Brake release circuit, brake release method, and control system

Abstract

To provide a brake release circuit that can suppress simultaneous release of operations of a plurality of electromagnetic brakes even if wirings for electrically conducting an exciting coil of the electromagnetic brake are short-circuited when selectively releasing the electromagnetic brake among from an electromagnetic brake group, a brake release method, and a control system.SOLUTION: An electromagnetic brake release circuit 30 comprises: a short circuit detector 52 that detects short circuit between wirings corresponding to a combination of m exciting coils 22, where m is an integer greater than or equal to 2 and less than or equal to N, of an exciting coil group 22 which is an aggregate of N exciting coils 24; and an electric conduction breaker 54 which breaks electric conduction to at least m exciting coils when short circuit is detected.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a brake release circuit, a brake release method, and a control system for releasing the operation of an electromagnetic brake group of a non-excitation operation type attached to a robot.

Background Art

[0002] In the technical field of industrial robots, electromagnetic brakes are respectively attached to the joint axes of the arm part in order to prevent the arm part from moving unintentionally when the robot is not in operation. As this electromagnetic brake, a non-excitation operation type that applies a braking force when not excited and releases the application of the braking force when excited is often used. For example, an electric circuit (hereinafter, a brake release circuit) for releasing the operation of a non-excitation operation type electromagnetic brake is provided in a robot control device.

[0003] Patent Document 1 discloses a brake release circuit that can selectively energize the excitation coil of an electromagnetic brake by inserting a plurality of plugs into a short-circuit connector. Specifically, according to the brake release circuit of Patent Document 1, it can be switched from an internal power source to an emergency power source through the operation of a connector without using a relay or a switch.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the brake release circuit disclosed in Patent Document 1, if the contacts of the connectors are short-circuited for some reason, the operation of an electromagnetic brake different from the electromagnetic brake that the operator tried to release may be released. In particular, in the case of a 6-axis vertical articulated robot, if the operations of a plurality of electromagnetic brakes are released simultaneously, the arm part may fall due to its own weight.

[0006] The present invention has been made in view of such problems, and its object is to suppress the simultaneous release of the operations of a plurality of electromagnetic brakes even when the wirings for energizing the excitation coils of the electromagnetic brakes are short-circuited when selectively releasing an electromagnetic brake from among an electromagnetic brake group. An object of the present invention is to provide a brake release circuit, a brake release method, and a control system.

Means for Solving the Problems

[0007] The brake release circuit according to the present invention is a circuit for releasing the operations of a group of non-energized operation type electromagnetic brakes attached to a robot, and is an aggregate of N excitation coils respectively included in N electromagnetic brakes, which are integers of 3 or more constituting the electromagnetic brake group. A wiring group including an operating wiring for energizing the coil group, a short-circuit detector for detecting a short circuit between the operating wirings corresponding to a combination of n excitation coils, which is an integer of 2 or more and N or less among the excitation coil groups, and when the short circuit is detected by the short-circuit detector, at least an energization cutoff device for cutting off the energization to the n excitation coils.

[0008] Further, the short-circuit detector includes m relays connected to m operating wirings, which are integers of n or more and N or less among the wiring group, and outputs a cutoff signal to the energization cutoff device while the short circuit is not detected by the m relays. The energization cutoff device connects the operating wiring while the cutoff signal is not output by the short-circuit detector, and disconnects the operating wiring while the cutoff signal is output, so as to switch the connection state of the operating wiring.

[0009] Further, each of the m relays includes a detection unit that detects the energization state of the operating wiring, and a plurality of opening / closing units that open and close according to the energization state detected by the detection unit. The power cut-off device outputs the cut-off signal through a stage circuit unit in which each stage in which combinations of the n opening / closing units are connected in parallel are connected in series.

[0010] Further, each of the m relays includes a detection unit that detects the energization state of the operating wiring, and a plurality of opening / closing units that open and close according to the energization state detected by the detection unit. The power cut-off device outputs the cut-off signal through a stage circuit unit in which each stage in which combinations of the n opening / closing units are connected in series are connected in parallel.

