JP2019111597A - Robot arm and robot device - Google Patents

Abstract

To provide a robot arm having a detection mechanism provided in a frame member thereof, which can reduce influences of heat generated by a driving source of a motor and the like on the detection mechanism such as a torque sensor.SOLUTION: The robot arm has a plurality of links constituted of frame members covered with cover members. The plurality of links have a first link mounted with a driving source and a detection mechanism and a second link that is driven by output from the driving source. An output shaft of the driving source and a driving shaft connecting the first link to the second link are arranged in parallel. The output shaft is connected to the driving shaft with a belt member. In a part of the frame member in the first link is provided a contact part that contacts the cover members, and the contact part is surrounded by the belt members.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a robot arm having a detection mechanism at a joint and a robot apparatus using the robot arm.

  Conventionally, various robot apparatuses are used in a factory etc., and in recent years, robot apparatuses provided with multi-axis articulated robot arms for performing more complicated operations are widely spread. Such robot devices are desired to be downsized so that they can be used in various factories and production sites.

  In recent years, therefore, there has been proposed a method in which the motor shaft of the motor serving as the drive source and the joint shaft serving as the rotation center of the link are arranged in parallel in the joint portion of the robot arm and the motor shaft and the rotation shaft are connected by a wire via a pulley. It is considered. By doing this, the link can be driven without connecting the joint shaft of the link in series to the motor shaft, and the motor and the joint shaft can be centrally arranged by adjusting the wire length, so the joint part can be compact and the robot device It can be miniaturized.

  However, in the above method, since the drive of the motor is transmitted to the joint shaft of the link through the wire and the pulley, mechanical errors due to the wire and the pulley affect the positional accuracy of the link.

  Therefore, in order to control the position of the link with high accuracy in Patent Document 1, a potentiometer for detecting the rotation angle of the joint axis of the link is provided directly on the joint axis of the link. The position of the link is directly detected by this potentiometer to control the robot device with high accuracy.

Unexamined-Japanese-Patent No. 2006-55927

  However, in the joint drive device described in Patent Document 1, heat from the motor is transmitted to the potentiometer through the frame member, so that the detection accuracy of the potentiometer is deteriorated due to the temperature change of the potentiometer.

  In addition to the potentiometer, there is also a method of providing a detection mechanism for detecting a force such as a torque sensor on the joint axis of the link to detect the force acting on the link and control it with high accuracy. Since such a torque sensor is also affected by temperature change, detection accuracy is degraded.

  Therefore, in view of the above problems, in the robot arm having a detection mechanism provided on the frame member, the present invention can reduce the influence of heat from a drive source such as a motor on the detection mechanism such as a torque sensor. Intended to provide.

  In view of the above problems, the present invention is a robot arm having a plurality of links constituted by a frame member covered by a cover member, wherein a first driving source and a detection mechanism are attached among the plurality of links. And a second link driven by an output from the drive source, wherein an output shaft of the drive source and a drive shaft connecting the first link and the second link Arranged in parallel, the output shaft and the drive shaft are connected by a belt member, and the first link is provided with a contact portion in contact with the cover member at a part of the frame member, the contact portion Used a robot arm characterized by being surrounded by the belt member.

  According to the present invention, a portion of the frame member between the drive source and the detection mechanism is provided with a portion in contact with the cover member, and heat from the drive source can be dissipated into the atmosphere before being transmitted to the detection mechanism. The influence of heat from the driving source on the detection mechanism can be reduced.

FIG. 1 is a perspective view schematically showing a robot system 500 according to a first embodiment of the present invention. It is a block diagram showing a control system of robot system 500 in a 1st embodiment of the present invention. It is sectional drawing of the joint of the robot arm main body 100 in the 1st Embodiment of this invention. It is a figure showing a heat dissipation course of a joint of robot arm main part 100 in a 1st embodiment of the present invention. It is a perspective view of the joint of robot arm main part 100 in a 1st embodiment of the present invention. It is a figure showing modification 1 of a joint of robot arm main part 100 in a 1st embodiment of the present invention. It is a figure showing modification 2 of a joint of robot arm main part 100 in a 1st embodiment of the present invention. It is a block diagram showing a control system of robot system 500 in a 2nd embodiment of the present invention. It is sectional drawing of the joint of the robot arm main body 100 in the 2nd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are merely examples, and the configuration of the details can be changed as appropriate without departing from the spirit of the present invention. Further, the numerical values taken up in the present embodiment are reference numerical values and do not limit the present invention.

