JP2010082784A - Method for controlling parallel link stage, and parallel link stage - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique for surely preventing damage to a signal line due to friction without requiring a larger signal line routing space than necessary in a parallel link stage. <P>SOLUTION: In the parallel link stage 7 to control the displacement of an end effector 1 by separatingly subjecting servo motors 5a to 5f of a parallel link mechanism p disposed between the end effector 1 and a base 6 to closed-loop control at a servo driver group 20, slave modules 8a to 8f disposed correspondingly to these servo motors 5a to 5f and a master module 23 connected to the servo driver group 20 are connected to one another by a serial communication cable 10. Motor position information and the like are fed back from the servo motors 5a to 5f to the servo driver group 20 by serial communication. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a parallel link stage control method and a parallel link stage.

  For example, as disclosed in Patent Document 1 and the like, a parallel link stage having a parallel link mechanism that has a high rigidity and a high degree of freedom can be used as a base for a machine tool or an observation device, a robot It is used in a wide range of application fields such as simulators for vehicles.

  By the way, in this parallel link stage, since a plurality of actuators such as servo motors are mounted in a relatively limited space between the base and the end effector, a large number of cables connected from the outside to control the actuators. The efficiency of routing is an important technical issue.

  For example, Patent Document 1 discloses a reference technique method as shown in FIG. 4 in order to prevent friction between the wiring cable of the parallel link stage 107 and the machine component.

  First, the cable clamp member 111 is arranged at the center of the base 106 positioned below the end effector 101, and wired to each servo motor 105a to 105f and each servo motor. The cable clamp member 111 is formed by two surfaces bent by 90 degrees, one surface is a mounting surface to the base 106, and the other surface is a fixing surface of the wiring cable 110.

  The wiring cable 110 is drawn into the base 106 from one place, then bent at 90 degrees with respect to the surface of the base 106, clamped on the cable clamp member 111, and connected to the servo motors 105a to 105f. Each wiring cable 110 is connected to each servo motor 105a to 105f with play so as not to obstruct the movement of the servo motors 105a to 105f.

  After the wiring cable 110 is clamped by the cable clamp member 111, it rises in the vertical direction from the surface of the base 106 and is guided such that the upper end side is radially dispersed, and the servo motors 105a to 105f move to move the wiring cable 110. However, the wiring cable 110 fixed by the cable clamp member 111 does not come into contact with the base 106 or the like even if it moves accordingly.

  That is, the wiring cable 110 is not rubbed because it does not come into contact with other constituent members, and it can be prevented that the coating of the cable is broken due to the friction and a short circuit or disconnection occurs. The wiring cable 110 is connected to the controller 121 via the servo driver 120.

  In the above-described reference technique, the cable clamp is used to prevent friction between the machine component and the wiring cable. However, a space for arranging the cable clamp member 111 on the base 106 is necessary, and there is no room for this space. In this case, the above-mentioned countermeasure cannot be realized.

In addition, since the wiring cable is laid separately for each servo motor, when there is no space between each servo motor, the wiring cable contacts the link mechanism 103 or the like, and further, the wiring itself is difficult. There is concern about becoming.
JP 2000-126954 A

  An object of the present invention is to provide a technique for reliably preventing damage due to friction of a signal line without requiring an unnecessarily large signal line routing space in a parallel link stage.

The first aspect of the present invention is:
Base and
An end effector;
A parallel link mechanism interposed between the base and the end effector and provided with a plurality of actuators;
A parallel link stage control method including:
Provided is a parallel link stage control method for controlling the operation of each actuator by performing serial communication of control signals using a signal line provided in common to the plurality of actuators.

The second aspect of the present invention is:
Base and
An end effector;
A parallel link mechanism interposed between the base and the end effector and provided with a plurality of actuators;
A signal line provided in common to the plurality of actuators;
Serial communication control means for controlling the operation of each actuator by performing serial communication of control signals using the signal line;
A parallel link stage including

  ADVANTAGE OF THE INVENTION According to this invention, the technique which prevents reliably the damage by the friction of a signal wire | line can be provided in a parallel link stage, without requiring the signal wire routing space larger than necessary.