[0011] The brake release method in the present invention is a method for releasing the operation of a non-energized operation type electromagnetic brake group attached to a robot. The brake release circuit includes a wiring group including an operating wiring for energizing an exciting coil group that is an aggregate of N exciting coils each of which is included in N electromagnetic brakes that are integers of 3 or more constituting the electromagnetic brake group, and detects a short circuit between the operating wirings corresponding to combinations of n exciting coils that are 2 or more and an integer of N or less among the exciting coil group. When the short circuit is detected, at least the energization to the n exciting coils is cut off.

[0012] The control system in the present invention includes the above-described electromagnetic brake group and a robot control device configured to include the above-described brake release circuit.

Effects of the Invention

[0013] According to the present invention, when selectively releasing an electromagnetic brake from among an electromagnetic brake group, even when wirings for energizing exciting coils of the electromagnetic brake are short-circuited, it is possible to suppress simultaneous release of operations of a plurality of electromagnetic brakes.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. For ease of understanding of the description, the same reference numerals are given to the same components in each drawing as much as possible, and redundant descriptions are omitted. Also, the term "part" may be replaced with other terms such as unit, module, device, or element.

[0016] [Configuration of Robot System 10] [Overall Configuration] FIG. 1 is a diagram showing the configuration of a robot system 10 incorporating a brake release circuit 30 according to an embodiment of the present invention. This robot system 10 includes an industrial robot (hereinafter simply referred to as "robot 12") and a control system 14.

[0017] Robot 12 is, for example, an articulated robot having an arm unit 16. The arm unit 16 is configured by connecting a plurality of links in series and has six joint axes 18. The six joint axes 18 include a swivel axis (J1 axis) for rotating the body, a lower arm axis (J2 axis) for moving the body back and forth, an upper arm axis (J3 axis) for moving the arm up and down, a wrist swivel axis (J4 axis) for rotating the arm, a “wrist bending axis” (J5 axis) for swinging the wrist up and down, and a wrist rotation axis (J6 axis) for rotating the wrist. Note that a tool (not shown) can be attached to the tip of the robot 12.

[0018] A servo motor (not shown) that performs rotational drive clockwise or counterclockwise through servo control is connected to each of the joint axes 18. The robot 12 can perform various operations including gripping, moving, welding, or painting of a workpiece by independently driving the plurality of joint axes 18 according to a command from the robot control device 20 of the control system 14.

[0019] The control system 14 controls the operation of the robot 12. Specifically, this control system 14 is configured to include a robot control device 20 and an electromagnetic brake group 22G.

[0020] The electromagnetic brake group 22G is an aggregate of N (N ≥ 3, here N = 6) electromagnetic brakes 22. The electromagnetic brakes 22 are respectively attached to the joint axes 18 of the robot 12. In the example of FIG. 1, the electromagnetic brake 22 is a non-excitation operation type brake that applies a braking force to the joint axis 18 when not excited and releases the application of the braking force when excited.

[0021] The robot control device 20 is a computer that controls the operation of the robot 12. Specifically, the robot control device 20 is configured to include a brake release circuit 30, a control unit 32, and an internal power supply 34.

[0022] The brake release circuit 30 is an electric circuit for operating or releasing the operation of the electromagnetic brake group 22G. In addition to the electromagnetic brake group 22G, a control unit 32, an internal power supply 34, and an emergency power supply 36 are connected to the brake release circuit 30, respectively. The internal power supply 34 is a DC power supply provided inside the robot control device 20. The emergency power supply 36 is a DC power supply provided separately from the internal power supply 34.

[0023] The control unit 32 performs drive control of the servo motor based on the position signal from the position sensor. For the drive control, for example, PWM (Pulse Width Modulation) with the current flowing through the servo motor as the control amount is used. Further, the control unit 32 performs switching control for operating or releasing the operation of the electromagnetic brake group 22G by outputting a control signal to the brake release circuit 30.

