JP2022174858A - Direct teaching device and direct teaching method - Google Patents

Abstract

To achieve motion by which performance as a whole can be improved during direct teaching.SOLUTION: A direct teaching device comprises: a torque sensing part 4 that senses torque applied to an arm 2; a position and attitude calculating part 112 that calculates a position and an attitude of the arm; an external force sensing part 111 that senses external force applied to the arm on the basis of the torque; a first driven control calculating part 13 that calculates movements of the arm according to the torque to drive the arm; a second driven control calculating part 114 that calculates movements of the arm according to the external force; a control part that calculates the movement of the arm satisfying a restriction on at least either of the position and attitude of the arm or a speed thereof; a combining part 117 that combines a calculated result by the second driven control calculating part with a calculated result by the control part; a second driving control part 122 that drives the arm on the basis of a combined result by the combining part; and a switching part 119 that effectively switches the first driven control calculating part 13 or the second driven control calculating part, the control part, and either of the combining part and the second driving control part.SELECTED DRAWING: Figure 1

Description

The present invention relates to a direct teaching device and a direct teaching method for directly teaching a robot.

In industrial robots, work called teaching is carried out in advance in order to cause the robot to perform work. One method of teaching the robot is a method called direct teaching.

For example, Patent Literature 1 discloses a direct teaching method for a robot using a force sensor. Further, for example, Patent Document 2 and Non-Patent Document 1 disclose a direct robot teaching method using torque detection means. A schematic configuration of the direct teaching device disclosed in Non-Patent Document 1 is shown below.

In the direct teaching device shown in FIG. 11, first, the main controller 201 uses the torque measured by the torque sensor 202 (torque per joint of the robot) to apply torque to the arm 203 of the robot by the operator. Detects the applied external force.
Next, main controller 201 calculates a torque command value and a torque compensation value in order to realize movement of arm 203 according to the detected external force. The torque command value is the sum of the estimated value of the component of the torque measured by the torque sensor 202 that is caused by gravity and the static disturbance such as the offset value of the torque sensor 202 . The torque compensation value is the torque required to prevent the robot from moving due to gravity. Note that the main controller 201 calculates a torque command value (a driven control command value) based on the angle (joint angle of the arm 203) detected by the encoder 204 in the driven control calculation.

Next, the servo driver 205 performs torque control so that the torque measured by the torque sensor 202 matches the driven control command value. That is, the servo driver 205 subtracts the torque measured by the torque sensor 202 from the torque command value, multiplies the result by the gain, and then adds the torque compensation value. Then, the servo driver 205 calculates an updated drive current command value based on the result of torque control. That is, the servo driver 205 multiplies the torque control result by the torque-current conversion coefficient. Then, the servo driver 205 performs current control (not shown) so that the drive current command value matches the drive current measured value (not shown), and outputs the drive current.
The servo motor 206 is then driven according to the drive current output by the servo driver 205 . The driving force generated by the servomotor 206 is transmitted to the arm 203 via the reduction gear 207, and the arm 203 is driven.

Through this series of operations, the direct teaching device shown in FIG. 11 can control the arm 203 to move according to the external force applied by the operator. Then, when the position and orientation of the arm 203 are brought into a state intended by the operator, the direct teaching device records the parameters at that time as teaching points. The teaching points recorded by this direct teaching device are used when the robot works.

As described above, driven control is realized by controlling the value of a torque sensor that can be placed near the drive control unit for each joint, and the drive control unit executes the main control operations. , it is possible to reduce the room for dead time and improve quick response. In other words, it becomes possible to perform adjustment (gain adjustment of 1-variable control for each joint) corresponding to high gain of the controller capable of maintaining stability. Therefore, a light operational feeling can be obtained (see Patent Document 3, for example).

In this way, the direct teaching of the robot has the advantage of being intuitive and easy for the operator to understand because the operator directly operates the arm to teach the position and orientation. On the other hand, the feature that the arm moves as it is according to the external force applied by the operator is not the only advantage.

For example, consider a case in which the operator teaches the robot the position of a certain point P and then teaches the position of another point Q directly below it. In this case, the operator moves the arm directly downward (in the Z-axis direction). However, it is difficult for the operator to accurately apply an external force directly downward to the arm, and the X-axis and Y-axis coordinates of the arm often deviate. Although it is possible to correct only the X-axis and Y-axis coordinates of the arm later using a teaching pendant or the like, this reduces the advantage of direct teaching.

Also, for example, consider a case where the operator instructs with the end effector provided at the tip of the arm directed directly downward. Even in this case, it is difficult for the operator to directly operate the arm while maintaining a state in which the arm is directed directly downward, and the posture of the arm often deviates.

