JP2015157332A - Robot device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a robot device that does not require a battery for storing the number of revolutions of a link.SOLUTION: A lever switch 250 is supported swingably by a link 213. A guide member 260 which guides the lever switch 250 is provided for a link 214.The guide member 260 swings the lever switch 250 to a first position when the link 214 makes less than one revolution, and to a second position when the link 214 makes one revolution or more and less than two revolutions. A contact sensor 270 detects to which of the first position and second position the lever switch 250 swings. When the lever switch 250 is swung to the first position, a detection result of an absolute encoder 237 is employed as the rotational angle of the link 214. When the lever switch 250 is swung to the second position, the sum of the detection result of the absolute encoder 237 and 360° is employed as the rotational angle of the link 214.

Description

  The present invention relates to a robot apparatus including a link that can rotate within a movable range of less than two rotations.

  In general, a robot apparatus incorporated in a production system includes a robot arm and an end effector attached to the tip of the robot arm, and the robot arm is configured by connecting a plurality of links with joints. The rotation angle (joint angle) of the link is detected by installing a rotary encoder on the rotation shaft.

  Rotary encoders can be divided into two types: an incremental encoder that detects the difference in rotation angle and an absolute encoder that detects the absolute value of the rotation angle. Incremental encoders use a method of calculating an angle by accumulating a difference in angle change from a certain reference angle in a memory, and an origin sensor is used as a reference angle detection method. On the other hand, the absolute encoder can detect the absolute value of the rotation angle of less than 1 rotation, and the rotation angle of 1 rotation or more can be calculated by counting the number of rotations and storing it in the memory. can do. Therefore, an absolute encoder installed on a multi-rotating link is used as a set with a memory.

  As described above, a memory is required to detect the rotation angle of the multi-rotating link. However, the link may rotate by receiving a force from the outside in a state where the power is stopped and no power is supplied to the memory. In view of this, it has been proposed that a battery is built in the apparatus as a standby power source to continue calculating the rotation angle of the link (see Patent Document 1).

Japanese Patent Publication No. 3-8916

  However, when the battery is installed, when the robot apparatus is used for a long period of time, it is necessary to periodically replace the battery, resulting in a problem that the maintenance cost becomes high. Moreover, the installation space of the battery itself and the wiring space of the power cable for supplying power from the battery to the memory are required, which causes a problem that the robot apparatus becomes large.

  Accordingly, an object of the present invention is to provide a robot apparatus that does not require a battery for storing the number of rotations of a link.

  The robot apparatus according to the present invention rotates the first link, the second link rotatably connected to the first link, and the second link within a movable range of less than two rotations relative to the first link. A rotation drive unit for driving, a control unit for controlling the rotation drive unit such that a rotation angle of the second link with respect to the first link becomes a target rotation angle, and an absolute angle of the second link of 0 ° to 360 ° An angle detection unit that detects a value less than °, a moving member supported by the first link so as to be movable to a first position and a second position different from the first position, and the second link. The moving member moves to the first position when the rotation of the second link relative to the first link is less than one rotation, and the rotation of the second link relative to the first link is not less than one rotation and less than two rotations. When A guide member that guides the moving member so as to move to a second position, and a detection unit that detects which of the first position and the second position the moving member has moved, When the detection unit detects that the moving member has moved to the first position, the control unit sets the rotation angle of the second link as a detection result of the angle detection unit, and the detection unit When it is detected that the moving member has moved to the second position, an angle calculation process is performed in which the rotation angle of the second link is a result of adding 360 ° to the detection result of the angle detection unit. And

  According to the present invention, the angle detection unit detects the absolute angle of the second link with respect to the first link, and the detection unit detects the position of the moving member, whereby the control unit rotates in less than two rotations with respect to the first link. The rotation angle of the second link is determined. Thereby, even if the second link rotates with respect to the first link when the power is stopped, the rotation angle of the second link can be obtained, so that a battery for storing the number of rotations in the memory becomes unnecessary. . By eliminating the need for a battery, it is not necessary to replace the battery regularly, and a power cable for the battery is not required, so that the robot apparatus can be reduced in size and cost.

