Robot, robot control method, method for manufacturing articles using a robot, control program, and recording medium

Abstract

To reduce a risk of damage of a sensor for detecting a force in a case that a robot is stopped by a mechanical stopper.SOLUTION: A robot includes: a first link; a drive device which rotates the first link; a transmission member which outputs rotation of the drive device; and a first stopper and a second stopper which are respectively provided at the first link and the transmission member and contact with each other by relative movement between the first link and the transmission member. The robot is adopted to achieve the above object.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a robot.

Background Art

[0002] In recent years, in a robot having links that operate by joints, a robot that can place a sensor for acquiring information on the force applied to the links on the links and perform control based on the force information has attracted attention. In particular, by arranging a torque sensor that can acquire torque information as force information, it has become easier to control the force generated in the links of the robot and the load or force applied by the end effector arranged at the tip of the robot to the parts. However, when the robot operates in an unintended direction during the execution of work by the robot or the teaching work of the robot, there is a risk that the robot and the peripheral device will collide and be damaged. To address such problems, in Patent Document 1, a stopper that mechanically limits the movable range of the joints of the robot is arranged on the joints, and the movable range of the joints is limited by arbitrarily changing the position of the stopper. By doing so, even when the robot operates in an unintended direction, the risk of the robot and the peripheral device colliding and being damaged is reduced.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the technology described in Patent Document 1, depending on the magnitude of the impact force when the robot arm (link) and the stopper collide, the stopper alone, which is in contact with the robot arm (link), may not be able to sufficiently mitigate the driving force. In particular, force-detecting sensors such as torque sensors are designed to deform to some extent in order to detect force. Therefore, if an impact force that has not been sufficiently mitigated is transmitted to a force-detecting sensor such as a torque sensor installed on the robot arm (link), there is a risk that the torque sensor will be damaged because it will exceed the allowable deformation range.

[0005] In light of the above issues, the present invention aims to reduce the risk of damage to the sensor used to detect force when a robot is stopped by a mechanical stopper. [Means for solving the problem]

[0006] To solve the above problems, the present invention provides a first link and a drive device for displacing the first link, The second link on which the aforementioned drive device is provided, The aforementioned drive device Displaced together with the first link by Components and The torque sensor connected to the first link and the member, A robot equipped with a first stopper provided on the first link, and Records Department A second stopper is provided in the material, The third stopper provided on the second link, Equipped with When the first link is displaced and the first stopper and the third stopper come into contact, or when the first link is displaced and the second stopper and the third stopper come into contact, the first stopper and the second stopper come into contact. ru The first stopper and the second stopper are provided in this manner. A robot with the following characteristics was adopted. [Effects of the Invention]

[0007] According to the present invention, the risk of damage to the force detection sensor when the robot stops due to a mechanical stopper can be reduced. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows the schematic configuration of the robot system 1000 in an embodiment. [Figure 2] This is a control block diagram of the robot system 1000 in an embodiment. [Figure 3] This is a schematic diagram of the link 201 and base 210 in the embodiment. [Figure 4] This is a cross-sectional view of the torque sensor 221 in the embodiment. [Figure 5] This is a detailed diagram showing the connection relationship between link 201 and base 210 in the embodiment. [Figure 6] This is a detailed diagram showing the connection relationship between link 201 and base 210 in the embodiment. [Figure 7] This figure shows the operation of the stopper 252 and the movable piece 254 in the embodiment. [Figure 8] This is a detailed diagram showing the connection relationship between link 201 and base 210 in the embodiment. [Figure 9] This is a detailed diagram showing the connection relationship between link 201 and base 210 in the embodiment. [Figure 10] This is a detailed diagram of stoppers 252 and 253 in the embodiment. [Figure 11] This is a detailed diagram showing the connection relationship between link 201 and base 210 in the embodiment. [Modes for carrying out the invention]

[0009] Hereinafter, embodiments for carrying out the present invention will be described with reference to the examples shown in the attached drawings.

[0010] The embodiments shown below are merely examples, and those skilled in the art can modify the details of the configuration as appropriate without departing from the spirit of the present invention. Furthermore, the numerical values ​​used in these embodiments are for reference only and do not limit the present invention. In the following drawings, the arrows X, Y, and Z indicate the overall coordinate system of the robot system. Generally, the XYZ 3D coordinate system represents the world coordinate system of the entire installation environment. In addition, a local coordinate system may be used for the robot hand, fingers, joints, etc., depending on control considerations.

[0011] (First embodiment) Figure 1 shows the schematic configuration of the robot system 1000 of the present embodiment. In Figure 1, the robot system 1000 includes a robot arm main body 200 configured as an articulated robot, a control device 300 that controls the robot arm main body 200, and an external input device 400.

[0012] The robot arm main body 200 of the present embodiment is composed of a 6-axis articulated structure. The robot arm main body 200 includes a base 210 and six links 201 to 206. Each of the links 201 to 206 is rotationally driven by six drive devices 231 to 236 that rotate the respective joint axes A1 to A6 around the arrows shown. The drive devices 231 to 236 each include a motor and a speed reducer that reduces the output of the motor. In the present embodiment, a harmonic drive speed reducer is used. That is, the motors provided in the drive devices 231 to 236 serve as drive sources that generate a driving force for relatively displacing the links 201 to 206 to which the respective joints are connected. Each motor also incorporates an encoder 211 to 216 that detects the rotational angle of the motor itself.

[0013] Torque sensors 221 to 226, which are sensors for detecting force information, are provided between the output ends of the drive devices 231 to 236 and the links 201 to 206 that rotate together with the output ends. The torque sensors 221 to 226 include an optical encoder that detects a structure and its relative movement amount described later. When the joints of the robot arm main body 200 are driven, the relative movement amount of the structures of the torque sensors 221 to 226 accompanying the relative displacement of the links of the robot arm main body 200 is detected by the optical encoder.

[0014] As shown in the figure, the link 201 of the robot arm body 200 is connected to the base 210 by a bearing (not shown) so as to be rotatable together with the torque sensor 221 by the drive device 231 in the figure. The drive device 231 is assumed to have a movable range in the direction of the arrow from the initial posture. The link 202 of the robot arm body 200 is connected to the link 201 by a bearing (not shown) so as to be rotatable together with the torque sensor 222 by the drive device 232 in the figure. The drive device 232 is assumed to have a movable range in the direction of the arrow from the initial posture.

