JP2023167685A - Multi-shaft system and control method of multi-shaft system - Google Patents

Abstract

To provide a multi-shaft system having a simplified system configuration and a high degree of freedom of a control method.SOLUTION: A multi-shaft system 1 includes a multi-shaft motor 4, an operation part 5, and a tool 2. The multi-shaft system 1 can perform a recording phase of recording an operation by a user and a reproduction phase of reproducing the recorded operation. In the recording phase, the multi-shaft motor 4 is controlled so as to generate a reverse driving force having an operation force acting from the operation part 5 to the multi-shaft motor 4 as a predetermined operation force command, and a controlled state of the multi-shaft motor 4 and an action force acting from the operation part 5 to an object to be processed are recorded. In the reproduction phase, the multi-shaft motor 4 is controlled to reproduce the recorded controlled state of the multi-shaft motor 4 and action force.SELECTED DRAWING: Figure 1

Description

The present invention relates to a multi-axis system and a method of controlling the multi-axis system.

In a multi-axis system, bilateral control is known in which when a user operates an arm operated by a multi-axis motor, the recorded position and orientation of the multi-axis motor are reproduced.

In the technique disclosed in Patent Document 1, a dummy robot (slave side) is used in addition to a working robot (master side). The working robot operates when an external force is applied to it by an operator, and a disturbance that acts on the working robot during operation is identified using a disturbance estimating means. At the same time, in the dummy robot, the disturbance is identified by the disturbance estimating means in a state where no external force is applied by the operator and the robot is affected by forces other than external forces such as gravity and frictional force. Then, by subtracting the disturbance force identified by the dummy robot from the disturbance force identified by the work robot, the pure external force caused by the operation can be obtained.

Japanese Patent Application Publication No. 2005-212054

According to the technique disclosed in Patent Document 1, two multi-axis systems, a working robot and a dummy robot, are required, so there is a problem that the equipment is large-scale and the installation cost may increase. Furthermore, according to the technology disclosed in Patent Document 1, pure external force is obtained by subtracting the disturbance force identified by the dummy robot from the disturbance force identified by the work robot. Among the forces applied by the robot, it is not possible to separately record the acting force acting on the workpiece via the tool and the operating force on the work robot. As a result, there is a problem in that the control method is limited, for example, it is not possible to perform advanced vibration damping control such as vibration suppression in the acceleration dimension.

The present invention has been made to solve these problems, and provides a multi-axis system that simplifies the system configuration and improves the degree of freedom of the control method by recording various parameters. Another object of the present invention is to provide a method for controlling a multi-axis system.

A multi-axis system according to one aspect of the present invention includes a multi-axis motor capable of multi-axis operation using a plurality of motors, an operation section connected to the tip of the multi-axis motor and operated by applying force by a user, and an operation section. A recording phase in which operations by the user are recorded and a reproduction phase in which the recorded operations are reproduced can be executed. In the recording phase, the multi-axis motor is controlled so that the operating force acting on the multi-axis motor from the operating unit generates a reverse driving force that becomes a predetermined operating force command, and the control state and operation of the multi-axis motor are recorded. Record the force acting on the workpiece from the part. In the reproduction phase, the multi-axis motor is controlled so that the recorded control state and acting force of the multi-axis motor are reproduced.

A method for controlling a multi-axis system according to one aspect of the present invention includes a multi-axis motor that can perform multi-axis operations using a plurality of motors, and an operating section that is connected to the tip of the multi-axis motor and that is operated by applying force to the multi-axis motor. and a tool that is connected to the operation unit and processes the workpiece, and is capable of performing a recording phase in which user operations are recorded and a reproduction phase in which the recorded operations are reproduced. It is a method of controlling the system. In the recording phase, the multi-axis motor is controlled so that the operating force acting on the multi-axis motor from the operating unit generates a reverse driving force that becomes a predetermined operating force command, and the control state and operation of the multi-axis motor are recorded. Record the force acting on the workpiece from the part. In the reproduction phase, the multi-axis motor is controlled so that the recorded control state and acting force of the multi-axis motor are reproduced.

