JP2015160298A - parallel link robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a parallel link robot 10 of which a manufacturing cost can be suppressed by decreasing a weight of a movable part 30 hanging over arm parts 41 to 43.SOLUTION: A parallel link robot 10 includes: a base part 20; a movable part 30; arm parts 41 to 43; servo motors 51 to 53; link parts 61 to 63; force action members 73, 78; and a control part. The control part controls the servo motors 51 to 53, and moves the movable part 30 in three directions, i.e., a vertical direction, a longitudinal direction and a lateral direction, by the arm parts 41 to 43 and the link parts 61 to 63. The force action members 73, 78 apply an upward force onto the movable part 30 when the movable part 30 is moved in said three directions.

Description

  The present invention relates to a parallel link robot.

  Conventionally, there has been a parallel link robot as disclosed in Patent Document 1 (Japanese Patent Publication No. 63-501860). The parallel link robot has, for example, a motor that drives three arm portions, and a movable portion that holds an end effector is connected to a link portion that extends from each arm portion to control the three motors. Move the part up and down, back and forth, and left and right.

  In the parallel link robot, the weight of the movable part is applied to the arm part via the link part. That is, the motor that drives the arm unit must output torque for supporting the weight of the movable unit in addition to torque for moving the movable unit. For this reason, it is necessary to increase the size of the motor.

  However, if the size of the expensive motor that drives the arm unit in the parallel link robot is increased, the manufacturing cost increases.

  The subject of this invention is providing the parallel link robot which can reduce the weight of the movable part concerning an arm part, and can suppress manufacturing cost.

  A parallel link robot according to the present invention includes a base portion, a movable portion, first to third arm portions, first to third drive portions, first to third link portions, a control portion, and a force action. And a member. The movable part is located below the base part and has first to fourth connection parts. The first to third arm portions extend from the base portion. The 1st-3rd drive part is supported by the base part, and drives each of the 1st-3rd arm part. One end of the first to third link portions is rotatably connected to each of the first to third arm portions, and the other end is rotatably connected to each of the first to third connection portions of the movable portion. A control part controls a 1st-3rd drive part, and moves a movable part to three directions of up-down, front-back, and right-and-left by the 1st-3rd arm part and the 1st-3rd link part. The force acting member is connected to the fourth connection part of the movable part. The force acting member applies an upward force to the movable part when the movable part is moved in three directions.

  Here, when the 1st-3rd drive part supported by the base part drives the 1st-3rd arm part, the posture and position of the 1st-3rd link part change in connection with it, and the 1st-3rd The movable part to which the link part is connected moves up and down, back and forth, and left and right. And at least when the movable part is moved, the force acting member applies an upward force to the movable part via the fourth connection part. Accordingly, at least a part of the weight of the movable part is supported by the force acting part, the weight of the movable part applied to the arm part is reduced, and the first to third drives that move the movable part via the arm part The load on the part is also reduced. Therefore, the driving force required for the first to third driving units is reduced, and the manufacturing cost of the parallel link robot can be reduced.

  Moreover, it is preferable that the parallel link robot further includes a fourth drive unit supported by the base unit, and causes the upward force to act on the force acting member by the fourth drive unit. If the control unit controls the fourth driving unit to apply an upward force corresponding to the weight of the movable unit to the force acting member, the weight of the end effector applied to the arm unit is more reliably reduced.

  The parallel link robot preferably further includes a fifth drive unit and an end effector. The fifth drive unit is supported by the base unit and causes the force acting member to apply a rotational force. The end effector is provided to be rotatable with respect to the movable part. In this case, the control unit can control the fourth driving unit and the fifth driving unit, apply an upward force to the movable unit and the end effector, and rotate the end effector relative to the movable unit.

  According to the parallel link robot according to the present invention, the force acting unit applies an upward force to the movable unit via the fourth connection unit, so that the weight of the movable unit applied to the arm unit is reduced. The driving force required for the third drive unit is reduced, and the manufacturing cost of the parallel link robot can be reduced.

1 is an external perspective view of a parallel link robot according to an embodiment of the present invention. The simplified diagram which shows the structure of a parallel link robot. The control block diagram of a parallel link robot. FIG. 9 is a simplified diagram showing a configuration of a parallel link robot according to Modification A.

  An appearance of a parallel link robot 10 according to an embodiment of the present invention is shown in FIG. The parallel link robot 10 is suitably used for picking work or boxing work in a food production line or the like.