1 is a perspective view showing a robot apparatus according to a first embodiment. It is a fragmentary sectional view showing a joint of a robot arm of a robot device concerning a 1st embodiment. It is sectional drawing of the robot arm of the robot apparatus which concerns on 1st Embodiment. It is a perspective view which shows the lever switch and contact sensor in 1st Embodiment. It is a block diagram of the principal part of the robot apparatus which concerns on 1st Embodiment. It is a top view which shows the guide member of the robot apparatus which concerns on 1st Embodiment. It is explanatory drawing which shows the state of a guide member when rotating a 2nd link in 1st Embodiment. FIG. 4 is an explanatory diagram showing a state of a lever switch when a second link is rotated in the first embodiment. 4 is a graph showing a relationship between a rotation angle θ of a first link, a detection angle φ of an absolute encoder, and an output of a contact sensor in the first embodiment. It is a flowchart which shows the angle calculation process of the calculation unit in 1st Embodiment. It is a top view which shows the guide member of the robot apparatus which concerns on 2nd Embodiment. It is a graph which shows the relationship between the rotation angle (theta) of the 2nd link in 2nd Embodiment, the detection angle (phi) of an absolute encoder, and the output of a contact sensor. It is a perspective view which shows the guide member of the robot apparatus which concerns on 3rd Embodiment. It is a side view which shows the guide member of the robot apparatus which concerns on 3rd Embodiment.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 is a perspective view showing a robot apparatus according to the first embodiment of the present invention. The robot apparatus 100 includes a robot 200, a control device 300 as a control unit that controls the operation of the robot 200, and a teaching pendant 400 as a teaching unit that teaches the operation of the robot 200 by a user operation. The robot 200 includes a vertical articulated robot arm 201 and a robot hand 202 as an end effector attached to the tip of the robot arm 201.

  In the robot arm 201, a base portion 210 serving as a base end link fixed to a work table and a plurality of links 211 to 216 that transmit displacement and force are connected to be bent (turned) or rotated at joints J1 to J6. ing. In the first embodiment, the robot arm 201 is configured by six-axis joints J1 to J6 of three axes that bend and three axes that rotate. Here, bending (turning) means that the link rotates relatively around the rotation axis in a direction perpendicular to the longitudinal direction of the two links, and rotation means that the link is relative around the rotational axis in the longitudinal direction of the two links. Each is called a bent part and a rotating part. The robot arm 201 includes six joints J1 to J6. The joints J1, J4, and J6 are rotating parts, and the joints J2, J3, and J5 are bending parts.

  The robot hand 202 is an end effector that is coupled to a link (tip link) 216 and performs an assembling operation of the workpiece W, and has a plurality of fingers 220. The workpiece W can be gripped by closing the plurality of fingers 220, and the workpiece W can be gripped and released by opening the plurality of fingers 220.

  The robot arm 201 includes a plurality (three) of rotation driving units 230 that are provided for the respective joints J1, J4, and J6 and that rotationally drive the respective joints J1, J4, and J6. The robot arm 201 is provided with respect to the joints J2, J3, and J5, and includes a plurality (three) of bending drive units (swing drive units) that drive the respective joints J2, J3, and J5 to bend (pivot drive). Have.

  In FIG. 1, for the sake of convenience, the rotation drive unit 230 is illustrated only for the joint J4 and is not illustrated for the other joints J1 and J6. Part 230 is arranged. In addition, although 1st Embodiment demonstrates the case where all the joints J1, J4, and J6 are comprised by the rotational drive part 230, at least 1 is driven by the rotational drive part 230 among joints J1, J4, and J6. What is necessary is just to be comprised. Hereinafter, the joint J4 will be described as an example, and the other joints J1 and J6 may be different in size and performance, but the description is omitted because they have the same configuration.

  FIG. 2 is a partial cross-sectional view showing the joint J4 of the robot arm 201. As shown in FIG. 2, the robot arm 201 includes a link 213 that is a first link, and a link 214 that is a second link that is rotatably connected to the link 213. The link 213 and the link 214 are rotatably coupled via a bearing 238.

  The rotational drive unit 230 rotationally drives the link 214 within a movable range of less than two rotations from a reference angle (posture) with respect to the link 213. The rotation drive unit 230 includes a rotation motor (hereinafter referred to as “motor”) 231 that is an electromagnetic motor, and a speed reducer 233 that decelerates the rotation of the rotation shaft 232 of the motor 231 and transmits it to the link 214. . Furthermore, the rotation drive unit 230 includes a transmission mechanism 234 that transmits the rotation of the motor 231 to the speed reducer 233. An input shaft 244 and an output shaft 236 are fixed to the speed reducer 233. The output shaft 236 is integrally fixed to the link 214. The output shaft 236 is rotatably supported with respect to the link 213 via a bearing 238.

  The transmission mechanism 234 includes a pulley 241 fixed to the rotation shaft 232 of the motor 231, a pulley 242 fixed to the input shaft 244, and an endless belt 243 wound between the pulleys 241 and 242. Yes. In addition, the structure of the transmission mechanism 234 is not limited to this, For example, the gear mechanism comprised combining the some gearwheel may be sufficient.

  The robot arm 201 includes an incremental rotary encoder that detects a change in the angle of the rotation shaft 232 of the motor 231, that is, an incremental encoder 235.

  The robot arm 201 also has an absolute rotary encoder, that is, an absolute encoder 237, which is an angle detection unit that detects the rotation angle of the output shaft 236 (link 214 with respect to the link 213) of the speed reducer 233. The absolute encoder 237 detects the absolute angle of the link 214 with respect to the link 213 with a value of 0 ° or more and less than 360 °. That is, the absolute encoder 237 does not have a counter that counts the number of rotations, a memory that stores the number of counts, a battery that supplies power to the counter and the memory.