[0015] The link 203 of the robot arm body 200 is connected to the link 202 by a bearing (not shown) so as to be rotatable together with the torque sensor 223 by the drive device 233 in the figure. The drive device 233 is assumed to have a movable range in the direction of the arrow from the initial posture. The link 204 of the robot arm body 200 is connected to the link 203 by a bearing (not shown) so as to be rotatable together with the torque sensor 224 by the drive device 234 in the figure. The drive device 234 is assumed to have a movable range in the direction of the arrow from the initial posture.

[0016] The link 205 of the robot arm body 200 is connected to the link 204 by a bearing (not shown) so as to be rotatable together with the torque sensor 225 by the drive device 235 in the figure. The drive device 235 is assumed to have a movable range in the direction of the arrow from the initial posture. The link 206 of the robot arm body 200 is connected to the link 205 by a bearing (not shown) so as to be rotatable together with the torque sensor 226 by the drive device 236 in the figure. The drive device 235 is assumed to have a movable range in the direction of the arrow from the initial posture.

[0017] Furthermore, an end effector body, such as an (electric) hand or an (pneumatically driven) air hand, for performing assembly and movement tasks on a production line, is connected to the tip of the link 206 of the robot arm body 200. This end effector body can be attached to the link 206 by (semi)fixed means such as screws (not shown), or by attachment / detachment means such as a latch (ratchet) (not shown). In particular, if the end effector body is detachable, a method can be considered in which the robot arm body 200 is controlled to attach, detach, or replace the end effector body positioned at the supply position (not shown) by the movement of the robot arm body 200 itself.

[0018] Here, the end effector of the robot arm body 200 refers to the link 206 and / or the end effector body in this embodiment. If the end effector body is gripping an object, the end effector body and the object being gripped (e.g., a part or tool) together are referred to as the end effector of the robot arm body 200. In other words, the link 206 and / or the end effector body are referred to as the end effector regardless of whether the end effector body is gripping an object or not.

[0019] The external input device 400 includes an operating section that includes, for example, operation keys for controlling the posture (position and angle) of the joints of the robot arm body 200, or for moving the end effector of the robot arm body 200. When any operation is performed on the operating section of the external input device 400, the control device 300 transmits signals to the drive units 231 to 236 of each joint in response to the operation of the external input device 400, thereby controlling the movement of the robot arm body 200. At that time, the control device 300 executes a robot control program, including the control program described later, thereby controlling each part of the robot arm body 200.

[0020] With the above configuration, the robot arm body 200 can move the link 206 and / or the end effector body to any position and perform a desired operation. For example, by using a predetermined workpiece and other workpieces as materials and performing a process of assembling the predetermined workpiece and other workpieces, an assembled workpiece can be manufactured as a deliverable. Thus, articles can be manufactured using the robot arm body 200. In this embodiment, the manufacturing of articles by assembling workpieces with the robot arm body 200 has been described as an example, but it is not limited to this. For example, articles can be manufactured by equipping the robot arm body 200 with tools such as cutting tools or grinding tools and processing workpieces.

[0021] Figure 2 is a block diagram showing the detailed configuration of the control system of the robot system 1000 shown in Figure 1. The control device 300 is composed of a computer and is equipped with a CPU (Central Processing Unit) 301 as a processor. It also has a memory unit consisting of a ROM (Read Only Memory) 302, a RAM (Random Access Memory) 303, an HDD (Hard Disk Drive) 304, and a recording disk drive 305. It also has interfaces 306, 307, 308, 309, 310, and 311 for communication with each device. The CPU 301, ROM 302, RAM 303, and interfaces 306 to 309 are connected to each other by a bus 311 so that they can communicate with one another.

[0022] Of these, RAM 303 is used for temporary storage of data such as teaching points and control commands obtained from the operation of the external input device 400. ROM 302 stores basic programs 330, such as the BIOS, which allows the CPU 301 to execute various arithmetic processes. The CPU 301 executes various arithmetic processes based on the control programs recorded (stored) in HDD 304. HDD 304 is a storage unit that stores various data, etc., which are the results of the CPU 301's arithmetic processes. The recording disk drive 305 can read various data and control programs, etc., recorded on the recording disk 331. Furthermore, interfaces 307 and 308 are connected to a monitor 411 that displays various images, and external storage devices 412 such as rewritable non-volatile memory and an external HDD.

[0023] The external input device 400 could be, for example, an operating device such as a teaching pendant (TP), but it could also be another computer device (PC or server) capable of editing the robot program. The external input device 400 can be connected to the control device 300 via wired or wireless communication means and has user interface functions such as robot operation and status display. The target joint angles of each joint input by the external input device 400 are output to the CPU 301 via interface 306 and bus 311.

[0024] The CPU 301 receives teaching point data input from, for example, an external input device 400 via interface 306. It can also generate trajectories for each axis of the robot arm body 200 based on the teaching point data input from the external input device 400 and transmit them to the drive units 231-236 via interface 309 using the arm motor driver 230. The CPU 301 outputs drive command data indicating the control amount of the rotation angle of each drive unit 231-236 motor to the arm motor driver 230 via bus 311 and interface 309 at predetermined intervals.

[0025] The arm motor driver 230 calculates the amount of current output to the motors of each drive unit 231-236 based on the drive command input from the CPU 301, and supplies current to each motor to control the joint angle of each joint. It also outputs detection signals from each encoder 211-216 and torque sensors 221-226 to the CPU 301 via the interface 309 and bus 311. That is, the CPU 301 performs feedback control of the motors of each drive unit 231-236 via the arm motor driver 230 so that the current joint angle value of the joint detected by each encoder 211-216 becomes the target joint angle. Similarly, it performs feedback control of each motor so that the current torque value of the joint detected by each torque sensor 221-226 becomes the target torque. In this embodiment, there is only one arm motor driver 230, but each drive unit 231-236 may be provided with its own arm motor driver.

[0026] Furthermore, by returning the outputs of the torque sensors 221-226 to the control device 300 and feeding them back to the drive of each drive unit 231-236, the torque applied to each link 201-206 during drive can be controlled. In addition, the force generated at the link 206 of the robot arm body 200 can be calculated from the values ​​of each torque sensor 221-226, making it possible to feedback control the load applied to the parts being assembled.

