JP2017013168A - Robot arm device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a robot arm device capable of generating counter torque reflecting relation between a rotation angle of an arm and a drive load of a driving source without requiring a complicated contour-shaped pulley.SOLUTION: A second arm 7 has a rotation center at a position separated from a rotation center of a first arm 4 on a base 2, and the first arm 4 and the second arm 7 rotate on the same plane. A tension spring 9 is arranged between the first arm 4 and the second arm 7, and makes energization force in a direction for reducing a load of a stepping motor 3 act on the first arm 4. In a connection link 8, one end is connected with a position at first distance from the rotation center in the first arm 4, and the other end is connected with a position at second distance larger than the first distance from the rotation center in the second arm 7.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a robot arm device mounted on various robots.

  2. Description of the Related Art Robot arm devices that rotate an arm provided on a base so as to be rotatable by a drive source are widely used in various robots. In the robot arm device, generally, as the rotation angle of the arm approaches horizontal, the torque for maintaining the weight of the arm increases and the driving load of the driving source increases. For this reason, various balancers have been proposed that use a spring force to reduce the load on the drive source by applying a large counter torque (compensation torque) to the arm as the rotation angle of the arm approaches horizontal (Patent Literature). 1, 2).

  Patent Document 3 proposes a balancer that provides a pulley with a special contour shape that rotates integrally with the arm, and applies a counter torque in the direction of lifting the arm by urging the rope wrapped around the pulley with a tension spring. Has been. Here, the rotation angle of the arm and the driving source of the driving source are changed from those in Patent Documents 1 and 2 by changing the radius from the biasing position where the pulley with a special contour shape rotates and the spring force acts to the rotation center. Counter torque that accurately reflects the relationship with the driving load is generated.

JP-A-6-170780 JP-A-8-47885 JP 2009-291843 A

  The balancer shown in Patent Document 3 requires a pulley having a contour shape designed based on the relationship between the rotation angle of the arm and the driving load of the driving source, and thus the manufacturing cost is high. As will be described later, when a tension spring is attached to a pulley that rotates integrally with the arm, there is a disadvantage that the structure around the rotation center of the arm is enlarged.

  An object of the present invention is to provide a robot arm device capable of generating a counter torque reflecting a relationship between an arm rotation angle and a driving load of a driving source without requiring a pulley having a complicated contour shape.

  The robot arm device of the present invention includes a base, a tool, a first arm rotatably provided on the base, a drive source that drives and rotates the first arm, and the base The first arm and the first arm so that the angle formed by the second arm provided rotatably on the table and the distortion direction and the vertical direction increases as the inclination angle of the first arm from the horizontal direction increases. The first arm and the second arm are interlocked so that the elastic body provided between the two arms and the amount of strain of the elastic body become smaller as the angle of inclination of the first arm from the horizontal direction becomes larger. And an interlocking mechanism to be provided.

  In the robot arm apparatus according to the present invention, as the inclination angle of the first arm from the horizontal direction increases, the amount of strain of the elastic body decreases in addition to the amount of distortion of the elastic body increases in addition to the vertical direction. For this reason, by adjusting the arrangement of the second arm and the elastic body and the interlocking mechanism, the relationship between the rotation angle of the first arm and the biasing amount (counter torque) of the first arm by the elastic body is relatively free. It can be set. For this reason, it is possible to generate a counter torque reflecting the relationship between the rotation angle of the arm and the driving load of the driving source without requiring a pulley having a complicated contour shape.

FIG. 2 is an explanatory diagram of a configuration of the robot arm device according to the first embodiment. It is explanatory drawing of operation | movement of a balancer. It is a diagram of the load torque due to gravity and the counter torque generated by the balancer. It is explanatory drawing of the structure of the robot arm apparatus of Embodiment 2. FIG. It is explanatory drawing of the structure of the robot arm apparatus of Embodiment 3. FIG. It is explanatory drawing of the balancer of the manipulator of the comparative example 3.

  Embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<Embodiment 1>
(Robot arm device)
FIG. 1 is an explanatory diagram of the configuration of the robot arm device according to the first embodiment. As shown in FIG. 1, the robot arm device 1 has a base 2 fixed to the installation surface G.