As described above, direct teaching is intuitive and easy to understand, but there are cases where it is difficult to operate.

On the other hand, Patent Literatures 4 and 5, for example, disclose techniques for solving the above problems. Further, Patent Document 5 discloses a direct teaching device in which an operation mode can be switched between a restraint mode and an omnidirectional movement mode by an input device. Constraint mode allows the tip of the end effector to move along a specific constraint axis or constraint surface. Also, in the omnidirectional movement mode, normal direct teaching can be performed. By switching to the restraint mode during direct teaching, this direct teaching device makes it possible to accurately move the tip of the arm in the vertical direction, thereby reducing the difficulty of operation in direct teaching. Furthermore, Patent Document 6 discloses a direct teaching device capable of switching between normal direct teaching and constrained direct teaching while an operator is operating an arm.

JP-A-05-204441 JP-A-05-250029 JP 2020-146765 A JP-A-05-285870 JP-A-05-303425 JP 2019-202383 A

Kodai Sugimoto, Koji Shimizu, Tetsuya Tabaru; Lead-Through Programming of Robotic Manipulators by Joint Torque Control, Proc. of the SICE Annual Conference 2020, pp. 462-466, 2020)

The direct teaching operation by torque control for each joint (each axis torque control) shown in Non-Patent Document 1 can lighten the operation feeling as shown in Patent Document 3, but there are restrictions such as position and posture constraints. There is a problem that it is difficult to improve the constraint performance in direct teaching motion with attachment.

This is because the position and orientation must be handled in constraint control, but the position and orientation cannot be directly controlled if the joint control unit is torque control, which complicates the control. For example, when direct teaching motion is performed by constraining in the Z-axis direction, a control command value that suppresses the positional deviation from the constraining position is calculated in the upper main control unit. The value must be given in torque. For this reason, it becomes a complicated control in which the position is indirectly controlled via the torque command value.

Also, since the joint control unit cannot control the position and orientation, the control is mainly based on feedback control by the main control unit, but since there is generally a communication delay between the main control unit and the joint control unit, stable operation It is difficult to increase the control gain of the main control section in order to realize For the reasons described above, there is a problem that it is difficult to sufficiently reduce the control deviation from the restrained position in the method of controlling torque on each axis.

A similar problem can occur in direct teaching that has a function of simultaneously controlling position or speed in addition to direct teaching with constraints. For example, when it is desired to control the speed of the hand of the arm or the angular speed of each joint to a predetermined value or less for the safety of the operator, it is necessary to control the speed via torque in each axis torque control method, Similar challenges arise.

If the joint control unit is position control or speed control, the above problem does not exist. In this case, a position (joint angle) or velocity (angular velocity) command value can be given to the joint control unit, so that the position or velocity can be directly adjusted to satisfy the functional requirements without calculating the torque command value. Because it can be controlled. However, the light feeling of operation, which is an advantage of each axis torque control, is lost.

The present invention has been made to solve the above-mentioned problems. It is an object of the present invention to provide a direct teaching device capable of realizing a direct teaching operation with improved overall performance when performing teaching.

A direct teaching device according to the present invention includes a torque detection unit that detects torque applied to an arm of a robot, a position/orientation calculation unit that calculates at least one of the position and orientation of the arm, a torque An external force detection unit that detects an external force applied to the arm based on the torque detected by the detection unit, and a first driven control calculation that calculates the movement of the arm according to the torque detected by the torque detection unit and drives the arm. a second driven control calculation unit that calculates the movement of the arm according to the external force detected by the external force detection unit; a control unit that calculates the movement of the arm that satisfies the conditions, a synthesizing unit that synthesizes the calculation result of the second driven control arithmetic unit and the calculation result of the control unit, and the second that drives the arm based on the synthesis result of the synthesizing unit A drive control section, and a switching section for effectively switching one of a first driven control calculation section or a second driven control calculation section, a control section, a synthesizing section, and a second drive control section. do.

According to the present invention, since it is configured as described above, in contrast to the conventional art, when performing normal direct teaching without imposing restrictions, it is possible to move with a light operational feeling, and when performing direct teaching with imposing restrictions, it is possible to move it with a light operational feeling. can realize direct teaching operation with improved overall performance.

