Robotic device

Abstract

The present invention aims at detecting the distance of each direct motion element with respect to the fixed element in a robot device having an arm portion including a fixed element and a plurality of direct motion elements assembled in multiple stages at the fixed element. A robot device (1) has an arm portion (5) having a fixed element (54) and a plurality of direct motion elements (51, 52, 53) assembled in multiple stages at the fixed element (54) in a telescopic manner, a movement driving mechanism (7, 8) driving the movement of the foremost direct motion element (51) among the plurality of direct motion elements (51, 52, 53), and a position determining portion determining the position of at least one direct motion element (53) other than the foremost direct motion element (51) among the plurality of direct motion elements (51, 52, 53) with respect to the fixed element (54) or the foremost direct motion element (51).

Description

Technical Field

[0001] This invention relates to a robotic device. Background Technology

[0002] For collaborative robots, the requirement is that the robot safely stops upon contact with a person or object. One method for detecting contact between a person or object and the robot is to install torque sensors at the robot's joints and sense the load applied to the torque sensors. According to this method, if the output value of the torque sensor exceeds a predetermined reference value, it is possible to detect that "the robot has contacted a person or object." However, the torque sensor detects a combined torque resulting from the contact with the robot and the torque generated by the robot's movement. Therefore, in order for the torque sensor to accurately detect contact with a person or object, it is necessary to remove the torque generated by the robot's movement from the torque sensor's detection results.

[0003] The torque generated by the robot's movements can be calculated based on the arm's movement and weight. However, in the case of a linear motion mechanism with an arm consisting of a fixed element and multiple linear motion elements assembled in multiple stages on the fixed element, the linear motion elements other than the fixed element fixed to the arm support member and the linear motion elements connected to the arm's drive mechanism can move freely relative to adjacent elements. Therefore, there is a problem that the amount of arm movement varies, making it impossible to accurately determine the torque generated by the robot's movements. For example, Patent Document 1 discloses a configuration in which a telescopic boom of an aerial work platform is equipped with a telescopic length detector for detecting the telescopic length of the boom.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Utility Model Application Publication No. 61-697089 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] In a robotic device having an arm consisting of a fixed element and multiple linearly moving elements assembled in multiple stages on the fixed element, it is desirable to determine the relative positional relationship between the fixed element and the multiple linearly moving elements.

[0009] means for solving problems

[0010] A robotic device according to one aspect of this disclosure includes: an arm having a fixed element and a plurality of linear moving elements assembled in multiple stages on the fixed element in a telescopic manner; a motion drive mechanism for driving the movement of the foremost linear moving element among the plurality of linear moving elements; and a position determination unit for determining the position of at least one linear moving element among the plurality of linear moving elements, excluding the foremost linear moving element, relative to the fixed element or the foremost linear moving element.

[0011] Invention Effects

[0012] According to one approach, for a robotic device having an arm, the arm includes a fixed element and multiple linearly moving elements assembled in multiple stages on the fixed element, and the position of the linearly moving elements relative to the fixed element can be determined. Attached Figure Description

[0013] Figure 1 This is an external view of the robot device according to this embodiment.

[0014] Figure 2 It is shown Figure 1 A 3D diagram of the arm in a contracted state.

[0015] Figure 3 It is shown Figure 1 A three-dimensional diagram of the arm in an extended state.

[0016] Figure 4 It is shown with the arms excluded. Figure 2 A side view of the internal structure of the direct-acting mechanism.

[0017] Figure 5 It is shown Figure 4 A side view of the center of gravity position when the arm is extended.

[0018] Figure 6 It is shown Figure 2 A side view of the internal structure of the direct-acting mechanism during arm retraction.

[0019] Figure 7 It is shown Figure 3 A side view of the internal structure of the direct-acting mechanism when the arm extends.

[0020] Figure 8 It is shown Figure 1 Side view of other examples of the arm.

[0021] Explanation of reference numerals in the attached figures

[0022] 5…arm, 51, 52, 53, 54…cylindrical body, 100…detection section. Detailed Implementation

[0023] Hereinafter, the robot device of this embodiment will be described with reference to the accompanying drawings. In the following description, the same reference numerals will be used to denote constituent elements having substantially the same function and structure, and the description will be repeated only where necessary.