[0027] The control device 300 may also be connected to a hand motor (not shown) via an interface and a hand motor driver when a robot hand body is used as an end effector (not shown). The hand motor driver calculates the amount of current output to the hand motor based on the drive command input from the CPU 301, supplies current to the hand motor, and controls the speed of the hand motor. It also outputs pulse signals from the hand motor encoder to the CPU 301 via the interface and bus. In other words, the CPU 301 performs feedback control of the hand motor via the hand motor driver so that the current value of the hand motor speed detected by the encoder becomes the target speed.

[0028] Figure 3 schematically shows the connection relationship between the base 210 and the link 201 of the robot arm body 200. For the sake of simplicity, this explanation will use the base 210 and the link 201 as an example, but other joints will be assumed to have similar connection relationships. As shown in Figure 3, the drive unit 231 is mounted on the base 210 and makes the link 201 rotatable around axis A1 as the axis of rotation. The drive unit 231 is fastened to the base 210.

[0029] Furthermore, the drive flange 241 is positioned between the output shaft of the reduction gear of the drive unit 231 and the torque sensor 221 on the link 201 side. The drive flange 241 acts as a transmission member that transmits the operation from the output shaft of the reduction gear to the link 201. The torque sensor 221 is fastened at one end to the drive flange 241 and at the other end to the link 201. The torque sensor 221 is equipped with an optical encoder that detects the structure and its relative movement, which will be described later. When the link 201 is driven by the drive unit 231, the relative movement of the structure of the torque sensor 221 due to the relative displacement between the drive flange 241 and the link 201 is detected by the optical encoder, and torque is detected based on the relative movement.

[0030] Figure 4 is a cross-sectional view of the torque sensor 221 in this embodiment. For the sake of simplicity, the torque sensor 221 will be used as an example in this explanation, but the torque sensors of other joints will be assumed to have a similar connection relationship. As can be seen in the figure, the torque sensor 221 has a cylindrical first fixing member 511, a second fixing member 512, a connecting member 513, and an optical encoder 514. The optical encoder 514 is positioned opposite to the torque sensor 221 on the circumference of the torque sensor 221 centered on axis A1.

[0031] The first fixing member 511 and the second fixing member 512 are connected by a plurality of connecting members 513 arranged on the circumference of the torque sensor 221, which connect them so that they can move relative to each other. In this embodiment, the first fixing member 511, the second fixing member 512, and the connecting members 513 are integrally made of the same material. The first fixing member 511 is fastened to the drive flange 241, and the second fixing member 512 is fastened to the link 201. A stay member 515 is also attached to the first fixing member 511. This stay member 515 acts as a support member for the detection head 521 of the optical encoder 514, which will be described later. The stay member 515 is fixed to the first fixing member 511.

[0032] The connecting member 513 is configured as a rib-shaped member that connects the donut-shaped first fixing member 511 and the second fixing member 512. These multiple connecting members 513 are arranged in a circular pattern between the first fixing member 511 and the second fixing member 512, with axis A2 as the center. Each part of the torque sensor 221 is made of a predetermined material having an elastic modulus corresponding to the desired torque detection range and its required resolution, such as resin or metal (steel, stainless steel, etc.). Furthermore, the first fixing member 511, the second fixing member 512, and the connecting member 513 may be manufactured by a 3D printer. Specifically, these can be manufactured by creating slice data for a 3D printer from their design data (e.g., CAD data) and inputting that data into a conventional 3D printer. In this embodiment, the first fixing member 511, the second fixing member 512, and the connecting member 513 constituting the torque sensor 222 are made of the same material, but it is also possible to use different materials.

[0033] The optical encoder 514 consists of a detection head 521, which is the detection unit, and a scale 522, which is the unit to be detected. The detection head 521 is provided on a stay member 515, and the scale 522 is provided on a second fixing member 512. The scale 522 is fixed to the first fixing member 511 and the second fixing member 512, respectively, and the detection head 521 is fixed to the stay member 515.

[0034] The scale 522 is a reflective scale and has a grid-arranged optical pattern 531. The optical pattern 531 is made of, for example, Al and Cr. The detection head 521 is a reflective detection head and has a light-emitting element 541 and a light-receiving element 542. An opening 516 is provided in the stay member 515 to irradiate the optical pattern 531 with light from the light-emitting element 541 of the detection head 521. Furthermore, this irradiation space is sealed by a sealing member 517 to prevent dust from entering, and wiring 518 is provided to supply power to the light-emitting element 541. The detection head 521 irradiates the scale 522 with light from the light-emitting element 541, and the light-receiving element 542 receives the light reflected from the optical pattern 531 of the scale 522.

[0035] The detection head 521 is provided on the first fixed member 511 and the scale 522 is provided on the second fixed member 512, but the order may be reversed. As long as the relative amount of movement can be detected, it is sufficient for the detection head 521 to be provided on either the first fixed member 511 or the second fixed member 512, and the scale 522 to be provided on the other.

[0036] Here, a torque is applied around axis A2, causing the first fixed member 511 and the second fixed member 512 to rotate relative to each other, which changes the relative position of the detection head 521 and the scale 522. As a result, the irradiation position of the light illuminating the scale 522 moves along the scale 522.

[0037] At this time, when the light illuminating the scale 522 passes through the pattern 531 provided on the scale 522, the amount of light detected by the light-receiving element 542 of the detection head 521 changes. From this change in light amount, the relative movement between the first fixed member 511 and the second fixed member 512 is detected. The torque detection value is calculated (acquired) by a calculation circuit or control device 300 (not shown) provided on the torque sensor 221, which converts the relative movement amount detected by the detection head 521 into a torque acting on the torque sensor 221 using a sensitivity coefficient.

[0038] Furthermore, depending on the calculation method, this scale pattern can consist of not only one line, but also multiple lines of varying intensity (for example, with different arrangement phases). The pitch of the scale pattern is determined according to the resolution required for position detection, but in recent years, with the increasing precision and resolution of encoders, patterns with a pitch on the order of μm are also available. In this way, torque sensors 221 to 226 can detect torque around the axis at the joint in which they are installed.

[0039] Figure 5 is a diagram showing in more detail the connection relationship between the base 210 and the link 201 of the robot arm body 200 in this embodiment. For the sake of simplicity, the connection relationship between the base 210 and the link 201 will be used as an example in this explanation, but other joints may have similar connection relationships. Figure 5(a) is an exploded view, and Figure 5(b) is an assembled view. In this embodiment, the link 201 that rotates relative to the base 210 may be referred to as the first link, and the base 210 as the second link.