According to a multi-axis system and a control method thereof according to one aspect of the present invention, a recording phase for recording an operation and a reproduction phase for reproducing the recorded operation are executed using one multi-axis system. , the system configuration can be simplified.

Furthermore, in the recording phase, not only various parameters related to the multi-axis motor but also the force acting on the workpiece from the tool are recorded. As a result, in the reproduction phase, the degree of freedom of the control method can be improved. As an example, hybrid control of force and position enables damping control in the acceleration dimension.

FIG. 1 is a perspective view of the multi-axis system of this embodiment in the recording phase. FIG. 2 is a perspective view of the multi-axis system in the reproduction phase. FIG. 3 is a block diagram of the controller of the multi-axis system during the recording phase. FIG. 4 is a block diagram of the controller of the multi-axis system in the reproduction phase. FIG. 5 is a timing chart showing simulation results of the operation of the multi-axis system.

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 are perspective views of the multi-axis system 1 of this embodiment. FIG. 1 shows the multi-axis system 1 in the recording phase, and FIG. 2 shows the multi-axis system 1 in the reproduction phase.

As shown in FIG. 1, in the recording phase, the tool 2 connected to the multi-axis system 1 is operated by the operator 6, and the operation is recorded in a controller (not shown). As shown in FIG. 2, in the reproduction phase, the operation of the tool 2 recorded in the recording phase is reproduced without being operated by the operator 6. Note that the recording phase is also called a direct teaching phase, and the reproduction phase is also called a motion reproduction phase.

A workpiece 3 is machined by a tool 2 included in the multi-axis system 1 . In this example, tool 2 is a polishing device and workpiece 3 is a knife blade. Then, when the tool 2 is operated by the operator 6, the workpiece 3 is processed.

The multi-axis system 1 has a multi-axis motor 4 that is attached to a fixed base and has a multi-axis structure and includes a plurality of motors. A tool 2 is attached to the tip of the multi-axis motor 4 via a handle 5. When the operator 6 operates the tool 2 via the handle 5, the workpiece 3 is processed. The handle 5 is provided with an operating force detector 7 on the multi-axis motor 4 side, and an acting force detector 8 on the workpiece 3 side. Note that the handle 5 and the acting force detector 8 are connected via a freely movable joint. Further, the multi-axis motor 4 is provided with a torsional torque detector 9 capable of detecting generated torsional torque.

Here, the force generated between the operator 6 and the multi-axis motor 4 is referred to as an operating force. The multi-shaft motor 4 has a large self-weight, inertia force caused by it, and indirect frictional force, and furthermore, since the rotating parts such as the motor are equipped with a transmission, the operator 6 can manually operate the multi-shaft motor. 4 is difficult to operate smoothly. Therefore, the multi-axis motor 4 is controlled to generate a reverse driving force such that the operating force detected by the operating force detector 7 becomes zero. As a result, the operator 6 can control the multi-axis motor 4 without applying a large force, and can apply force only to the operation of the tool 2.

Furthermore, when the operator 6 operates the tool 2, the force that acts on the workpiece 3 from the tool 2 is referred to as acting force. As mentioned above, since the handle 5 and the acting force detector 8 are connected through a freely movable joint with a low load, the acting force detector 8 detects the action from the tool 2 on the workpiece 3. force can be detected. Here, an acting force acts on the workpiece 3 from the tool 2, and a reaction force acts on the tool 2 from the workpiece 3. Therefore, the acting force detector 8 can also detect the reaction force from the workpiece 3 to the tool 2.

FIG. 3 shows the processing within the controller 10 in the recording phase. Upon receiving the input of the operating force detected from the operating force detector 7, the controller 10 calculates and outputs a current command value for the multi-axis motor 4. The controller 10 generates a current command value that provides an operating force that corresponds to an externally input operating force command value. In this example, it is assumed that the operating force command is zero, and a current command value that causes the operating force to be zero is generated. The controller 10 also includes a storage device 11, and records various parameters in time series during the recording phase.