1 is a diagram showing a configuration example of a direct teaching device according to Embodiment 1; FIG. 4 is a flow chart showing an operation example of the direct teaching device according to Embodiment 1 (in the case of direct teaching without constraint); 4 is a flow chart showing an operation example (in the case of direct teaching with restraint) of the direct teaching device according to Embodiment 1; FIG. 10 is a diagram showing a configuration example of a direct teaching device according to Embodiment 2; It is a figure explaining a restraint axis. It is a figure explaining a restraint surface. It is a figure explaining a restraint direction. 8A and 8B are diagrams for explaining the restricted rotation shaft. It is a figure explaining constraint which combined surface constraint and direction constraint. FIG. 11 is a diagram showing a configuration example of a direct teaching device according to Embodiment 3; It is a figure which shows the structural example of the conventional direct teaching apparatus.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Embodiment 1.
FIG. 1 is a diagram showing a configuration example of a direct teaching device (robot control device) 1 according to Embodiment 1 of the present invention.
A direct teaching device 1 performs direct teaching of a robot. The robot has a motor (not shown) for driving the arm 2 and an encoder 3 for each joint. The motor (arm 2 in FIG. 1) and the encoder 3 are connected to the direct teaching device 1 by power lines or the like. Encoder 3 detects the angle of the corresponding joint.

Further, the robot is provided with a torque detection unit 4 for each joint. The torque detection unit 4 detects torque applied to the arm 2 by the operator.
For example, the torque detector 4 may use a torque sensor attached to the motor drive shaft of the arm 2 and detect the torque (τ) measured by this torque sensor as the torque. In addition, the torque detection unit 4 does not directly measure the torque using a torque sensor, but indirectly calculates the torque from the electric power of the motor of the arm 2 or the measured value of the joint angle (θ) of the arm 2. An observer may be used to detect the torque.

The direct teaching device 1 includes, as direct teaching methods, normal direct teaching that does not impose restrictions on the position and orientation of the hand end of the arm 2 and the speed of the hand end of the arm 2, It is possible to switch to constrained direct teaching that limits the speed of

Note that the position and orientation of the hand of the arm 2 means at least one of the position of the hand of the arm 2 and the orientation of the hand of the arm 2 . Further, the position of the hand of the arm 2 means the tip of an end effector provided at the tip of the arm 2 or the position of an arbitrary point with the tip as a reference. Also, the posture of the hand of the arm 2 means the orientation of the end effector. Note that the position and orientation of the hand of the arm 2 may be described as the position and orientation of the arm 2, but unless otherwise specified, they have the same meaning.

Also, the speed of the end of the arm 2 means the moving speed of the end effector. Note that the speed of the tip of the arm 2 may be described as the speed of the arm 2, but unless otherwise specified, it has the same meaning.

Examples of applications of constrained direct teaching include the case of direct teaching while imposing the following constraints. Examples of constraints include a positional constraint that limits the position that the hand of the arm 2 can take, a posture constraint that limits the posture that the hand of the arm 2 can take, or a predetermined speed that the hand of the arm 2 can take. For example, a speed limit that imposes a limit not to exceed a value.

The direct teaching device 1 includes a main controller 11 and a plurality of joint controllers 12, as shown in FIG. The joint control unit 12 is provided for each joint of the robot. The main controller 11 and each joint controller 12 are connected by communication lines. In FIG. 1, only one joint control unit 12 is shown.

The main control unit 11 controls the entire robot by outputting command values to each joint control unit 12 . As shown in FIG. 1, the main control unit 11 includes an external force detection unit 111, a position/posture calculation unit 112, a speed calculation unit 113, a second driven control calculation unit 114, a position/posture control unit 115, a speed control unit 116, and a synthesis unit. 117 , a torque command value calculation unit 118 and a switching unit 119 .
The joint control section 12 includes a first drive control section 121 and a second drive control section (drive control section) 122 .

The direct teaching device 1 is implemented by a processing circuit such as a system LSI (Large-Scale Integration) or a CPU (Central Processing Unit) that executes a program stored in a memory or the like.

The external force detection unit 111 uses the torque detected by the torque detection unit 4 to detect the external force applied to the arm 2 by the operator.
Note that the torque detected by the torque detection unit 4 may include not only the external force applied to the arm 2 by the operator, but also a component caused by gravity, depending on the structure of the sensor. Therefore, in such a case, the external force detection unit 111 calculates only the external force component by calculating the component caused by gravity and subtracting the component caused by the gravity from the detected external force. This is a well-known technique called gravity compensation, which is disclosed in, for example, Patent Document 7.
JP-A-01-066715

The position/orientation calculator 112 calculates the position/orientation of the arm 2 based on the angle of each joint of the robot detected by the encoder 3 . The angle of each joint of the robot is expressed in a joint coordinate system, and the position/orientation calculation unit 112 converts the angle of each joint into a position/orientation expressed in an orthogonal coordinate system.