(1) Configuration As shown in FIGS. 1 and 2, the parallel link robot 10 includes a base unit 20, a movable unit 30, first to third arm units 41 to 43, and first to third servos for movement. Motors 51 to 53, first to third link parts 61 to 63, a pulling / rotating mechanism 70, an end effector 80, and a control unit 90 (see FIG. 3) are provided.

(1-1) Base Part The base part 20 is a structure installed on the ceiling of a food production factory, for example, and includes first to third servo motors 51 to 53 for movement and a fourth servo motor 79 for lifting described later. The fifth servomotor 76 for rotation and the like are supported and enclosed.

(1-2) Movable Part The movable part 30 is located in the space below the base part 20. First to fourth connection parts 31 to 34 are formed in the movable part 30. The lower ends of the first to third link parts 61 to 63 are connected to the first to third connection parts 31 to 33. The fourth connecting portion 34 is a portion to which an outer race (outer ring) of a bearing 34a that is a deep groove ball bearing is fixed. The bearing 34a is a bearing capable of receiving a radial load and an axial load. A first force acting member 71 described later is fixed to the inner race (inner ring) of the bearing 34a.

(1-3) 1st-3rd arm part The 1st-3rd arm part 41-43 is extended toward the outer side from the base part 20. As shown in FIG. As for the 1st-3rd arm parts 41-43, the inner end is attached to the output shaft of the 1st-3rd servomotors 51-53 for a movement, and an outer end is the 1st-3rd link part via a joint. 61 to 63 are rotatably connected.

(1-4) First to Third Servo Motors for Movement The first servo motor 51 for movement is fixed to the base part 20 and rotates the first arm part 41 with its output shaft as the center of rotation. The moving second servo motor 52 is fixed to the base portion 20 and rotates the second arm portion 42 with its output shaft as the rotation center. The moving third servo motor 53 is fixed to the base portion 20 and rotates the third arm portion 43 with its output shaft as the rotation center.

  The first to third servomotors 51 to 53 for movement and the first to third arm portions 41 to 43 are arranged at equal angular intervals (120-degree intervals) in plan view.

(1-5) First to third link portions 61 to 63
As described above, the first to third link parts 61 to 63 are rotatably connected to the outer ends of the first to third arm parts 41 to 43 via joints. Moreover, the lower end of the 1st-3rd link parts 61-63 is connected with the 1st-3rd connection parts 31-33 of the movable part 30 so that rotation is possible via the joint. The lengths of the first to third link parts 61 to 63 are larger (longer) than the lengths of the first to third arm parts 41 to 43.

(1-6) Lifting / Rotating Mechanism The lifting / rotating mechanism 70 includes a first force acting member 71, a first universal joint (universal joint) 72, a second force acting member 73, and a third force acting member 78. , A fourth force acting member 74, a second universal joint 75, a lifting fourth servomotor 79, and a rotating fifth servomotor 76.

  The rod-shaped first force acting member 71 is connected to the fourth connecting portion 34 of the movable portion 30 via a bearing 34a. An end effector 80, which will be described later, is fixed to the lower end portion of the first force acting member 71 extending downward from the inner race of the bearing 34a.

  The rod-shaped second force acting member 73 is connected to the first force acting member 71 via the first universal joint 72. The first force acting member 71 rotates according to the rotation of the second force acting member 73.

  The cylindrical fourth force acting member 74 has a second force acting member 73 inserted therein, and moves relative to the second force acting member 73 when the movable portion 30 moves relative to the base portion 20. To do. The second force acting member 73 and the fourth force acting member 74 are connected so as to be relatively movable in the axial direction, while the second force acting member 73 and the fourth force acting member 74 do not rotate relative to each other. It is connected to. That is, as the fourth force acting member 74 rotates, the second force acting member 73 also rotates.

  The fifth servomotor for rotation 76 is fixed to the base portion 20, and its output shaft is horizontally arranged. A bevel gear is fixed to the tip of the output shaft 76a of the fifth servomotor 76 for rotation. When the output shaft 76a rotates, the vertical cylindrical member 76b with the bevel gear fixed to the upper end rotates. That is, the bevel gear at the tip of the output shaft 76a and the bevel gear at the upper end of the vertical cylindrical member 76b are meshed with each other. Further, the vertical cylindrical member 76b is fixed to the base portion 20 so as to be capable of relative rotation around the vertical axis and not to be relatively vertically movable.