  A stepping motor 3 that is an actuator of the first arm 4 is fixed to the base 2. A fixed end 4e of the first arm 4 is fixed to a drive shaft 3a of a stepping motor 3 which is an example of a drive source to constitute a joint portion J1.

  An openable / closable chuck 5, which is an example of a tool or an effector, is coupled to a tip (rotating end) of a first arm 4, which is an example of an arm, in a suspended state. The chuck 5, which is an example of an operation unit, is provided at the rotation end of the first arm 4 and executes a necessary operation or process. The chuck 5 is closed to grip the workpiece 6, and is opened to release the workpiece 6.

  The robot arm apparatus 1 holds the workpiece 6 in a state where the first arm 4 is lowered to the horizontal position, and rotates the first arm 4 to release the workpiece 6 at a position where the workpiece 6 is raised. Thereby, the workpiece | work 6 is delivered from the workpiece conveyance apparatus not shown to the workpiece processing apparatus not shown.

  The robot arm device 1 conveys the workpiece 6 by rotating the first arm 4 and the chuck 5 in a vertical plane. For this reason, a large moment due to gravity, including the weight of the workpiece, acts on the driving shaft 3 a of the stepping motor 3 on the weight of the first arm 4 and the chuck 5.

  Therefore, a large torque is required to rotationally drive the first arm 4 in the direction opposite to the direction in which the gravity acts, and a large output stepping motor must be provided.

  Therefore, in the first embodiment, the balancer 1B is mounted to cancel the moment due to gravity acting on the drive shaft 3a of the stepping motor 3, and the load applied to the stepping motor 3 that drives the first arm 4 is reduced. Yes.

(Balancer)
As shown in FIG. 1, the balancer 1 </ b> B includes a second arm 7, a connection link 8, and a tension spring 9. The balancer 1B lifts the first arm 4 via the tension spring 9, thereby generating a counter torque (compensation torque) that acts in the opposite direction to the load torque due to the weight of the first arm 4 and the like. It is made to act on the drive shaft 3a.

  The second arm 7 has a rotation center at a position separated from the rotation center of the first arm 4 to the opposite side of the chuck 5, and the first arm 4 and the second arm 7 rotate on the same plane. . A fixed end 7e of the second arm 7 is rotatably provided at the joint J2 of the base 2. The joint portion J2 is provided at a position separated from the joint portion J1 on the base 2 and rotates the second arm 7 on the same plane as the first arm 4.

  The connection link 8 is a link member that connects the first arm 4 and the second arm 7. The first arm 4 is provided with a joint portion J3, and the second arm 7 is provided with a joint portion J4. One end 8a of the connecting link 8 is rotatably attached to the joint J3, and the other end 8b of the connecting link 8 is rotatably attached to the joint J4.

  For this reason, when the first arm 4 rotates about the joint portion J1, the second arm 7 rotates about the joint portion J2 via the connecting link 8. The rotation angle (output angle) of the second arm 7 with respect to the rotation angle (input angle) of the first arm 4 is calculated from a four-joint link mechanism model in which the joint portion J1 and the joint portion J2 are fixed joints. Can do.

  The tension spring 9 always biases the first arm 4 toward the second arm 7 side. One end 9a of the tension spring 9 engages with a fixed point 4a provided near the tip (free end) of the first arm 4, and the other end 9b of the tension spring 9 is the tip (free) of the second arm 7. Engage with a fixed point 7a provided near the end.

  As shown in FIG. 1, the distance from the joint part J1 of the first arm 4 to the joint part J3 is L1, and the distance from the joint part J2 of the second arm 7 to the joint part J4 is L2. At this time, the positions of the joint portion J3 and the joint portion J4 of the connecting link 8 are set to satisfy L1 <L2.

  Therefore, when the first arm 4 and the second arm 7 are rotated in conjunction with each other via the connecting link 8, the rotation angle of the second arm 7 is greater than the rotation angle of the first arm 4. Becomes smaller. As a result, the urging force of the tension spring 9 can act on the first arm 4 as the rotation angle of the first arm 4 approaches the horizontal position.

  As described above, the tension spring 9, which is an example of an elastic body, increases the strain as the tilt angle of the first arm 4 from the horizontal direction increases, and biases the first arm 4 by biasing the first arm 4. The load on the stepping motor 3 due to the weight of is reduced. The tension spring 9 has one end connected to the first arm 4 and the other end connected to the second arm 7.