The velocity calculator 113 calculates the velocity of the arm 2 based on the position and orientation of the arm 2 calculated by the position and orientation calculator 112 .

The external force detection unit 111, the position/orientation calculation unit 112, and the velocity calculation unit 113 have the same configuration as that used in normal direct teaching without restrictions, and are well-known technologies.

The second driven control calculator 114 calculates the movement (driven control command value) of the arm 2 according to the external force detected by the external force detector 111 .

The position/posture control unit 115 calculates the motion of the arm 2 that satisfies the constraints on the position/posture of the arm 2 calculated by the position/posture calculation unit 112 .

The speed control unit 116 calculates the motion of the arm 2 that satisfies the restrictions on the speed of the arm 2 calculated by the speed calculation unit 113 .

Note that the position/posture control unit 115 and the speed control unit 116 “calculate the motion of the arm 2 that satisfies at least one of the position/posture and speed of the arm 2 based on the calculation result of the position/posture calculation unit 112 . configure the control unit.

The synthesis unit 117 obtains a synthesized control command value by synthesizing the calculation result by the second driven control calculation unit 114 and the calculation result by the control unit.

Note that while the physical quantity of the synthesized control command value is a command value expressed in a joint coordinate system, each control command value input to the synthesizing unit 117 is expressed in an orthogonal coordinate system such as the position and orientation of the arm 2 or the speed of the arm 2. is the indicated command value. Therefore, the synthesizing unit 117 converts the command value represented by the orthogonal coordinate system into the command value represented by the joint coordinate system. For example, the synthesizing unit 117 calculates the angular velocity command value by multiplying the velocity command value expressed in the orthogonal coordinate system by the inverse matrix of the Jacobian matrix. The synthesizing unit 117 also performs variable transformation from the orthogonal coordinate system to the rotating coordinate system when calculating the command value of the joint angle or the joint angular acceleration.

Torque command value calculator 118 calculates a torque command value based on the external force detected by external force detector 111 . The torque command value is the sum of an estimated value of the component caused by gravity in the torque detected by the torque sensor and a static disturbance such as an offset value of the torque sensor.

The switching unit 119 can switch the direct teaching by the direct teaching device 1 to normal direct teaching without restrictions or direct teaching with restrictions. Here, when switching to normal direct teaching that does not impose restrictions, the switching unit 119 enables the processing by the torque command value calculation unit 118 and the first drive control unit 121, and the second driven control calculation unit 114, the control unit, The processing by the synthesizer 117 and the second drive controller 122 is disabled. Further, when switching to direct teaching with restrictions, the switching unit 119 disables the processing by the torque command value calculation unit 118 and the first drive control unit 121, the second driven control calculation unit 114, the control unit, the synthesis unit 117 and Processing by the second drive control unit 122 is enabled.

In the above description, a method of disabling the processing by the second driven control calculation section 114, the control section, the synthesizing section 117, and the second drive control section 122 when switching to the normal direct teaching that does not impose any restrictions has been shown. It is sufficient if the processing by these series of calculation units can be substantially disabled, and the present invention is not limited to this.
Here, in the second drive control unit 122, the control deviation is obtained by subtracting the current measured value from the combined control command value obtained by the combining unit 117, and the output value is obtained by multiplying the control deviation by the gain. obtain. Therefore, for example, the gain of the second drive control section 122 may be set to 0 as a method of substantially disabling the above series of processing by the calculation section. As a result, the output value of the second drive control section 122 becomes 0, and the same effect as above can be obtained. Further, for example, as a method of substantially invalidating the above-described series of processing by the arithmetic unit, the combined control command value obtained by the combining unit 117 may be set to the same value as the current measured value. As a result, the control deviation in the second drive control section 122 and the output value of the second drive control section 122 become very small, and the same effect as described above can be obtained. Note that the control deviation may not be completely 0 due to the influence of communication delays between the synthesizing unit 117 and the second drive control unit 122 .

Mode switching by the switching unit 119 is performed by an operator using an input device such as an HMI (Human Machine Interface) or a mode switching switch, or by an operator operating the arm 2 as in Patent Document 6. A control device capable of determining switching between direct teaching and constrained direct teaching is used to designate normal direct teaching without constraints or direct teaching with constraints.

The first drive control unit 121 drives the arm 2 by performing torque control based on the torque detected by the torque detection unit 4 and the torque command value calculated by the torque command value calculation unit 118 . That is, the first drive control unit 121 subtracts the torque detected by the torque detection unit 4 from the torque command value, multiplies the result by a gain, and drives the arm 2 based on the result.