  The motor 231 is a servo motor, for example, a brushless DC servo motor or an AC servo motor. A brake unit (not shown) is provided between the motor 231 and the encoder 235. The main function of the brake unit is to maintain the posture of the robot arm 201 when the power is turned off.

  In the first embodiment, the speed reducer 233 is a wave gear speed reducer that is small and light and has a large reduction ratio. The wave gear reducer has an angle transmission error and elastic deformation. Even if the rotation angle of the output shaft 236 is to be detected by the incremental encoder 235, the angle transmission error and elastic deformation of the speed reducer 233 are included. For this reason, an absolute encoder 237 is installed on the output shaft 236 side in order to accurately detect the rotation angle on the output shaft 236 side. The absolute encoder 237 includes a sensor element 237A, a sensor board 237B on which the sensor element 237A is mounted, and a disk-shaped pattern plate 237C fixed to the link 214 so as to face the sensor element 237A. doing.

  FIG. 3 is a cross-sectional view of the robot arm 201. 3A is a cross-sectional view of the robot arm 201 seen in the direction of arrow IIIA in FIG. 2, and FIG. 3B is a cross-sectional view of the robot arm 201 seen in the direction of arrow IIIB in FIG.

  In the first embodiment, the robot arm 201 includes a lever switch (moving member) 250 that is a swinging member supported swingably (movable) on the link 213 as shown in FIG. ing. Further, as shown in FIG. 3B, the robot arm 201 includes a guide member 260 that is provided on the link 214 and guides and swings the lever switch 250. In addition, the robot arm 201 includes a contact sensor (detection unit) 270 that detects the contact state of the lever switch 250 as shown in FIG.

  FIG. 4 is a perspective view showing the lever switch 250 and the contact sensor 270. As shown in FIG. 4, the contact sensor 270 is disposed in the vicinity of the lever switch 250. The lever switch 250 has a main body 251 and a protrusion 252 that protrudes from one end 251A of the main body 251 in the direction of the arrow X on the guide member 260 side (a direction parallel to the rotation center line C in FIG. 2). ing. A rotation shaft 253 is provided at a portion between the one end 251A and the other end 251B of the main body 251, and the main body 251 is supported by the link 213 so as to be rotatable around the rotation shaft 253 (an axis parallel to the rotation center line C). . As the main body 251 of the lever switch 250 swings (rotates about the rotation shaft 253), the other end 251B of the main body 251 approaches or separates from the contact sensor 270. The contact sensor 270 is fixed to a sensor substrate 271 fixed to the link 213. The lever switch 250 (main body 251) is supported by the link 213 so as to be swingable between a first position that is separated from the contact sensor 270 and a second position that is in contact with the contact sensor 270 and is different from the first position. Yes.

  That is, the protrusion 252 that is the tip of the lever switch 250 is guided by the guide member 260 and the lever switch 250 swings, and the other end 251 </ b> B of the main body 251 that is the rear end of the lever switch 250 is connected to the contact sensor 270. Proximity or separation.

  The contact sensor 270 is a pressure sensor whose electrical resistance value decreases as the contact pressure increases. Therefore, the output (energization current) of the contact sensor 270 increases as the contact pressure increases. When the lever switch 250 swings to the first position, the contact sensor 270 is separated from the other end 251B of the main body 251 of the lever switch 250, so that the output (current) becomes the first level. When the lever switch 250 swings to the second position, the contact sensor 270 is pressed against the other end 251B of the main body 251 of the lever switch 250 to decrease the electrical resistance value, and the output (current) is higher than the first level. Level 2 That is, the contact sensor 270 can detect to which position the lever switch 250 is swung between the first position and the second position.

  Hereinafter, it is assumed that the contact sensor 270 is turned off when the output of the contact sensor 270 is equal to or lower than the first level, and the contact sensor 270 is turned on when the output of the contact sensor 270 is equal to or higher than the second level.

  The guide member 260 shown in FIG. 3B is formed integrally with the link 214. When the rotation of the link 214 relative to the link 213 is less than one rotation, the guide member 260 guides the lever switch 250 so that the main body 251 of the lever switch 250 swings to the first position. The guide member 260 guides the lever switch 250 so that the main body 251 of the lever switch 250 swings to the second position when the rotation of the link 214 with respect to the link 213 is not less than one rotation and less than two rotations.

  FIG. 5 is a block diagram of a main part of the robot apparatus according to the first embodiment of the present invention. The control device 300 serving as a control unit includes a control unit 301, a calculation unit 302, and a storage unit 303 that stores a calculation program that causes the calculation unit 302 to perform calculation processing. The arithmetic unit 302 is a CPU, for example.

  The arithmetic unit 302 executes angle calculation processing according to a calculation program. The arithmetic unit 302 obtains a rotation angle θ of less than two rotations of the link 214 with respect to the link 213 based on the detection result (detection angle) φ by the absolute encoder 237 and on / off of the contact sensor 270, and outputs it to the control unit 301. . The rotation angle θ is the angle of the joint J4. The control unit 301 controls the motor 231 of the rotation driving unit 230 so that the rotation angle θ becomes the target rotation angle, that is, the rotation angle θ approaches the target rotation angle.

