Drive device, control method, robot, recording medium, and product manufacturing method

Abstract

The invention provides a driving apparatus, a control method, a robot, a recording medium, and a product manufacturing method. The drive device is configured to displace the second link relative to the first link. The driving device includes: a driving portion including an output portion configured to output a driving force that displaces the second link; a sensor configured to obtain information about the force; a connection member configured to connect the output portion and the sensor; a first bearing; and a second bearing. The sensor is connected between the second connecting rod and the connecting component. The first bearing and the second bearing are connected to the connecting member to displace the second link relative to the first link.

Description

Technical Field

[0001] The present invention relates to a drive device including a torque sensor for use in a robot. Background Art

[0002] In recent years, articulated robot manipulators have been increasingly used and applied to fields that require flexible movements of robot manipulators, such as collaborative work with humans and assembly work in factories. Since such robots are required to have stable and broadband force control functions to adapt to external forces, it is preferred to use a control system based on joint torque control (torque servo) rather than a motion control system based on joint position control (position servo). Therefore, a joint mechanism that can accurately detect the torque to be output is required.

[0003] Generally, a measuring mechanism (torque sensor) for output torque is provided between the output side of the driving part consisting of the motor and the reduction mechanism and the output connecting rod. The torque sensor includes an elastic member (which deforms according to the torque applied thereto) and measures the output torque by detecting the amount of deformation or distortion of the elastic member. In addition, the output connecting rod is supported via multiple bearings to ensure mechanical robustness and stable action of the joint.

[0004] Japanese Patent Laid-Open No. 2012-242114 describes a joint mechanism including a torque sensing mechanism for measuring torque output by a driving portion. The joint mechanism includes a first link as a base end side link and a second link as a distal end side link, and the second link is supported via a plurality of bearings. Summary of the invention

[0005] According to a first aspect of the present invention, there is provided a driving device configured to displace a second connecting rod relative to a first connecting rod. The driving device comprises: a driving portion including an output portion configured to output a driving force for displacing the second connecting rod; a sensor configured to obtain information about the force; a connecting member configured to connect the output portion and the sensor; a first bearing; and a second bearing. The sensor is connected between the second connecting rod and the connecting member, and the first bearing and the second bearing are connected to the connecting member to displace the second connecting rod relative to the first connecting rod.

[0006] According to a second aspect of the present invention, there is provided a control method for a driving device, the driving device causing a second connecting rod to be displaced relative to a first connecting rod, the control method comprising: controlling a driving part based on information about a force obtained by a sensor through a control part. The driving device comprises: the driving part, which comprises an output part, the output part being configured to output a driving force for displacing the second connecting rod; the sensor, which is configured to obtain information about the force; a connecting member, which is configured to connect the output part and the sensor; a first bearing; and a second bearing. The sensor is connected between the second connecting rod and the connecting member, and the first bearing and the second bearing are connected to the connecting member, so that the second connecting rod is displaced relative to the first connecting rod.

[0007] According to a third aspect of the present invention, there is provided a robot configured to displace a second link relative to a first link, the robot comprising: a driving portion including an output portion configured to output a driving force for displacing the second link; a sensor configured to obtain information about the force; a connecting member configured to connect the output portion and the sensor; a first bearing; and a second bearing. The sensor is connected between the second link and the connecting member, and the first bearing and the second bearing are connected to the connecting member to displace the second link relative to the first link.

[0008] According to a fourth aspect of the present invention, there is provided a control method for a robot, the robot displacing a second link relative to a first link, the control method comprising: controlling a driving part based on information about a force obtained by a sensor by a control part. The robot comprises: the driving part, which comprises an output part, the output part being configured to output a driving force that displaces the second link; the sensor, which is configured to obtain information about the force; a connecting member, which is configured to connect the output part and the sensor; a first bearing; and a second bearing. The sensor is connected between the second link and the connecting member, and the first bearing and the second bearing are connected to the connecting member so that the second link is displaced relative to the first link.

[0009] Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a schematic cross-sectional view for illustrating the joint mechanism of the embodiment.

[0011] Figure 2 An example of a robot including the joint mechanism of the embodiment is shown.

[0012] Figure 3A It is a front view for showing the external shape of the joint mechanism 200 .

[0013] Figure 3B It is a side view for showing the external shape of the joint mechanism 200 .

[0014] Figure 4 It is a cross-sectional view for illustrating the structure of the joint mechanism 200 .

[0015] Figure 5 11 is a diagram showing a state where the side cover member 1112 is removed.

[0016] Figure 6 is a perspective view of the appearance of the internal structure of the joint mechanism 200 obtained by removing some components from the joint mechanism 200 .

[0017] Fig. 7A is a diagram showing the external shape of one example of a torque sensor.

[0018] Figure 7B is a schematic diagram for illustrating the operating principle and configuration of a torque sensor.

[0019] Fig. 8A It is a front view for showing the external shape of the joint mechanism 300 .

[0020] Figure 8B It is a side view for showing the external shape of the joint mechanism 300 .

[0021] Fig.9A It is a front view for showing the external shape of the joint mechanism 500 .

[0022] Fig. 9B It is a side view for showing the external shape of the joint mechanism 500 .