[0024] By the way, one button 38 and three connectors 40, 42, 44 are provided on the operation panel (not shown) of the robot control device 20, respectively. The button 38 is connected to the enable switches 56, 57 (Fig. 2) of the brake release circuit 30. The connector 40 detachably receives the first plug PLG1. The connector 42 detachably receives the second plug PLG2. The connector 44 detachably receives the third plug PLG3.

[0025] Fig. 2 is a diagram schematically showing the configuration of the brake release circuit 30 in Fig. 1. Actually, six electromagnetic brakes 22 are connected to the brake release circuit 30, but for convenience of explanation, only one electromagnetic brake 22 is shown. The electromagnetic brake 22 is configured to include an excitation coil 24 that induces an excitation signal by energization. The high potential side (x-point side) of the excitation coil 24 is connected to the branch point P1 of the wiring L1 to which power is supplied from the internal power supply 34 or the emergency power supply 36. The low potential side (y-point side) of the excitation coil 24 is connected to the wiring L2 having the contact point T1 of the connector 40 as the end point.

[0026] The brake release circuit 30 includes, in addition to the connectors 40, 42, and 44 described with reference to FIG. 1, wiring groups 50x and 50y, a short-circuit detector 52, a power cut-off device 54, enable switches 56 and 57, and a switching element 58.

[0027] The wiring groups 50x and 50y include operating wiring for energizing the excitation coil 24. The wiring group 50x is at least one wiring for connecting the x-side of the excitation coil 24 to the emergency power source 36. The wiring group 50y is at least one wiring for connecting the y-side of the excitation coil 24 to the ground potential (or GND). That is, the wiring L1 belongs to the wiring group 50x, and the wiring L2 belongs to the wiring group 50y.

[0028] The short-circuit detector 52 detects a short circuit between the operating wirings included in the wiring groups 50x and 50y. This short circuit can occur, for example, when a conductive foreign object is caught inside the connector 40. The input side of the short-circuit detector 52 is connected to the branch point P3 on the wiring L2, and the output side of the short-circuit detector 52 is connected to the power cut-off device 54. The specific circuit configuration of the short-circuit detector 52 will be described in detail with reference to FIG. 3.

[0029] The power cut-off device 54 cuts off the power supply to the excitation coil 24 when a short circuit is detected by the short-circuit detector 52. The power cut-off device 54 is provided between two branch points P2 and P3 on the wiring L2. The specific circuit configuration of the power cut-off device 54 will be described in detail with reference to FIG. 3.

[0030] The enable switches 56 and 57 switch the connection state of the wiring groups 50x and 50y in response to the operation of the button 38 (FIG. 1) by the operator. The enable switch 56 is provided between the contact T2 of the connector 40 and the contact T1 of the connector 42. The enable switch 57 is provided between the internal power source 34 and the contact T3 of the connector 42.

[0031] The switching element 58 switches the connection state of the wiring group 50y according to the control signal from the control unit 32 (FIG. 1). The switching element 58 is provided between the contact T2 of the connector 44 and the ground potential.

[0032] The connector 40 is provided with two contacts T1 and T2. The contact T1 of the connector 40 is connected to the power cut-off device 54 via the wiring L2. The contact T2 of the connector 40 is connected to the enable switch 56. By inserting the first plug PLG1, the contacts T1 and T2 of the connector 40 are short-circuited.

[0033] The connector 42 is provided with four contacts T1, T2, T3, and T4. The contact T1 of the connector 42 is connected to the enable switch 56. The contact T2 of the connector 42 is connected to the ground potential. The contact T3 of the connector 42 is connected to the enable switch 57. The contact T4 of the connector is connected to the emergency power supply 36. By inserting the second plug PLG2, the contacts T1 and T2 of the connector 42 are short-circuited and the contacts T3 and T4 are short-circuited.