  FIG. 6 is a plan view showing the guide member 260 of the robot apparatus 100 according to the first embodiment of the present invention. In the first embodiment, the guide member 260 is formed with a guide groove (cam groove) 261 in which the protruding portion 252 of the lever switch 250 is fitted. The protrusion 252 of the lever switch 250 enters the guide groove 261 and moves relative to the guide member 260 along the guide groove 261 when the link 214 rotates around the rotation center line C.

  The guide member 260 has an end surface 262 facing the link 213 with the rotation center line C of the link 214 as a normal line. The guide groove 261 is formed on the end face 262. The guide groove 261 is formed in a spiral shape so as to approach the rotation center line C stepwise (go away). As the link 214 rotates relative to the link 213, the guide member 260 rotates about the rotation center line C, and the protrusion 252 of the lever switch 250 slides in the guide groove 261. When the protrusion 252 of the lever switch 250 is guided by the guide groove 261, the main body 251 of the lever switch 250 follows the guide groove 261 and swings around the rotation shaft 253. As a result, the main body 251 of the lever switch 250 swings between the first position and the second position.

  The guide groove 261 is divided into three regions, a first region 261A, a second region 261B, and a third region 261C. The first region 261A and the third region 261C are formed in arc shapes having different radii, and are arranged concentrically. The first region 261A and the third region 261C are formed so as to avoid a fan-shaped region having an angle α ° with the rotation center line C as the center. In the sector region having an angle α °, the first region 261A and the third region 261C are connected by the second region 261B. ing. Here, the movable range of the link 214 (output shaft side) is limited to less than two rotations by a stopper mechanism (not shown), and the movable range is set to 0 ° or more and less than (720−α) °.

  The posture of the main body 251 of the lever switch 250 when the protrusion 252 of the lever switch 250 moves to each of the first region 261A, the second region 261B, and the third region 261C will be described.

  7 is an explanatory view showing the state of the guide member 260 when the link 214 is rotated, and FIG. 8 is an explanatory view showing the state of the lever switch 250 when the link 214 is rotated. FIGS. 7A and 8A show a state in which the link 214 is rotated with respect to the link 213 in the range of 0 ° or more and less than (360−α) °. FIGS. 7B and 8B show a state in which the link 214 is rotated with respect to the link 213 in a range of (360−α) ° or more and less than 360 °. FIGS. 7C and 8C show a state in which the link 214 is rotated with respect to the link 213 in a range of 360 ° or more and less than (720−α) °.

  That is, FIGS. 7A and 8A show a state in which the lever switch 250 swings to the first position, and FIGS. 7C and 8C show the lever switch 250 in the second position. Fig. 2 shows the state of swinging. FIGS. 7B and 8B show a state where the lever switch 250 swings to a position between the first position and the second position.

  When the rotation angle θ of the link 214 is 0 ° ≦ θ <360−α °, the protrusion 252 moves in the first region 261A of the guide groove 261 as shown in FIG. Further, when 360−α ° ≦ θ <360 °, the protrusion 252 moves in the second region 261B as shown in FIG. 7B. Further, when 360 ° ≦ θ <720−α °, the protrusion 252 moves in the third region 261C as shown in FIG. 7C.

  That is, the guide member 260 moves the lever switch 250 to the first position when the rotation angle of the link 214 is 0 ° or more and less than (360−α) °. Further, the guide member 260 moves the lever switch 250 to a position between the first position and the second position when the rotation angle of the link 214 is not less than (360−α) ° and less than 360 °. The guide member 260 moves the lever switch 250 to the second position when the rotation angle of the link 214 is 360 ° or more and less than (720−α) °.

  When the protrusion 252 moves in the first region 261A, the first region 261A is formed in an arc shape on the first virtual perfect circle centered on the rotation center line C, so the main body 251 is in the first position. To position. Similarly, when the projecting portion 252 moves in the third region 261C, the third region 261C is formed in an arc shape on the second virtual perfect circle centered on the rotation center line C. Located in position 2. The first virtual perfect circle is assumed to have a larger radius than the second virtual perfect circle.

  On the other hand, when the protrusion 252 moves in the second region 261B, the distance in the radial direction of the second region 261B with respect to the rotation center line C differs in the circumferential direction orthogonal to the radial direction. Swing between two positions.

  The other end 251B of the main body 251 of the lever switch 250 is separated from the contact sensor 270 as shown in FIG. 8A while the protrusion 252 moves in the first region 261A. Is turned off (first level). When the protrusion 252 moves in the second region 261B along with the rotation of the link 214, the main body 251 swings in a direction in which the other end 251B of the main body 251 approaches the contact sensor 270, as shown in FIG.