First Embodiment
FIG. 1 is a perspective view schematically showing a robot system 500 according to a first embodiment of the present invention. As shown in FIG. 1, the robot system 500 includes a robot arm body 100 for assembling the workpiece W, a control device 200 for controlling the robot arm body 100, and an external input device 300 connected to the control device 200. There is.

  The robot arm body 100 includes a base portion 103 fixed to a work bench, a plurality of links 121 to 126 for transmitting displacement and force, and a plurality of joints 111 to 116 for pivotally or rotatably connecting the links 121 to 126. And have. In the figure, portions surrounded by dotted lines are joints 111 to 116. Further, each joint 111 to 116 is provided with a torque sensor 5 for detecting a torque value acting on the joint (FIG. 3).

  From the figure, the base portion 103 of the robot arm body 100 and the link 121 are connected by the joint 111. The joint 111 has, for example, a movable range of about ± 180 degrees from the initial posture.

  The link 121 and the link 122 of the robot arm body 100 are connected by a joint 112. The joint 112 has, for example, a movable range of about ± 80 degrees from the initial posture.

  The link 122 and the link 123 of the robot arm body 100 are connected by a joint 113. The joint 113 has, for example, a movable range of about ± 70 degrees from the initial posture.

  The link 123 and the link 124 of the robot arm body 100 are connected by a joint 114. The joint 114 has, for example, a movable range of about ± 180 degrees from the initial posture.

  The link 124 and the link 125 of the robot arm body 100 are connected by a joint 115. The joint 115 has a movable range of about ± 120 degrees from the initial posture.

  The link 125 and the link 126 of the robot arm body 100 are connected by a joint 116. The joint 116 has a movable range of about ± 240 degrees from the initial posture.

  In the present embodiment and embodiments to be described later, since the plurality of joints 111 to 116 have substantially the same configuration, the joint 115 provided between the link 124 and the link 125 will be described as an example. The description of the other joints 111 to 114 and 116 is omitted. The present embodiment can be implemented as long as joints having the same configuration as the joints 115 are provided at at least one of the plurality of joints 111 to 116 of the robot arm main body 100, and all joints are the same as the joints 115. It does not have to be a configuration of

  A distal end link 126 of the robot arm body 100 is provided with a force sensor (not shown) capable of detecting a force or the like, and the robot hand body 102 is provided.

  The robot hand body 102 includes a plurality of fingers capable of gripping the workpiece W, and an actuator (not shown) for driving the plurality of fingers, and is configured to be capable of gripping the workpiece by driving the plurality of fingers. The force sensor detects a force or a moment acting on the robot hand body 102 when the robot hand body 102 grips the workpiece W with a plurality of fingers.

  FIG. 2 is a block diagram showing a control system of the robot system 500 according to the first embodiment of the present invention. As shown in FIG. 2, the control device 200 includes a CPU 201, a ROM 202, a RAM 203, an HDD 204, a recording disk drive 205, and various interfaces 211 to 216.

  A ROM 202, a RAM 203, an HDD 204, a recording disk drive 205, and various interfaces 211 to 216 are connected to the CPU 201 via a bus 217. The ROM 202 stores a basic program such as a BIOS. The RAM 203 is a storage device that temporarily stores the calculation processing result of the CPU 201.

  The HDD 204 is a storage unit that stores various data and the like that is the calculation processing result of the CPU 201, and records a program 330 for causing the CPU 201 to execute various calculation processing. The CPU 201 executes various arithmetic processing based on the program 330 recorded in the HDD 204. The recording disk drive 205 can read various data and programs recorded on the recording disk 331.

  Further, the rotational drive system of each of the joints 111 to 116 is provided with an interface, and is connected to the external input device 300 via the bus 217. The external input device 300 outputs the input target joint angles of the joints 111 to 116 to the CPU 201 via the interface 211 and the bus 217.

  Further, the torque sensor 5 is connected to the interface 212, and the torque detection value described above is output to the CPU 201 via the interface 212 and the bus 217. Furthermore, the motor encoder 11 is connected to the interface 213. Then, a pulse signal is output to the CPU 201 via the interface 213 and the bus 217 in order to detect the relative position between the base unit 103 and each of the links 121 to 126.

  Further, to the interfaces 214 and 215, a monitor 311 on which various images are displayed, and an external storage device 312 such as a rewritable non-volatile memory or an external HDD are connected. Further, a servo control device 313 is connected to the interface 216. The CPU 201 outputs data of a drive command indicating the control amount of the rotation angle of the motor 1 to the servo control device 313 via the bus 217 and the interface 216 at predetermined intervals.