[0034] The connector 44 is provided with two contacts T1 and T2. The contact T1 of the connector 44 is connected to the branch point P2 on the wiring L2. The contact T2 of the connector 44 is connected to the switching element 58. By inserting the third plug PLG3, the contacts T1 and T2 of the connector 44 are short-circuited.

[0035] FIG. 3 is a diagram showing an example of the circuit configuration of the short-circuit detector 52 and the power cut-off device 54 in FIG. 2. For the sake of illustration, only the circuit configurations corresponding to the J2 axis, J3 axis, and J5 axis among the J1 axis to J6 axis of the arm portion 16 are schematically shown. The J2 axis, J3 axis, and J5 axis are all common in that they are joint axes 18 for changing the angle formed by adjacent links.

[0036] In FIG. 3, with respect to the components for each joint axis 18, they are denoted by adding an alphabet to the numbers of the reference signs in FIG. 2. For example, when associating the J2 axis with "a", the J3 axis with "b", and the J5 axis with "c" respectively, the electromagnetic brake 22 and the excitation coil 24 corresponding to the J2 axis are denoted as "electromagnetic brake 22a" and "excitation coil 24a" respectively.

[0037] The short-circuit detector 52 is composed of including three relays 60a, 60b, 60c which are either a contact relay or a non-contact relay. The relay 60a is connected to a branch point P3a on the wiring L2a corresponding to the J2 axis. The relay 60b is connected to a branch point P3b on the wiring L2b corresponding to the J3 axis. The relay 60c is connected to a branch point P3c on the wiring L2c corresponding to the J5 axis.

[0038] The relay 60a includes a detection unit 62a for detecting the energization state of the wiring L2a, and two opening / closing units 64a, 66a that open and close according to the energization state detected by the detection unit 62a. In the example of FIG. 3, the opening / closing units 64a, 66a are normally closed (or B contact) type switches that are in the "closed" state when the wiring L2a is in a non-energized state.

[0039] The relay 60b includes a detection unit 62b for detecting the energization state of the wiring L2b, and two opening / closing units 64b, 66b that open and close according to the energization state detected by the detection unit 62b. In the example of FIG. 3, the opening / closing units 64b, 66b are normally closed (or B contact) type switches that are in the "closed" state when the wiring L2b is in a non-energized state.

[0040] The relay 60c includes a detection unit 62c for detecting the energization state of the wiring L2c, and two opening / closing units 64c, 66c that open and close according to the energization state detected by the detection unit 62c. In the example of FIG. 3, the opening / closing units 64c, 66c are normally closed (or B contact) type switches that are in the "closed" state when the wiring L2c is in a non-energized state.

[0041] By combining the six opening / closing parts 64a to 64c and 66a to 66c described above, a stage circuit section 70 that outputs a signal (hereinafter referred to as a "cut-off signal") for cutting off the power supply to the exciting coils 24a to 24c is configured. The stage circuit section 70 is provided between the emergency power supply 36 and the power cut-off device 54. Specifically, the stage circuit section 70 has a circuit configuration in which a first stage 71, a second stage 72, and a third stage 73 are connected in series. The first stage 71 is formed by connecting the opening / closing part 64a and the opening / closing part 64b in parallel. The second stage 72 is formed by connecting the opening / closing part 66b and the opening / closing part 64c in parallel. The third stage 73 is formed by connecting the opening / closing part 66a and the opening / closing part 66c in parallel.

[0042] The power cut-off device 54 switches the connection state of the wirings L2a to L2c so as to connect the wirings L2a to L2c while the cut-off signal is not output by the short-circuit detector 52 and not to connect the wirings L2a to L2c while the cut-off signal is output. The power cut-off device 54 is composed of, for example, a contact relay or a non-contact relay. Specifically, the power cut-off device 54 includes a detection unit 76 that detects a cut-off signal from the short-circuit detector 52 (more specifically, the stage circuit section 70), and three opening / closing parts 78a, 78b, and 78c that open and close according to the detection result by the detection unit 76. In the example of FIG. 3, the opening / closing parts 78a to 78c are normally open (or A-contact) type switches that are in the "open" state when the cut-off signal is "L" (that is, the detection unit 76 is in a non-energized state).