In the parallel link stage of the present embodiment, as an example, the number of signal wires between each servo motor and servo driver is reduced as follows.
That is, in the first aspect of the present embodiment, a servo motor for moving the parallel link stage, a servo driver for driving the servo motor, an encoder and a sensor for detecting a machine position, and the servo A controller is provided for controlling the driver.

  In the vicinity of the servo motor, there are as many slave modules as the servo motor, and the signals from the encoder and the sensor are taken in, converted into parallel / serial, and serially using a common signal line. Send as a signal.

A master module is provided near the servo driver, which receives the serial signal from the slave module, performs serial / parallel conversion, and transmits an encoder signal and a sensor signal to each servo driver.

  Further, in the serial communication method according to the second aspect of the present embodiment, each servo motor is provided with as many slave modules as the number of servo motors that transmit serial communication, and is transmitted from the master module. Only the slave module that has received the transmission request transmits a signal.

The operation of the parallel link stage of each aspect in the present embodiment will be described below.
In the present embodiment, signals from the encoders of the servo motors and signals from the sensors are captured by each slave module, and the captured signals are parallel / serial converted and transmitted. The master module installed on the driver side controls the timing at which each slave module sends a signal. The master module sends a transmission request, and only the slave module that receives the transmission request starts sending the serial signal. To do.

  The master module that has received the serial signal performs serial / parallel conversion and transmits an encoder signal and a sensor signal to each servo driver. By using the time division multiplexing method in this way, it is possible to avoid contact with the machine component by physically reducing the number of wires physically.

  That is, a signal common to each servo motor encoder signal and sensor signal transmission between the slave modules installed in each servo motor, that is, a plurality of slave modules and one master module installed near the servo driver. By using a time-division multiplexing method using lines, it is possible to logically realize a large number of wiring cables conventionally required with a single wiring cable.

  By greatly reducing the number of wiring cables in this way, it is possible to avoid contact between the wiring cables and the machine components without requiring an unnecessarily large routing space, and wiring is easy. It becomes.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(Constitution)
FIG. 1 is a side view showing an example of the configuration of a parallel link stage that implements a method for controlling a parallel link stage according to an embodiment of the present invention.

FIG. 2 is a conceptual diagram showing a configuration example of a control system in the parallel link stage of the present embodiment.
FIG. 3 is a conceptual diagram showing an example of serial communication of the control system in the parallel link stage of the present embodiment.

  In this embodiment, as an example, a parallel link stage 7 including a parallel link mechanism p capable of relative motion of 6 degrees of freedom in total of 3 degrees of freedom of translation and 3 degrees of freedom of rotation will be described.

  As illustrated in FIG. 1, the parallel link stage 7 of the present embodiment is disposed between an end effector 1 that is a stage that moves in six degrees of freedom, a base 6, and between the end effector 1 and the base 6. A parallel link mechanism p, a servo driver group 20 (servo drivers 20a to 20f) for controlling the parallel link mechanism p, and a controller 21 are provided.

The controller 21 realizes a desired displacement in the end effector 1 by controlling the operation of the parallel link mechanism p through the servo driver group 20 as described later.
The parallel link mechanism p includes a movable link 2a, a movable link 2b, a movable link 2c, a movable link 2d, a movable link 2e, and a movable link 2f connected to the end effector 1.

  The parallel link mechanism p includes a servo link 5a, a servo link 5a, a servo motor 5b, a servo motor 5c, a servo motor 5e, and a servo motor 5f (actuator). 4b, a drive link 4c, a drive link 4d, a drive link 4e, and a drive link 4f are provided.

The drive link 4a to the drive link 4f are formed of, for example, a ball screw, and convert the rotational displacement of each of the servo motors 5a to 5f into an axial expansion / contraction displacement.
Further, the parallel link mechanism p has a plurality of links 3a, links 3b, links 3c, links 3d, links 3e, one end of which is connected to each of the drive links 4a to 4f and the other end of each of the movable links 2a to 2f. A link 3f is provided.