  The tension spring 9 is arranged between the first arm 4 and the second arm 7 so that the angle between the strain direction and the vertical direction of the tension spring 9 increases as the inclination angle of the first arm 4 from the horizontal direction increases. Has been placed.

  The connecting link 8, which is an example of an interlocking mechanism, is connected to the first arm 4 and the first arm 4 so that the rotation amount of the second arm 7 accompanying the rotation of the first arm 4 is smaller than the rotation amount of the first arm 4 at that time. The two arms 7 are interlocked in the same direction. The connection link 8 connects one end to a position at a first distance from the rotation center in the first arm 4 and connects the other end to a position at a second distance larger than the first distance from the rotation center in the second arm 7. Has been.

(Balancer operation)
FIG. 2 is an explanatory diagram of the operation of the balancer. FIG. 3 is a diagram of the load torque due to gravity and the counter torque generated by the balancer. In FIG. 2, (a) is the state which the 1st arm rotated upwards. (B) is the state which the 1st arm rotated to the horizontal position. In FIG. 3, a curve (A) is a load torque that acts on the drive shaft 3 a of the stepping motor 3 in accordance with the posture (rotation angle) of the first arm 4. A curve (B) is a counter torque generated in the first arm by the tension spring 9.

  FIG. 3 shows an example of the relationship between the load torque A and the counter torque. The horizontal axis in FIG. 3 is the angle (rotation angle) θ (deg) formed by the first arm 4 with the horizontal plane, and the vertical axis is the torque T (Nm).

  As shown in FIG. 2A, the load torque A acting on the drive shaft 3 a of the stepping motor 3 is torque due to the weight of the first arm 4. The load torque A is a function of cos θ, as shown in FIG. 3, where θ is the angle formed by the first arm 4 and the horizontal plane. The load torque A is a function of cos θ that varies depending on the posture (rotation angle) of the first arm 4.

  Therefore, as shown in FIG. 3, in the range of 0 ° ≦ θ ≦ 90 °, θ = 0 ° shown in FIG. 2B, that is, the maximum when the first arm 4 is in the horizontal position, As shown in FIG. 2 (a), it decreases as θ increases.

  As shown in FIG. 2A, the tension spring 9 that connects the first arm 4 and the second arm 7 has a load torque A acting on the first arm 4 in accordance with the rotation angle θ of the first arm 4. Compensate. The balancer 1 </ b> B changes the extension amount of the tension spring 9 according to the rotation angle of the first arm 4 due to the difference in the rotation angle due to the interlocking of the first arm 4 and the second arm 7.

  As shown in FIG. 2B, when θ = 0 °, that is, when the first arm 4 is horizontal, a large tensile force acts on the first arm 4 because the extension amount of the tension spring 9 is large. Therefore, as shown in FIG. 3, a large counter torque B is generated in a range where the angle θ is small.

  As shown in FIG. 2A, as the rotation angle θ of the first arm 4 increases, the extension amount of the tension spring 9 decreases and the tension force by the tension spring 9 decreases. Therefore, as shown in FIG. 3, the counter torque B generated in the first arm 4 is small in the range where the angle θ approaches 90 degrees.

  As shown in FIG. 3, the counter torque B changes in accordance with the rotation angle θ of the first arm 4 because the extension amount of the tension spring 9 and the tension direction (the angle formed by the vertical direction and the tension spring 9) change. Curve (B).

  The curve (B) of the counter torque B is obtained by changing the elastic coefficient and length of the tension spring 9, the mounting position (L1) on the first arm 4, and the mounting position (L2) on the second arm 7. ). It is possible to approach not only the torque curve due to the weight of the first arm 4 but also the torque curve due to the weight including the chuck 5 and the workpiece 6.

  The counter torque B can be calculated by calculation as a function of the rotation angle θ of the first arm 4. Accordingly, by appropriately setting the position of the second arm 7 and the connecting link 8, the spring constant and the mounting position of the tension spring 9 so that the curve (A) and the curve (B) coincide with each other, the first arm Thus, it is possible to maintain the torque balance around the four joints J1.