Note that the torque command value calculation unit 118 and the first drive control unit 121 are the "first driven control calculation unit 13 that calculates the movement of the arm 2 according to the torque detected by the torque detection unit 4 and drives the arm 2". configure.

The second drive control section 122 drives the arm 2 according to the combined control command value obtained by the combining section 117 .

Next, an operation example of the direct teaching device 1 according to the first embodiment shown in FIG. 1 will be described.
First, an example of the operation of the direct teaching device 1 when the switching unit 119 selects normal direct teaching that does not impose restrictions as the direct teaching by the direct teaching device 1 and enables processing by the first driven control calculation unit 13. will be described with reference to FIG.

In the direct teaching device 1 according to Embodiment 1 shown in FIG. 1, when normal direct teaching without imposing restrictions is performed, as shown in FIG. Using the torque obtained, the external force applied to the arm 2 by the operator is detected (step ST201).

Next, the first driven control calculation section 13 calculates the movement of the arm 2 according to the torque detected by the torque detection section 4, and drives the arm 2 (step ST202). At this time, first, the torque command value calculator 118 calculates the torque command value detected by the torque sensor based on the external force detected by the external force detector 111 . The first drive control unit 121 drives the arm 2 by performing torque control based on the torque detected by the torque detection unit 4 and the torque command value calculated by the torque command value calculation unit 118 .

As described above, in the direct teaching device 1 according to the first embodiment, in the case of normal direct teaching without imposing restrictions, the first driven control calculation unit 13 executes control calculations so as to realize control for each joint. do.

The first driven control calculation section 13 is configured by a combination of the torque command value calculation section 118 and the first drive control section 121 . The torque detected by the torque detection unit 4 includes static disturbances such as the estimated value of the component caused by gravity and the offset value of the sensor, in addition to the external force applied by the operator. Therefore, the torque command value calculation unit 118 calculates the sum of the estimated value of the component caused by gravity in the torque detected by the torque detection unit 4 and the static disturbance such as the offset value of the sensor as the torque command value. As a result, the first drive control unit 121 can perform zero torque control (control such that the torque output by the arm 2 becomes zero or a very small value). When the operator applies an external force, the zero torque control causes the arm 2 to move so as to counteract it, and as a result the arm 2 moves in the direction of the external force applied by the operator. Through this series of operations, the direct teaching device 1 can implement follow-up control such that the arm 2 moves according to the external force applied by the operator.

Next, the switching unit 119 selects direct teaching with restrictions as the direct teaching by the direct teaching device 1, and enables processing by the second driven control calculation unit 114, the control unit, the synthesizing unit 117, and the second drive control unit 122. An example of the operation of the direct teaching device 1 in the case of , will be described with reference to FIG.

In the direct teaching device 1 according to the first embodiment shown in FIG. 1, when direct teaching with restrictions is performed, as shown in FIG. is used to detect the external force applied to the arm 2 by the operator (step ST301).

The position/orientation calculation unit 112 also calculates the position/orientation of the arm 2 based on the angle of each joint of the robot detected by the encoder 3 (step ST302). The angles of the joints of the robot detected by the encoder 3 are expressed in a joint coordinate system, and the position/orientation calculator 112 converts the angles of the joints into positions and orientations expressed in an orthogonal coordinate system.

Next, speed calculation section 113 calculates the speed of arm 2 based on the position and orientation of arm 2 calculated by position and orientation calculation section 112 (step ST303).

Next, second driven control calculation section 114 calculates the movement (driven control command value) of arm 2 according to the external force detected by external force detection section 111 (step ST304).

The position/posture control section 115 also calculates the motion of the arm 2 that satisfies the constraints on the position/posture of the arm 2 calculated by the position/posture calculation section 112 (step ST305).

In addition, speed control section 116 calculates the motion of arm 2 that satisfies the restrictions on the speed of arm 2 calculated by speed calculation section 113 (step ST306).

Next, the synthesis unit 117 obtains a synthesized control command value by synthesizing the calculation result by the second driven control calculation unit 114, the calculation result by the position/orientation control unit 115, and the calculation result by the speed control unit 116 ( step ST307).

Next, second drive control section 122 drives arm 2 according to the combined control command value obtained by combining section 117 (step ST308).

As described above, in the direct teaching device 1 according to the first embodiment, when the constrained direct teaching is performed, the movement (driven control command value) of the arm 2 according to the external force calculated by the second driven control calculation unit 114 and the position The motion of the arm 2 that satisfies the constraint on the position and orientation of the arm 2 calculated by the posture control unit 115 and the motion of the arm 2 that satisfies the constraint on the speed of the arm 2 calculated by the speed control unit 116 are synthesized.