[0024] like Figure 1 As shown, the robot device 1 of this embodiment includes a polar coordinate type robot arm mechanism 2 and a control device 3 for controlling the robot arm mechanism 2.

[0025] The robot arm mechanism 2 has a flat base 20. A support frame is vertically erected on the base 20. The support frame is divided into a lower support frame 21 and an upper support frame 22. The lower support frame 21 and the upper support frame 22 are connected by a first rotary joint J1, allowing them to rotate freely left and right. The first rotary joint J1 has a rotation axis (first rotation axis RA1) perpendicular to the base 20. The linear motion mechanism 4 is fixed to a side frame 23 on the upper part of the upper support frame 22 via a second rotary joint J2, allowing it to rotate freely up and down. The second rotary joint J2 has a rotation axis (second rotation axis RA2) orthogonal to the first rotation axis RA1. The linear motion mechanism 4 has an arm 5, which is telescopic. The arm 5 extends and retracts freely along a linear motion axis RA3 orthogonal to the second rotation axis RA2, forming a third linear motion joint J3. A wrist 9 is connected to the front end of the arm 5, and the wrist 9 has three rotary joints J4, J5, and J6 with mutually orthogonal rotation axes. Rotary joint J4 has a rotation axis RA4 orthogonal to the direct-acting axis RA3. Rotary joint J5 has a rotation axis RA5 perpendicular to the rotation axis RA4. Rotary joint J6 has a rotation axis RA6 perpendicular to both rotation axes RA4 and RA5. A connector for mounting end effectors such as grippers is provided at the wrist portion 9.

[0026] Arm 5 includes a fixed element and multiple linearly moving elements assembled in multiple stages on the fixed element. For example... Figure 2 , Figure 3 As shown, in this embodiment, the arm 5 is composed of multiple cylindrical bodies forming a telescopic structure (multi-level nested structure), specifically four cylindrical bodies 51, 52, 53, and 54. Adjacent cylindrical bodies are connected along the cylinder centerline CL1 via a sliding mechanism (not shown) for free sliding. The cylinder centerline CL1 corresponds to the direct motion axis RA3 of the third direct motion joint J3. Of the four cylindrical bodies 51, 52, 53, and 54, the last cylindrical body 54 is fixed to the housing 6, and the first cylindrical body 51 is connected to the arm drive mechanism. The last cylindrical body 54 fixed to the housing 6 corresponds to a fixing element, while the other cylindrical bodies 51, 52, and 53 correspond to multiple direct motion elements. Furthermore, the cylindrical bodies can be cylindrical or rectangular, etc.

[0027] When the foremost cylinder 51 moves forward using the arm drive mechanism, cylinders following it are pulled out sequentially, resulting in the arm 5 extending forward along the cylinder centerline CL1. When the foremost cylinder 51 moves backward using the arm drive mechanism, cylinders following it are retracted into the cylinders following it sequentially, resulting in the arm 5 retracting backward along the cylinder centerline CL1.

[0028] During the extension and retraction of arm 5, the foremost cylinder 51 is connected to the arm drive mechanism. Therefore, the distance from the last cylinder 54 to the foremost cylinder 51 can be calculated based on the control value of the arm extension and retraction length. On the other hand, for the other cylinders 52 and 53 among the four cylinders 51, 52, 53, and 54, excluding the foremost cylinder 51 and the last cylinder 54, they are only connected to adjacent cylinders via sliding mechanisms and can slide freely. Therefore, whenever the robot arm mechanism 2 performs actions such as the undulating motion of arm 5 or the rotating motion of arm 5, the distance from the last cylinder 54 to the other cylinders 52 and 53 may change. Therefore, the distance from the last cylinder 54 to the other cylinders 52 and 53, in other words, the position of the other cylinders 52 and 53 relative to the last cylinder 54, cannot be uniquely determined based on the control value of the arm extension and retraction length.