[0040] As shown in Figures 5(a) and 5(b), the drive unit 231 is bolted inside the base 210 using a housing 231b that rotatably supports the reducer output shaft 231a. Furthermore, the drive flange 241 is bolted to the surface of the reducer output shaft 231a. The torque sensor 221 is bolted to the drive flange 241, and the link 201 is further bolted to the structure of the torque sensor 221. For clarity of the drawing, the bolts fastening the drive flange 241 and the torque sensor 221 are not shown. Also as shown in the same figure, the base 210 is provided with a stopper 251, the drive flange 242 is provided with a stopper 252, and the link 201 is provided with a stopper 253. When the base 210 and the link 201 move relative to each other, the stoppers 252 and 253 come into contact, mechanically limiting the range of motion. In this embodiment, stopper 253 may be referred to as the first stopper, stopper 252 as the second stopper, and stopper 251 as the third stopper.

[0041] Furthermore, as shown in Figures 5(a) and 5(b), the stopper 252 of the drive flange 241 is provided with an opening 252a as a space for the placement of the stopper 253, and the stopper 253 of the link 201 is provided with a convex-shaped boss 253a. When the link 201 is fastened to the drive flange 241 via the torque sensor 221 from above in the figure, the stopper 253 is inserted into the opening 252a of the stopper 252 and fastened. When the stopper 253 is inserted into the opening 252a, the clearance between the stopper 253 and the stopper 252 is secured to the extent of the relative displacement between the drive flange 241 and the link 201 within the detection range of the torque sensor 221 in both clockwise and counterclockwise rotation. In this embodiment, a clearance of about 1.0 mm is provided on each side of the stopper 252, but the predetermined clearance may be changed as appropriate depending on the specifications of the torque sensor. Therefore, when the load is within the range detectable by the torque sensor 221 and the motor is rotating clockwise or counterclockwise, the stopper 253 and the stopper 252 will not come into contact.

[0042] However, when stopper 252 and stopper 251 collide forcefully, and an unexpected load (a predetermined force) such as an impact load is applied to the torque sensor 221, stopper 253 and stopper 252 come into contact. Therefore, when stopper 252 and stopper 251 collide forcefully and an unexpected load is generated, it is possible to reduce the transmission of the unexpected load directly to the torque sensor 221 via the drive flange 241. In this way, an unexpected load is not applied to the torque sensor 221, and the risk of damage to the torque sensor 221 is reduced.

[0043] The torque sensor 221 and stoppers 251, 252, and 253 are made of a predetermined material having an elastic modulus and tensile strength corresponding to the desired torque detection range and the required resolution and strength, such as resin or metal (steel, stainless steel, etc.). In this embodiment, the torque sensor 221 and stoppers 251, 252, and 253 are made of the same material, but it is also possible to use different materials.

[0044] As described above, according to this embodiment, when stopper 252 and stopper 251 collide forcefully and a load exceeding expectations is generated, the transmission of the excess load directly to the torque sensor 221 via the drive flange 241 can be reduced. Therefore, the risk of damage to the force detection sensor when the robot stops at a mechanical stopper can be reduced. Furthermore, stopper 252, which is part of stoppers 251 and 252 that limit the range of motion of the joints, can be used together with stopper 253 as a mechanical stopper that reduces the risk of damage to the torque sensor. Therefore, the number of mechanical stoppers required can be reduced, and the cost of the robot can be reduced.

[0045] [Differentiation] Next, modifications of this embodiment will be described in detail. In the above-described embodiment, a mechanical stopper was used to reduce the range of motion of link 201 to less than 360°, but this is not the only method. For example, if it is desired to restrict the range of motion of link 201 to 360° or more, it is more effective to use a movable mechanical stopper. This will be described in detail below.

[0046] Figure 6 shows the connection relationship between the base 210 and the link 201 of the robot arm body 200 in this embodiment. Figure 6(a) is an exploded view, and Figure 6(b) is an assembled view. As shown in Figure 6(a), the drive unit 231 is bolted to the base 210 via the housing 231b, and the drive flange 241 is bolted to the output shaft 231a of the drive unit 231. The torque sensor 221 is bolted to the drive flange 241, and the link 201 is bolted to the opposite surface of the torque sensor 221. For clarity of the drawing, the bolts fastening the drive flange 241 and the torque sensor 221 are not shown.

[0047] Figure 6(a) shows that a stopper 251 is provided on the inside of the base 210 to mechanically limit the range of motion of the link 201. It also shows the movable piece 254 detached from the sliding part 255. As shown in Figure 6(b), the movable piece 254 is positioned on the sliding part 255. A stopper 252 is provided on the drive flange 241 so as to be smaller than the diameter from the center of the base 210 to the stopper 251 (so as not to come into contact with the stopper 251). The stopper 252 has an opening 252a into which the stopper 253 provided on the link 201 is inserted. When the link 201 and drive flange 241 move, the movable piece 254 comes into contact with the stopper 252, and the movable piece 254 slides on the sliding part 255, moving together with the link 201. The movable link 254 and the stopper 251 then come into contact, limiting the range of motion of the link 201.

[0048] Figure 7 shows the operation of the stopper in this embodiment. In Figure 7, the link 201 and torque sensor 221 are transparent, allowing the operation of the stopper 252 and movable piece 254 to be seen. In reality, in Figure 10, the link 201 is assumed to be covering the stopper, and the stopper 253 is assumed to be inserted into the stopper 252. The coordinate system is shown together in the lower right corner of the page.

[0049] Figure 7(a) shows the initial state of the stopper 252. In the initial state, the movable piece 254 is on the sliding part 255 and is in contact with the right side of the stopper 251 in the plane of the paper, and the stopper 252 of the drive flange 241 is positioned opposite to the stopper 251. From this state, as shown in Figure 7(b), if the drive flange 241 and stopper 252 are rotated to the right in the direction of the arrow, the stopper 252 and the movable piece 254 will come into contact. Subsequently, as shown in Figure 7(c), if the drive flange 241 and stopper 252 are rotated to the right as indicated by the arrow, the movable piece 254 will move while in contact with the stopper 252. Furthermore, as shown in Figure 7(d), if the drive flange 241 and stopper 252 are rotated to the right as indicated by the arrow, the movable piece 254 will be clamped between the stopper 251 and stopper 252 and will not rotate any further.