The damping zero operating force controller 12 generates a current command value for the multi-axis motor 4 such that both zero operating force and damping control are realized. Zero operating force is a reverse drive in which when the operator 6 applies an external force to the multi-axis system 1 via the handle 5, the operating force becomes zero and the multi-axis motor 4 operates smoothly according to the external force. This is to realize the following. Generally, the self-weight, inertia force, and frictional force of the multi-axis motor 4 viewed from the load side are increased by the reducer included in the multi-axis motor 4, so these forces are reduced by reverse driving the multi-axis motor 4. Zero operation force is realized. Note that the operating force command may be a value other than zero. When the operating force command is a small value other than zero, the multi-axis motor 4 is controlled so that the operating force becomes the operating force command, so that the operator 6 can feel the operating feeling. Further, vibration generated on the load side is suppressed by the vibration damping control. The vibration damping zero operating force controller 12 is realized by known means including, for example, resonance ratio control.

Specifically, the damping zero operating force controller 12 receives input of the operating force by the operator 6 detected by the operating force detector 7 and the motor side speed fed back from the multi-axis motor 4 . Here, as described above, the damping zero operating force controller 12 further receives an operating force command, but it is assumed that the operating force command is zero. Based on these inputs, the vibration damping zero operating force controller 12 controls the operating force so that it matches the operating force command and suppresses the vibration generated in the multi-axis motor 4 (so that vibration damping control is performed). ), generates an operating force compensation current for operating the multi-axis motor 4.

The dynamic compensator 13 is a block that performs calculations according to inverse dynamics, and calculates the driving force of the multi-axis motor 4 that realizes the position and speed based on the input position and speed of the multi-axis motor 4. demand. Specifically, upon receiving the motor side position and motor side speed of the multi-axis motor 4, the dynamic compensator 13 generates a dynamic compensation current such that the driving force is realized in the multi-axis motor 4. .

The adder 14 adds the operating force compensation current output from the damping zero operating force controller 12 and the dynamic compensation current output from the dynamic compensator 13 to obtain a current command value for the multi-axis motor 4. Output as . By using such a current command value, the multi-axis motor 4 continues its current operation using the component of the dynamic compensation current, and the operating force by the operator 6 becomes zero due to the component of the operating force compensation current. controlled by.

The Jacobian matrix calculator 15 calculates the Jacobian matrix in mechanical engineering, and can determine the speed of the tip of the tool 2, which is the hand of the multi-axis motor 4, from the speed of the multi-axis motor 4 output from the multi-axis motor 4. can. Specifically, the Jacobian matrix calculator 15 can receive speed input from the multi-axis motor 4 and determine the speed of the tip of the tool 2.

The forward kinematics calculator 16 performs forward kinematics calculations in mechanical engineering, and can determine the position and orientation of the tip of the tool 2 from the displacement of the multi-axis motor 4 output from the multi-axis motor 4. Specifically, the forward kinematics calculator 16 receives position input from the multi-axis motor 4 and can determine the position and orientation of the tip of the tool 2.

The storage device 11 stores the acting force detected by the acting force detector 8 in addition to the parameter acting forces output from the damping zero operating force controller 12, the Jacobian matrix calculator 15, and the forward kinematics calculator 16. Remember. In this way, in the recording phase, the acting force from the workpiece 3 detected by the acting force detector 8, the operating force compensation current output from the vibration damping zero operating force controller 12, the operating force compensation current output from the vibration damping zero operating force controller 12, and the Jacobian matrix calculator 15 The velocity of the tip of the tool 2 outputted from the forward kinematics calculator 16 and the position/attitude of the tip of the tool 2 outputted from the forward kinematics calculator 16 are stored in the storage device 11.