[0029] One feature of the robot device 1 in this embodiment is that it has a position determination unit that determines the positions of the two cylindrical bodies 52 and 53 relative to the last cylindrical body 54. Typically, the robot device 1 has a 2ch laser displacement meter, which serves as a detection unit 100 for detecting the distance between the two cylindrical bodies 52 and 53 and the last cylindrical body 54. Figure 4 , Figure 5 As shown, the detection unit 100 is installed inside the last cylindrical body 54, with its two detection axes parallel to the cylinder centerline CL1, and located below the moving axis BL1 of the block array 70. Data on the distance from the last cylindrical body 54 to the cylinder 53 and the distance from the last cylindrical body 54 to the cylinder 52, measured by the laser displacement gauge, are input to the control device 3. In practice, the laser displacement gauge measures the distance from the reference position to the cylinder 53 and the distance from the reference position to the cylinder 52. The reference position is, for example, a position predetermined in the laser displacement gauge. On the other hand, the relative positional relationship between the laser displacement gauge and the last cylindrical body 54 is fixed. Therefore, the amount of movement of the cylinder 53 relative to the reference position corresponds to the distance from the last cylindrical body 54 to the cylinder 53, and the amount of movement of the cylinder 52 relative to the reference position corresponds to the distance from the last cylindrical body 54 to the cylinder 52.

[0030] The control device 3 includes a storage device such as an HDD (Hard Disk Drive) storing programs, and an arithmetic processing unit such as a CPU that executes the programs stored in the storage device. The programs stored in the storage device include: a task program recording a series of actions performed by the robot arm mechanism 2 and a robotic hand (not shown) mounted on the robot arm mechanism 2; a position determination program determining the relative positional relationships of the multiple cylinders 51, 52, 53, and 54 constituting the arm 5; a center of gravity estimation program estimating the center of gravity position of the arm 5; and a contact detection program detecting contact between a person or object and the robot arm mechanism 2. The arithmetic processing unit functions as a position determination unit when executing the position determination program, as a center of gravity estimation processing unit when executing the center of gravity estimation program, and as a contact detection unit when executing the contact detection program to detect contact between a person or object and the robot arm mechanism 2.

[0031] The position determination unit determines the positions of the other cylinders 52 and 53 relative to the last cylinder 54 based on the distances from the detection unit 100 to the cylinders 52 and 53 detected by the detection unit 100. The positional relationship between the last cylinder 54 and the detection unit 100 is fixed, and its distance is known. Therefore, the positions of the other cylinders 52 and 53 relative to the last cylinder 54 can be determined based on the distances from the last cylinder 54 to the detection unit 100 and the distances from the detection unit 100 to the cylinders 52 and 53.

[0032] The center of gravity position estimation processing unit estimates the center of gravity position of the arm 5 based on the positions of the other cylinders 52 and 53 relative to the last cylinder 54, the position of the foremost cylinder 51 relative to the last cylinder 54 obtained by executing the position determination program, and the weights of the four cylinders 51, 52, 53, and 54. For example, as Figure 5 As shown in (a), the center of gravity position estimation processing unit estimates the center of gravity position G1 based on the distance D11 from the last cylinder 54 to the cylinder 53, the distance D12 from the last cylinder 54 to the cylinder 52, the distance D13 from the last cylinder 54 to the cylinder 51, and the weight of each cylinder 51, 52, 53, and 54. Figure 5 (b) shows the cylinders 52 and 53 moving to the position of... Figure 5 The state of the arm 5 in front of the arm shown in (a) is as follows. The center of gravity position estimation processing unit estimates the center of gravity position G2 in front of the center of gravity position G1 based on the distance D21 from the last cylinder 54 to the cylinder 53, the distance D22 from the last cylinder 54 to the cylinder 52, the distance D23 from the last cylinder 54 to the cylinder 51, and the weight of each cylinder 51, 52, 53, 54. Figure 5 (c) shows the cylinders 52 and 53 moving to the position of... Figure 5 The state of the arm 5 compared to the state shown in (a) is as follows. The center of gravity position estimation processing unit estimates the center of gravity position G3, which is located behind the center of gravity position G1, based on the distances D31 from the last cylinder 54 to cylinder 53, D32 from the last cylinder 54 to cylinder 52, D33 from the last cylinder 54 to cylinder 51, and the weight of each cylinder 51, 52, 53, and 54. The distance from the last cylinder 54 to cylinder 51 can be calculated based on the arm extension length. Figure 5 (a) in the middle, Figure 5 (b) Figure 5 In (c) of the equation, it is assumed that the distance is the same.