  Then, when the protrusion 252 moves to the third region 261C, as shown in FIG. 8B, the other end 251B comes into contact with and comes into contact with the contact sensor 270 by swinging about the rotation shaft 253 of the main body 251. The output of the sensor 270 is turned on (second level). That is, when the protrusion 252 moves in the first region 261A, the main body 251 does not swing from the first position, and the output of the contact sensor 270 remains off. When the protrusion 252 moves in the third region 261C, the main body 251 does not swing from the second position, and the output of the contact sensor 270 remains on. When the protrusion 252 moves in the second region 261B, the main body 251 swings, and the output of the contact sensor 270 is in a transient state in which the output is switched from off to on or from on to off.

  FIG. 9 is a graph showing the relationship between the rotation angle θ of the link 214, the detection angle φ of the absolute encoder 237, and the output of the contact sensor 270. As shown in FIG. 9, when the detection angle φ as the detection result of the absolute encoder 237 is 0 ° ≦ φ <360−α °, the rotation of the link 214 is the first turn (0 ° or more and less than 360 °) or the second turn. There are two candidates for the rotation angle θ for each eye (360 ° or more and less than 720 °). For example, when the movable range is 630 °, the angle α is 90 °. When the detection angle φ is 200 °, there are two candidates for the rotation angle θ of 200 ° and 560 °. Here, when the output of the contact sensor 270 is OFF, the protrusion 252 is positioned in the first region 261A, and thus θ = 200 °. When the output of the contact sensor 270 is on, the protrusion 252 is positioned in the third region 261C, and θ = 200 ° + 360 ° = 560 °. Thus, it can be determined from the output of the contact sensor 270 whether the first or second round.

  When the detected angle φ is 360−α ° ≦ φ <360 °, the rotation angle θ is uniquely determined as 330 ° when the angle α is 90 ° and the detected angle φ is 330 °. This is because, since the movable range is 0 ° or more and less than 630 °, θ = 690 ° when the protrusion 252 is on the second turn, but it is outside the movable range of the rotation angle and can be excluded.

  Thus, the rotation angle θ of the link 214 can be calculated by comparing the detection angle φ detected by the absolute encoder 237 with the output of the contact sensor 270.

  Next, each step of the angle calculation process performed by the calculation unit 302 will be described. FIG. 10 is a flowchart showing an angle calculation process executed by the calculation unit 302 based on a program stored in the storage unit 303.

  The arithmetic unit 302 is activated when the power is turned on, reads the arithmetic program from the storage unit 303, and executes the arithmetic program (S1). When the power supply is stopped, since power is not supplied to the absolute encoder 237 and the contact sensor 270, the absolute encoder 237 and the contact sensor 270 are not operating. Therefore, even if the joint axis of the robot arm 201 is forcibly rotated manually by a hand, the amount of change in the rotation angle cannot be detected by the absolute encoder 237. When the power supply is started from the power supply stop state, power is supplied to the absolute encoder 237 and the contact sensor 270.

  Next, the arithmetic unit 302 acquires the value of the detection angle φ as a detection result from the absolute encoder 237 (S2).

  Next, the arithmetic unit 302 determines whether or not the value of the detected angle φ acquired from the absolute encoder 237 is within a predetermined angle range (S3). Specifically, when 0 ≦ α <360, the movable range of the link 214 with respect to the link 213 is 0 ° or more and less than (720−α) °. Therefore, the arithmetic unit 302 satisfies 0 ≦ φ <360−α. Judge whether there is. That is, the arithmetic unit 302 determines whether or not the detection angle φ is not less than 0 ° and less than (360−α) °. Here, in the case of 0 ≦ φ <360−α, the projecting portion 252 has moved to one of the first region 261A and the third region 261C in the guide groove 261. When 360−α ≦ φ <360, the protrusion 252 moves to the second region 261B in the guide groove 261.

  Next, when the arithmetic unit 302 determines that 0 ≦ φ <360−α (S3: Yes), it checks (acquires) the output of the contact sensor 270 (S4).

  Next, the arithmetic unit 302 determines whether or not the output of the contact sensor 270 is on (is off) (S5). When the protrusion 252 is located in the first region 261A, the main body 251 of the lever switch 250 is not in contact with the contact sensor 270, and the output of the contact sensor 270 is off. When the protrusion 252 is located in the third region 261C, the main body 251 of the lever switch 250 is in contact with the contact sensor 270, and the output of the contact sensor 270 is on.

  When the output of the contact sensor 270 is on (S5: Yes), the arithmetic unit 302 performs a process of adding 360 ° to the detection angle φ (a process of θ = φ + 360), and the result of the addition is rotated by the link 214. The angle θ is set (S6). That is, the arithmetic unit 302 detects the rotation angle θ of the link 214 as a result of detection by the absolute encoder 237 when the contact sensor 270 detects that the lever switch 250 is swung to the second position (when the output is on). Let 360 be the result of adding 360 ° to φ.

  That is, since the rotation angle (joint angle) θ of the link 214 is positioned at the second rotation (360 ° or more and less than 720−α °), θ = φ + 360.