In such a recording phase, both force and position recording (direct teaching) becomes possible. That is, in addition to the position, posture, and speed of the tip of the tool 2, the force acting on the workpiece 3 can be recorded. Furthermore, in the recording phase, not only zero operating force but also vibration damping control is performed. This shows that by reproducing the polishing and assembly work of skilled technicians, it is possible to replace skilled technicians with robots, which is extremely useful in industry.

FIG. 4 shows the processing within the controller 10 in the reproduction phase. In the reproduction phase, the controller 10 outputs a current command value to the multi-axis motor 4, and receives a motor-side position and a motor-side speed from the multi-axis motor 4. At the same time, the controller 10 receives the acting force on the workpiece 3 from the acting force detector 8 .

In the controller 10, similarly to the recording phase, the dynamic compensator 13, the Jacobian matrix calculator 15, and the forward kinematics calculator 16 are operating. In the reproduction phase, the feedforward current compensator 21, force controller 22, position controller 23, acceleration calculator 24, and load acceleration controller 25 further operate.

When receiving the operating force compensation current command from the storage device 11, the feedforward current compensator 21 generates a feedforward compensation current using, for example, a transfer function representing a model of the multi-axis motor 4. The operating force compensation current command corresponds to the operating force compensation current recorded in the recording phase.

Upon receiving the force command output from the storage device 11, the force controller 22 generates a force control-side acceleration command. Here, the input force command is a force corresponding to the acting force recorded in the recording phase, and the output force control side acceleration command is an acceleration command of the tip of the tool 2 that operates in response to the force command. It is. The force command corresponds to the applied force recorded during the recording phase.

The position controller 23 receives the position/attitude command and speed command output from the storage device 11, the position/attitude of the tip of the tool 2 output from the forward kinematics calculator 16, and the output from the Jacobian matrix calculator 15. The speed of the tip of tool 2 is accepted. The position controller 23 generates an acceleration command ( position control side acceleration command). The position/attitude command and the speed command correspond to the position/attitude and speed of the tip of the tool 2 recorded in the recording phase.

The acceleration calculator 24 receives a force control side acceleration command inputted from the force controller 22, a position control side acceleration command outputted from the position controller 23, and the tip of the tool 2 outputted from the Jacobian matrix calculator 15. When the speed is received, a load-side acceleration command is output.

The load-side acceleration controller 25 receives the torsion torque output from the torsion torque detector 9 and the load-side acceleration command input from the acceleration calculator 24. Since the torsional torque indicates the current operation of the multi-axis motor 4, the load-side acceleration controller 25 calculates a load-side acceleration compensation current that realizes the load-side acceleration command in the multi-axis motor 4. .

In the adder 26, the feedforward compensation current outputted from the feedforward current compensator 21, the load side acceleration compensation current outputted from the load side acceleration controller 25, and the dynamics outputted from the dynamics compensator 13. Once the sum of the compensation currents is determined, it is output to the multi-axis motor 4 as a current command value. In response to such a current command value, the multi-axis motor 4 can realize a desired load-side acceleration, so that the operation of the tool 2 can be reproduced.

In such a reproduction phase, hybrid control of force and position becomes possible. The execution block for the hybrid force and position control is indicated by a dotted line frame within the controller 10 and is designated by the reference numeral 27. If we look at the configuration of 27 in detail, based on the force control side acceleration command generated based on the force command and the position control side acceleration command generated based on the position/attitude command and the speed command, A load-side acceleration command is generated. As a result, both the previously stored position of the tool 2 and the force acting on the tool 2 can be reproduced. In this way, since control based on force in addition to position is possible, vibration suppression in the acceleration dimension can also be achieved. This shows that by reproducing the polishing and assembly work of skilled technicians, it is possible to replace skilled technicians with robots, which is extremely useful in industry.

