JP2011152620A - Robot arm driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a robot arm driving device which increases a movable range of the robot arm using artificial muscles as an actuator, and prevents breakdown of the actuator due to reaction force from the front end of the arm. <P>SOLUTION: The robot arm driving device includes a pulley 201; a link 213 directly connected to the pulley; wires 207, 208, 211, and 212; and a motor 202. The robot arm driving device also includes a warm 203, a warm wheel 204, wire winding pulleys 205 and 206; wire guide mechanisms 214 and 215; and the artificial muscles 209 and 210 in the middle of the wires. The warm is driven by the motor. The rotation of the warm is transmitted to the warm wheel. The wire winding pulleys are installed in the shaft of the warm wheel. The pulleys are driven by the tension of the wires. In a warm gear, the torque from the load side is hardly transmitted to the motor, causing no damage to the motor. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a driving device for a robot arm that works safely in a human environment.

  Next-generation robots that coexist with humans are required to be safe, but a drive mechanism equipped with a speed reducer and an electric motor, like current industrial robots, cannot ensure safety. This is because the current industrial robot demands accuracy (positioning, locus, etc.), and as a result, its own weight increases. More specifically, in order to ensure high accuracy, it is necessary to reduce the deflection of the arm. As a result, in order to increase the rigidity of the arm, since the high-rigidity material is heavy, the weight of the arm increases. In addition, a large speed reducer is necessary because the torque is small with only an electric motor, and using a large speed reducer reduces load inertia from the motor and improves motion performance, but increases moment and is dangerous when touching people. There are cases.

  Therefore, there is a demand for a drive mechanism that does not cause a problem even if it comes into contact with a person. For example, as one of the drive mechanisms, there is a mechanism using artificial muscles such as a McKibben type pneumatic actuator. In addition to the merit of softness, this artificial muscle has the merit of large generation force but has the demerit of low response characteristics. Furthermore, in the robot arm example where the McKibben type pneumatic actuator is the driving source and the wire is the transmission mechanism, and the displacement due to the extension of the actuator gives the rotational displacement of the pulley and the link, the controllability is caused by the generation of minute vibrations due to the elasticity of the actuator itself. There is a general problem that is bad.

  In order to solve this general technical problem, an actuator control device for which a conventional robot hand is applied is a highly responsive actuator such as an electric motor and a large force such as an artificial muscle or a spring element, but is responsive. The control performance of the robot hand is improved by using a low actuator. (For example, refer patent document 1) Moreover, there also exists what was equipped with the brake means which suppresses a motion of a rotation member (for example, refer patent document 2).

  In FIG. 3, the relative angle between the link 303 and the link 304 is determined by the expansion and contraction of the artificial muscle 302 composed of a polymer actuator such as a shape memory alloy, a hydrogen storage alloy actuator, or ionic EAP, and the rotation drive of the electric motor 301. Be controlled. In particular, the minute vibration of the artificial muscle 302 can be suppressed by driving the electric motor 301 with high response.

  In FIG. 4, by supplying compressed air from the fitting 406 to the artificial muscle 403, a contraction force is generated in the axial direction, and the contraction force rotates the pulley 401. The pulley 401 is supported by a frame member 405. Further, since the pulley 401 is rotated by the contraction force of the artificial muscle 403, it is supported by the fixing member 404. A brake drum 402 is disposed on the rotation shaft of the pulley 401, and the pulley 402 stops when the brake cam 409 contacts the brake shoe 407 and the brake shoe 407 contacts the brake drum 402. The brake cam 409 is controlled by antagonizing the force of the tension spring 410 and the artificial muscle 411.

  As described above, the conventional actuator device for a robot suppresses the minute vibration of the artificial muscle with the electric motor or the minute vibration of the artificial muscle with the brake mechanism.