[0050] From this state, if the drive flange 241 and stopper 252 are rotated counterclockwise as shown by the arrow in Figure 7(e), the stopper 252 and the movable piece 254 will come into contact as shown in Figure 7(f). Subsequently, if the drive flange 241 and stopper 252 are rotated counterclockwise as shown by the arrow in Figure 7(g), the movable piece 254 will move while in contact with the stopper 252. Furthermore, if the drive flange 241 and stopper 252 are rotated counterclockwise as shown by the arrow in Figure 7(h), the movable piece 254 will be clamped between the stopper 251 and stopper 252, and will not rotate any further. As a result, even if the link 201 can rotate more than 360°, the range of motion can be mechanically limited.

[0051] Furthermore, when the stopper 253 is inserted into the opening 252a, the clearance between the stopper 253 and the stopper 252 is ensured to the extent of the relative displacement between the drive flange 241 and the link 201 within the detection range of the torque sensor 221. In this embodiment, a clearance of approximately 1.0 mm is provided on each side of the stopper 252, but the clearance may be changed as appropriate depending on the specifications of the torque sensor. Therefore, when the load is within the range detectable by the torque sensor 221 and the mechanism is rotating clockwise or counterclockwise, the stopper 253 and the stopper 252 will not come into contact.

[0052] However, when stoppers 252 and 251 collide forcefully via the movable piece 254, and an unexpected load such as an impact load is applied to the torque sensor 221, stoppers 253 and 252 come into contact. Therefore, when stoppers 252 and 251 collide forcefully via the movable piece 254 and an unexpected load is generated, it is possible to reduce the transmission of the unexpected load directly to the torque sensor 221 via the drive flange 241. In this way, an unexpected load is not applied to the torque sensor 221, and the risk of damage to the torque sensor 221 is reduced.

[0053] According to the above modifications, even when using a movable mechanical stopper, if stopper 252 and stopper 251 collide forcefully and generate a load exceeding expectations, the transmission of the excess load directly to the torque sensor 221 via the drive flange 241 can be reduced. Therefore, the risk of damage to the force-detecting sensor when the robot stops at a mechanical stopper can be reduced. Furthermore, stopper 252, which is part of stoppers 251 and 252 that limit the range of motion of the joints, can be used together with stopper 253 as a mechanical stopper that reduces the risk of damage to the torque sensor. Therefore, the number of mechanical stoppers required can be reduced, making it possible to reduce the cost of the robot.

[0054] (Second embodiment) In the first embodiment described above, the clearance between stopper 252 and stopper 253 corresponding to the relative displacement between the drive flange 241 and link 201 within the detection range of the torque sensor 221 was secured by the opening 252a of stopper 252. However, this method can also be applied when the clearance is secured on the stopper 253 side. This will be described in detail below. Below, parts of the hardware and control system configuration that differ from the first embodiment will be illustrated and explained. Furthermore, parts that are the same as in the first embodiment will have the same configuration and operation as described above, and their detailed explanation will be omitted.

[0055] Figure 8 shows the connection relationship between the base 210 and the link 201 of the robot arm body 200 in this embodiment. For the sake of simplicity, the connection relationship between the base 210 and the link 201 will be used as an example in this explanation, but other joints may have similar connection relationships. Figure 8(a) is an exploded view, and Figure 8(b) is an assembly view.

[0056] As shown in Figures 8(a) and 8(b), the drive unit 231 is bolted to the base 210 via the housing 231b, and the drive flange 241 is bolted to the output shaft 231a of the drive unit 231. A torque sensor 221 is bolted to the drive flange 241, and a link 201 is bolted to the opposite surface of the torque sensor 221. For clarity of the drawing, the bolts fastening the drive flange 241 and the torque sensor 221 are not shown. Also as shown in the same figure, a stopper 251 is provided on the base 210, a stopper 253 is provided on the link 201, and a stopper 252 is provided on the drive flange 241. When the base 210 and the link 201 move relative to each other, the stoppers 251 and 253 come into contact, mechanically limiting the range of motion.

[0057] As shown in Figures 8(a) and 8(b), the stopper 253 of the link 201 is composed of two stoppers, with a gap 253e provided as a space for the stopper 252 to be positioned. When the link 201 is fastened to the drive flange 241 via the torque sensor 221 from above in the figure, the stopper 252 is positioned in the gap 253e of the stopper 253 and fastened. When the stopper 252 is positioned in the gap 253e, the clearance between the stopper 253 and the stopper 252 is ensured to the extent of the relative displacement between the drive flange 241 and the link 201 within the detection range of the torque sensor 221 during both clockwise and counterclockwise rotation. In this embodiment, a clearance of approximately 1.0 mm is provided on each side of the stopper 252, but the clearance may be changed as appropriate depending on the specifications of the torque sensor. Therefore, when the load is within the range detectable by the torque sensor 221 and the link is rotating clockwise or counterclockwise, the stopper 253 and the stopper 252 will not come into contact.

[0058] However, when stopper 253 and stopper 251 collide forcefully, and an unexpected load such as an impact load is applied to the torque sensor 221, stopper 253 and stopper 252 come into contact. Therefore, when stopper 253 and stopper 251 collide forcefully and an unexpected load is generated, it is possible to reduce the transmission of the unexpected load directly to the torque sensor 221 via link 201. In this way, an unexpected load is not applied to the torque sensor 221, and the risk of damage to the torque sensor 221 is reduced.

[0059] As described above, according to this embodiment, when stopper 253 and stopper 251 collide forcefully and a load exceeding expectations is generated, the transmission of the excess load directly to the torque sensor 221 via link 201 can be reduced. Therefore, the risk of damage to the force detection sensor when the robot stops at a mechanical stopper can be reduced. Furthermore, stopper 253, which is part of stoppers 251 and 253 that limit the range of motion of the joint, can be used together with stopper 252 as a mechanical stopper that reduces the risk of damage to the torque sensor. Therefore, the number of mechanical stoppers required can be reduced, and the cost of the robot can be reduced. Note that this embodiment and its modifications may be combined with the various embodiments and modifications described above in a given robot.