  The individual servo motors 5a, 5b, 5c, 5d, 5e, 5f of the parallel link mechanism p are provided with position detecting encoders 30a, 30b, 30c, 30d, 30e, 30f.

The encoders 30a to 30f output the rotational positions of the corresponding servo motors 5a to 5f as encoder signals SE.
Each of the servo motors 5a to 5f is driven by the corresponding servo driver 20a to servo driver 20f via the power signal cable 9.

  Although not particularly illustrated, the parallel link mechanism p includes a sensor that detects information such as an expansion position, a displacement amount, a speed, and an acceleration of each of the links 3a to 3f driven by each of the servo motors 5a to 5f. Provided and output as sensor signals S1 to S3.

  In the case of the present embodiment, control signals such as the encoder signal SE and sensor signals S1 to S3 between the parallel link mechanism p and the servo driver group 20 are sent to a single serial communication cable 10 (signal line). Via serial communication.

  That is, in the case of the present embodiment, each of the individual servo motors 5a to 5f is provided with slave modules 8a, 8b, 8c, 8d, 8e, and 8f. A master module 23 (serial communication control means) that is commonly connected to these via the communication cable 10 is provided.

  The serial communication cable 10 has a configuration in which a data line 10a used for serial communication of control signals and a power supply line 10b for supplying power to the slave modules 8a to 8f (serial communication control means) are bundled together. It has become.

  The slave modules 8a, 8b, 8c, 8d, 8e, and 8f receive the encoder signals SE and sensor signals S1 to S3 from the encoders 30a, 30b, 30c, 30d, 30e, and 30f, and serial communication of the received signals. And send it to the master module 23 via the serial communication cable 10.

The master module 23 is connected to the servo drivers 20a to 20f of the servo driver group 20 via the parallel communication cable 22, and control signals from each of the slave modules 8a, 8b, 8c, 8d, 8e, and 8f. Are distributed and transmitted to each of the corresponding servo drivers 20a to 20f.

With reference to FIG. 2, the structure of the control system by serial communication in the parallel link stage 7 of this Embodiment is demonstrated in detail.
As illustrated in FIG. 2, each of the slave modules 8a to 8f provided corresponding to each of the servo motor 5a to the servo motor 5f includes a signal holding circuit 31a to f, a timing signal generation circuit 32a to f, It includes parallel / serial conversion circuits 33a-f, own station ID detection circuits 34a-f, serial / parallel conversion circuits 35a-f, line drivers 36a-f, line receivers 37a-f, and power supply circuits 38a-f.

  Since the slave module 8a to the slave module 8f have the same configuration, the components other than the slave module 8a are simplified in FIG. Hereinafter, the internal configuration will be described focusing on the slave module 8a.

The signal holding circuit 31a holds the encoder signal SE and sensor signals S1 to S3 from the encoder 30a at a prescribed timing.
The parallel / serial conversion circuit 33a performs parallel / serial conversion on the signal from the signal holding circuit 31a.

The line driver 36a sends out a serial signal from the parallel / serial conversion circuit 33a.
The line receiver 37a receives the transmission request signal from the master module 23.

The serial / parallel conversion circuit 35a performs serial / parallel conversion for converting the serial communication signal received by the line receiver 37a into a parallel communication signal.
The own station ID detection circuit 34a detects whether or not the parallel signal from the serial / parallel conversion circuit 35a has the ID of the own station (identification information of the slave modules 8a to 8f on the serial communication cable 10). .

The timing signal generation circuit 32a generates a timing signal necessary for each circuit block in the slave module 8a.
The power supply circuit 38a supplies the power received from the master module 23 side through the power supply line 10b to each circuit block described above.

  On the other hand, the master module 23 provided on the servo driver group 20 side includes a line receiver 50, a line driver 51, a serial / parallel conversion circuit 52, a signal holding circuit 53, an ID generation circuit 54, a timing signal generation circuit 55, and a power supply circuit. 56.