  The lower end of the vertical cylindrical member 76 b and the upper end of the fourth force acting member 74 are connected via a second universal joint 75. When the fifth servomotor for rotation 76 is driven and the vertical cylindrical member 76b rotates, the fourth force acting member 74 rotates accordingly. That is, when the fifth servo motor 76 for rotation is driven, the rotational force is transmitted to the end effector 80 via the fourth force acting member 74, the second force acting member 73, the first force acting member 71, and the like. That is, when the rotation fifth servomotor 76 is driven, a rotational force is applied to the first force acting member 71 connected to the end effector 80.

  The third force acting member 78 is a wire whose tip is fixed to the upper end of the second force acting member 73. The third force acting member 78 extends upward from the upper end of the second force acting member 73, passes through the inner space of the cylindrical fourth force acting member 74 and the vertical cylindrical member 76 b, and moves up to the fourth servo motor 79 for lifting. Head. The proximal end of the third force acting member 78 is wound around the output shaft of the lifting fourth servomotor 79. When the fourth lifting servomotor 79 winds up the third force acting member 78, the second force acting member 73 to which the tip of the third force acting member 78 is fixed is pulled up. When the second force acting member 73 is pulled up, the first force acting member 71 connected to the second force acting member 73 via the first universal joint 72 is also lifted and fixed to the first force acting member 71. The end effector 80 and the movable part 30 connected to the first force acting member 71 via the bearing 34a are also lifted. That is, the rotational torque of the lifting fourth servomotor 79 is changed to a force for lifting the movable part 30 and the end effector 80 upward via the first to third force acting members 71, 73, 78, and the like. That is, when the fourth lifting servomotor 79 is driven, an upward force is applied to the first force acting member 71 connected to the movable portion 30 and the end effector 80. The first to third force acting members 71, 73, 78 are connected by a vertical cylindrical member 76 b fixed to the base portion 20 and a second universal joint 75, and are directed from the base portion 20 toward the movable portion 30. It extends.

(1-7) End Effector The end effector 80 is an article gripper that can hold an article such as food by suction. The end effector 80 includes a suction part 81 and is connected to a hose (not shown) extending from a vacuum mechanism that makes the inside of the suction part 81 have a negative pressure from atmospheric pressure. A vacuum ON / OFF mechanism 82 (see FIG. 3) for switching between gripping / holding of articles by the suction unit 81 is an electromagnetic on-off valve provided in a hose extending from the vacuum mechanism, for example, and the state is switched by the control unit 90. .

  The end effector 80 is positioned below the movable unit 30 and supported by the movable unit 30 so that the end effector 80 can rotate around the vertical axis with respect to the movable unit 30. Specifically, the inner race of the bearing 34 a where the outer race is fixed to the movable portion 30 is fixed to the first force acting member 71, and the lower end of the first force acting member 71 is connected to the end effector 80. It is fixed at the top.

(1-8) Control Unit The control unit 90 shown in FIG. 3 includes first to third servo motors 51 to 53 for movement, a fourth servo motor 79 for lifting, a fifth servo motor 76 for rotation, and a vacuum ON / OFF mechanism. A control command is sent to 82 and the like, and the movable unit 30 having three degrees of translation is moved in three directions, up and down, front and rear, and left and right. Normally, the control unit 90 includes first to third encoders built in the first to third servomotors 51 to 53 for movement, a fourth encoder built in the fourth servomotor 79 for lifting, and a fifth servomotor 76 for rotation. Receives position detection information from the fifth encoder built in the motor, and controls each motor.

  However, when the origin position of the first to third servo motors 51 to 53 for movement is lost due to a power failure or the like, the control unit 90 is based on the detection information of the first to third gyro sensors 91 to 93. The movements of the first to third servomotors 51 to 53 for movement are controlled. As shown in FIG. 2, the first to third gyro sensors 91 to 93 are attached to the first to third arm portions 41 to 43.

(2) Operation As described above, when the control unit 90 sends a drive command to the first to third servomotors 51 to 53 for movement, the movable unit 30 having three degrees of translation moves up and down, back and forth, and left and right. Move to the desired position. Further, by driving the fifth servomotor 76 for rotation, the control unit 90 rotates the end effector 80 to change the posture so that the article can be easily gripped. Therefore, after controlling the vacuum ON / OFF mechanism 82 and causing the end effector 80 to grip the article, the control unit 90 sends the drive command to the first to third servo motors 51 to 53 again to place the article. The movable part 30 is moved up to.