[0060] (Third embodiment) In the embodiments described above, the case in which the stoppers 252 and 253 are always fixed to the drive flange 241 and link 201 was explained. However, in the present invention, the stopper 252 or the stopper 253 may be configured to be removable. This will be described in detail below. In the following, parts of the hardware and control system configuration that differ from the embodiments described above will be illustrated and explained. Furthermore, parts that are the same as in the embodiments described above will have the same configuration and operation as described above, and their detailed explanation will be omitted.

[0061] Figure 9 shows the connection relationship between the base 210 and the link 201 of the robot arm body 200 in this embodiment. For the sake of simplicity, the connection relationship between the base 210 and the link 201 will be used as an example in this explanation, but other joints may have similar connection relationships. Figure 9(a) is an exploded view, and Figure 9(b) is an assembly view. From Figures 9(a) and (b), the drive unit 231 is bolted to the base 210 via the housing 231b, and the drive flange 241 is bolted to the output shaft 231a of the drive unit 231. A torque sensor 221 is bolted to the drive flange 241, and the link 201 is bolted to the opposite surface of the torque sensor 221.

[0062] To improve the clarity of the drawing, the bolts fastening the drive flange 241 and the torque sensor 221 are not shown. Also, as shown in the drawing, a stopper 251 is provided on the base 210. Furthermore, a stopper 253 is provided on the link 201, which is removable using a pair of bolts 273 and a pair of screw holes 253b. The link 201 is provided with a pair of through holes 273a through which the bolts 273 pass.

[0063] Furthermore, a stopper 252 is provided on the drive flange 241 so as to be removable by a bolt 271 and a mounting portion 272. When the base 210 and the link 201 move relative to each other, the stoppers 251 and 253 come into contact, mechanically limiting the range of motion. Multiple mounting portions 272 are provided at arbitrary locations on the circumference of the drive flange 241. In this embodiment, there are a total of four mounting portions: two shown in Figure 9(a) and two more located 180° opposite to the two shown in the figure on the far side of the page. Similarly, one set of through holes 273a is provided at the position corresponding to each of the mounting portions 272, resulting in four sets (eight) of through holes 273a.

[0064] As shown in Figures 9(a) and 9(b), the stopper 253 of the link 201 has a gap 253e provided as a space for the stopper 252 to be positioned. When the link 201 is fastened to the drive flange 241 via the torque sensor 221 from above in the figure, the stopper 252 is positioned in the gap 253e of the stopper 253 and fastened. When the stopper 252 is positioned in the gap 253e, the clearance between the stopper 253 and the stopper 252 is secured to the extent of the relative displacement between the drive flange 241 and the link 201 within the detection range of the torque sensor 221 during both clockwise and counterclockwise rotation. In this embodiment, a clearance of about 1.0 mm is provided on each side of the stopper 252, but the clearance may be changed as appropriate depending on the specifications of the torque sensor. Therefore, when the load is within the range detectable by the torque sensor 221 and the link is rotating clockwise or counterclockwise, the stopper 253 and the stopper 252 will not come into contact.

[0065] However, when stopper 251 and stopper 253 collide forcefully, and an unexpected load such as an impact load is applied to the torque sensor 221, stopper 253 and stopper 252 come into contact. Therefore, when stopper 253 and stopper 251 collide forcefully and an unexpected load is generated, the transmission of the unexpected load directly to the torque sensor 221 via link 201 can be reduced. In this way, an unexpected load is not applied to the torque sensor 221, and the risk of damage to the torque sensor 221 can be reduced.

[0066] Figure 10 shows details of stoppers 252 and 253 in this embodiment. From Figure 10, stopper 252 is provided with a through hole 252b through which a bolt 271 passes, and two pins 252c. Although only one pin 252c is shown in Figure 10, it is assumed that another one is provided on the far side of the page. Mounting portion 272 is provided with two pin holes 272a through which the pins 252c are inserted, and a threaded hole 272b through which the bolt 271 is fastened. The through hole 252b is provided so that the threaded portion 271a of the bolt 271 passes through and fastens to the threaded hole 272b, and the head 271b of the bolt 271 does not pass through the through hole 52b. By inserting the pin 252c of the stopper 252 into the pin hole 272a, the stopper 252 can be positioned relative to the drive flange 241. The stopper 252 can be fixed by passing the bolt 271 through the through hole 252b and fastening it with the screw hole 272b. By loosening the bolt 271, the stopper 252 can be removed from the drive flange 241.

[0067] As shown in Figure 10, the stopper 253 is provided with two threaded holes 253b through which the bolt 273 is fastened to the gap 253e. The link 201 is also provided with two through holes 273a through which the bolt 273 passes. The stopper 253 can be fixed to the link 201 by passing the threaded portion 273c of the bolt 273 through the through holes 273a and fastening it to the threaded holes 253b. The stopper 253 can be removed from the link 201 by loosening the fastening of the bolt 273. Here, the diameter of the through holes 273a is larger than the diameter of the threaded portion 273c and threaded holes 253b of the bolt 273, but smaller than the head 273b of the bolt 273. As a result, with the stopper 252 fixed to the drive flange 241 and the link 201 fastened to the torque sensor 221, the fastening position of the stopper 253 can be adjusted within the range of the diameter of the through hole 273a.

[0068] As described above, according to this embodiment, when stoppers 251 and 253 collide forcefully and generate a load exceeding expectations, the transmission of the excess load directly to the torque sensor 221 via link 201 can be reduced. Therefore, the risk of damage to the force-detecting sensor when the robot stops at a mechanical stopper can be reduced. Furthermore, stopper 253, which is part of stoppers 251 and 253 that limit the range of motion of the joints, can be used together with stopper 252 as a mechanical stopper that reduces the risk of damage to the torque sensor. Therefore, the number of mechanical stoppers required can be reduced, making it possible to reduce the cost of the robot.

[0069] Furthermore, in this embodiment, the stoppers 252 and 253 are detachable. Therefore, the stoppers 252 and 253 can be installed when the robot arm body 200 is assembled, thus reducing the possibility of damage caused by contact between the stoppers 252 and 253 during assembly of the robot arm body 200. In addition, the stopper 253 can be installed in an adjustable position, so the relative positions of the stoppers 252 and 253 can be adjusted when the robot arm body 200 is assembled. Furthermore, the mounting portion 272 and the through hole 273a allow the stoppers 252 and 253 to be fixed at any desired position.