  When the output of the contact sensor 270 is OFF in step S5 (S5: No), the arithmetic unit 302 sets the rotation angle θ of the link 214 as the detection result φ of the absolute encoder 237 (S7). That is, the arithmetic unit 302 sets θ = φ when the contact sensor 270 detects that the lever switch 250 swings to the first position.

  That is, the protrusion 252 is positioned in the first region 261A, and the rotation angle (joint angle) θ of the link 214 is positioned at the first rotation (0 ° or more and less than 360−α °). , Θ = φ.

  If the arithmetic unit 302 determines that the detected angle φ acquired from the absolute encoder 237 in step S3 is not less than (360−α) ° and less than 360 ° (S3: No), the arithmetic unit 302 detects the rotation angle θ of the link 214. The angle φ is set (S8). That is, since the protrusion 252 is located in the second region 261B, the rotation angle (joint angle) θ is uniquely determined as θ = φ.

  Next, the arithmetic unit 302 transmits the value of the rotation angle (joint angle) θ obtained in steps S6, S7, and S8 to the control unit 301 (S9). The control unit 301 controls the motor 231 so that the rotation angle θ becomes the target rotation angle.

  As described above, according to the first embodiment, the absolute encoder 237 detects the absolute angle of the link 214 with respect to the link 213, and the contact sensor 270 detects the swing position of the lever switch 250. Thereby, the arithmetic unit 302 of the control device 300 obtains the rotation angle θ of the link 214 that rotates with respect to the link 213 in less than two rotations. As a result, even if the link 214 rotates relative to the link 213 when the power is stopped, the rotation angle θ of the link 214 can be obtained, so that a battery for storing the number of rotations in the memory becomes unnecessary. Since the battery is unnecessary, there is no need to periodically replace the battery, and the battery power cable and the like are also unnecessary, so that the robot apparatus 100 can be reduced in size and cost.

  Further, when the protrusion 252 is moving in the second region 261B, that is, when the detection angle φ is (360−α) ° or more and less than 360 °, the rotation angle θ is unique regardless of the output of the contact sensor 270. Is determined by φ. Therefore, the rotation angle θ can be obtained even in the transition period when the lever switch 250 is displaced from the first position to the second position or from the second position to the first position. Therefore, the rotation angle θ of the link 214 is accurately obtained over the entire movable range of the link 214, and the control operation of the robot 200 is stabilized while reducing the size and cost of the robot apparatus 100.

  In the first embodiment, the rotation angle θ of the link 214 relative to the link 213 can be obtained with a simple configuration in which the lever switch 250 (main body 251) that is a swinging member is swung along the guide groove 261. it can.

  Furthermore, in the first embodiment, since the guide groove 261 is formed on the end surface 262 of the guide member 260, the lever switch 250 can be disposed between the links 213 and 214, and the robot apparatus 100 is further downsized.

[Second Embodiment]
Next, a robot apparatus according to a second embodiment of the present invention will be described. FIG. 11 is a plan view showing a guide member of the robot apparatus according to the second embodiment of the present invention. FIG. 12 is a graph showing the relationship between the rotation angle θ of the second link, the detection angle φ of the absolute encoder, and the output of the contact sensor in the second embodiment. Note that in the second embodiment, identical symbols are assigned to configurations similar to those in the first embodiment and descriptions thereof are omitted. In 2nd Embodiment, the shape of the guide groove 561 of the guide member 560 differs from the guide groove 261 of the guide member 260 of the said 1st Embodiment, and the structure of other than that is the same as that of the said 1st Embodiment. That is, in the first embodiment, the first position and the second position, which are the swing positions of the lever switch 250, are determined as one point, but there may be a range in the first position and the second position.

  Specifically, the contact sensor 270 is a pressure sensor whose electrical resistance value decreases as the contact pressure increases. Therefore, the output (energization current) of the contact sensor 270 increases as the contact pressure increases. When the output of the contact sensor 270 is equal to or lower than the first level, it may be determined that the contact sensor 270 is off, that is, the lever switch 250 has moved to the first position. Further, when the output of the contact sensor 270 is equal to or higher than the second level, it may be determined that the contact sensor 270 is on, that is, the lever switch 250 has moved to the second position.

  In the second embodiment, as illustrated in FIG. 11, the guide groove 561 of the guide member 560 is formed in a spiral shape on the end surface 562 so as to continuously approach (or move away from) the rotation center line C. Therefore, the output of the contact sensor 270 changes linearly as shown in FIG.

  The guide groove (cam groove) 561 can be divided into three regions: a first region 561A, a second region 561B, and a third region 561C. Since these three areas 561A, 561B, and 561C are continuous, there is no clear separation. As the link 214 rotates in the clockwise direction in FIG. 11 from 0 °, the protrusion 252 moves relative to the guide member 560 along the guide groove 561 in the counterclockwise direction in FIG. At that time, the protrusion 252 in the guide groove 561 continuously moves in a direction away from the rotation center line C. Therefore, the output of the contact sensor 270 is turned off when the rotation angle of the link 214 is 0 ° or more and less than (360−α) °, and the output of the contact sensor 270 is turned on when the rotation angle is 360 or more and less than (720−α) °. The contact sensor 270 is adjusted so that That is, the first level and the second level that are threshold values for the output of the contact sensor 270 in the arithmetic unit 302 are set. At this time, in the case of (360−α) ° or more and less than 360 °, the value of the contact sensor 270 may be either on or off.