  The line receiver 50 is connected to the data line 10a of the serial communication cable 10 and receives serial communication signals transmitted from the line drivers 36a to 36f of the slave modules 8a to 8f.

The serial / parallel conversion circuit 52 performs serial / parallel conversion for converting the serial communication signal from the line receiver 50 into a parallel communication signal.
The signal holding circuit 53 holds parallel signals corresponding to each of the slave modules 8a to 8f coming from the serial / parallel conversion circuit 52 at a prescribed timing.

The signal holding circuit 53 is connected to each of the servo drivers 20a to 20f of the upper servo driver group 20 via the parallel communication cable 22.
Then, parallel communication signals corresponding to each of the slave modules 8a to 8f held in the signal holding circuit 53 are transmitted in parallel to the corresponding servo drivers 20a to 20f.

  The ID generation circuit 54 includes one piece of identification information (servo motor described later) from the servo motor 5a included in the transmission request 72 sent as described later to each of the slave modules 8a to 8f. Identification information 74b) is generated.

The line driver 51 sends a transmission request 72 including the servo motor identification information 74 b output from the ID generation circuit 54 to the data line 10 a of the serial communication cable 10.
The timing signal generation circuit 55 generates a timing signal necessary for each circuit block in the master module 23.

  The power supply circuit 56 supplies power to the above-described circuit blocks in the master module 23, and supplies power to each of the slave modules 8a to 8f via the power supply line 10b of the serial communication cable 10.

  FIG. 3 shows an example of transmission / reception timing of serial communication placed between the master module 23 via the serial communication cable 10 and each of the plurality of slave modules 8a to 8f in the parallel link stage 7 of the present embodiment. FIG.

  In the transmission request 72, each of the slave modules 8a to 8f from the master module 23 using the transmission request signal 70a, the transmission request signal 70b, the transmission request signal 70c, the transmission request signal 70d, the transmission request signal 70e, and the transmission request signal 70f. A transmission request for a response frame 74 (control signal) to be described later is made.

Each of the transmission request signal 70a to the transmission request signal 70f includes servo motor identification information 74b of the servo motors 5a to 5f to be controlled.
On the other hand, a response 73 indicates a response signal 71a, a response signal 71b, a response signal 71c, a response signal 71d, a response signal 71e, and a response signal 71f from each of the slave modules 8a to 8f to the master module 23.

For the convenience of illustration, FIG. 3 shows the transmission request signal 70a to the transmission request signal 70c and the corresponding response signal 71a to the response signal 71c.
In the case of the present embodiment, each of the response signal 71a to the response signal 71f includes a response frame 74 generated by each of the slave modules 8a to 8f.

  The response frame 74 is composed of a header portion 74a, servo motor identification information 74b, encoder value 74c, sensor signal 74d, and error correction code portion 74e in this order from the top.

Information indicating the start position of the response frame 74 is set in the header portion 74a.
In the servo motor identification information 74b, information for identifying any one of the servo motors 5a to 5f is set.

In the encoder value 74c, the value of the encoder signal SE output from each of the encoders 30a to 30f of the servo motors 5a to 5f is set.
The sensor signals S1 to S3 described above are set in the sensor signal 74d.

Information such as a cyclic redundancy code (CRC) for improving the reliability of the entire response frame 74 is set in the error correction code unit 74e.
Each of the transmission request signal 70a to the transmission request signal 70f indicates a transmission request signal for each of the slave module 8a to the slave module 8f. Correspondingly, each of the response signal 71a to the response signal 71f is the slave module. A response frame 74 sent from each of 8a to 8f to the master module 23 is shown.
(Function)
An example of the operation of the parallel link stage 7 of the present embodiment will be described.

First, the overall operation of the parallel link stage 7 will be briefly described.
In order to displace the end effector 1 of the parallel link stage 7 to a predetermined position, the controller 21 instructs the servo driver group 20 to operate the necessary servo motors 5a to 5f, and appropriately expands and contracts the links 3a to 3f. Displace.