  In addition to the normal operation of the parallel link robot, the parallel link robot 10 according to the present embodiment performs a movement assist operation by driving the fourth servomotor 79 for lifting. When the control unit 90 moves the movable unit 30 in three directions, the drive torque of the fourth servomotor 79 for lifting is changed to an upward force by the first to third force acting members 71, 73, 78. It acts on the movable part 30. The control unit 90 calculates the upward force applied to the first force acting member 71 connected to the movable unit 30 in consideration of the acceleration of the movable unit 30 moved in three directions, and includes the end effector 80. An upward force is applied to the first force application member 71 by the weight of 30. As a result, the torques of the first to third servomotors 51 to 53 for movement necessary for the movement of the movable part 30 in three directions are reduced, and the movable part 30 moves at high speed.

(3) Features (3-1)
In the parallel link robot 10, when the first to third servomotors 51 to 53 for movement supported by the base unit 20 drive the first to third arm units 41 to 43, the first to third link units accordingly. The positions of 61 to 63 change, and the movable unit 30 to which the first to third link parts 61 to 63 are connected moves in three translational directions, up and down, front and rear, and left and right. And when the movable part 30 is moved, the control part 90 applies upward force with respect to the movable part 30 via the 1st-3rd force action member 71,73,78 grade | etc.,. As a result, all or part of the weight of the movable part 30 is supported by the first to third force acting members 71, 73, 78, etc., and the movable part 30 is suspended from the first to third arm parts 41 to 43. Weight is reduced. Thereby, the load concerning the 1st-3rd servomotors 51-53 for movement which are moving the movable part 30 via the 1st-3rd arm parts 41-43 is also small. Accordingly, the driving force required for the first to third servomotors 51 to 53 for movement is reduced, and the small first to third servomotors 51 to 53 for movement can be selected. Costs are reduced. Further, since the torques of the first to third servomotors 51 to 53 for movement necessary for moving the movable unit 30 in three directions are small, the movable unit 30 can be moved at high speed.

(3-2)
In the parallel link robot 10, the control unit 90 calculates the upward force to be applied to the movable unit 30 and the end effector 80 in consideration of the acceleration of the movable unit 30 moved in the three translational directions, and the fourth servomotor for lifting. A control command is sent to 79. For this reason, the weight of the movable part 30 and the end effector 80 applied to the first to third arm parts 41 to 43 rotated by the first to third servomotors 51 to 53 for movement is appropriately reduced. The magnitude of the upward force to be applied to the movable unit 30 and the end effector 80 is basically a size corresponding to the weight of the movable unit 30 and the end effector 80.

(3-3)
Assuming that the origin position of the first to third servo motors 51 to 53 for movement is lost due to a power failure or the like, one solution is to re-detect the origin position after a power failure. It is conceivable to provide automatic home return.

  However, since the position of the end effector 80 is not known until the return to origin is completed, there is a possibility that the end effector 80 may come into contact with or collide with the vehicle when returning to the origin.

  For this reason, if the home position return is not performed by manual operation, a function for holding the motor home position even during a power failure is required.

  In view of this, in the parallel link robot 10 according to the present embodiment, when a power failure occurs and the origin positions of the first to third servomotors 51 to 53 for movement are lost, the control unit 90 performs the first to first operations. The movements of the first to third servomotors 51 to 53 for movement are controlled based on the detection information of the three gyro sensors 91 to 93. As a result, the absolute positions of the arm angles of the first to third arm portions 41 to 43 can be known, and even when the rotation origin positions of the moving first to third servomotors 51 to 53 are not known, the control unit 90. Can grasp the current position.

(4) Modification (4-1) Modification A
In the above-described embodiment, the pull-up / rotation mechanism 70 is provided to allow the end effector 80 to rotate. However, the present invention can also be applied to a parallel link robot that does not need to rotate the end effector.

  FIG. 4 shows a configuration of the parallel link robot 110 according to the modified example A. The parallel link robot 110 includes a base part 120, a movable part 130, first to third arm parts 141 to 143, first to third servo motors 151 to 153 for movement, and first to third link parts 161. ˜163, a lifting mechanism 170, and an end effector (not shown) fixed to the lower part of the movable portion 130.

  The base portion 120 supports the first to third servomotors 151 to 153 for movement, the lifting linear actuator 179 described later, and the like.

  The movable part 130 is located in a space below the base part 120. The movable part 130 is formed with first to fourth connection parts 131 to 134. The lower ends of the first to third link portions 161 to 163 are connected to the first to third connection portions 131 to 133. The fourth connecting portion 134 is a portion to which the lower end of the rod-shaped first force acting member 171 is fixed.