[0023] Fig.10 11 is a cross-sectional view showing an embodiment in which the first bearing mechanism 211 supports the sensor connecting member 205 so that the sensor connecting member 205 can rotate relative to the first link 1100 .

[0024] Fig.11 3 is a schematic cross-sectional view of the joint mechanism 3000 of the reference embodiment, taken along the rotation center axis 3220 . DETAILED DESCRIPTION

[0025] In Japanese Patent Publication No. 2012-242114, the second connecting rod used as the output connecting rod is supported via a plurality of bearings. However, there is a case where the torque sensor cannot detect the torque output by the driving part with high accuracy. Therefore, the control accuracy of driving the joint by using torque control (torque servo) cannot be fully improved, making it difficult to realize a robot that performs precision assembly work.

[0026] Therefore, it is desirable to realize a technology capable of detecting the torque applied to the output link with high accuracy in a case where the output link is supported via a plurality of bearings.

[0027] The present inventors have studied the situation that the torque applied to the output link cannot be detected with high accuracy in the conventional joint mechanism in which the output link is supported via a plurality of bearings, and found the cause. First, the cause found by the present inventors will be described with reference to the reference embodiment.

[0028] Reference Examples

[0029] Fig.11 32 is a schematic cross-sectional view of the joint mechanism 3000 of the reference embodiment taken along the rotation center axis 3220 of the output link (i.e., the second link 3200). The joint mechanism 3000 includes a first link 3100, a second link 3200, a first bearing mechanism 3211, a second bearing mechanism 3212, a driving portion 3202, and a torque sensor 3203.

[0030] The first link 3100 is a fixed end side link linked to the base side of the robot arm, and the second link 3200 corresponds to a distal end side link or an output link rotated by the driving part 3202. The driving part 3202 includes a motor (including a stator 3202S and a rotor 3202R) and a speed reduction mechanism. The stator 3202S of the motor is fixed to the first link 3100.

[0031] The output side of the driving part 3202 (ie, the output side of the speed reduction mechanism) is connected to one end of the torque sensor 3203, and the other end of the torque sensor 3203 is connected to the second connecting rod 3200. The rotation torque output by the driving part 3202 is transmitted to the second connecting rod 3200 via the torque sensor 3203.

[0032] The first bearing mechanism 3211 is disposed between the first connecting rod 3100 and the output side of the driving part 3202, and supports the output side of the driving part 3202 relative to the first connecting rod 3100, so that the output side of the driving part 3202 and the first connecting rod 3100 can rotate relative to each other. The second bearing mechanism 3212 is disposed between the first connecting rod 3100 and the second connecting rod 3200, and supports the second connecting rod 3200 relative to the first connecting rod 3100, so that the first connecting rod 3100 and the second connecting rod 3200 can rotate relative to each other. In order to mechanically firmly support the second connecting rod 3200 relative to the first connecting rod 3100, when the first bearing mechanism 3211 and the second bearing mechanism 3212 are observed along the rotation center axis 3220, the first bearing mechanism 3211 and the second bearing mechanism 3212 are spaced apart from each other and form a so-called double-end support structure.

[0033] exist Fig.11 In FIG. 1 , arrows are schematically shown to illustrate how force is transmitted when a torque (moment) T is applied to the second link.

[0034] Each of the arrow T1 and the arrow T2 schematically shows a transmission path for the torque T applied to the second link 3200 to be transmitted to the first link 3100. The torque T applied to the second link 3200 (i.e., the torque T to be measured and controlled) can be transmitted to the first link 3100 via two transmission paths (the first transmission path T1 and the second transmission path T2). Specifically, the first transmission path T1 is a path for the torque T to be transmitted to the first link 3100 through the torque sensor 3203, the first bearing mechanism 3211, and the driving portion 3202. In addition, the second transmission path T2 is a path for the torque T to be transmitted from the second link 3200 to the first link 3100 through the second bearing mechanism 3212.

[0035] In the second transmission path T2, the freely rotatable second bearing mechanism 3212 is located between the second connecting rod 3200 and the first connecting rod 3100. Therefore, the torque transmitted through the second transmission path T2 is ideally zero and does not affect the force transmitted to the torque sensor 3203 through the first transmission path T1. However, in reality, resistance (operating torque), friction torque, etc. are generated as reaction torque (T loss ). The resistance (operating torque) is generated by the rotation of the second bearing mechanism 3212, and the friction torque is generated according to the external torque when the second bearing mechanism 3212 is in a stopped state. Therefore, not all the torque T to be measured is transmitted to the torque sensor 3203 through the transmission path T1, and the torque transmitted to the torque sensor 3203 is affected by the reaction torque (T loss ) is reduced. If the torque sensor 3203 can measure the torque with T ts If Tts =TT loss Therefore, the reaction torque (T loss ) corresponds to an area (dead zone), in which the torque sensor 3203 cannot measure the torque.

[0036] Therefore, in the joint mechanism as in the reference embodiment, the torque sensor included in the joint cannot accurately measure the torque applied to the output link. Therefore, the sensitivity of the torque control and the responsiveness of the torque servo are deteriorated. Therefore, in the articulated robot including the joint mechanism, since the control and measurement accuracy of the force at the far end of the robot arm is deteriorated, it is difficult for the robot to perform work such as precision assembly work with high precision.