[0033] The contact detection unit calculates the torque generated at each joint due to the movement of the robot arm mechanism 2 based on the center of gravity position of the arm 5 estimated by the center of gravity position estimation processing unit, the center of gravity position of each link connecting each joint of the robot arm mechanism 2, and the amount of movement (rotation) of each joint, using methods such as the Newton-Euler method or the Lagrange method. Based on the detection values ​​of torque sensors installed at each joint and the calculated torque generated at each joint accompanying the movement of the robot arm mechanism 2, the external force can be calculated. When the external force exceeds a predetermined value, the contact detection unit detects that a person or object has come into contact with the robot arm mechanism 2.

[0034] Even when the robot arm mechanism 2 is not in motion, for example, if the arm 5 is stationary in a position other than horizontal, the cylinders 52 and 53 may move relative to the last cylinder 54, and the center of gravity of the arm 5 may change. Even when the robot arm mechanism 2 is stationary, in order to maintain the accuracy of contact detection performed by the contact detection unit, it is desirable that the calculations performed by the position determination unit, the center of gravity position estimation processing unit, and the contact detection unit are executed at predetermined intervals, regardless of whether the robot arm mechanism 2 is in motion.

[0035] According to the robot device 1, the arm 5 includes a fixed element (the last cylindrical body 54) and multiple linearly moving elements (cylinders 51, 52, 53) assembled in multiple stages on the fixed element. When the foremost linearly moving element (the foremost cylindrical body 51) is driven to move, the detection unit 100 can determine the position of the other linearly moving elements (cylinders 52, 53) relative to the fixed element (the last cylindrical body 54). Thus, for example, the center of gravity position of the arm 5 can be estimated, and the force generated by the movement of the robot arm mechanism 2 can be separated from the force generated by the contact between a person or object and the robot arm mechanism 2 in the torque sensor provided at the joint, thereby improving the accuracy of contact detection.

[0036] In this embodiment, the laser displacement meter 100 is installed inside the last cylindrical body 54 and below the moving axis of the block column 7, but the installation position of the laser displacement meter 100 is not limited to this embodiment. For example, the laser displacement meter 100 can be installed above the moving axis BL1 of the block column 7. Alternatively, the laser displacement meter 100 can be installed to the left or right of the moving axis BL1 of the block column 7. From the viewpoint of lowering the center of gravity of the arm 5, it is preferable to install the laser displacement meter 100 below the moving axis BL1 of the block column 7. Furthermore, as long as distance can be measured, the detection unit 100 is not limited to a laser displacement meter; for example, it can be a laser reflection type distance sensor, etc.

[0037] In this embodiment, to determine the positions of the two cylindrical bodies 52 and 53 relative to the last cylindrical body 54, a 2ch laser displacement meter is installed inside the last cylindrical body 54 as a detection unit 100 to detect the distance from the detection unit 100 to the two cylindrical bodies 52 and 53. The configuration of the detection unit 100 is not limited to this, as long as the relative positional relationships of the multiple cylindrical bodies 51, 52, 53, and 54 can be determined. For example, the 2ch laser displacement meter 100 can be mounted on the housing 6 to which the last cylindrical body 54 is fixed. Furthermore, since the distance from the last cylindrical body 54 to the first cylindrical body 51 can be calculated based on the arm extension length, the 2ch laser displacement meter 100 can also be installed on the first cylindrical body 51 to measure the distance from the laser displacement meter 100 to the other cylindrical bodies 52 and 53, thus determining the positions of the other cylindrical bodies 52 and 53 relative to the first cylindrical body 51. Of course, two 1ch laser displacement meters can also be used. In this case, a laser displacement meter is installed on the last cylindrical body 54 to measure the distance from the last cylindrical body 54 to the cylindrical body 53 in front of it. Another laser displacement meter is installed on the cylindrical body 53 to measure the distance from the cylindrical body 53 to the cylindrical body 52 in front of it. Based on these results, the positions of the other cylindrical bodies 52 and 53 relative to the last cylindrical body 54 can be determined. From the viewpoint of suppressing the weight load caused by the installation of the laser displacement meters, it is preferable to install the laser displacement meters on the last cylindrical body 54 or on the housing 6 to which the last cylindrical body 54 is fixed.