JP 2008-87143 A (page 5-7, FIG. 1A) Sho 61-14887 (6th page, Fig. 1)

  However, since the artificial muscle drives the joint by the expansion / contraction operation, and the expansion / contraction amount is about 30% of the total length of the artificial muscle, the technology has a small joint movable range compared to the joint actuator by the electric motor and the speed reducer. There was a problem.

  The present invention has been made in view of these problems, and when using a McKibben type pneumatic actuator, the movable range can be expanded, and the robot arm drive capable of reliably moving and fixing the McKibben type pneumatic actuator. An object is to provide an apparatus.

  In order to solve the above problem, the present invention is configured as follows.

  The invention according to claim 1 is a robot arm driving device including an arm, a pulley, a wire, and an electric motor, and includes a worm, a worm wheel, a wire take-up pulley, and a wire guide mechanism, and the electric motor The worm is driven, the rotation of the worm is transmitted to the worm wheel, the shaft of the worm wheel is provided with the wire take-up pulley, and the pulley is driven by the tension of the wire. It is.

  The invention according to claim 2 is characterized in that an artificial muscle is provided between the wire and the pulley.

  The invention described in claim 3 is characterized in that a coupling and a second electric motor are provided.

  According to a fourth aspect of the present invention, there is provided a wire guide mechanism including a ball screw that changes to linear motion in synchronization with the rotation of the worm, and a movable table with a wire through hole.

  According to the first aspect of the invention, the pulley and the arm can be driven by one actuator, and the worm gear does not easily transmit the torque from the load side to the electric motor, so that the electric motor is not broken.

  Further, according to the invention described in claim 2, since the artificial muscle is provided, the weight of the arm can be increased, and the soft force of the artificial muscle can absorb the reaction force even if the arm hits a person. Since the torque from the load side is not easily transmitted to the motor, the motor is not broken.

  According to the invention described in claim 3, since the arm shaft is provided with the electric motor, it is possible to suppress the minute vibration at the time of stopping.

  Moreover, according to invention of Claim 4, since a wire guide mechanism is provided, the lifetime of a wire can be extended compared with the conventional usage method.

1 is a side sectional view of a robot arm driving apparatus showing a first embodiment of the present invention. Side sectional view of a robot arm driving apparatus showing a second embodiment of the present invention. Side view of a conventional actuator control device Sectional view showing the operation of a conventional robot arm Sectional view of the wire guide mechanism of the present invention Side sectional view of a robot arm driving apparatus showing a third embodiment of the present invention. Block diagram of the control device of the present invention

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a side view of a robot arm driving apparatus for explaining a first embodiment of the present invention. In the figure, the ends of the wires 107 and 108 are connected to the pulley 101 and the wire take-up pulleys 105 and 106, and the worm wheel 104 is driven by the rotation of the worm 103 connected to the electric motor 102, and the wire connected to the worm wheel 104. Driving the take-up pulleys 105 and 106 drives the pulley 101. When the pulley 101 is driven, the linked link 109 is driven. In order to angle-control the pulley 101 and the link 109 with high accuracy, the angle information of the encoder 112 is used. The merit of using the worm gear composed of the worm 103 and the worm wheel 104 is that the worm gear has a large frictional force, and the motor 102 does not move due to the reaction force from the load side. It is in the point which can maintain a stop state. In this robot arm mechanism, the wire winding pulleys 106 and 107 change the wire winding direction in order to realize the antagonistic operation of the pulley 101. For example, when the wire take-up pulley 106 is clockwise and the worm wheel 104 is turned clockwise, the wire 108 is taken up by the wire take-up pulley 106, and the wire 107 is released by the wire take-up pulley 105. The antagonistic operation of the pulley 101 can be realized. Furthermore, if the wires 107 and 108 are wound so as to overlap at the same position of the wire winding pulleys 105 and 106, the wire is easily scratched, and the wire release amount and the winding amount are different. May change, resulting in a shortened life of the wire. Therefore, in order to avoid the wires overlapping at the same place on the pulley, a wire guide mechanism was provided.