  The first to third arm portions 141 to 143 extend outward from the base portion 120. The inner ends of the first to third arm portions 141 to 143 are attached to the output shafts of the first to third servomotors 151 to 153 for movement, and the outer ends are connected to the first to third link portions via joints. 161 to 163 are rotatably connected.

  The first servo motors 151 to 153 for movement rotate the first to third arm portions 141 to 143.

  The lower ends of the first to third link parts 161 to 163 are rotatably connected to the first to third connection parts 131 to 133 of the movable part 130 via joints.

  The lifting mechanism 170 includes a first force acting member 171, a first ball joint 172, a second force acting member 173, a second ball joint 175, and a lifting linear actuator 179. The upper end of the rod-shaped first force acting member 171 and the lower end of the second force acting member 173 are connected by a first ball joint 172. The upper end of the second force acting member 173 and the lower end of the rod 179a of the lifting linear actuator 179 are connected by a second ball joint 175. The lifting linear actuator 179 is an electric ball screw type electric slider whose rod 179a extends in the vertical direction, and has a built-in servo motor. The casing of the lifting linear actuator 179 is fixed to the base portion 120. When the controller drives the lifting linear actuator 179, the rod 179a moves up and down.

  Also in the parallel link robot 110 according to the modified example A having the above-described configuration, the advantages of the present invention described in the above (3-1) and (3-2), that is, the first to third servo motors for movement. Advantages such as manufacturing cost reduction accompanying the downsizing of 151 to 153 and high-speed movement of the movable unit 130 can be enjoyed.

(4-2) Modification B
In the above embodiment, the present invention is applied to the three-degree-of-freedom control parallel link robot 10 called a delta type, but also for a six-degree-of-freedom control parallel link robot called a hexa-type having six arms, The present invention can be applied.

(4-3) Modification C
In the above embodiment, the third force acting member 78, which is a wire, is wound around the output shaft of the lifting fourth servomotor 79, and the lifting fourth servomotor 79 is driven to move the movable part 30 and the end effector 80 upward. Although a configuration of pulling up is adopted, when high speed is not required, a counterweight corresponding to the weight of the movable portion 30 and the end effector 80 may be employed instead of the motor.

  When the moving range of the movable part 30 is narrow, a configuration is adopted in which an upward force is applied to the movable part 30 and the end effector 80 with a wire by fixing the spring member to the base part 20 instead of the motor or the counterweight. You can also.

10, 110 Parallel link robot 20, 120 Base portion 30, 130 Movable portion 41-43, 141-143 First to third arm portions 51-53, 151-153 Moving first to third servo motors (first to third servo motors) (3rd drive part)
61-63, 161-163 First to third link parts 71 First force acting member 72 First universal joint 73 Second force acting member 74 Fourth force acting member 75 Second universal joint 76 Fifth servo motor for rotation ( (Fifth drive unit)
78 Third force acting member 79 Lifting fourth servo motor (fourth drive unit)
80 End effector 171 First force acting member 172 First ball joint 173 Second force acting member 175 Second ball joint 179 Lifting linear actuator

JP-T63-501860

Claims (3)

A base part;
A movable part located below the base part and having first to fourth connection parts;
First to third arm portions extending from the base portion;
First to third driving units supported by the base unit and driving the first to third arm units, respectively.
First to third link portions, one end of which is rotatably connected to each of the first to third arm portions, and the other end of which is rotatably connected to each of the first to third connection portions of the movable portion; ,
A control unit that controls the first to third drive units, and moves the movable unit in three directions of up and down, front and rear, and left and right by the first to third arm units and the first to third link units;
A force acting member that is connected to the fourth connection portion of the movable portion and applies an upward force to the movable portion when the movable portion is moved in the three directions;
Parallel link robot with A fourth drive part (79) supported by the base part and acting upward force on the force acting member;
Further comprising
The control unit controls the fourth driving unit to cause an upward force corresponding to the weight of the movable unit to act on the force acting member.
The parallel link robot according to claim 1. A fifth drive unit supported by the base unit and causing a rotational force to act on the force acting member;
An end effector provided rotatably with respect to the movable part;
Further comprising
The control unit controls the fourth driving unit and the fifth driving unit to apply an upward force to the movable unit and the end effector, and to rotate the end effector with respect to the movable unit.
The parallel link robot according to claim 2.

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