[0037] Example

[0038] Hereinafter, a driving device according to an embodiment of the present invention will be described with reference to the accompanying drawings. Note that since the embodiment described below is only an example, those skilled in the art may appropriately modify its detailed configuration without departing from the spirit of the present invention.

[0039] Note that, in the drawings to be referred to in the description of the following embodiments, unless otherwise specified, components assigned the same symbols have the same functions. In addition, if a plurality of the same components are shown in the drawings, the assignment of symbols and their description may be omitted.

[0040] In addition, there are also cases where, for the convenience of illustration and description, a diagram may be schematically shown. In this case, the shape, size, arrangement, etc. of the components shown in the diagram may not be exactly the same as the actual components.

[0041] Joint mechanism

[0042] Figure 1 2 is a schematic cross-sectional view for illustrating a joint mechanism (i.e., a driving device) of an embodiment; and shows a cross-sectional view taken along the rotation center axis CA of the output link of the joint mechanism 200. The joint mechanism 200 includes a first link 1100, a second link 1200, a first bearing mechanism 211, a second bearing mechanism 212, a driving portion 202, and a torque sensor 203.

[0043] The first link 1100 is a fixed end side link coupled to the base side of the robot arm, and the second link 1200 corresponds to a distal end side link or an output link rotated by the driving portion 202. The second link 1200 is displaceable relative to the first link with the rotation center axis CA as a rotation center.

[0044] The driving portion 202 includes a motor (including a stator 202S and a rotor 202R) and a speed reduction mechanism. The stator 202S of the motor is fixed to the first link 1100.

[0045] The output side of the driving part 202 (i.e., the output side of the speed reduction mechanism) is connected to the sensor connecting member 205 via the connecting portion CP1. The sensor connecting member 205 is connected to one end of the torque sensor 203 via the connecting portion CP2, and the other end of the torque sensor 203 is connected to the second connecting rod 1200 via the connecting portion CP3. The rotational torque output by the driving part 202 is transmitted to the second connecting rod 1200 via the torque sensor 203. For ease of description, the portion of the torque transmission path located on the driving part 202 side relative to the torque sensor 203 may be referred to as the driving part side torque transmission path, and the portion of the torque transmission path located on the second connecting rod 1200 side relative to the torque sensor 203 may be referred to as the output connecting rod side torque transmission path.

[0046] The first bearing mechanism 211 is arranged (or maintained) between the first connecting rod 1100 and the output side of the driving part 202, and supports the output side of the driving part 202 relative to the first connecting rod 1100, so that the output side of the driving part 202 and the first connecting rod 1100 can rotate relative to each other. The second bearing mechanism 212 is arranged (or maintained) between the sensor connecting member 205 and the first connecting rod 1100, and supports the sensor connecting member 205 relative to the first connecting rod 1100, so that the sensor connecting member 205 and the first connecting rod 1100 can rotate relative to each other. In order to mechanically firmly support the second connecting rod 1200 relative to the first connecting rod 1100, when the first bearing mechanism 211 and the second bearing mechanism 212 are observed along the rotation center axis CA, the first bearing mechanism 211 and the second bearing mechanism 212 are spaced apart from each other and form a so-called double-end support structure. That is, when observed in the direction of the rotation axis, at least a portion of the second connecting rod is located between the first bearing and the second bearing. With this arrangement, the second connecting rod can be firmly supported relative to the first connecting rod.

[0047] In the above-mentioned reference embodiment, in the torque transmission path, the first bearing mechanism 3211 is provided on the driving portion 3202 side relative to the torque sensor 3203, and the second bearing mechanism 3212 is provided on the output connecting rod side (i.e., the second connecting rod 3200 side) relative to the torque sensor 3203. Therefore, the reaction torque (T) generated in the second bearing mechanism 3212 and included in the torque (torque) T applied to the second connecting rod 3200 loss ) is not transmitted to the torque sensor 3203 and is not detected by the torque sensor 3203. That is, in the reference embodiment, since the bearing mechanism is disposed on the torque transmission path on the output connecting rod side, the reaction torque (T loss ) is not transmitted to the torque sensor, making it impossible for the torque sensor to accurately detect the torque applied to the output connecting rod.

[0048] On the contrary, in the joint mechanism of the embodiment, both the first bearing mechanism 211 and the second bearing mechanism 212 constituting the double-end support structure are arranged on the torque transmission path on the driving part side of the torque transmission path, while the bearing mechanism is not arranged on the torque transmission path on the output connecting rod side. That is, the first bearing mechanism 211 and the second bearing mechanism 212 support the component arranged on the driving part side relative to the torque sensor 203 in the torque transmission path. Therefore, when the torque is transmitted to the torque sensor 203 via the connecting part CP3, the torque applied to the second connecting rod 1200 will not be reduced due to the reaction torque. Therefore, the torque sensor 203 can detect the rotational torque applied to the output connecting rod (i.e., the second connecting rod 1200) with high precision.