  As described above, according to the second embodiment, the rotation angle θ of the link 214 can be obtained through the same process as the flowchart of FIG. 10 described in the first embodiment. Therefore, even if the link 214 rotates with respect to the link 213 when the power is stopped, the rotation angle θ of the link 214 can be obtained, so that a battery for storing the number of rotations in the memory becomes unnecessary. By eliminating the need for a battery, it is not necessary to replace the battery regularly, and a power cable for the battery is not required, so that the robot apparatus can be reduced in size and cost.

[Third Embodiment]
Next, a robot apparatus according to a third embodiment of the invention will be described. FIG. 13 is a perspective view showing a guide member of the robot apparatus according to the third embodiment of the present invention. FIG. 14 is a side view showing the guide member of the robot apparatus according to the third embodiment of the present invention. Note that in the third embodiment, identical symbols are assigned to configurations similar to those in the first and second embodiments and descriptions thereof are omitted. In the third embodiment, the formation position of the guide groove 661 of the guide member 660 and the arrangement positions of the lever switch 250 and the contact sensor 270 are different from those in the first and second embodiments.

  In the third embodiment, the guide member 660 is formed in a cylindrical (or column) shape. The guide member 660 has a peripheral surface whose normal is a line orthogonal to the rotation center line C of the link 214, specifically, an outer peripheral surface (side surface) 663. The guide groove 661 is formed in a spiral shape on the outer peripheral surface 663 of the guide member 660. That is, the guide groove 661 is formed so that the position of the protrusion 252 is changed stepwise in accordance with the rotation of the guide member 660 in the arrow Z direction parallel to the rotation center line C.

  The lever switch 250 is disposed at a position facing the outer peripheral surface 663. The lever switch 250 is arranged so that the protruding portion 252 enters the guide groove 661. When the guide member 660 rotates around the rotation center line C, the protrusion 252 slides relative to the guide groove 661 along the guide groove 661 formed on the outer peripheral surface (side surface) of the guide member 660. Thereby, the protrusion part 252 moves to the arrow Z direction parallel to the rotation center line C of a cylinder. By the movement of the projecting portion 252, the main body 251 of the lever switch 250 swings (rotates about the rotation shaft 253).

  As shown in FIG. 14, the guide grooves 661 formed on the outer peripheral surface (side surface) 663 are three of the first region 661A, the second region 661B, and the third region 661C, like the guide groove 261 of the first embodiment. Divided into two areas.

  The first region 661A is formed above the guide member 660 in FIG. 14 and the third region 661C is formed below the guide member 660 in FIG. 14. The first region 661A and the third region 661C are angled from the rotation center line C. They are formed at intervals of α °. The first region 661A and the third region 661C are connected via the second region 661B. The operation in which the main body 251 of the lever switch 250 swings around the rotation shaft 253 and contacts or separates from the contact sensor 270 is the same as in the first embodiment.

  As described above, even when the guide groove 661 is formed on the outer peripheral surface 663 of the guide member 660, the relationship between the rotation angle θ of the link 214 and the output of the contact sensor 270 as in FIG. 9 described in the first embodiment. Is guided. Therefore, also in the third embodiment, similarly to the first embodiment, the robot apparatus can be reduced in size and cost.

  In the third embodiment, the case where the guide groove 661 is formed so as to change stepwise in the direction of the arrow Z parallel to the rotation center line C has been described. However, as in the second embodiment, the guide groove 661 changes continuously. You may form so that it may do.

[Modification]
In the first to third embodiments, the case has been described in which the output of the absolute encoder 237 and the contact sensor 270 is always calculated by the arithmetic unit 302 while the robot 200 is activated, and the absolute angle of the joint is calculated. On the other hand, the joint angle θ may be calculated by the arithmetic unit 302 using the output of the contact sensor 270 only at the time of activation, and after the activation, the angle change of the incremental encoder 235 may be added to the joint angle θ calculated at the time of activation. That is, the arithmetic unit 302 may have a control mode for obtaining the current rotation angle of the link 214 from the angle change Δθ detected by the incremental encoder 235 with reference to the rotation angle θ obtained by the angle calculation process. Thereby, the arithmetic unit 302 can detect the absolute angle of the joint angle without always performing the arithmetic operation of FIG. 10 described in the first embodiment after the activation of the robot apparatus.

  The present invention is not limited to the embodiment described above, and many modifications are possible within the technical idea of the present invention.