[0070] Furthermore, although the position of the stopper 253 is adjustable in this embodiment, the position of the stopper 252 may also be adjusted. Also, in this embodiment, a positioning pin is provided on the stopper 252 and a pin hole is provided on the mounting portion 272, but the pin hole may be provided on the stopper 252 and the pin may be provided on the mounting portion 272. Alternatively, the stopper 253 may be provided with a pin or pin hole, and the link 201 may be provided with a mounting portion and a pin or pin hole. It should be noted that this embodiment and its variations may be combined with the various embodiments and variations described above in a given robot.

[0071] (Fourth embodiment) In the embodiments described above, the case in which the stoppers 252 and 253 are provided on the drive flange 241 and link 201 on the outside of the torque sensor 221 was explained. However, in the present invention, the stopper 252 or stopper 253 may be provided on the inside of the torque sensor 221. This will be described in detail below. In the following, parts of the hardware and control system configuration that differ from the embodiments described above will be illustrated and explained. Furthermore, parts that are the same as in the embodiments described above will have the same configuration and operation as described above, and their detailed explanation will be omitted.

[0072] Figure 11 is a diagram showing in more detail the connection relationship between the base 210 and the link 201 of the robot arm body 200 in this embodiment. For the sake of simplicity, the connection relationship between the base 210 and the link 201 will be used as an example in this explanation, but other joints may have similar connection relationships. Figure 11(a) is an exploded view, and Figure 11(b) is an assembled view. From Figures 11(a) and (b), the drive unit 231 is bolted inside the base 210 using a housing 231b that supports the reduction gear output shaft 231a so that it can rotate. Furthermore, the drive flange 241 is bolted to the surface of the reduction gear output shaft 231a. A torque sensor 221 is bolted to the drive flange 241, and a link 201 is bolted to the structure of the torque sensor 221. For the sake of clarity in the drawing, the bolts that fasten the drive flange 241 and the torque sensor 221 are not shown.

[0073] In this embodiment, the structure of the torque sensor 221 is divided into a partial torque sensor 221a and a partial torque sensor 221b, which are mounted on the drive flange 241, with a stopper 252 in between. The partial torque sensors 221a and 221b are fastened to the link 201 such that they have roughly the same relative displacement when the link 201 is operated. Also as shown in the figure, the base 210 is provided with a stopper 251, and the link 201 is provided with an inverted L-shaped stopper 253. When the base 210 and the link 201 move relative to each other, the stopper 251 and the stopper 253 come into contact, mechanically limiting the range of motion.

[0074] Furthermore, as shown in Figures 11(a) and 11(b), the stopper 252 of the drive flange 241 is provided with a groove 252d as a space for the stopper 253 to be positioned. The stopper 253 also has a contact portion 253c that is positioned in the groove 252d and a contact portion 253d that contacts the stopper 251. When the link 201 is fastened to the drive flange 241 from above via the torque sensor 221, the contact portion 253c of the stopper 253 is positioned in the groove 252d of the stopper 252 and fastened. When the contact portion 253c of the stopper 253 is positioned in the groove 252d, the clearance between the stopper 253 and the stopper 252 is secured to the extent of the relative displacement between the drive flange 241 and the link 201 within the detection range of the torque sensor 221 during both clockwise and counterclockwise rotation. In this embodiment, a clearance of approximately 1.0 mm is provided on each side of the stopper 253, but the clearance may be changed as appropriate depending on the specifications of the torque sensor. Therefore, when the load is within the range detectable by the torque sensor 221 and the mechanism is rotating clockwise or counterclockwise, the stopper 253 and stopper 252 will not come into contact.

[0075] However, when the contact portion 253d of stopper 253 and stopper 251 collide forcefully, and an unexpected load such as an impact load is applied to the torque sensor 221, stopper 253 and stopper 252 come into contact. Therefore, when stopper 253 and stopper 251 collide forcefully and an unexpected load is generated, it is possible to reduce the transmission of the unexpected load directly to the torque sensor 221 via link 201. In this way, an unexpected load is not applied to the torque sensor 221, and the risk of damage to the torque sensor 221 is reduced.

[0076] As described above, according to this embodiment, when stoppers 253 and 251 collide forcefully and a load exceeding expectations is generated, the transmission of the excess load directly to the torque sensor 221 via link 201 can be reduced. Therefore, the risk of damage to the force-detecting sensor when the robot stops at a mechanical stopper can be reduced. In addition, stopper 253, which is part of stoppers 251 and 253 that limit the range of motion of the joint, can be used together with stopper 252 as a mechanical stopper that reduces the risk of damage to the torque sensor. Therefore, the number of mechanical stoppers required can be reduced, and the cost of the robot can be reduced. Furthermore, since the stopper can be placed inside the torque sensor, the radial size of the joint portion of the robot arm body 200 can be made more compact. In this embodiment, the torque sensor 221 is divided into two, but it may be divided into two or more depending on the number of stoppers 252 that are placed. It should be noted that this embodiment and its variations may be combined with the various embodiments and variations described above in a given robot.

[0077] (Other embodiments) The processing procedures of the embodiments described above are specifically executed by the CPU 301 of the control device 300. Therefore, it is also possible to configure the device to read and execute a recording medium containing a software program capable of executing the above-described functions. In this case, the program read from the recording medium itself will realize the functions of each embodiment described above, and the program itself and the recording medium on which the program is recorded will constitute the present invention.

[0078] Furthermore, in each embodiment, the computer-readable recording medium was described as a ROM, RAM, or flash ROM, and the program was stored in the ROM, RAM, or flash ROM. However, the present invention is not limited to these embodiments. The program for carrying out the present invention may be recorded on any recording medium that is computer-readable. For example, an HDD, external storage device, recording disk, etc., may be used as the recording medium for supplying the control program.

[0079] Furthermore, while the various embodiments described above have explained the case where the robot arm body 200 is a multi-joint robot arm having multiple joints, the number of joints is not limited to this. Although a vertical multi-axis configuration was shown as the type of robot arm, the same configuration can be implemented with different types of joints such as horizontal multi-joint, parallel link, and Cartesian robots, and the drive source that drives each joint may be a device such as an artificial muscle. It may also be applied to prosthetic arms, prosthetic legs, and powered suits (power assist suits) equipped with force-detecting sensors such as torque sensors.