FIG. 5 is a graph showing simulation results of the operation of the multi-axis system 1 in the recording phase. In this simulation, the acting force, the operating force, and the position (angle: rad) of the tip of the tool 2 are shown in time series. In this simulation, the operation of bringing the tool 2 into contact with the workpiece 3 from a non-contact state and pushing it back is repeatedly performed. Specifically, a state in which the operator 6 applies operating force and acting force from the tool 2 to the workpiece 3 via the multi-axis motor 4 is shown.

According to this result, the acting force momentarily increases due to the impact at the start of contact, then increases while the tool 2 is pushed into the workpiece 3, and then It becomes smaller as you move away from it, and eventually reaches zero. It can be seen that the operating force is zero except for the contact start timing and is controlled to suppress vibration. Further, the tip position of the tool 2 increases while being pushed into the workpiece 3, and decreases as it moves away from the workpiece 3. Such operations can be recorded in the recording phase, and the multi-axis motor 4 can be controlled using the recorded parameters in the reproduction phase.

In this way, in the recording phase, the operating force is controlled to be zero, so the operator 6 can operate the multi-axis motor 4 without feeling the load on the multi-axis motor 4, and at the same time is recorded in the storage device 11. Furthermore, in the reproduction phase, since force (acting force) is recorded in addition to position in the storage device 11, hybrid control using both force and position is possible.

Note that the above time-series data stored in the storage device 11 may be edited as appropriate, and the multi-axis system 1 may be reproduced using the edited data. For example, after repeating the recording phase multiple times, the reproduction phase may be executed using the average value of these parameters.

Note that in the present embodiment, the operating force of the operator 6 on the multi-axis motor 4 is detected by the operating force detector 7, but the present invention is not limited to this. As another aspect, the operating force applied to the multi-axis motor 4 may be determined based on the torsional torque detected by the torsional torque detector 9 included in the multi-axis motor 4. In yet another embodiment, a disturbance observer may be used to obtain the operating force based on the equation of motion.

According to the multi-axis system 1 shown in such an embodiment, since only one system is used, the configuration can be simplified compared to the case where two systems are used.

Furthermore, in the recording phase, the multi-axis motor 4 is controlled to generate a reverse driving force that reduces the operating force to zero, so the operator 6 can operate the multi-axis motor without feeling the load on the multi-axis motor 4. 4 is controlled. In addition to the position, attitude, and speed of the tip of the tool 2, the operating force compensation current that generates the reverse driving force and the acting force are recorded. As a result, the degree of freedom of the control method in the reproduction phase can be improved. Specifically, in the reproduction phase, vibration damping control in the acceleration dimension becomes possible through hybrid control using both the force (acting force) recorded in the storage device 11 and the position, attitude, and velocity.

The present invention is capable of various embodiments and modifications without departing from the broad spirit and scope of the invention. Moreover, the embodiments described above are for explaining the present invention, and do not limit the scope of the present invention. That is, the scope of the present invention is indicated by the claims rather than the embodiments. Various modifications made within the scope of the claims and the meaning of the invention equivalent thereto are considered to be within the scope of the present invention.

1 Multi-axis system 2 Tool 3 Workpiece 4 Multi-axis motor 5 Handle (operation part)
6 Operator 7 Operating force detector 8 Acting force detector 9 Torque detector 10 Controller 12 Vibration damping zero operating force controller 25 Load side acceleration controller

Claims (16)