  The servo control device 313 calculates the output amount of the current to the motor 1 based on the drive command received from the CPU 201, supplies the current to the motor 1, and the joint angles of the joints 111 to 116 of the robot arm body 100. Control the That is, the CPU 201 controls the drive of the joints 111 to 116 by the motor 1 via the servo control device 313 so that the torque detection values of the joints 111 to 116 become the target torque.

  FIG. 3 is a cross-sectional view in the vicinity of each of the joints 111 to 116 of the robot arm body 100 shown in FIG. FIG. 3 shows a cross-sectional view of the joint 115, and is a cross-sectional view when the chain line AA of FIG. 1 is cut in the arrow S direction.

  As shown in FIG. 3, the joint 115 includes a motor 1, a reduction gear 6, a torque sensor 5 for detecting a torque generated between the link 124 and the link 125, and a cover member 7 covering a drive unit, wiring, etc. Have.

  The links 124 and 125 are composed of frames 124a and 125a, and the frames 124a and 125a are provided with various mechanisms such as the motor 1, the reduction gear 6, and the torque sensor 5.

  The motor 1 is an electromagnetic motor and can be exemplified by a brushless DC motor or an AC servo motor. The power of the motor 1 is transmitted from the motor output shaft 1 c of the motor 1 to the reduction gear input shaft 6 a via the timing pulley 2, the timing belt 3 and the timing pulley 4.

  The motor encoder 11 is provided in the motor 1, generates an input pulse signal as the motor 1 rotates, and outputs the generated input pulse signal to the control device 200. If necessary, a brake unit may be provided between the motor 1 and the motor encoder 11 to maintain the posture of the robot arm body 100 when the power is off. The motor encoder 11 may be either an optical type or a magnetic type, as in a general rotary encoder.

  The reduction gear 6 includes a reduction gear input shaft 6a for inputting power from the motor 1, a reduction gear housing 6b for holding members of the reduction gear, and a reduction gear output shaft 6c for outputting a torque after deceleration. The reduction gear housing 6 b includes an arbitrary reduction means such as a spur gear train or a wave gear reduction gear, and is attached to the torque sensor 5 by bolt fastening or the like. The reduction gear output shaft 6c is attached to the frame 125a by bolt fastening or the like, transmits the output torque from the reduction gear 6 to the link 125, and drives the link 125.

  A cross roller bearing is provided inside the speed reducer housing 6 b, whereby the link 125 is rotatably supported on the link 124. The power of the motor 1 is transmitted to the reduction gear input shaft 6a through the timing pulley 2, the timing belt 3 and the timing pulley 4, and decelerated to 1 / N by the reduction means and transmitted to the link 125 through the reduction gear output shaft 6c. Be done. The reduction gear input shaft 6 a and the reduction gear output shaft 6 c described above are an example of a drive shaft connecting the first link and the second link according to claim 1.

  The torque sensor 5 detects the amount of deformation of the elastic member constituting the torque sensor 5 by an optical encoder and converts it into torque, or detects the amount of deformation of the elastic member constituting the torque sensor 5 by magnetism Any of the following methods may be used. It is installed between the link 124 and the reduction gear housing 6 b and detects the torque acting between the link 124 and the link 125.

  As described above, the link 125 is driven by the motor 1 and the robot arm body 100 operates. The torque sensor 5 detects a torque generated between the link 124 and the link 125. The motor output shaft 1c rotates around the axis O1, and the reduction gear output shaft 6c rotates around the axis O2. The motor output shaft 1c and the reduction gear output shaft 6c are arranged in parallel.

  The cover member 7 is a cover that covers the timing pulley 2, the timing belt 3, and the timing pulley 4, which is a mechanism for transmitting power from the motor 1, and one side of the cover member 7 is exposed to the atmosphere. In addition, you may use the cover member 7 as a cover which covers wiring, such as a power line and a communication line.

  Here, it should be noted that the link 124 has a contact portion 9 and a contact portion 10 at the position of the frame 124 a between the motor 1 and the torque sensor 5 for radiating heat by coming into contact with the cover member 7. It is a point.

  Thus, as shown in FIG. 4, the heat generated from the motor is conducted from the contact portion 9 and the contact portion 10 to the cover member 7 before being transmitted to the torque sensor 5 largely affected by the heat, and these cover members 7 The heat can be dissipated to the atmosphere through the By making the cover member 7 and the frame 124 a in contact with each other, heat can easily flow to the atmosphere, so the heat radiation path of the heat from the motor 1 can be kept away from the torque sensor 5, and the amount of heat transmitted to the torque sensor 5 Is reduced.