[0080] Furthermore, the various embodiments described above are applicable to machines that can automatically perform actions such as extension and retraction, bending and straightening, vertical movement, horizontal movement, or rotation, or combinations thereof, based on information stored in a memory device provided in the control device.

[0081] Furthermore, while the torque sensors in the various embodiments described above use an optical encoder to detect the relative movement between the first fixed member 511 and the second fixed member 512, other configurations are also possible. For example, regarding a method of measuring displacement magnetically, the magnetic flux source and magnetoelectric conversion element may be placed on either the first fixed member 511 or the second fixed member 512 for detection. As the first fixed member 511 and the second fixed member 512 move relative to each other, the magnitude of the magnetic flux density flowing into the magnetoelectric conversion element changes with the change in distance between the magnetic flux source and the magnetoelectric conversion element, and the output of the magnetoelectric conversion element changes in accordance with the change in magnetic flux density. By detecting this change in the output of the magnetoelectric conversion element, the displacement can be measured.

[0082] It should be noted that the present invention is not limited to the embodiments described above, and many modifications are possible within the technical concept of the present invention. Furthermore, the effects described in the embodiments of the present invention are merely a list of the most preferred effects arising from the present invention, and the effects of the present invention are not limited to those described in the embodiments of the present invention. [Explanation of symbols]

[0083] 200 Robot Arm Body Links 201, 202, 203, 204, 205, 206 210 base 211, 212, 213, 214, 215, 216 encoders 221, 222, 223, 224, 225, 226 Torque Sensor 221a, 221b Split Torque Sensor 230 Arm Motor Driver 231, 232, 233, 234, 235, 236 Drive unit 231a Output shaft 231b Housing 241 Drive flange 251, 252, 253 Stopper 252a, 516 opening 252b, 273a through hole 252c pin 252d Groove 253a Boss 253b, 272b Screw holes 253c, 253d Contact part 253e Cavity 254 movable links 255 Sliding part 271, 273 volts 272 Mounting part 271a, 273c Screw portion 271b, 273b head 272a Pinhole 300 Control device 400 External Input Device 511 First fixing member 512 Second fixing member 513 Connecting member 514 Optical Encoder 515 Stay member 517 Sealing material 518 Wiring 521 detection head 522 scale 531 Optical Patterns 541 Light-emitting element 542 Photodetector

Claims

1. A robot comprising: a first link; a drive device for displacing the first link; a second link to which the drive device is provided; a member that is displaced together with the first link by the drive device; and torque sensors connected to the first link and the member, It comprises a first stopper provided on the first link, a second stopper provided on the member, and a third stopper provided on the second link, The first stopper and the second stopper are provided such that they come into contact when the first link is displaced and the first stopper and the third stopper come into contact, or when the first link is displaced and the second stopper and the third stopper come into contact. A robot characterized by the following features.

2. In the robot according to claim 1, The first stopper and the second stopper come into contact with each other due to the relative movement of the first link and the member. A robot characterized by the following features.

3. In the robot according to claim 1 or 2, The second stopper is provided with a space in which the first stopper is positioned, and the first stopper is positioned in the space with a predetermined clearance. A robot characterized by the following features.

4. In the robot according to claim 3, The aforementioned space is an opening. A robot characterized by the following features.

5. In the robot according to any one of claims 2 to 4, The first stopper is provided with a boss. A robot characterized by the following features.

6. In the robot according to claim 1 or 2, The first stopper is provided with a space for the second stopper to be positioned, and the second stopper is positioned in the space with a predetermined clearance. A robot characterized by the following features.

7. In the robot according to claim 6, The aforementioned space is an air gap. A robot characterized by the following features.

8. In the robot according to any one of claims 1 to 7, The first stopper or the second stopper is provided in a removable manner. A robot characterized by the following features.

9. In the robot according to claim 8, The first stopper or the second stopper is provided so that its position can be adjusted. A robot characterized by the following features.

10. In the robot according to claim 8 or 9, The first link or the member is provided with a mounting portion for attaching the first stopper or the second stopper. A robot characterized by the following features.

11. In the robot according to claim 10, Multiple mounting portions are provided on the first link or the member. A robot characterized by the following features.

12. In the robot according to any one of claims 8 to 11, The first stopper or the second stopper is removable by a bolt. A robot characterized by the following features.

13. In the robot according to any one of claims 8 to 12, The first stopper or the second stopper is positioned by a pin. A robot characterized by the following features.

14. In the robot according to any one of claims 1 to 13, A force-detecting sensor is provided between the first link and the member. The second stopper is provided between the sensors. A robot characterized by the following features.

15. In the robot according to claim 14, The second stopper is provided with a groove in which the first stopper is positioned with a predetermined clearance. A robot characterized by the following features.

16. In the robot according to claim 14 or 15, The sensor is divided into at least two parts and is provided between the first link and the member. A robot characterized by the following features.

17. In the robot according to any one of claims 1 to 16, The first stopper or the second stopper comes into contact with the third stopper with a predetermined force, causing the first stopper and the second stopper to come into contact. A robot characterized by the following features.

18. In the robot according to claim 17, When a force smaller than the predetermined force is acting on the first link and the member and the first link and the member are displaced, the first stopper and the second stopper do not come into contact. A robot characterized by the following features.

19. In the robot according to any one of claims 1 to 18, The second link is provided with a sliding part, The sliding part is provided with a movable piece that is arranged to slide along the sliding portion, moves together with the first link while in contact with the first stopper or the second stopper, and comes into contact with the third stopper. A robot characterized by the following features.

20. In the robot according to any one of claims 1 to 19, The drive device comprises a motor and a reduction gear for reducing the displacement of the motor. The aforementioned member is connected to the output shaft of the reduction gear. A robot characterized by the following features.

21. A method for manufacturing an article, characterized by manufacturing the article using a robot described in any one of claims 1 to 20.

22. A robot control method comprising a first link, a drive device for displacing the first link, a second link to which the drive device is provided, and a member that is displaced together with the first link by the drive device, It comprises a first stopper provided on the first link, a second stopper provided on the member, and a third stopper provided on the second link. The control device controls the drive device to displace the first link, The first stopper and the second stopper are provided such that they come into contact with each other when the first stopper and the third stopper come into contact or when the second stopper and the third stopper come into contact. A control method characterized by the following:

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