  In each of the servo drivers 20a to 20f of the servo driver group 20, an operation command (drive current) is given to each of the corresponding servo motors 5a to 5f via the power signal cable 9, and actually The closed loop control for detecting the displacement of the mechanical parts such as the servo motors 5a to 5f and the links 3a to 3f by the encoder signals SE and the sensor signals S1 to S3 output from the encoders 30a to 30f is performed. .

  In this closed loop control, for example, when attention is paid to one slave module 8a provided corresponding to the servo motor 5a, the encoder signal SE and the sensor signals S1 to S3 from the encoder 30a are generated in the signal holding circuit 31a. It is held at the specified timing generated by the circuit 32a.

Next, the held signal is parallel / serial converted by the parallel / serial conversion circuit 33a to generate a response frame 74.
Next, the serially converted response frame 74 is sent to the line receiver 50 of the master module 23 by the line driver 36a.

  At this time, the line driver 36a has an enable / disable function, and the serial signal from the line driver 36a is not output unless the enable given from the local station ID detection circuit 34a is valid.

  The condition for enabling the enable from the own station ID detection circuit 34a is that the servo corresponding to the servo motor 5a in the transmission request 72 generated by the ID generation circuit 54 of the master module 23 and transmitted by the line driver 51. This is only when the transmission request signal 70a including the motor identification information 74b is received.

  The transmission request 72 (transmission request signal 70a) is received by the line receiver 37a, serial-parallel converted by the serial / parallel conversion circuit 35a, and then detected by the local station ID detection circuit 34a.

The response signal 71a (response frame 74), which is a serial signal output from the line driver 36a of the slave module 8a, is received by the line receiver 50 of the master module 23 by the enable / disable function, and serial / parallel conversion is performed. The signal is converted from serial to parallel by the circuit 52, held by the signal holding circuit 53, and output to the servo driver 20a corresponding to the slave module 8a.

The same operation is performed in the other slave modules 8b to 8f.
As a result, the response signal 71a output from one slave module 8a and the response signals 71b to 71f output from the other slave modules 8b, 8c, 8d, 8e, and 8f do not collide with each other. Serial communication between each of the 8a to 8f slave modules and each of the servo drivers 20f and the servo drivers 20f of the servo driver group 20 is possible.

  Further, by sufficiently increasing the communication frequency of the data line 10a of the serial communication cable 10, a transmission delay of the response frame 74 (response signal 71a to response signal 71f) from each of the slave modules 8a to 8f occurs. In addition, the closed-loop control of the parallel link stage 7 in real time is possible.

  In this way, by shifting the output timings of the plurality of outputs from the slave modules 8a to 8f provided in each of the plurality of servo motors 5a to 5f with respect to the master module 23, Many-to-one communication is possible on one logical line (serial communication cable 10), and the number of wiring cables between the parallel link mechanism p of the parallel link stage 7 and the servo driver group 20 can be greatly reduced.

  In other words, in the parallel link stage 7, it is possible to reliably prevent damage due to friction of the signal lines without requiring an unnecessarily large routing space for the signal lines such as the serial communication cable 10.

  That is, according to the parallel link stage 7 of the embodiment of the present invention as described above, in the configuration in which the servo motors 5a to 5f are concentratedly arranged at the center of the parallel link mechanism p, the servo motor 5a to the servo motor are arranged. The number of cable connections of the parallel link structure that makes it difficult to route the wiring cable between 5f and the servo driver group 20 is reduced, and damage to the serial communication cable 10 due to contact with the machine component is prevented, and serial communication The cable 10 can be easily routed.

Furthermore, by reducing the number of signal cables, it is possible to reduce the size of the parallel link stage 7 and reduce the installation space and manufacturing cost.
Needless to say, the present invention is not limited to the configuration exemplified in the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

For example, the actuator is not limited to a servo motor, and other displacement generating means such as a fluid pressure cylinder, a solenoid, and a piezoelectric element may be used.
(Appendix 1)
A base, an end effector, a drive link having a servo motor fixed to the base, a movable link coupled to the end effector, at least three coupled to the drive link at one end and the movable link at the other end In the parallel link stage having the links, the encoder signal and the sensor signal between each servo motor and the servo driver are serially communicated and communicated logically through one line.