  Further, the cover member 7 is provided so as not to be in contact with the torque sensor 5, and the amount of heat transmitted to the torque sensor 5 is further reduced.

  Furthermore, in the present embodiment, aluminum is used as the material of the frame 124 a and the cover member 7 in order to improve the heat conduction. Although aluminum is used in the present embodiment, a member such as steel may be used depending on the strength of the robot arm body 100.

  FIG. 5 is a perspective view of the joint 115 in FIG. For the sake of explanation, the link 124 is shown in a transparent view. The cover member 7 is a portion shown by a dotted line, and the cover member 7 is provided also on the link 125.

  As apparent from FIG. 5, the contact portion 9 is formed on a part of the frame 124a located inside surrounded by the timing belt 3 which is a belt member. Thus, when the motor 1 and the torque sensor 5 are disposed apart from each other so as not to transmit the heat from the motor 1 to the torque sensor 5 as much as possible, the portion surrounded by the timing belt 3 is effectively utilized for heat dissipation. it can.

  As described above, according to the first embodiment, the frame 124 a constituting the link 124 is in contact with the cover member 7 between the motor 1 and the torque sensor 5. Furthermore, since one side of the cover member 7 is exposed to the atmosphere, the heat generated in the motor 1 can be dissipated to the atmosphere through the contact portion 9 and the contact portion 10 between the frame 124a and the cover member 7 The heat transfer to 5 can be suppressed.

  Furthermore, since the cover member 7 has a large surface area exposed to the atmosphere, the heat radiation effect is high, and the heat transfer to the torque sensor 5 can be suppressed.

  Therefore, by suppressing the heat transfer to the torque sensor 5, the temperature change of the torque sensor 5 can be suppressed, and the deterioration of the torque detection accuracy between the base 103 and the links 121 to 126 can be reduced. As a result, a robot apparatus capable of highly accurate torque control can be realized.

  It simulated by how much the temperature change of the torque sensor 5 by the heat which generate | occur | produces from the motor 1 was suppressed by the structure of the joint demonstrated above. The amount of heat generated from the motor 1 (single) was 20 W, and the physical property values of the frame member 124 a and the cover member 7 were set to aluminum (thermal conductivity is 236 W / (m · K)). Further, the external temperature of the robot arm body 100 was set to 25 ° C., the motor 1 was driven, the heat from the motor 1 was transmitted to the entire frame member 124 a, and the temperature change of the torque sensor 5 until the steady state was calculated.

  As a result of the calculation, the temperature change when the frame 124a was not brought into contact with the cover member 7 was Δ56 ° C. However, it was shown by simulation that the temperature is suppressed to Δ38 ° C. by using this embodiment. From the above, it can be seen that the temperature change of the torque sensor 5 can be significantly improved.

  As shown in FIG. 6, the contact portion 9 and the contact portion 10 may be provided with a flexible heat conduction sheet 20 as a high heat conduction member as a first modification of the present embodiment. Thereby, the amount of heat transmitted to the contact portion 9 and the contact portion 10 can be increased, and the heat radiation effect can be enhanced. Therefore, the amount of heat transmitted to the torque sensor 5 can be further reduced, and the deterioration of the torque detection accuracy can be further reduced. Examples of the heat conductive sheet 20 include a heat conductive filler and a resin compound.

  Further, as shown in FIG. 7, in the area surrounded by the timing belt 3 as a modification 2 of this embodiment, the wiring 30 disposed on the robot arm body 100 is provided in the extension of the frame 124 a provided to contact the cover member 7. It may be wound. In the present embodiment, the wire 30 is used as a wire connecting the control device 200 to the torque sensor 5.

  By doing this, the wiring 30 can be routed without stress in the rotating portion. In addition to the heat radiation from the cover member 7, the heat generated from the motor 1 can be dissipated by transferring heat to the wiring 30.

  Further, in the present embodiment, although the case where the robot arm body 100 is the vertical articulated robot arm has been described, it may be a horizontal articulated robot arm (SCARA robot), a single axis robot, or the like. The contact portion 9 and the contact portion 10 may be either one.

Second Embodiment
In the first embodiment, the torque sensor is used as the detection unit for suppressing the temperature change, but the detection unit whose accuracy is deteriorated due to the temperature is not limited to the torque sensor. In order to control with high accuracy regarding the position of the robot arm, there is a method of providing an encoder directly to the link and acquiring position information of the link. In the present embodiment, the case of using an encoder as a detection mechanism will be described in detail.

  In the following, hardware and control system configuration parts different from the first embodiment are illustrated and described. Moreover, about the part similar to 1st Embodiment, the structure and effect similar to the above shall be possible, and the detailed description shall be abbreviate | omitted. The same reference numerals are used for members and control functions that are the same as or equivalent to those of the first embodiment.