Note that the combined control command value is a command value for each joint of the robot, such as a command value for a joint angle, joint angular velocity, or joint angular acceleration for each joint of the arm 2 . Therefore, according to the content of the direct teaching having a function of simultaneously controlling the position or speed, the second drive control unit 122 selects a suitable control method, such as position control, speed control, or acceleration control for each joint of the arm 2. Choose a control method.

As a result, in the direct teaching device 1 according to the first embodiment, it is possible to realize the movement of the arm 2 that satisfies the constraints while following the external force detected by the external force detection section 111 . Although FIG. 3 shows a case where both the position/attitude control unit 115 and the speed control unit 116 perform processing, the present invention is not limited to this. good too.

Here, when direct teaching with constraints is performed, if the joint control unit 12 performs each axis torque control, it is difficult to improve the performance of making the position and orientation follow the constraints. Therefore, if the joint control unit 12 performs position control on a joint-by-joint basis so as to suppress the positional deviation from the restrained position, it is easier to improve the overall performance by adding position and orientation follow-up performance to direct teaching.
On the other hand, during the normal direct teaching operation, light operation feeling is important, and in order to achieve this, rather than performing position or speed control for each joint, the arm 2 should be moved according to the external force. Direct control of the torque is preferable in terms of performance.

That is, in general, the joint control section 12 can be controlled with a lower delay than the main control section 11, so it is easy to increase the gain. Therefore, when zero torque control is performed by the first drive control section 121, it is advantageous in terms of performance to perform torque control.
On the other hand, in the case of direct teaching with restrictions, since the restrictions are the position and orientation or the speed of the hand, it is advantageous in terms of performance that the second drive control unit 122 performs position control, speed control, and acceleration control, respectively.

As described above, the requirements required for the control method of the joint control unit 12 are different between the restricted direct teaching and the normal direct teaching. Therefore, in the direct teaching device 1 according to the first embodiment, the control system is switched between the control system suitable for the restricted direct teaching and the normal direct teaching. That is, in the direct teaching device 1 according to the first embodiment, the control method in the joint control unit 12 is each axis torque control at the time of normal direct teaching without imposing restrictions, and the arm with restrictions at the time of direct teaching with restrictions. The control method of the joint control unit 12 is switched so that the control method is suitable for the parameter such as the position or velocity of the second hand.

As described above, according to the first embodiment, the direct teaching device 1 includes the torque detection unit 4 for detecting the torque applied to the arm 2 of the robot, and at least one of the position and orientation of the arm 2. , an external force detection unit 111 that detects an external force applied to the arm 2 based on the torque detected by the torque detection unit 4, and the torque detected by the torque detection unit 4 A first driven control calculation unit 13 that calculates the movement of the arm 2 according to the torque and drives the arm 2, and a second driven control calculation unit 114 that calculates the movement of the arm 2 according to the external force detected by the external force detection unit 111. , a control unit that calculates a motion of the arm 2 that satisfies at least one constraint on the position/orientation or velocity of the arm 2 based on the calculation result by the position/orientation calculation unit 112; A synthesizing unit 117 that synthesizes the result and the calculation result by the control unit, a second drive control unit 122 that drives the arm 2 based on the synthesizing result of the synthesizing unit 117, the first driven control calculation unit 13, or the second A switching unit 119 for effectively switching one of the driven control calculation unit 114 , the control unit, the synthesis unit 117 and the second drive control unit 122 is provided. As a result, the direct teaching device 1 according to the first embodiment can be operated with a light operational feeling when performing normal direct teaching without imposing restrictions, and when performing direct teaching with restrictions. , it is possible to realize direct teaching operation with improved overall performance.

Embodiment 2.
Embodiment 2 will explain an example of direct teaching with restrictions. Embodiment 2 describes a case where the position and orientation of the arm 2 are directly taught while being constrained to a constraint target.
FIG. 4 is a diagram showing a configuration example of the direct teaching device 1 according to the second embodiment. Unlike the direct teaching device 1 according to the first embodiment shown in FIG. 1, the direct teaching device 1 according to the second embodiment shown in FIG. Illustration is omitted. The position/posture control unit 115 also includes a position/posture target acquisition unit 1151 and a position/posture control calculation unit 1152 .

The position/posture target acquisition unit 1151 acquires a restriction target (restraint target) for the position/posture of the arm 2 .

The position/posture control computation unit 1152 computes the motion of the arm 2 according to the constraint target acquired by the position/posture target acquisition unit 1151 , where the position/posture computed by the position/posture computation unit 112 conforms to the constraint target.