[0049] In the joint mechanism of the embodiment, when viewed in the direction of the double-end support structure or the direction of the rotation axis, at least a portion of the second connecting rod is located between the first bearing and the second bearing. With this arrangement, the second connecting rod can be firmly supported relative to the first connecting rod. In addition, the joint torque for driving the connecting rod can be measured and controlled with high sensitivity and high precision without being affected by the reaction force (torque disturbance) generated in the bearing mechanism. If the joint mechanism of the embodiment is used, the responsiveness of the torque control of a robot (such as an articulated robot) can be improved, and a robot that performs work such as precision assembly work can be realized. In this case, there is no need to complicate the control of the robot. For example, there is no need to predetermine the reaction force generated in the bearing by experiment, and store the reaction force data as correction data in the control part of the robot. In addition, there is no need to correct the driving force by making the control part calculate the reaction force generated in the bearing using the bending angle and bending speed of the joint. Therefore, if the joint mechanism of the present embodiment is used, the torque of the joint mechanism can be controlled with high sensitivity and high precision without using any complex control method.

[0050] Robotic Device

[0051] Next, a robot apparatus including the joint mechanism of the embodiment will be described. Figure 2 The appearance of an articulated robot device 1 as one example of a robot including the joint mechanism of the embodiment is shown.

[0052] The robot device 1 includes: a robot 2; and a control device 3 serving as a control section for controlling the robot 2. The robot 2 includes: a vertically articulated robot arm 20 including a plurality of joint mechanisms (eg, joint mechanisms 100 to 600) and a robot hand 21 as an end effector.

[0053] The robot arm 20 includes a plurality of links (e.g., links 1000 to 1600), and one of the links 1000 to 1600 is connected to another link via a joint mechanism provided at the base end side of the link. The joint mechanisms 100 to 600 may be referred to as joints J1 to J6 provided from the base end side to the distal end side, respectively.

[0054] In the present embodiment, the robot arm 20 includes six axis joints J1 to J6; three axis joints J2, J3 and J5 are capable of swinging, and three axis joints J1, J4 and J6 are capable of rotating. Note that being able to swing may be referred to as being able to pivot or bend.

[0055] A link 1000 as a base end portion (base portion) of the robot arm 20 is fixed to a base frame. Links 1000 to 1600 are connected in series to each other through joint mechanisms 100 to 600. Each joint includes a torque sensor provided on an output side of the joint to measure torque transmitted to a corresponding link via the joint.

[0056] The robot hand 21 as an end effector is attached to and supported by the link 1600 provided at the distal end of the robot arm 20. The motion (position and posture) and force (force and torque) of the robot hand 21 are adjusted by the motion of the robot arm 20. The robot hand 21 includes: a hand body 24 and a plurality of fingers 23 provided to move relative to the hand body 24. By using the fingers 23, the robot hand 21 can hold an object such as a workpiece.

[0057] The end effector is not limited to the robot hand 21 described as an example, and any of various types of devices may be attached to the robot arm 20, depending on the work performed by the robot. For example, a peripheral device (external extension device) such as a camera (hand-eye) (not shown), a wrist multi-axis force sensor (force-torque sensor: F / T sensor), or a proximity sensor may be mounted on a link provided on the distal end side or wrist of the robot.

[0058] The robot 2 and the control device 3 are connected to each other via a wiring member 5 including electric wires including signal wires and power wires. If the robot 2 includes an arm or an end effector that moves by driving a fluid (i.e., by using air pressure, oil pressure, etc.), a fluid pipeline or the like may be included in the wiring member 5. The wiring member 5 has flexibility and is configured to extend from the base end portion (fixed end) of the robot arm 20 to the distal end portion (free end). In addition, each of the electric wires and pipelines constituting the wiring member 5 is branched according to the situation; and is connected to the actuators or sensors of the joints J1 to J6, or is connected to the actuators, sensors, or peripheral devices of the robot hand 21.

[0059] The swingable joint mechanism 200 has a reference Figure 1Similarly, each of the joint mechanisms 300 and 500 that can swing also has a construction similar to that of the joint mechanism 200. Therefore, in the joint mechanisms 200, 300, and 500, the connecting rod is firmly supported by the double-end support structure, and the joint torque for driving the connecting rod can be measured and controlled with high sensitivity and high precision without being affected by the reaction force (torque disturbance) generated in the bearing mechanism.

[0060] Detailed description of the swing joint mechanism

[0061] Reference above Figure 1 The basic configuration of the joint mechanisms 200, 300, and 500 which are included in the robot 2 and are swingable is described. Furthermore, it will be described in detail.

[0062] Figure 3A is a front view for showing the external shape of the joint mechanism 200, Figure 3B 1 is a side view for showing the external shape of the joint mechanism 200. The joint mechanism 200 of the joint J2 connects the first link 1100 as a fixed end side link and the second link 1200 as an output link located on the distal end side. The first link 1100 includes a joint support member 1101 and a joint support member 1102; and the joint support member 1101 and the joint support member 1102 support the side of the second link 1200 from both sides.

[0063] Figure 4 is a cross-sectional view for illustrating the structure of the joint mechanism 200, and shows Figure 3B The side view is a cross-sectional view taken along line AA. The joint mechanism 200 includes a side cover member 1111 and a side cover member 1112 for protecting the inside of the joint mechanism 200. In addition, the joint mechanism 200 accommodates the wiring and piping portion 206.