(Appendix 2)
In the parallel link stage described in Appendix 1,
As a means of serial communication, the servo driver side has a master module that receives information on the parallel link stage machine component side via serial communication, and each servo motor side serializes the information on the parallel link stage machine component side. A parallel link stage characterized in that the number of servo modules to be transmitted by communication is the same as the number of servo motors, and a signal is transmitted only to the slave module that has received a transmission request from the master module.

It is a side view which shows an example of a structure of the parallel link stage which enforces the control method of the parallel link stage which is one embodiment of this invention. It is a conceptual diagram which shows the structural example of the control system in the parallel link stage which is one embodiment of this invention. It is a conceptual diagram which shows an example of the serial communication of the control system in the parallel link stage which is one embodiment of this invention. It is a side view which shows the parallel link stage of the reference technique of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 End effector 2a-2f Movable link 3a-3f Link 4a-4f Drive link 5a-5f Servo motor 6 Base 7 Parallel link stage 8a-8f Slave module 9 Power signal cable 10 Serial communication cable 10a Data line 10b Power line 20 Servo driver Group 20a-20f Servo driver 21 Controller 22 Parallel communication cable 23 Master module 30 Encoder 30a-30f Encoder 31a-f Signal holding circuit 32a-f Timing signal generation circuit 33a-f Parallel / serial conversion circuit 34a-f Own station ID detection circuit 35a-f Serial / parallel conversion circuit 36a-f Line driver 37a-f Line receiver 38a-f Power supply circuit 50 Line receiver 51 Line driver 52 Serial / parallel conversion circuit 5 3 Signal holding circuit 54 ID generation circuit 55 Timing signal generation circuit 56 Power supply circuits 70a to 70f Transmission request signals 71a to 71f Response signal 72 Transmission request 73 Response 74 Response frame 74a Header part 74b Servo motor identification information 74c Encoder value 74d Sensor signal 74e Error correction code units S1 to S3 Sensor signal SE Rotational position signal p Parallel link mechanism

Claims (6)

Base and
An end effector;
A parallel link mechanism interposed between the base and the end effector and provided with a plurality of actuators;
A parallel link stage control method including:
A method for controlling a parallel link stage, comprising: performing serial communication of control signals using a signal line provided in common to the plurality of actuators to control the operation of each of the actuators. The parallel link stage control method according to claim 1,
A method for controlling a parallel link stage, wherein only the control signal related to the actuator that has received a transmission request is selectively transmitted by the serial communication. In the control method of the parallel link stage of Claim 1 or Claim 2,
The actuator comprises a servo motor,
The control signal including at least one of an encoder signal indicating the rotational position of each of the plurality of servo motors and a sensor signal indicating a displacement state of the parallel link mechanism is transmitted to the control side of the servo motor by the serial communication. A method for controlling a parallel link stage. Base and
An end effector;
A parallel link mechanism interposed between the base and the end effector and provided with a plurality of actuators;
A signal line provided in common to the plurality of actuators;
Serial communication control means for controlling the operation of each actuator by performing serial communication of control signals using the signal line;
The parallel link stage characterized by including. The parallel link stage according to claim 4,
The serial communication control means includes
A slave module that is provided for each of the actuators of the parallel link mechanism, and that transmits and receives the control signal related to the actuators by the serial communication;
A master module that is provided on the side of an actuator driving unit that controls a plurality of the actuators from the outside, and that transmits and receives the control signals by the serial communication;
The parallel link stage characterized by including. The parallel link stage according to claim 5,
The actuator comprises a servo motor,
The control signal including at least one of an encoder signal indicating each rotational position of the plurality of servo motors and a sensor signal indicating a displacement state of the parallel link mechanism is transmitted from the slave module to the master module by the serial communication. A parallel link stage characterized by transmitting.