  In the first embodiment, the tension spring 9 that connects the first arm 4 and the second arm 7 is provided near the distal ends (free ends) of the first arm 4 and the second arm 7 that are separated from the respective joint portions. Is preferred. This is because a large counter torque B can be efficiently obtained with a small spring constant.

  Further, in the first embodiment, the position of the joint portion J2 of the second arm 7 is not limited to the position of FIG. 1, and can be determined in consideration of the degree of freedom in design.

  In the first embodiment, as shown in FIG. 3, the curve (B) is deviated from the curve (A) in a range close to 90 degrees of the angle θ. This is because it was necessary to maintain a tension state in order to prevent the portion from sagging. If necessary, the tension spring 9 and the mounting position can be changed so that the curve (B) can be further brought closer to the curve (A) even in a range where the angle θ is close to 90 degrees.

(Relationship with detent torque of stepping motor)
By the way, in the first embodiment, the first arm 4 is connected to the drive shaft of the stepping motor 3, and therefore the holding (holding) torque of the stepping motor 3 is applied to the first arm 4 when the stepping motor 3 is excited. Works.

  For this reason, even if the curves of the load torque A and the counter torque B in FIG. 3 do not exactly match, as long as the difference between them is within the range of the holding torque value of the stepping motor 3, the dynamic balancer The function can be maintained.

  Further, when the stepping motor 3 is in a non-excited state, the detent torque due to the residual magnetization of the magnetic poles of the stepping motor 3 acts on the first arm 4.

  For this reason, even if the curves of the load torque A and the counter torque B in FIG. 3 do not exactly match, if the difference between the two is within the range of the detent torque of the stepping motor 3, the balancer in the stopped state The function can be maintained.

  That is, at any rotation angle θ, the sum of the counter torque B generated in the first arm 4 and the motor detent torque is set equal to or greater than the load torque A. Thereby, even when the power supply to the stepping motor 3 is cut off and the arm holding force is released at the time of power stop or emergency stop, it is possible to prevent the first arm 4 from being lowered.

  Accordingly, it is possible to prevent the arm 4 from descending without using expensive parts such as an electromagnetic brake, and it is possible to prevent the workpiece 6 and the robot arm device 1 from being damaged.

  As described above, the stepping motor 3 has a detent torque and uses the drive shaft 3a, which is an example of the output shaft, as the rotation shaft of the first arm 4. The torque value obtained by subtracting the load torque that the weight of the first arm 4 acts on the drive shaft 3a from the counter torque that the tension spring 9 acts on the drive shaft 3a is defined as the differential torque. At this time, the maximum value of the differential torque in the movable range of the first arm 4 is less than the detent torque.

(Comparative Example 1)
The robot arm device of Comparative Example 1 includes a balancer disclosed in Patent Document 1 (Japanese Patent Laid-Open No. Hei 6-170780). A first arm is rotatably provided on the base, and the first arm is driven by a motor provided on the base. The first arm and the base are simply connected by a tension spring.

  In the balancer of Comparative Example 1, since the range in which the tension spring can generate the counter torque is narrow, the counter torque is generated only in the range where the first arm is close to the horizontal position. This is because, unlike the first embodiment, since the second arm that rotates following the rotation of the first arm 4 is not provided, the strain amount of the tension spring changes suddenly as the first arm rotates. For this reason, in a wide range from the standing position of the first arm to the horizontal position, it is impossible to generate counter torque that can cancel the load torque according to the rotation angle θ of the first arm.

(Comparative Example 2)
The robot arm device of Comparative Example 2 includes a balancer disclosed in Patent Document 2 (Japanese Patent Laid-Open No. 8-47885). A first arm is rotatably provided on the base, and the first arm is driven by a motor provided on the base. And one end of the wire wound around the circular pulley that rotates integrally with the first arm and the base are connected by a tension spring. That is, in FIG. 6, the non-circular pulley 130 is circular.

  Since the balancer of Comparative Example 2 has a circular pulley that rotates integrally with the first arm, the range in which the counter torque can be generated using the tension spring is wider than that of Comparative Example 1. However, in the case of a circular pulley, the amount of strain of the tension spring changes in proportion to the rotation angle of the circular pulley. Therefore, even when optimally designed, it becomes a straight line (C) shown in FIG. For this reason, it is impossible to generate counter torque that can cancel the load torque (A) corresponding to the rotation angle θ of the first arm. The load torque (A) corresponding to the rotation angle θ of the first arm can be sufficiently canceled only at the first and last part in a wide range from the standing position of the first arm to the horizontal position. A large difference δ is generated at an intermediate angle.