[0064] Figure 5 and Figure 6 Each of is a perspective view for illustrating a three-dimensional shape of each component of the joint mechanism 200 , in which some components are removed from the joint mechanism 200 . Figure 5 A state is shown in which the side cover member 1112 of the joint supporting member 1102 is removed to show the internal wiring or wiring and piping portion 206 provided inside the joint mechanism. Figure 6 2 is a perspective view of the external appearance of the internal structure of the joint mechanism 200 , in which the second link 1200 as the output link, the second bearing mechanism 212 , and the joint supporting member 1102 are further removed in order to specifically describe the fixing method of the wiring and piping portion 206 .

[0065] Hereinafter, the structures of the components of the joint mechanism 200 will be described in sequence. In the joint mechanism 200, the first link 1100 as a fixed side link and the second link 1200 as an output side link are connected to each other via the first bearing mechanism 211 and the second bearing mechanism 212 as a joint support mechanism, so that the first link 1100 and the second link 1200 can rotate freely relative to each other.

[0066] The first link 1100 includes two support members: a joint support member 1101 and a joint support member 1102. The joint support member 1101 is connected to the first bearing mechanism 211, and the joint support member 1102 is connected to the second bearing mechanism 212.

[0067] The first bearing mechanism 211 and the second bearing mechanism 212 hold the second connecting rod 1200 relative to the first connecting rod 1100, so that the second connecting rod 1200 can only rotate relative to the first connecting rod 1100 around the driving axis of the joint. Appropriately, a cross roller bearing is used as the first bearing mechanism 211, and a ball bearing (ball bearing) is used as the second bearing mechanism 212. However, the bearings used in the embodiment are not limited to the above-mentioned components. For example, multiple angular bearings can be used. In another case, bearing mechanisms with other structures can be used in combination with each other.

[0068] Components of a driving mechanism required to drive the joint are provided on the joint supporting member 1101 side in the first link 1100. Next, the arrangement of components, the operation of driving the joint, and the operating principle of measuring torque will be described.

[0069] The driving part 202 is a driving part that generates a rotation torque applied between the first connecting rod 1100 and the second connecting rod 1200; and includes a motor and a speed reduction mechanism 202G, the motor including a stator 202S and a rotor 202R. The rotor 202R is an output end to which the motor power is output, and is connected to an input end of the speed reduction mechanism 202G. The motor can be a built-in motor. In this case, the frame member of the connecting rod also serves as a housing of the motor.

[0070] At the end of the motor, a rotary encoder 204 is provided. The rotary encoder 204 measures the rotation angle of the motor and sends the measurement data to the control device 3. The driving portion 202 includes a brake mechanism (not shown) for maintaining the rotation angle of the motor. In addition, a cable is connected to the driving portion 202 to drive the motor, send a signal to the rotary encoder or / receive a signal from the rotary encoder, and control the opening and closing operation of the brake.

[0071] Preferably, the reduction mechanism 202G may be a strain wave gear mechanism including three components (an input end, an output portion, and a fixed portion). The reduction ratio may be 1:80, but may also be appropriately changed. In the present embodiment, the inner ring of the cross roller bearing as the first bearing mechanism 211 is integrated with the output portion of the reduction mechanism 202G, and the outer ring of the cross roller bearing is integrated with the fixed portion of the reduction mechanism 202G. The rotor 202R of the motor as the driving source rotates the input end of the reduction mechanism 202G. The reduction mechanism 202G increases the torque generated by the motor according to the reduction ratio, and reduces the rotation angle according to the reduction ratio. Therefore, the reduction mechanism 202G outputs the increased rotational torque from the output portion. The torque generated by the motor is increased to a level suitable for driving the joint by the reduction mechanism 200; and the torque output from the reduction mechanism 202G actively rotates the second connecting rod 1200 supported by the joint support mechanism (bearing).

[0072] Generally speaking, the torque efficiently generated by small motors is much smaller than the torque required to drive the joints, while the rated speed generated by small motors is much higher than the speed required for the output shaft of the rotary joint. Therefore, most robots generally include a reduction mechanism with a high reduction ratio of about 1:30 to 1:200. In this case, the drive mechanism has a high torque loss due to friction and rotational resistance caused by the speed reduction. Therefore, the rotational torque applied to the output side connecting rod of the joint mechanism cannot be detected with high precision by measuring only the motor torque. Even if the motor torque is not measured directly but the motor current is measured, the rotational torque applied to the output side connecting rod of the joint mechanism cannot be detected with high precision. Since it is difficult to accurately model the torque loss and it is difficult to obtain sufficient reproducibility of the torque loss, it is also difficult to estimate the torque loss and correct the output torque of the motor. Therefore, it is necessary to accurately measure the torque applied to the output side connecting rod of the joint mechanism by using a torque sensor.

[0073] As described above, in the present embodiment, the output side of the driving part 202 (i.e., the output side of the speed reduction mechanism) is connected to the sensor connecting member 205 via the connecting part CP1. The sensor connecting member 205 is connected to one end of the torque sensor 203 via the connecting part CP2, and the other end of the torque sensor 203 is connected to the second connecting rod 1200 via the connecting part CP3. The rotational torque output by the driving part 202 is transmitted to the second connecting rod 1200 via the torque sensor 203.

