _i is less than 1, the expected maximum angular velocity V _maxi
Is multiplied by the square root of the ratio ρ _i (√ρ _i ) as the allowable maximum angular velocity V _maxi , while, when the ratio ρ _i is 1 or more, the value of the expected maximum angular velocity V _maxi is used as it is. _The point of _maxi will be described. The expected maximum angular velocity V _maxi is calculated from the recorded information of the teaching point as described above, and the recorded information of the teaching point does not take into account the allowable torque of the drive shaft. Therefore, if the maximum allowable angular velocity is set only from the recording information of the teaching point,
Depending on the operation mode, the drive shaft may exceed the allowable torque. Specifically, when the ratio ρ _i is less than 1, that is, when the expected maximum value C _maxi is larger than the limit value (T _splyi −P _i ) that the torque due to the centrifugal force and Coriolis force can occupy, the intermediate value Due to the torque due to the centrifugal force and Coriolis force at the position θ _i ^half , the i-th drive shaft may be in an allowable torque over state.

Therefore, when the ratio ρ _i is less than 1, considering that the torque due to the centrifugal force and Coriolis force is approximately proportional to the square of the angular velocity, the expected maximum angular velocity V _maxi is √ (ρ _i ).
Is corrected by replacing the value multiplied by as the allowable maximum angular velocity. On the other hand, when the ratio ρ _i is 1 or more, the expected maximum value C of the torque due to centrifugal force and Coriolis force
_{Since maxi} has _settled within the limit value (T _splyi -P _i ), no correction is necessary in this case, and the value of the predicted maximum angular velocity V _maxi is used as the allowable maximum angular velocity as it is.

According to the above configuration, the torque C _maxi due to the centrifugal force and the Coriolis force is the intermediate position θ _i between the teaching points.
^half and the expected maximum angular velocity V at this intermediate position θ _i ^half
_{maxi. In} the end, C _maxi only needs to be calculated once when moving between the teaching points. Meanwhile, in the prior art, the torque C _i by a centrifugal force and Coriolis force, and the command position theta _i, has been stored in the memory theta _i 1 calculation period before the (1 scan time ago) command position theta _i ' And Ci is calculated based on the angular velocity ω _i obtained as described above. In the end, C _i has to be calculated every calculation cycle (each scan time). Generally, the operation cycle (scan time) in the operation unit of the control device is several tens of milliseconds, but the time required to move between the teaching points is several hundred milliseconds to several seconds. In the calculation of the torque by the Coriolis force, the calculation load on the control device of the present invention is much smaller than that of the related art.

[0030]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 2 is a block diagram showing an example of a system to which the control method of the present invention is applied. In FIG.
Is a command position generator, 4 is a target position generator, and 5 is a calculator for calculating the maximum allowable angular acceleration α _maxi and the maximum allowable angular velocity V _maxi . The target position generator 4 outputs the position recorded in the memory or the position obtained by calculation to the command position generator 3 as a target position to be reached by the robot. Command position generator 3, the target position, designated speed, current position, and from the values of such acceleration limitation, to calculate the command position theta _i as directive angles of the drive shaft of every moment for the robot to operate properly , To the servo amplifier 2.

The computing unit 5 of the allowable maximum angular acceleration alpha _maxi and maximum allowable angular velocity V _maxi is allowable maximum angular acceleration alpha _maxi is calculated in the control method of the present invention and the allowable maximum angular velocity V
It is a calculation device for _maxi , and inputs a command position θ _i as an arm angle of each drive shaft, which is an output of the command position generation device 3, and outputs an allowable torque T _gi of a speed reducer of each drive shaft and a generated torque of a drive shaft motor. The allowable maximum angular acceleration α _maxi and the allowable maximum angular velocity V _maxi are calculated from the limit T _mi , and the command position generator 3
Form a loop to output to The servo amplifier 2 receives the command position theta _i from command position generator 3, and outputs an operation command for operating the robot body 1. A drive shaft motor, an encoder, a speed reducer, and the like (not shown) are attached to the robot body 1, and these constitute a servo loop.

FIG. 1 shows the maximum allowable angular acceleration α _maxi and the maximum allowable angular velocity V _maxi of each drive shaft, which are performed by the calculation device 5 for calculating the maximum allowable angular acceleration α _maxi and the maximum allowable angular velocity V _{maxi shown} in FIG. It is a flowchart which shows the flow of a calculation process. First, obtain a command position theta _i of the drive shaft for the robot from the command position generator 3 to operate properly (step 11). From the command position theta _i of the respective drive shaft, the torque margin rate xi] _i of each drive shaft is calculated by the equation (6) (step 12).

[0033]

(Equation 6)

In the equation (6), P _i (θ _1, θ _2, ...
, Θ _n ) is the unbalanced torque on the ith drive shaft (i is the drive shaft number). T _splyi is the maximum allowable torque on the i-th drive shaft, and this value is
The torque is given by the smaller of the generated torque limit _Tmi of the motor of the drive shaft and the allowable torque _Tgi of the speed reducer.