Note that the synthesizing unit 117 in the second embodiment synthesizes the calculation result by the position/orientation control arithmetic unit 1152 and the driven control command value by the second driven control arithmetic unit 114 to obtain a synthetic control command value. Since the combined control command value at this time is constrained by the position and orientation of the arm 2, it is preferable to use the angle command value for each joint.
Further, the second drive control unit 122 performs position control so that the current value of each joint angle of the arm 2 becomes the command value of each joint angle, which is the combined control command value.

Here, the restraint target is the restraint destination of the position and orientation of the arm 2 .
Constraint targets for the position of the arm 2 include constraint points, constraint axes, and constraint surfaces.

A constraint point is an arbitrary point that fixes the position of the arm 2 . If the position of the arm 2 is restrained at this restraint point, it becomes impossible to change the position of the hand. At this time, if the posture is not restricted, the orientation (posture) of the hand can be changed.
A constraint axis is an axis (line) that is specified when constraining the position of the arm 2 to a certain straight line or curve (see FIG. 5). FIG. 5 shows a case where only the Z-coordinate of the arm 2 can be changed while maintaining the X-coordinate and Y-coordinate in the robot coordinate system (the arm 2 can be moved up and down).
A constraint plane is a plane that is specified when the position of the arm 2 is constrained to a plane or curved surface (see FIG. 6). FIG. 6 shows a case where the arm 2 is constrained to a constraining curved surface 601 represented by z=f(x, y) in the robot coordinate system.

Constraint targets for the posture of the arm 2 include a constraining direction, a constraining rotation axis (one), and a constraining rotation axis (two).

The restraint direction is a posture (direction) designated when the direction (posture) of the hand of the arm 2 is completely fixed in one direction (see FIG. 7). FIG. 7 shows a case where the binding direction is the direction of the arrow indicated by reference numeral 701 .

The restricted rotation axis (one) is a rotation axis when performing restriction that allows the direction of the end of the arm 2 to be changed along only one rotation axis.

The (two) restricted rotation axes are the rotation axes used when performing a restriction that allows changing the direction of the end of the arm 2 along certain two rotation axes. For example, if the rotations shown in FIGS. 8A and 8B are both allowed. In the case of FIG. 8, posture change with the X-axis and Z-axis as the rotation axes is permitted, and posture change with the Y-axis as the rotation axis is not allowed. The two rotation axes are not limited to the X, Y, and Z axes, and axes in arbitrary directions can be selected.

Also, the number of restraint targets is not limited to one, and may be plural. FIG. 9 shows an example of a constraint that combines a curved surface constraint and a directional constraint. Reference numeral 901 in FIG. 9 indicates a constraint curved surface represented by z=f(x, y) in the robot coordinate system.

As described above, the direct teaching device 1 according to the second embodiment can realize a direct teaching operation that satisfies the constraint target of the position and orientation of the arm 2 . Thus, if the only constraint is the position and orientation of the arm 2, the speed controller 116 may not necessarily be used.

When the position and orientation of the arm 2 are restricted in this way, the combined control command value is a value obtained by differentiating the command value of each joint angle with respect to time, and the second drive control unit 122 calculates the current angular velocity of each joint of the arm 2. The speed control may be performed so that the value becomes the combined control command value. Similarly, the second drive control unit 122 performs acceleration control so that the current value of the angular acceleration of each joint of the arm 2 becomes the combined control command value, with the combined control command value being the time second-order differential value of the command value of each joint angle. may be performed.

Embodiment 3.
Embodiment 3 describes another example of constrained direct teaching. In the third embodiment, a case will be described in which the speed of the arm 2 is directly taught while limiting it to a certain threshold value or less.
FIG. 10 is a diagram showing a configuration example of the direct teaching device 1 according to the third embodiment. Unlike the direct teaching device 1 according to the first embodiment shown in FIG. 1, the direct teaching device 1 according to the third embodiment shown in FIG. ing. The speed control unit 116 also has a speed target acquisition unit 1161 and a speed control calculation unit 1162 .

A speed target acquisition unit 1161 acquires a constraint target (restraint target) for the speed of the arm 2 .

The speed control calculation unit 1162 calculates the movement of the arm 2 according to the constraint target obtained by the speed target obtaining unit 1161 , where the speed calculated by the speed calculation unit 113 follows.

Synthesizing section 117 in Embodiment 3 synthesizes the calculation result of speed control computing section 1162 and the driven control command value of second driven control computing section 114 to obtain a combined control command value. Since the combined control command value at this time is restricted by the speed of the arm 2, it is preferable to use the angular velocity command value for each joint.
Further, the second drive control unit 122 performs speed control so that the current values of the joint angular velocities of the arm 2 become command values of the joint angular velocities, which are combined control command values.