[0074] Fig. 7A An external shape of an example of the torque sensor 203 is shown. Figure 7B is a schematic diagram for illustrating the operating principle and construction of a torque sensor. Fig. 7AAs shown, the torque sensor 203 includes two disk-shaped members 203IF1 and 203IF2 arranged to face each other, and the two disk-shaped members are connected to each other and formed into one body via a plurality of beam-shaped members 203E. One of the disk-shaped members 203IF1 and 203IF2 can be called the first end of the torque sensor, and the other can be called the second end of the torque sensor.

[0075] Each of the disk-shaped members 203IF1 and 203IF2 includes a fixing bolt hole (not shown) for mechanically connecting the disk-shaped member with a component disposed before or after the torque sensor in the torque transmission path.

[0076] Each of the beam members 203E is an elastic member formed like a thin plate, so that the rigidity of the beam member is lower than that of the disk members 203IF1 and 203IF2. The disk members 203IF1 and 203IF2 are connected to each other, and a plurality (eg, 12) of elastic members formed like thin plates are arranged radially.

[0077] The torque sensor 203 includes an encoder 203OE used as a displacement measuring device. That is, a displacement detection detector 203OED is provided on the disc-shaped member 203IF1, and a scale 203OES is provided on the disc-shaped member 203IF2. The displacement detection detector 203OED and the scale 203OES are provided to face each other and are used as an optical encoder for measuring the relative displacement between the two disc-shaped members.

[0078] The torque sensor 203 includes a plurality of groups (e.g., three groups) of optical encoders installed in the torque sensor 203. The torque sensor 203 can convert the displacement measured as described above into a torque applied to the torque sensor 203, and output the torque value to the control device. In this case, the torque sensor 203 converts the displacement into a torque value by performing digital signal processing for multiplying the output of each encoder by the sensor stiffness matrix.

[0079] That is, the torque sensor 203 detects the rotational torque applied to the torque sensor 203 by measuring the relative displacement (in the circumferential direction) between the two disc-shaped members generated when the rotational torque AT about the central axis is applied due to an external force. In other words, the torque sensor 203 is a sensor that obtains information about the torque applied between the first end and the second end.

[0080] Return to reference Figure 4 In the first link 1100, the joint support member 1101 and the joint support member 1102 are connected to each other via bolts, and the joint support member 1102 holds the second bearing mechanism 212. Figure 1 and Figures 4 to 6As shown, the sensor connecting member 205 has a shape (e.g., a cylindrical shape) formed like a cylinder extending in the direction of the rotation center axis CA of the joint mechanism. One end of the sensor connecting member 205 extending from the connection portion between the sensor connecting member 205 and the driving portion 202 is supported by a second bearing mechanism 212 provided between the end and the first link 1100.

[0081] Preferably, a dustproof and waterproof structure is used in this embodiment, and in this structure, the gap between the sensor connecting member 205 and the second connecting rod 1200 is sealed. Figure 4 As shown in the sealing member 209, a relatively elastic sealing member such as an O-ring or an oil seal may be provided. One of the characteristics of the joint mechanism of this embodiment is that even if such a sealing structure is used, the torque measurement performance does not significantly deteriorate.

[0082] Next, a method of arranging the wiring member inside the joint in the joint mechanism of the embodiment will be described. Figure 4 As shown, the first connecting rod 1100 includes two supporting members: Figure 4 The left side joint support member 1101 and the joint support member 1102 are provided in Figure 4 In the internal space of the joint mechanism defined by the side cover members 1111 and 1112, the drive portion 202 is provided on the joint support member 1101 side, and the wiring and piping portion 206 is accommodated on the joint support member 1102 side. In this arrangement, the wiring can be accommodated in the internal space of the joint on a large scale.

[0083] Figures 4 to 6 The wiring and piping section 206 shown is a harness that bundles together power lines for motors driving joints, signal lines connected to sensors, fluid piping for driving actuators (if used), etc. In the wiring and piping section 206 provided in each joint, wiring and piping sections extending to the joint or end effector on the distal side of the joint are bundled.

[0084] The wiring and piping portion 206 inserted into the internal space of the joint mechanism 200 is fixed to the joint support member 1102 of the first link 1100 via the base end side fixing portion 208. In addition, the wiring and piping portion 206 is guided to the second link 1200 side through the inside of the sensor connecting member 205 having a cylindrical shape, and is fixed to the wiring support mechanism 207 near the second link 1200.

[0085] like Figure 6As shown, the wiring support mechanism 207 is fixed to the sensor connection member 205. In the sensor connection member 205 formed like a cylinder having a relatively large diameter, an opening portion is formed in one portion of the side of the cylinder to form a path for passing the wiring and piping portion 206. The wiring and piping portion 206 is guided to the inside of the second link 1200 through the opening portion.

[0086] like Figures 4 to 6 As shown, the sensor connection member 205 is formed like a cylinder having a relatively large diameter, and the wiring and piping portion 206 is fixed to the sensor connection member 205 at a fixed position 207P separated from the rotation center of the joint and located on the second link side by using a wiring support mechanism 207. In this configuration, when the joint swings, the wiring and piping portion 206 can be bent without being prevented from moving due to interference between the wiring and piping portion 206 and other members, and the wiring and piping portion 206 can be stably supported without generating any excessive stress.