  FIG. 8 is a block diagram showing a control system of a robot system 500 according to the second embodiment of the present invention. The difference from FIG. 8 from the first embodiment is that an output shaft encoder 15 is provided, and an interface 218 for connecting the output shaft encoder 15 and the bus 217 is provided.

  FIG. 9 is a cross-sectional view of the joint 115 of the robot arm body 100 according to the second embodiment. The cross-sectional direction is a cross-sectional view when the chain line AA of FIG. 1 is cut in the arrow S direction. In the first embodiment, the torque sensor 5 is mounted on the side of the reduction gear input shaft 6a. However, in the present embodiment, the output shaft encoder 15 is mounted between the frame 124a and the reduction gear output shaft 6c.

  The output axis encoder 15 detects the relative angle between the link 124 and the link 125. The output shaft encoder 15 includes a scale 15a storing rotation angle information, and detectors 15b and 15c that read the scale information.

  The scale 15a is disposed on the reducer output shaft 6c that rotates with the link 125, and the detectors 15b and 15c are disposed on the frame 124a. Further, in order to cancel the detection error due to the eccentricity of the scale 15a, the detectors 15b and 15c are disposed opposite to each other at approximately 180 degrees with respect to the scale 15a.

  By averaging the detection values from the detectors 15b and 15c disposed opposite to each other, accuracy deterioration due to the eccentricity of the scale 15a can be reduced. At the same time, the accuracy deterioration due to the swing in the rotational direction P of the scale 15a can be reduced. If the eccentricity of the scale 15a is small and there is no problem in the detection value of the output shaft encoder 15, only one of the detectors 15b and 15c may be used.

  As described above, according to the joint 115 in the second embodiment, the frame 124 a is in contact with the cover member 7 between the motor 1 and the output shaft encoder 15. Furthermore, since one side of the cover member 7 is exposed to the atmosphere, the heat generated in the motor 1 can be dissipated to the atmosphere through the contact portion 9 and the contact portion 10 between the frame 124 a and the cover member 7. Therefore, the heat transfer to the output shaft encoder 15 can be suppressed.

  Therefore, the temperature change of the detectors 15b and 15c of the output shaft encoder 15 can also be suppressed. Therefore, deterioration in detection accuracy of the force axis encoder 15 between the base 103 and the links 121 to 126 can be reduced. As a result, a robot device capable of highly accurate position control can be realized.

  Further, it is also possible to apply the first modification and the second modification described in the first embodiment to the present embodiment.

  In the first and second embodiments described above, the robot arm body 100 is mounted with a torque sensor and an output shaft encoder. However, a robot arm is mounted with a detection unit that degrades in accuracy due to a temperature change. It can be applied to Therefore, the present invention is not limited to the type and number of detection units.

  The present invention is applicable to industrial robots.

Reference Signs List 1 motor 1c motor output shaft 2, 4 timing pulley 3 timing belt 5 torque sensor 6 reduction gear 6a reduction gear input shaft 6b reduction gear housing 6c reduction gear output shaft 7 cover member 11 motor encoder 15 output shaft encoder 15a scale 15b, 15c detection 100 Robot arm body 102 Robot hand body 111 to 116 Joint 121 to 126 Link 200 Control device 300 External input device 500 Robot system

Claims (7)

A robot arm having a plurality of links constituted by a frame member covered by a cover member, the robot arm comprising:
Of the plurality of links,
A first link attached with a drive source and a detection mechanism;
And a second link driven by an output from the drive source,
The output shaft of the drive source and the drive shaft connecting the first link and the second link are arranged in parallel,
The output shaft and the drive shaft are connected by a belt member,
The first link is
A contact portion which contacts the cover member is provided on a part of the frame member,
The robot arm characterized in that the contact portion is surrounded by the belt member. In the robot arm according to claim 1,
A material of the frame member and the cover member is aluminum. The robot arm according to claim 1 or 2,
A heat transfer member is provided in the contact portion between a part of the frame member and the cover member. The robot arm according to any one of claims 1 to 3.
A robot arm characterized in that a wire inside the robot arm is wound around an extension of the frame member provided with the contact portion. The robot arm according to any one of claims 1 to 4.
The robot arm characterized in that the detection mechanism is a torque sensor. The robot arm according to any one of claims 1 to 5.
A robot arm characterized in that the detection mechanism is an encoder.   A robot apparatus comprising a robot hand according to any one of claims 1 to 6 in a robot arm.

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