(Comparative Example 3)
FIG. 6 is an explanatory diagram of a balancer mounted on the robot arm of Comparative Example 3. The robot arm device of Comparative Example 3 includes a balancer disclosed in Patent Document 3 (Japanese Unexamined Patent Application Publication No. 2009-291843). As shown in FIG. 6, the balancer of Comparative Example 3 includes a non-circular pulley 130 that rotates integrally with the first arm 120, and between the one end of the wire 140 wound around the non-circular pulley 130 and the base 110. Are connected by a tension spring 150. That is, the above-described problem in the balancer of Comparative Example 2 is solved by replacing the circular pulley of Comparative Example 2 with the non-circular pulley 130.

  That is, the non-circular pulley 130 is formed in a contour shape reflecting a change in load torque according to the rotation angle θ of the first arm 120 in a wide range from the standing position of the first arm to the horizontal position. For this reason, as long as the contour of the non-circular pulley 130 is appropriate, the balancer of Comparative Example 3 generates an appropriate counter torque according to the rotation angle θ of the first arm 120 and extends over a wide movable range. Thus, the load torque due to the weight of the first arm 120 can be compensated.

  However, forming the non-circular pulley 130 with an appropriate contour according to the rotation angle θ of the first arm 120 causes an increase in manufacturing cost.

  Further, in Comparative Examples 1 to 3, since the tension spring and the wire are arranged at positions close to the rotation axis of the first arm, in order to generate the counter torque that cancels the load torque due to the weight of the first arm. A tension spring having a large elastic modulus is required. As a result, the radial load on the joint may reach several times the total weight of the first arm. When the load on the joint portion is large, the joint portion becomes large, which causes an increase in manufacturing cost.

  Further, in Comparative Example 3, the movement range of the wire 140 connecting the first arm 120 and the base 110 via the non-circular pulley 130 and the tension spring 150 is increased, and the joint portion of the base 110 and the first arm 120 is increased. It is necessary to secure a large space around. As a result, the structure around the base 110 increases.

(Effect of Embodiment 1)
As shown in FIG. 1, the balancer 1B according to the first embodiment is configured to reduce the load torque of the stepping motor 3 due to the weight of the first arm 4, the chuck 5, and the workpiece 6 with a simple and inexpensive configuration. It is possible to cancel over a wide range of the rotation angle θ.

  The balancer 1B according to the first embodiment has a simple configuration and does not depend on the rotation angle θ of the first arm 4 and can compensate for the weight of the first arm 4 in a wide rotation range. The robot arm device 1 can be realized.

  In the first embodiment, the tension spring 9 is connected not to the vicinity of the joint portion J1 of the first arm 4 but to the vicinity of the rotating end of the first arm 4, so that the counter torque necessary for canceling the load torque is generated. Therefore, the tensile force can be reduced. Since a coil spring or a wire that generates a tensile force is not connected at a position close to the joint portion J1 of the first arm 4, a large elasticity is generated in order to generate a counter torque that cancels a load torque due to the weight of the first arm 4. There is no need for modulus springs or heavy weights. For this reason, the radial load of the joint portion J1 is also suppressed to be smaller than those in the first to third comparative examples, and the tension spring 9 can be designed to be light and compact.

  In the first embodiment, the tension spring 9 is disposed between the position of the first arm 4 close to the chuck 5 and the rotation end of the second arm 7. For this reason, the tension spring 9 having a relatively small elastic coefficient and a large length can be used.

  In the first embodiment, there is no need to arrange balancer parts near the joint portion J1 of the first arm 4, and therefore an actuator (stepping motor 3) for rotationally driving the first arm 4 is arranged at the joint portion J1. be able to.

  In the first embodiment, since the stepping motor 3 is arranged at the joint portion J1 of the first arm 4, the detent torque of the stepping motor 3 is used to prevent the first arm 4 from being lowered when the power supply is stopped or during an emergency stop. It is possible. Even when the power to the stepping motor 3 is cut off and the holding force of the first arm 4 is released, damage to the workpiece 6 and the robot arm device 1 can be avoided without relying on expensive parts such as an electromagnetic brake.