[0087] In addition, in the present embodiment, since the wiring and piping portion 206 is supported inside the joint in this way, the torque sensor 203 does not receive the reaction force generated by the wiring member that bends according to the swing of the joint. Therefore, the torque sensor 203 can measure the joint torque with high precision and high sensitivity. This is because the reaction force generated by the wiring member is applied to the sensor connecting member 205 and does not affect the torque applied to the torque sensor 203. Therefore, there is no need to complicate the control of the robot. For example, there is no need to predetermine the reaction force generated in the wiring and piping portion through experiments, and store the reaction force data as correction data in the control part of the robot. In addition, there is no need to correct the driving force by causing the control part to calculate the reaction force generated in the wiring and piping portion using the bending angle and bending speed of the joint. Therefore, the torque of the joint mechanism can be controlled with high sensitivity and high precision without using any complex control method.

[0088] The configuration of the joint mechanism 200 included in the robot 2 and capable of swinging has been described in detail. Figure 1 As described above, the joint mechanisms 300 and 500 are also swingable joint mechanisms, and the basic configurations of the joint mechanisms 300 and 500 are the same as the basic configuration of the joint mechanism 200 .

[0089] Fig. 8A is a front view for showing the external shape of the joint mechanism 300, and Figure 8B It is a side view for showing the external shape of the joint mechanism 300 . Fig.9A is a front view for showing the external shape of the joint mechanism 500, and Fig. 9B: is a side view for showing the external shape of the joint mechanism 500. Although the external shapes of the joint mechanisms 300 and 500 are different from the external shape of the joint mechanism 200, the joint mechanisms 300 and 500 produce the same effect as the joint mechanism 200 in the supporting method using the sensor connecting member, the setting method of the sealing member, and the supporting method of the wiring and piping parts.

[0090] Variations

[0091] Note that the present invention is not limited to the above-described embodiments, and various modifications can be made within the technical concept of the present invention.

[0092] In such Figure 1 In the illustrated embodiment, the first bearing mechanism 211 and the second bearing mechanism 212 that rotatably support the output connecting rod in the double-end support structure are provided in the driving portion side torque transmission path that is located on the driving portion 202 side relative to the torque sensor 203 in the torque transmission path. However, the arrangement method of the bearing mechanism in the embodiment is not limited to the above example as long as the bearing mechanism is not provided in the output connecting rod side torque transmission path that is located on the second connecting rod 1200 side relative to the torque sensor 203.

[0093] The first bearing mechanism 211 can support the rotor 202R of the motor of the driving part 202 so that the rotor 202R can rotate, or can support the output part of the speed reduction mechanism 202G of the driving part 202 so that the output part can rotate. Fig.10 As shown in the cross-sectional view, the first bearing mechanism 211 can support the sensor connecting member 205 so that the sensor connecting member 205 can rotate relative to the first link 1100.

[0094] In another case, as long as the bearing mechanism is not provided in the output link side torque transmission path on the second link 1200 side relative to the torque sensor 203, three or more bearing mechanisms may be provided in a single joint to give the joint a more robust structure.

[0095] In the driving part described as an example, an electric motor and a reduction mechanism are used in combination with each other. However, the construction of the driving part is not limited to this. For example, a motor having a direct drive system without using a reduction mechanism can be used. In addition, the motor is not limited to a built-in motor of a structure in which the frame member of the connecting rod also serves as the housing of the motor. In addition, the supply source of the driving torque is not limited to the electric motor. For example, a driving part with a fluid drive system using air pressure, oil pressure, etc. can be used according to the required output level or output characteristics.

[0096] The torque sensor is not limited to the configuration described as an example. For example, the torque sensor may be formed integrally with another component constituting the joint. For example, the wiring support portion and the main connection portion of the torque sensor may be formed integrally with each other, and the secondary connection portion and the second link of the torque sensor may be connected to each other via another member. In another case, the wiring support portion may be formed integrally with the output mechanism of the drive portion.

[0097] The robot of the embodiment is not limited to Figure 2 The robot shown includes a vertical articulated arm with six axes. For example, the robot may be any of various types of robots including vertical articulated robots with different numbers of axes, parallel link robots, and prismatic joint robots.

[0098] The actions of the robot device including the joint mechanism of the embodiment are generally actions of the process of manufacturing products such as assembly work, conveying work, machining work (including cutting, grinding, drilling, coating, bonding and welding) and cleaning work. However, the robot device can perform actions other than the above actions.

[0099] The joint mechanism of the embodiment is applicable to various machines and facilities as follows, including industrial robots, service robots, and machine tools operated under numerical control by computers. For example, the joint mechanism can be applied to the joints of machines or facilities that can automatically perform telescopic actions, bending and stretching actions, up and down actions, left and right actions, pivot actions, or a combination thereof according to the information data stored in the storage device of the control device. Any control method or control program for moving a robot including the joint mechanism of the embodiment, and any recording medium that can be read by a computer storing the control program are included in the embodiments of the present invention.

[0100] In the present invention, in a case where the output link is supported via a plurality of bearings, it is possible to detect the torque applied to the output link with high accuracy.