[0035] In the calculation of the torque margin rate xi] _i, and the processing in step 12 in this embodiment is compared with the processing in step 33 in Japanese Patent Application No. Hei 8-30120 are prior art, Japanese Patent Application 8 as shown in equation (3) is a No. -30120, C _i (ω ₁ is the torque due to centrifugal force and Coriolis force in the i drive _{shaft, ω 2, ···,}
ω _n , θ _1, θ _2, ..., θ _n ) are taken into account, but this is not taken into account in the present embodiment. In this embodiment, C _i is the torque due to centrifugal force and Coriolis force in the i drive shaft is taken into consideration in the process of calculating the allowable maximum angular velocity V _maxi described later.

Next, as shown in the equation (7), the one having the minimum value among the torque margins ξ _i of each drive shaft calculated from the equation (6) is extracted as the minimum torque margin ξ _min . (Step 13).

[0037]

(Equation 7)

Next, the minimum torque margin ξ _min calculated from the equation (7), the maximum allowable torque T on the i-th drive shaft
_{Let splyi} and inertia be J _i (θ _1, θ _2, ..., θ _n )
, The allowable maximum angular acceleration α _maxi in the ith drive axis
Is calculated by equation (8) (step 14).

[0039]

(Equation 8)

On the other hand, the torque C due to the centrifugal force and Coriolis force
It is the processing steps after step 15 in the flowchart shown in FIG. 1 that consider _i in a process different from the process of calculating the allowable maximum angular acceleration α _maxi . Torque C _i due to centrifugal force and the Coriolis force depends on the position and the angular velocity becomes higher generally angular velocity is large significantly. Therefore, in each drive axis, for a plurality of teaching points set by teaching, the position where the angular velocity becomes the largest when moving between adjacent teaching points, that is, the position θ which is just intermediate between the teaching points.
_i ^half is extracted as a representative point, and an approximate maximum angular velocity at the intermediate position θ _i ^half , that is, an estimated maximum angular velocity V _maxi is calculated from the recorded information of the teaching point (step 15). Here, the recording information of the teaching point is various parameters set when specifying the teaching point by teaching, and specifically, the position data of the teaching point, the moving speed data to the teaching point, and the data at the teaching point. The data includes positioning accuracy data, movement form data such as interpolation for movement to a teaching point, and the like.

From the intermediate position θ _i ^half and the expected maximum angular velocity V _maxi , the torque C _maxi due to the centrifugal force and Coriolis force on the i-th drive shaft is calculated by the equation (9) (step 16). C _maxi shown here is the intermediate position θ _i ^half
Is the maximum expected torque due to centrifugal and Coriolis forces at

[0042]

(Equation 9)

Here, the process of calculating the torque by the centrifugal force and the Coriolis force in the prior art and this embodiment will be compared. Torque C _i due to centrifugal force and Coriolis force in the prior art, the command position theta _i, theta has been stored in the memory
_It is calculated from the angular velocity ω _i obtained from the command position θ _i ′ one calculation cycle before (i.e., one scan time before) _i . After all, C _i is calculated every calculation cycle (each scan time). I had to. On the other hand, the torque C due to the centrifugal force and the Coriolis force in the present embodiment
_maxi is calculated from the intermediate position θ _i ^half between the teaching points and the predicted maximum angular velocity V _maxi at the intermediate position θ _i ^half , and after all, C _maxi is calculated when moving between the teaching points. It only needs to be calculated once. Generally, the operation cycle (scan time) in the operation unit of the control device is several tens of meters.
Although it is seconds, the time required for the movement between the teaching points is several hundred milliseconds to several seconds. Therefore, in the calculation of the torque by the centrifugal force and the Coriolis force, which requires a large amount of calculation, the present embodiment requires more calculation for the control device. The load becomes much smaller.

[0044] The intermediate position theta _i the i drive shaft unbalance torque P _i and the maximum permissible torque T _Splyi of the ^half
From this, the limit value (T _splyi -P _i ) at which the torque due to the centrifugal force and the Coriolis force can occupy at the same time can be obtained. Therefore, the intermediate value θ _i obtained from this limit value and the expression (9) can be obtained. The expected maximum value C _maxi of the torque due to the centrifugal force and Coriolis force in ^half is compared. Specifically, the ratio ρ _i is calculated by the equation (10) (step 17).

[0045]

(Equation 10)

The ratio ρ _i calculated by the equation (10) is 1
If the maximum value C _maxi is larger than the limit value (T _splyi -P _i ) that the torque due to the centrifugal force and Coriolis force can occupy, the intermediate position θ _i ^half
Due to the centrifugal and Coriolis forces at
There is a possibility that the i-th drive shaft will be in an allowable torque over state. Therefore, when the ratio ρ _i is less than 1, it is considered that the torque due to the centrifugal force and Coriolis force is approximately proportional to the square of the angular velocity, and is replaced with ρ _i ← √ (ρ _i ) (step 18). The approximate expected maximum angular velocity V _maxi at the intermediate position θ _i ^half calculated by
The corrected value is set as the allowable maximum angular velocity (step 19). On the other hand, when the ratio ρ _i is 1 or more, the expected maximum value C _maxi of the torque due to the centrifugal force and the Coriolis force is within the limit value (T _splyi −P _i ). Is not necessary, and ρ _i = 1 in Expression (11) in the actual arithmetic processing.