<Embodiment 2>
FIG. 4 is an explanatory diagram of the configuration of the robot arm device according to the second embodiment. The second embodiment is configured in the same manner as the first embodiment except for an interlocking mechanism that transmits torque between the first arm 4 and the second arm 7. For this reason, the same code | symbol as FIG. 1 is attached | subjected to the structure which is common in Embodiment 1, and the overlapping description is abbreviate | omitted.

  As shown in FIG. 4, in the second embodiment, a gear mechanism (10, 12, 13) is used as an interlocking mechanism for the first arm 4 and the second arm 7. A drive gear 10 is connected to the drive shaft 3a of the stepping motor 3 constituting the joint portion J1 of the first arm 4 and rotates integrally with the first arm 4.

  An idler gear 12 that meshes with the drive gear 10 is rotatably supported on the gear shaft 11 provided on the base 2. A follower gear 13 fixed to the fixed end of the second arm 7 is provided at the joint portion J <b> 2 on the base 2 so as to mesh with the idler gear 12.

  When the first arm 4 rotates, the drive gear 10 rotates the driven gear 13 via the idler gear 12, and the second arm 7 rotates in the same direction as the first arm 4. Then, by setting the gear ratio between the drive gear 10 and the driven gear 13, the drive from the drive gear 10 to the driven gear 13 is decelerated, so that the rotation angle of the second arm 7 is greater than the rotation angle of the first arm 4. It is small.

  As described above, in the second embodiment, the driving gear 10 that is an example of the first rotating body or the first gear rotates integrally with the first arm 4. The driven gear 13, which is an example of the second rotating body or the second gear, has a larger diameter than the drive gear 10 and rotates integrally with the second arm 7. An idler gear 12, which is an example of a transmission member or a third gear, meshes between the drive gear 10 and the driven gear 13 to transmit rotation and rotate in the same direction.

  Thereby, the tension spring that connects the first arm 4 and the second arm 7 according to the rotation angle of the first arm 4 due to the rotation angle difference when the first arm 4 and the second arm 7 are interlocked. The amount of elongation of 9 is limited. As a result, similarly to the first embodiment, it is possible to generate counter torque that can cancel the load torque due to the weight of the first arm in a wide range of the rotation angle of the first arm 4.

<Embodiment 3>
FIG. 5 is an explanatory diagram of the configuration of the robot arm device according to the third embodiment. The third embodiment is configured in the same manner as the first embodiment except for an interlocking mechanism that transmits torque between the first arm 4 and the second arm 7. For this reason, the same code | symbol as FIG. 1 is attached | subjected to the structure which is common in Embodiment 1, and the overlapping description is abbreviate | omitted.

  As shown in FIG. 5, in the third embodiment, a toothed pulley (14, 15) and a toothed belt (16) are used as the interlocking mechanism of the first arm 4 and the second arm 7. A drive pulley 14 is connected to the drive shaft 3a of the stepping motor 3 constituting the joint portion J1 of the first arm 4 and rotates integrally with the first arm 4.

  The joint J2 on the base 2 is provided with a driven pulley 15 fixed to the fixed end of the second arm 7. A toothed belt 16 is stretched between the driving pulley 14 and the driven pulley 15.

  When the first arm 4 is rotated, the drive pulley 14 rotationally drives the driven pulley 15 via the toothed belt 16 to rotate the second arm 7 in the same direction as the first arm 4. Then, by setting the pulley ratio of the drive pulley 14 and the driven pulley 15, the drive from the drive pulley 14 to the driven pulley 15 is decelerated, so that the rotation angle of the second arm 7 is larger than the rotation angle of the first arm 4. It is small.

  As described above, in Embodiment 3, the toothed belt 16, which is an example of an endless winding member, is wound around the driving pulley 14 and the driven pulley 15, and the driving pulley 14, the driven pulley 15, Torque is transmitted between the two.

  Thereby, the tension spring that connects the first arm 4 and the second arm 7 according to the rotation angle of the first arm 4 due to the rotation angle difference when the first arm 4 and the second arm 7 are interlocked. The amount of elongation of 9 is limited. As a result, similarly to the first embodiment, it is possible to generate counter torque that can cancel the load torque due to the weight of the first arm in a wide range of the rotation angle of the first arm 4.