Here, when the operator instructs a mode for performing direct teaching with a speed constraint using the input device, the switching unit 119 switches the joint control unit 12 so that the second drive control unit 122 is used. As a result, normal direct teaching without restrictions can be switched to direct teaching in which the speed of the arm 2 is restricted. Alternatively, a speed monitoring unit (not shown) may be separately provided to issue a switching instruction to the switching unit 119 when the speed is about to exceed the upper limit. Alternatively, an image sensor may be used to issue a switching instruction to the switching unit 119 when the arm 2 approaches an obstacle.

As described above, the direct teaching device 1 according to the third embodiment can implement a direct teaching operation that satisfies the restrictions on the speed of the arm 2 . Thus, if the only constraint is the speed of the arm 2, the position/orientation control calculator 1152 does not necessarily have to be used.

When the speed of the arm 2 is restricted in this way, the combined control command value is a value obtained by differentiating the command value of the angular velocity of each joint with respect to time. Acceleration control may be performed so that the current value becomes the combined control command value.

The control in the joint control section 12 for realizing constrained direct teaching is different from the control in normal direct teaching.

In addition, within the scope of the present invention, it is possible to freely combine each embodiment, modify any component of each embodiment, or omit any component in each embodiment. be.

1 Direct teaching device (robot control device)
2 Arm 3 Encoder 4 Torque detection unit 11 Main control unit 12 Joint control unit 13 First driven control calculation unit 111 External force detection unit 112 Position/attitude calculation unit 113 Speed calculation unit 114 Second driven control calculation unit 115 Position/attitude control unit 116 Speed Control unit 117 Synthesis unit 118 Torque command value calculation unit 119 Switching unit 121 First drive control unit 122 Second drive control unit (drive control unit)
1151 Position/attitude target acquisition unit 1152 Position/attitude control calculation unit 1161 Velocity target acquisition unit 1162 Velocity control calculation unit

Claims (4)

a torque detection unit that detects torque applied to an arm of the robot;
a position and orientation calculator that calculates a position and orientation that is at least one of a position and orientation of the arm;
an external force detection unit that detects an external force applied to the arm based on the torque detected by the torque detection unit;
a first driven control calculation unit that calculates the movement of the arm according to the torque detected by the torque detection unit and drives the arm;
a second driven control calculation unit that calculates the movement of the arm according to the external force detected by the external force detection unit;
a control unit that calculates a motion of the arm that satisfies at least one constraint on the position/posture or speed of the arm based on the result of calculation by the position/posture calculation unit;
a synthesizing unit that synthesizes the calculation result by the second driven control calculation unit and the calculation result by the control unit;
a drive control unit that drives the arm based on the result of synthesis by the synthesis unit;
A direct teaching device comprising: a switching section for effectively switching one of the first driven control calculation section, the second driven control calculation section, the control section, the synthesizing section, and the drive control section. The control unit
a position/orientation target acquiring unit that acquires a constraint target for the position/orientation of the arm;
2. The position/posture control calculation unit according to claim 1, further comprising a position/posture control calculation unit that calculates the movement of the arm according to the constraint target obtained by the position/posture target obtaining unit. Direct teaching device. a speed calculation unit that calculates a speed of the arm based on the position and orientation calculated by the position and orientation calculation unit;
The control unit
a speed target acquisition unit that acquires a constraint target for the speed of the arm;
2. The direct teaching device according to claim 1, further comprising a speed control calculation unit that calculates the movement of the arm according to the constraint target obtained by the speed target obtaining unit, the speed calculated by the speed calculation unit. a torque detection unit detecting a torque applied to an arm of the robot;
a position and orientation calculation unit calculating a position and orientation that is at least one of a position and an orientation of the arm;
an external force detection unit detecting an external force applied to the arm based on the torque detected by the torque detection unit;
a step in which the first driven control calculation unit calculates the movement of the arm according to the torque detected by the torque detection unit and drives the arm;
a second driven control calculation unit calculating the movement of the arm according to the external force detected by the external force detection unit;
a step of calculating a motion of the arm that satisfies at least one of position/orientation or speed of the arm based on the calculation result by the position/orientation calculation unit;
a combining unit combining a calculation result by the second driven control calculation unit and a calculation result by the control unit;
a drive control unit driving the arm based on the result of synthesis by the synthesis unit;
and a step in which a switching unit effectively switches one of the first driven control calculation unit, the second driven control calculation unit, the control unit, the synthesizing unit, and the drive control unit.

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