  In the above embodiment, the position at which the lever switch 250 is separated from the contact sensor 270 is the first position, and the position at which the lever switch 250 is in contact with the contact sensor 270 is the second position. The relationship may be That is, the lever switch 250 and the contact sensor 270 may be arranged so that the position where the lever switch 250 contacts the contact sensor 270 is the first position and the position where the lever switch 250 is separated from the contact sensor 270 is the second position.

  Moreover, although the case where the rotation drive unit has a transmission mechanism has been described in the above embodiment, the present invention can also be applied to a case where the rotation mechanism does not have a transmission mechanism. Furthermore, although the case where the rotational drive unit has a speed reducer has been described in the above embodiment, the present invention can also be applied to a case where the speed reducer does not have a speed reducer.

  In the above embodiment, the moving member is a swingable lever switch, and the lever switch is guided to the guide groove. However, even if there is no battery, the guide member is guided to the first or second turn. Other means may be used as long as it can be discriminated. For example, the same effect can be obtained by using a slidable slide switch instead of the lever switch 250. When the moving member is a slide type switch, the guide member may be configured to guide the slide between the first position and the second position. Further, instead of the contact sensor 270, a detection unit that continuously detects the position of the moving member, such as a variable resistor, a laser displacement meter, or a capacitance sensor, is used to determine whether it is the first or second turn. You may do it.

  Moreover, although the said embodiment demonstrated the case where the control apparatus 300 was divided into the control unit 301 and the arithmetic unit 302, it is not limited to this, The control unit 301 and the arithmetic unit 302 are one unit. It may be configured.

  In the above embodiment, the case where the link 213 is the first link and the link 214 is the second link has been described. However, the first link and the second link are relative, and the first link is The link 214 and the second link may be the link 213.

DESCRIPTION OF SYMBOLS 100 ... Robot apparatus, 213 ... Link (1st link), 214 ... Link (2nd link), 230 ... Rotation drive part, 237 ... Absolute encoder (angle detection part), 250 ... Lever switch (moving member), 260 ... Guide member, 270 ... contact sensor (detection unit), 300 ... control device (control unit)

Claims (8)

The first link,
A second link rotatably connected to the first link;
A rotational drive unit that rotationally drives the second link in a movable range of less than two rotations with respect to the first link;
A control unit that controls the rotation driving unit so that a rotation angle of the second link with respect to the first link becomes a target rotation angle;
An angle detector that detects an absolute angle of the second link with a value of 0 ° or more and less than 360 °;
A moving member supported by the first link so as to be movable to a first position and a second position different from the first position;
The second link provided on the second link moves to the first position when the rotation of the second link relative to the first link is less than one rotation, and the rotation of the second link relative to the first link. A guide member that guides the moving member to move to the second position when is less than or equal to 1 rotation and less than 2 rotations;
A detection unit that detects which position of the first position and the second position the moving member has moved;
When the detection unit detects that the moving member has moved to the first position, the control unit sets the rotation angle of the second link as a detection result of the angle detection unit, and the detection unit When it is detected that the moving member has moved to the second position, an angle calculation process is performed in which the rotation angle of the second link is a result of adding 360 ° to the detection result of the angle detection unit. A robot device. When 0 ≦ α <360, the movable range is 0 ° or more and less than (720−α) °,
The guide member moves the moving member to the first position when the rotation angle of the second link is not less than 0 ° and less than (360−α) °, and is not less than (360−α) ° and less than 360 °. Sometimes the moving member is moved to a position between the first position and the second position, and the moving member is moved to the second position when it is 360 ° or more and less than (720−α) °,
In the angle calculation process, the control unit detects the rotation angle of the second link when the angle detected by the angle detection unit is equal to or greater than (360-α) ° and less than 360 °. The robot apparatus according to claim 1, wherein the robot apparatus is a result. The moving member is supported by the first link so as to be swingable to the first position and the second position;
The moving member is formed with a protruding portion that protrudes toward the guide member.
The guide groove according to claim 1 or 2, wherein the guide member is formed with a guide groove on which the protrusion slides with the rotation of the second link so that the moving member swings. Robot device. The guide member has an end surface whose normal is the rotation center line of the second link;
The robot apparatus according to claim 3, wherein the guide groove is formed in a spiral shape on an end surface of the guide member. The guide member has a peripheral surface whose normal is a line orthogonal to the rotation center line of the second link,
The robot apparatus according to claim 3, wherein the guide groove is formed in a spiral shape on a peripheral surface of the guide member.   The robot apparatus according to claim 1, wherein the angle detection unit is an absolute encoder. The rotation drive unit has a rotation motor,
An incremental encoder for detecting an angular change of the rotation shaft of the rotary motor;
7. The control unit according to claim 1, further comprising a control mode for obtaining a rotation angle of the second link from an angle change detected by the incremental encoder based on a value obtained by the angle calculation process. The robot apparatus according to any one of the above.   The robot apparatus according to claim 7, wherein the rotation driving unit includes a speed reducer that decelerates and transmits the rotation of the rotation motor to the second link.

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