<Other embodiments>
In the first embodiment, the embodiment of the robot arm apparatus having one joint has been described. However, the present invention can also be implemented by an articulated robot arm apparatus having two or more joints.

  In the first embodiment, the chuck 5 is attached to the tip of the first arm 4, but an end effector such as a hand or a work tool for gripping a workpiece via the wrist may be attached.

  In the first embodiment, the joint portion J3 at both ends of the connecting link 8 is fixed at a fixed position of the first arm 4, and the joint portion J4 is fixed at a fixed position of the second arm 7. However, the joint portion J3 may be provided along the first arm 4 so that the position thereof can be adjusted. The joint J4 may be provided along the second arm 7 so that the position thereof can be adjusted. A plurality of joint portions J4 may be arranged in advance along the second arm 7, and one joint portion J4 that can generate a counter torque most suitable for canceling the load torque may be selected and used.

  In the first embodiment, the embodiment in which the joint portion J1 is configured by the drive shaft 3a of the stepping motor 3 has been described. However, the joint portion J1 may be configured by a rotation mechanism other than the shaft, and the first arm 4 may be driven and rotated by a method other than the shaft.

DESCRIPTION OF SYMBOLS 1 Robot arm apparatus, 1B balancer 2 Base, 3 Stepping motor, 3a Drive shaft 4 1st arm, 5 Chuck, 6 Work piece 7 2nd arm, 8 Connection link, 9 Tension spring 10 Drive gear, 12 Idler gear, 13 Drive gear 14 Drive pulley, 15 Drive pulley, 16 Toothed belt J1, J2, J3, J4 Joint

Claims (12)

The base,
A first arm having a tool and rotatably provided on the base;
A drive source for driving and rotating the first arm;
A second arm rotatably provided on the base;
An elastic body provided between the first arm and the second arm so that the angle between the strain direction and the vertical direction increases as the tilt angle of the first arm from the horizontal direction increases;
A robot comprising: an interlocking mechanism that interlocks the first arm and the second arm so that the amount of strain of the elastic body decreases as the tilt angle of the first arm from the horizontal direction increases. Arm device.   2. The robot according to claim 1, wherein the second arm is rotatable with respect to the base at a rotation center spaced from a rotation center of the first arm to an opposite side of the tool. Arm device.   The interlocking mechanism is a mechanism that interlocks the first arm and the second arm so that the rotation amount of the second arm accompanying the rotation of the first arm is smaller than the rotation amount of the first arm. The robot arm device according to claim 2, wherein the robot arm device is provided.   The interlocking mechanism has one end connected to a position at a first distance from the rotation center in the first arm, and the other end at a position at a second distance larger than the first distance from the rotation center in the second arm. The robot arm device according to claim 3, wherein the robot arm device is a linked link member.   The interlock mechanism includes a first rotating body that rotates together with the first arm, a second rotating body that has a larger diameter than the first rotating body that rotates together with the second arm, and the first The robot arm device according to claim 3, further comprising: a transmission member that transmits rotation between the rotating body and the second rotating body to rotate in the same direction.   The first rotating body is a first gear, the second rotating body is a second gear, and the transmission member is a third gear that meshes with the first gear and the second gear. The robot arm device according to claim 5, wherein   The transmission member is a winding member that is wound around the first rotating body and the second rotating body and transmits torque between the first rotating body and the second rotating body. The robot arm device according to claim 5.   The robot arm device according to claim 7, wherein the winding member is an endless toothed belt.   The robot arm device according to any one of claims 1 to 8, wherein the first arm and the second arm rotate on the same plane.   The robot arm according to claim 1, wherein the elastic body is a tension spring having one end connected to the first arm and the other end connected to the second arm. apparatus.   11. The robot arm device according to claim 10, wherein the elastic body is disposed between a position of the first arm adjacent to the tool and a rotation end of the second arm. The drive source is a stepping motor having a detent torque and having an output shaft as a rotation shaft of the first arm,
When the torque value obtained by subtracting the load torque that the weight of the first arm acts on the output shaft from the torque that the elastic body acts on the output shaft is used as the differential torque,
The robot arm device according to any one of claims 1 to 11, wherein a maximum value of the differential torque in a movable range of the first arm is smaller than the detent torque.

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