A multi-axis motor that can perform multi-axis operation using multiple motors,
an operating section connected to the tip of the multi-axis motor and operated by applying force by a user;
a tool that is connected to the operation section and processes the workpiece,
A multi-axis system capable of executing a recording phase in which the operation by the user is recorded and a reproduction phase in which the recorded operation is reproduced,
In the recording phase,
controlling the multi-axis motor so that the operating force acting on the multi-axis motor from the operating unit generates a reverse driving force that becomes a predetermined operating force command;
recording the control state of the multi-axis motor and the acting force acting on the workpiece from the operating unit;
In the reproduction phase,
A multi-axis system that controls the multi-axis motor so that the recorded control state of the multi-axis motor and the acting force are reproduced. The multi-axis system according to claim 1, further comprising an acting force detection section that is provided at a connection point between the operating section and the tool and detects the acting force. The multi-axis system according to claim 2, further comprising an operating force detection section that is provided between the operating section and the multi-axis motor and detects the operating force. Further comprising a torsional torque detector provided on the multi-axis motor,
The multi-axis system according to claim 2, wherein in the recording phase, the operating force is determined based on torsional torque detected by the torsional torque detector. The multi-axis system according to claim 2, further comprising a disturbance observer capable of estimating the operating force. The multi-axis motor according to any one of claims 3 to 5, wherein in the recording phase, the multi-axis motor is controlled so as to generate the reverse driving force and suppress vibrations generated in the multi-axis motor. system. The control state of the multi-axis motor recorded in the recording phase is:
the speed of the tip of the tool, which is determined from the speed of the multi-axis motor using a Jacobian matrix;
The multi-axis system according to claim 6, comprising time-series data of the position and orientation of the tip of the tool, which are determined from the position of the multi-axis motor using forward kinematics. The current command value used to control the multi-axis motor in the recording phase is determined by using the operating force compensation current that generates the reverse driving force and the position and speed of the multi-axis motor using inverse dynamics. It is the sum of the compensation current for the shaft motor,
The multi-axis system according to claim 7, wherein the control state of the multi-axis motor recorded in the recording phase includes the operating force compensation current. In the reproduction phase, the multi-axis motor is controlled so that the speed of the tip of the tool, the position and orientation of the tip of the tool, the compensation current, and the acting force recorded in the recording phase are reproduced. 9. The multi-axis system of claim 8. The control state of the multi-axis motor and the acting force recorded in the recording phase can be changed at a time other than the recording phase,
The multi-axis system according to claim 2, wherein in the reproduction phase, the multi-axis motor is controlled so that the changed control state of the multi-axis motor and the acting force are reproduced. In the reproduction phase, the position and orientation of the tip of the tool determined from the speed of the multi-axis motor using forward kinematics and the acquired acting force are the same as the tip of the tool recorded in the recording phase. The multi-axis system according to claim 2, wherein the multi-axis motor is controlled while suppressing vibration so as to match the position and orientation of the multi-axis motor with the acting force. 3. The multi-axis system according to claim 2, wherein in the reproduction phase, the multi-axis motor is controlled while performing load-side acceleration control capable of suppressing vibration in the acceleration dimension. In the reproduction phase, the force control side acceleration command is based on the acting force recorded in the recording phase, the position and orientation of the tip of the tool recorded in the recording phase, and the speed of the tip of the tool. The multi-axis system according to claim 2, wherein the multi-axis motor is controlled by load-side acceleration control that can suppress vibration in the acceleration dimension based on a load-side acceleration command that is a sum of a position control-side acceleration command. The multi-axis system according to claim 2, wherein in the reproduction phase, feedforward control is performed using a compensation current used to control the multi-axis motor to generate the reverse driving force. The multi-axis system according to claim 8, wherein in the reproduction phase, feedforward control using the operating force compensation current is performed. A multi-axis motor that can perform multi-axis operation using multiple motors,
an operating section connected to the tip of the multi-axis motor and operated by applying force by a user;
a tool that is connected to the operation section and processes the workpiece,
There is a method for controlling a multi-axis system capable of executing a recording phase in which the operation by the user is recorded and a reproduction phase in which the recorded operation is reproduced,
In the recording phase,
controlling the multi-axis motor so that the operating force acting on the multi-axis motor from the operating unit generates a reverse driving force that becomes a predetermined operating force command;
recording the control state of the multi-axis motor and the acting force acting on the workpiece from the operating unit;
In the reproduction phase,
A method for controlling a multi-axis system, comprising controlling the multi-axis motor so that the recorded control state of the multi-axis motor and the acting force are reproduced.

Images