  Details of the peripheral technology of the wire guide mechanism will be described with reference to FIG. A cross-sectional view of the wire take-up pulley is shown in FIG. 5a, and the wire 501 is fixed by a wire fixing jig 503 inside the wire take-up pulley through one hole formed in the wire take-up pulley 502. ing. The wire fixing jig 503 may be a screw or a method for fixing a wire by welding. As a result, the wire 501 can be prevented from coming off the wire take-up pulley 502.

  Next, the detailed drawing of the wire guide mechanism is FIG. 5b. A gear 504 and a wire take-up pulley 502 are directly connected to the worm wheel 104 of FIG. 1 via a shaft 505. When the gear 504 is rotationally driven, the wire guide mechanism 508 is linearly driven when the gear 506 and the ball screw 507 are rotated. In synchronization with the rotation of the gear 506, the wire guide mechanism 508 moves forward and backward by the pitch movement amount of the ball screw 507, and the wire 501 is wound so as not to overlap at the same place on the wire winding pulley 502. The original durability can be maintained.

  Next, the detailed drawing (FIG. 5c) of the wire guide mechanism of the link 518 will be described. The pulley 510, the bevel gear 511, and the link 518 are directly connected to the shaft 512, and the bevel gear 511 rotates in the direction in which the wire 501 is pulled. When the bevel gear 511 rotates, when the bevel gear 513 orthogonal to the bevel gear 511 rotates, the pulleys 514 and 515 directly connected to the bevel gear 513 rotate. The transmission element of the pulleys 514 and 515 is a wire 516, and a wire guide mechanism 517 coupled to the wire 516 moves in synchronization with the wire 516. The wire guide mechanism 517 has a wire through hole and is wound so that the wire 501 does not overlap the pulley 510. By providing this mechanism, the inherent durability of the wire can be maintained even on the link side. The transmission element of the wire 516 described here may be a belt. Using a belt can increase the durability of the guide mechanism.

  FIG. 2 is a side view of a robot arm driving apparatus for explaining a second embodiment of the present invention. In the figure, wires 207 and 208 are connected to one ends of the artificial muscles 209 and 210, and the wires 211 and 212 are connected to pulleys 205 and 206. The artificial muscles 209 and 210 contract and expand by discharging and supplying air. As a result, there is a basic robot arm mechanism in which the pulleys 201 rotate and the links 213 directly connected to the pulleys 201 are driven when the wires 207 and 208 perform antagonistic operations. This robot arm mechanism has a problem that the rotation angle of the link 213 is small because the amount of expansion and contraction of the artificial muscle is limited. Therefore, the problem can be solved by providing a worm gear and an electric motor. Furthermore, when the worm gear is used, the electric motor is not subjected to a load reaction force, so that there is an advantage that the electric motor is not broken. In order to control the angle of the pulley 201 and the link 213 with high accuracy using the artificial muscles 209 and 210, the angle information of the encoder 216 is used. In the figure, the ends of the wires 207 and 208 are connected to the pulley 201 and the artificial muscles 209 and 210, the other ends of the artificial muscles 209 and 210 are connected to the pulleys 205 and 206, and the rotation of the worm 203 connected to the electric motor 202 The worm wheel 204 and the wire take-up pulleys 205 and 206 are driven, and the wires 211 and 212 are driven in an antagonistic manner. According to the antagonistic drive of the wires 211 and 212, the artificial muscles 209 and 210 move, the pulley 201 rotates, and the link 213 rotates. The artificial muscles 209 and 210 are compressed / expanded by air exhaust / intake, but since the displacement is about 30% of the length of the artificial muscle, there is a demerit that the rotation angle of the link is small. The rotation angle range can be expanded by the worm gear (worm 203, worm wheel 204) and electric motor 202 shown.