[0038] In this embodiment, the center of gravity of the arm 5 is estimated based on the relative positional relationship of all the cylinders 51, 52, 53, and 54 constituting the arm 5. However, if only the center of gravity of the arm 5 is estimated, although the estimation accuracy is lower than the above estimation process, the center of gravity of the arm 5 can be estimated based on the relative positional relationship of the foremost cylinder 51, the last cylinder 54, and one of the other cylinders 52 and 53. In this case, the laser displacement meter 100 is installed on either the foremost cylinder 51 or the last cylinder 54, and only the distance of one of the cylinders 52 and 53 is measured. The cylinder to be used for determining the position is preferably the one among the cylinders 52 and 53 that is heavier, has a larger change in distance relative to the last cylinder 54, and thus has a greater influence on the change in the center of gravity.

[0039] For example, the direct-acting mechanism 4 is configured as follows.

[0040] Arm 5 is supported by housing 6. (As shown) Figure 4 As shown, typically, the housing 6 is configured as a roughly short cylindrical shape with approximately one-quarter of its upper portion cut off. A mounting plate 69 is installed at the cut-off portion of the upper part of the housing 6. A flange 59 is joined to the mounting plate 69 and fastened by bolts, etc. The flange 59 is formed at the rear end of the arm 5, i.e., the rear edge of the last cylindrical body 54. An opening 691 is formed in the mounting plate 69. Thus, the interior of the housing 6 communicates with the hollow interior of the cylindrical bodies 51, 52, 53, and 54 (the hollow interior of the arm 5). Figure 6 , Figure 7 As shown, a block array 7 is inserted into the space connecting the interior of the housing 6 to the interior of the cylindrical bodies 51, 52, 53, and 54. The opening 691 forms an inlet / outlet for the block array 7 to enter and exit the housing 6.

[0041] The block column 7 is composed of multiple blocks 71 connected in a column. Each block 71 has a cuboid shape, and cam followers 73 are mounted on its two sides. The shape of the blocks 71 and the connection structure of the blocks 71 are configured such that, when two adjacent blocks 71 are arranged in a straight line, further upward rotation is restricted, while downward rotation is allowed.

[0042] The foremost block 71 of the block array 7 is connected to the foremost cylinder 51 among the plurality of cylinders 51, 52, 53, and 54. With the arm 5 retracted, most of the block array 7 is housed inside the housing 6. Typically, inside the housing 6, the block array 7 is housed in an arc shape centered on the housing center Rc. Therefore, a pair of guide rails 63 and 64 are provided on the inner surfaces of the side plates on both sides of the housing 6, serving as a storage section for housing the block array 7 along the arc-shaped track. Typically, the pair of guide rails 63 and 64 are configured as curved lines, with the center of the arc coinciding with the housing center Rc, and the distance between the guide surface of the outer guide rail 64 and the guide surface of the inner guide rail 63 is equal to or slightly larger than the diameter of the cam follower 73 mounted on the block 71.

[0043] Inside the housing 6 is a block drive mechanism 8 that performs the sending and pulling-back actions of the block column 7. In this embodiment, the block drive mechanism 8 includes a motor (not shown) and a reducer 81 that slows down the rotation speed of the motor. The reducer 81 is configured such that the rotation center of its rotation shaft 83 coincides with the housing center Rc. One end (base end) of a rod-shaped rotating arm 85 is connected to the rotation shaft 83 of the reducer 81. The other end (front end) of the rotating arm 85 is connected to the last block 71.