[0047]

[Equation 11]

The maximum allowable angular acceleration α _maxi calculated by the equation (8) and the intermediate position θ _i corrected by the equation (11)
^The maximum allowable angular velocity V _{maxi in} ^half is determined by the command position generator 3
(Step 20), the command position generator 3 derives the next command position using these values as upper limits of the angular acceleration and angular velocity.

In the above processing, steps 11 to 14
Includes a command position theta _i, since the processing on the basis of the data of the command position theta _i 'of the stored in the memory theta _i 1 calculation period before the (1 scan time ago), for each calculation cycle Steps 15 to 19 need to be performed only once when moving between the teaching points, because steps 15 to 19 are based on the angular velocity at the intermediate position between the teaching points. As a result, the process of calculating the torque due to the centrifugal force and the Coriolis force is reduced from once for each calculation cycle of the prior art to once for each movement between the teaching points of the present embodiment, thereby reducing the calculation load on the control device. can do.

[0050]

According to the articulated robot acceleration / deceleration control method of the present invention, the torque due to the centrifugal force and the Coriolis force is calculated from the intermediate position between the teaching points and the expected maximum angular velocity at the intermediate position. Since the calculation process only needs to be performed once at the time of movement between the teaching points, the calculation does not need to be performed for each calculation cycle as in the prior art, and the allowable maximum angular acceleration of each drive shaft can be simply obtained. α _maxi and allowable maximum angular velocity V _maxi can now be calculated. By controlling the acceleration and deceleration of the articulated robot using the allowable maximum angular acceleration α _maxi and the allowable maximum angular velocity V _maxi , breakage of the speed reducer and reduction in the life thereof can be prevented.

Further, since the calculation load on the control device is reduced and the calculation cycle is not extended, problems of the prior art such as a decrease in short pitch movement performance and a decrease in follow-up performance of a real-time tracking system are solved. It became a thing.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a flow of a calculation process of an allowable maximum angular acceleration α _maxi and an allowable maximum angular velocity V _{maxi according} to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating an example of a system to which an acceleration / deceleration control method is applied according to an embodiment of the present invention.

FIG. 3 is a flowchart illustrating a flow of a calculation process of an allowable maximum angular acceleration α _{maxi according to} the related art.

Claims (1)

[Claims] An articulated robot in which the angle, angular velocity, and angular acceleration of each drive shaft of the articulated robot during operation are influenced by a force received from the operation of another drive shaft, that is, a reaction force. In the deceleration control method, for each of the drive shafts, the unbalanced torque P _i defined by the command position θ _i with respect to the drive shaft, the generated torque limit T _{mi of the} motor, or the allowable torque T _gi of the speed reducer, whichever is smaller. Torque value, that is, the maximum allowable torque T
calculating a torque margin rate xi] _i by the _Splyi, extracting those with the smallest value of the torque margin rate of all the drive shafts which are calculated as the minimum torque margin rate xi] _min, for each drive shaft, the maximum permissible The allowable maximum angular acceleration α _maxi is calculated from the torque T _splyi , the minimum torque margin ratio ξ _min , and the inertia J _i . On the other hand, for a plurality of teaching points set by teaching, an intermediate position θ between the teaching points is calculated. The angular velocity in _i ^half is calculated from the recorded information of the teaching point, and this is calculated as the expected maximum angular velocity V
_maxi , from the intermediate position θ _i ^half and the expected maximum angular velocity V _maxi ,
The expected maximum value C _maxi of the centrifugal force and Coriolis force at the intermediate position θ _i ^half is calculated, and the maximum allowable torque T _splyi and the unbalance torque P are calculated.
limits of the centrifugal force and the Coriolis force than _i (T _splyi -
P _i ), and the ratio of the limit value (T _splyi -P _i ) to the expected maximum value C _maxi ((T _splyi -P _i ) / C _maxi )
Is set as the ratio ρ _i of the two, and when the ratio ρ _i is less than 1, the expected maximum angular velocity V _maxi
Replaces the value obtained by multiplying the square root (√ρ _i) the ratio [rho _i as permissible maximum velocity V _maxi in, whereas the ratio [rho _i is 1 or more as the maximum allowed angular velocity value of the expected maximum velocity V _maxi when the V _maxi , for all the drive axes of the articulated robot in operation, the angular acceleration α _i of each drive axis does not exceed the allowable maximum angular acceleration α _maxi , and the angular velocity ω _i of each drive axis is the allowable maximum angular velocity An acceleration / deceleration control method for an articulated robot, wherein control is performed so as not to exceed V _maxi to prevent damage to the reduction gear and shortening of its life.