  The artificial muscles 209 and 210 described here are McKibben pneumatic actuators, which can absorb the reaction force of the link 213 due to the softness of the rubber material, and are expected as actuators that realize a safe robot. However, contrary to the merit of being soft, there is a demerit of poor control performance. The control performance here is the speed of response and the stopping accuracy. The artificial muscle has a slower response than the electric motor, and in order to improve this disadvantage, a drawing in which the second electric motor is provided on the opposite side of the link 213 of the pulley 201 in FIG. 2 will be described with reference to FIG. The basic configuration is the same as in FIG. 2 except that the pulley 601 is disposed between the link 613 and the second electric motor 616, and the link 613 and the electric motor 616 rotate in the same direction as the pulley 601.

  Next, a method for controlling the robot arm will be described. The robot arm is configured as shown in FIG. 6, and the actuators are artificial muscles 609 and 610 and electric motors 602 and 616. For the angles of the pulley 601 and the link 613, an encoder built in the electric motor 616 is used. When controlling the pulley 601 and the link 613 to a certain angle, the angle command 701 and the angle deviation of the encoder 705 are input to the first motor control unit 702, and the current command that is the output of the first motor control unit 702 is input to the first motor 703. To generate torque of the first electric motor, and angle control of the pulley and the link 704 is performed. The encoder 705 is a sensor built in the second electric motor. Since the artificial muscle actuator 708 and the second electric motor 711 only need to move so as to follow the speed of the first electric motor, when the angular velocity command 706 and the deviation of the angular velocity are input to the compressor control unit 707, the output air intake amount and The displacement is controlled, and by the compression / expansion of the artificial muscle actuator 708, the artificial muscle actuator 708 is controlled in angular velocity so as to be synchronized with the movement of the pulley and link 704. Similarly, when the second motor also inputs the angular velocity command 706 and the angular velocity deviation to the second motor control unit 710, a current command is output, and the second motor 711 is angularly controlled based on the current command. The angular velocity is a result obtained by performing a difference calculation 709 on the angle signal of the encoder 705.

When driving joints using artificial muscles, the demerit that the joint angle range is small can be overcome using worm gears and electric motors, so it can be applied to robot finger joints.

101, 201, 401, 509, 514, 515, 601 Pulley 102, 202, 301, 602, 616 Motor 109, 213, 303, 304, 517, 613 Link 103, 203, 603 Worm 104, 204, 604 Worm wheel 105 106, 205, 206, 502, 605, 606 Wire take-up pulleys 209, 210, 302, 403, 411, 609, 610, 708 Artificial muscles 107, 108, 207, 208, 211, 212, 501, 516, 607 608,
611, 612 Wire 110, 111, 214, 215, 508, 517, 614, 615 Wire guide mechanism 112, 216, 705 Encoder 402 Brake drum 404 Fixing member 405 Frame member 406 Fitting 407 Brake shoe 408 Lever arm 409 Brake cam 410 Pull Spring 503 Wire fixing jig 504, 506, 510, 512 Gear 507 Ball screw 509 Wire guide hole 505, 512 Shaft 511, 513 Bevel gear 701 Angle command 702, 710 Motor controller 703, 711 Motor 704 Pulley link 706 Angular speed command 707 Compressor control unit 709, 712 Difference calculation

Claims (4)

In a robot arm drive device comprising an arm, a pulley, a wire, and an electric motor,
A worm, a worm wheel, a wire take-up pulley, and a wire guide mechanism are provided, the worm is driven by the electric motor, the rotation of the worm is transmitted to the worm wheel, and the wire is taken up on the shaft of the worm wheel. A robot arm driving device comprising a pulley and driving the pulley by tension of the wire.   2. The robot arm driving apparatus according to claim 1, further comprising an artificial muscle between the wire and the pulley.   3. The robot arm driving device according to claim 2, further comprising a coupling and a second electric motor. The wire guide mechanism according to claim 1, further comprising a ball screw that changes into linear motion in synchronization with the rotation of the worm, and a movable table with a wire through hole.

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