[0044] As the motor rotates in the forward direction, block 7 is pushed out by rotating arm 35, and the foremost block 71 moves forward along the moving axis BL1 parallel to the cylinder centerline CL1. As the foremost block 71 moves forward, cylinders behind it are pulled out in sequence, starting from the foremost cylinder 51. As a result, arm 5 extends forward along the cylinder centerline CL1.

[0045] When the motor rotates in the reverse direction, block 7 is pulled back by rotating arm 35, and the foremost block 71 moves backward along the moving axis BL1 parallel to the cylinder centerline CL1. As the foremost block 71 moves backward, the cylinders from the foremost cylinder 51 to the rear are sequentially retracted, resulting in the arm 5 retracting backward along the cylinder centerline CL1.

[0046] Thus, the block column 7 and the block column drive mechanism 8 that drives the movement of the block column 7 constitute the arm drive mechanism. The arm drive mechanism drives the frontmost cylindrical body 51 to move back and forth, that is, the extension and retraction of the arm 5.

[0047] In this embodiment, the rotating arm 85 pushes out and pulls back the block array 7, thereby driving the movement of the foremost cylindrical body 51. The configuration of the arm drive mechanism is not limited to this embodiment as long as it can drive the movement of the foremost cylindrical body 51. For example, a rack and pinion mechanism can be used, where the block array 7 is pushed out and pulled back from the housing 6 by the meshing of a gear formed on the block 71 with a drive gear provided on the moving track of the block array 7. Alternatively, the block array 7 can be omitted, and the movement of the foremost cylindrical body 51 can be driven by an existing direct-acting mechanism such as a ball screw mechanism.

[0048] The arm 5 in this embodiment is not limited to a telescopic structure. For example, such as Figure 8 As shown, the arm 800 can be composed of multiple longitudinally connected linear guide mechanisms 801, 802, 803, and 804. Each of the linear guide mechanisms 801, 802, 803, and 804 consists of a linear guide member supported by a base and a movable body that allows the linear guide member to slide freely. The base supporting the linear guide member of the last linear guide mechanism 804 is fixed to the mounting plate 69 of the housing. The foremost block 71 of the block array 7 is connected to the movable body (sliding part) of the foremost linear guide mechanism 801. With respect to the detection unit 100, the block array 7, excluding the foremost linear guide mechanism 801, moves back and forth along the movement axis BL1 relative to the last linear guide mechanism 804, thereby extending and retracting the arm 800. Even if only the arm structure is different, the arm 800, which uses a direct telescopic mechanism consisting of multiple direct-acting guide mechanisms 801, 802, 803, and 804, can achieve the same effect as the arm 5, which uses a telescopic structure.

[0049] While some embodiments of the invention have been described, these embodiments are given by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments or variations thereof are included within the scope or spirit of the invention as well as within the scope of the invention as set forth in the claims and its equivalents.

Claims

1. A robotic device, wherein, have: The arm has a fixing element and multiple linear elements that are telescopically assembled in multiple stages to the fixing element; A moving drive mechanism drives the foremost linear element among the plurality of linear elements to move; The position determination unit detects the distance of each of the plurality of linear elements other than the foremost linear element relative to the fixed element. as well as The center of gravity estimation processing unit estimates the position of the arm's center of gravity based on a combination of the distance from the foremost linear element to the fixed element, known from the drive of the moving drive mechanism, and the detected distances of the other linear elements relative to the fixed element. The plurality of linearly moving elements extend and retract linearly. The foremost linear element is moved via the motion drive mechanism. The other linear actuators move freely as the foremost linear actuator moves.

2. The robot device according to claim 1, wherein, The position determination unit has a sensor that detects the distance of each of the other linearly moving elements relative to the fixed element.

3. The robot device according to claim 2, wherein, The sensor is mounted on the fixed element or a support member that supports the fixed element.

4. The robot device according to any one of claims 1 to 3, wherein, The arm is composed of multiple cylindrical bodies assembled into a multi-level nested structure.

5. The robot device according to any one of claims 1 to 3, wherein, The arm is composed of multiple linear guide members and multiple moving bodies that move along the linear guide members.

Images