[0101] Other embodiments

[0102] The embodiments of the present invention may also be implemented by reading and executing computer executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be more completely referred to as a "non-transitory computer-readable storage medium") to perform one or more functions in the above-mentioned embodiments, and / or a computer of a system or device including one or more circuits (e.g., an application-specific integrated circuit (ASIC)) for performing one or more functions in the above-mentioned embodiments, and the embodiments of the present invention may be implemented by, for example, reading and executing the computer executable instructions from the storage medium by the computer of the system or device to perform one or more functions in the above-mentioned embodiments, and / or controlling the one or more circuits to perform one or more functions in the above-mentioned embodiments. The computer may include one or more processors (e.g., a central processing unit (CPU), a microprocessing unit (MPU)), and may include a network of separate computers or separate processors to read and execute the computer executable instructions. The computer executable instructions may be provided to the computer, for example, from a network or the storage medium. The storage medium may include, for example, a hard disk, a random access memory (RAM), a read-only memory (ROM), a memory of a distributed computing system, an optical disk (such as a compact disc (CD), a digital versatile disc (DVD), or a Blu-ray disc (BD) TM ), flash memory devices, memory cards, etc.

[0103] The embodiments of the present invention may also be implemented by providing software (program) for performing the functions of the above-described embodiments to a system or device via a network or various storage media, and a computer or a central processing unit (CPU) or a microprocessing unit (MPU) of the system or device reads and executes the program.

[0104] While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. A driving device configured to displace a second connecting rod relative to a first connecting rod, the driving device comprising: a driving portion including an output portion configured to output a driving force for displacing the second link; a sensor configured to obtain information about the force; a connecting member configured to connect the output portion and the sensor; First bearing; as well as Second bearing, The sensor is connected between the second link and the connecting member, and the first bearing and the second bearing are connected to the connecting member so that the second link is displaced relative to the first link.

2. The driving device according to claim 1, wherein: The first bearing and the second bearing are provided on the driving portion side relative to the sensor in a force transmission path from the driving portion to the second link.

3. The driving device according to claim 1, wherein: The connecting member includes a cylindrical portion extending from the first bearing toward the second bearing.

4. The driving device according to claim 1, wherein: The connecting member is disposed inside the second connecting rod, and a gap is formed between the connecting member and the second connecting rod.

5. The driving device according to claim 1, wherein: The first bearing is configured to support the first connecting rod, the output portion, or the connecting member, and Wherein, the second bearing is configured to support the first connecting rod and the connecting member.

6. The driving device according to claim 1, wherein: At least a portion of the second connecting rod is located between the first bearing and the second bearing.

7. The driving device according to any one of claims 1 to 6, wherein: The driving portion includes a motor, and the first bearing is configured to support a rotor of the motor and the first connecting rod.

8. The driving device according to any one of claims 1 to 6, wherein: The driving portion includes a speed reduction mechanism, and the first bearing is configured to support an output portion of the speed reduction mechanism and the first connecting rod.

9. The driving device according to any one of claims 1 to 6, wherein: The connection member includes a fixing portion configured to fix a line extending from the first link to the second link.

10. The driving device according to claim 9, wherein: The connecting member has a cylindrical shape, the fixing portion is located at a fixing position on the second link side, and the line is fixed by the fixing portion. 11 . The driving device according to claim 1 , further comprising a sealing member provided between the connecting member and the second link.

12. The driving device according to any one of claims 1 to 6, wherein: At least one of the first bearing and the second bearing includes any one of a roller bearing and a ball bearing.

13. The driving device according to any one of claims 1 to 6, wherein: The second link is configured to be displaced about a rotation axis, and Wherein, when the first bearing and the second bearing are viewed along the rotation axis, the first bearing and the second bearing are spaced apart from each other.

14. A control method for a driving device, wherein the driving device causes a second connecting rod to shift relative to a first connecting rod, the control method comprising: controlling the driving portion based on information about the force obtained by the sensor by the control portion, Wherein, the driving device comprises: the driving portion including an output portion configured to output a driving force for displacing the second link; The sensor is configured to obtain information about the force; a connecting member configured to connect the output portion and the sensor; a first bearing; and Second bearing, The sensor is connected between the second link and the connecting member, and the first bearing and the second bearing are connected to the connecting member so that the second link is displaced relative to the first link.

15. A robot configured to displace a second link relative to a first link, the robot comprising: a driving portion including an output portion configured to output a driving force for displacing the second link; a sensor configured to obtain information about the force; a connecting member configured to connect the output portion and the sensor; First bearing; as well as Second bearing, The sensor is connected between the second link and the connecting member, and the first bearing and the second bearing are connected to the connecting member so that the second link is displaced relative to the first link.

16. A method for controlling a robot, wherein the robot causes a second link to shift relative to a first link, the method comprising: controlling the driving portion based on information about the force obtained by the sensor by the control portion, Wherein, the robot comprises: the driving portion including an output portion configured to output a driving force for displacing the second link; The sensor is configured to obtain information about the force; a connecting member configured to connect the output portion and the sensor; a first bearing; and Second bearing, The sensor is connected between the second link and the connecting member, and the first bearing and the second bearing are connected to the connecting member so that the second link is displaced relative to the first link.

17. A program product that causes a control section to execute the control method according to claim 14.

18. A computer-readable recording medium storing the program product according to claim 17.

19. A method of manufacturing a product by controlling the robot according to claim 15 and by performing work for manufacturing the product.

20. The method of manufacturing a product according to claim 19, wherein: The work includes at least one of a conveying work, an assembling work, a machining work and a cleaning work on components.

Images