[0043] On the output side of the stage circuit section 70 of the short-circuit detector 52, a light-emitting element 80 including an LED (Light Emitting Diode) and a resistor 82 for protecting the light-emitting element 80 are provided. The light-emitting element 80 emits light when the above-described cut-off signal is "H" (that is, the detection unit 76 is in an energized state).

[0044] In FIGS. 1 to 3, the case where the total number of the exciting coils 24 is "6", the number of the relays 60 included in the short-circuit detector 52 is "3", the number of the opening / closing parts 64 and 66 is "2", and the number of stages of the stage circuit section 70 is "3" has been described as an example. However, the relationship between the respective numbers can be generalized as follows.

[0045] Let the total number of exciting coils 24 that make up the exciting coil group 24G be N (where N is an integer satisfying N ≥ 3). Let the number of combinations of exciting coils 24 for detecting a short circuit between the operating wirings be n (where n is an integer satisfying 2 ≤ n ≤ N). Let the number of relays 60 connected to the operating wiring be m (where m is an integer satisfying n ≤ m ≤ N). In this case, the opening / closing part of the relay 60 is COMBIN(m - 1, n - 1), the number of connections of the opening / closing part for each stage of the multi-stage circuit part 70 is n, and the number of stages of the multi-stage circuit part 70 is COMBIN(m, n). Here, COMBIN(m, n) is a function for obtaining the total number of combinations and is also denoted as mCn.

[0046] [Operation of the brake release circuit 30] Subsequently, the operation of the brake release circuit 30 will be described with reference to FIGS. 1 to 4. Here, it is assumed that the operator performs a "release operation" to release the operation of the electromagnetic brake group 22G using the emergency power supply 36 while the operation of the robot 12 is stopped.

[0047] In FIG. 2, with the third plug PLG3 removed from the connector 44, the operator inserts the second plug PLG2 into the connector 42, inserts the first plug PLG1 into the connector 40a, and presses the button 38. Then, the x-point side of the exciting coil 24a is connected to the emergency power supply 36 via the branch point P1, the enable switch 57, and the connector 42 (contacts T3, T4). Also, the y-point side of the exciting coil 24a is connected to the ground potential via the power cut-off switch 54, the connector 40, the enable switch 56, and the connector 42 (contacts T1, T2).

[0048] For example, when the contacts of the connectors 40a to 40c are short-circuited for some reason, the operations of the electromagnetic brakes 22b and 22c other than the electromagnetic brake 22a that the operator attempts to release may be released. In particular, when the robot 12 is a six-axis vertical articulated robot, the arm portion 16 of the robot 12 may fall due to its own weight when the operations of the plurality of electromagnetic brakes 22 are released simultaneously. Therefore, by providing the short-circuit detector 52 and the power cut-off device 54, it is possible to suppress the simultaneous release of the operations of the plurality of electromagnetic brakes 22a to 22c.

[0049] FIG. 4 is a diagram showing the relationship between the short-circuit state of the wiring for operation and the presence or absence of interruption. More specifically, FIG. 4 shows the correspondence between [1] the short-circuit state between the wirings L2a to L2c, [2] the output level (H / L) of the brake release signal, [3] the energized state of the stage circuit section 70, [4] the output level (H / L) of the interruption signal, and [5] the presence or absence of interruption of the energization.

[0050] First, the state where no short circuit occurs between the wirings L2a to L2c (''no short circuit'' in FIG. 4) will be described. Under this non-short-circuit state, the output levels of the brake release signals at the J2 axis, J3 axis, and J5 axis are ''H'', ''L'', and ''L'', respectively. Then, the first stage 71, the second stage 72, and the third stage 73 of the stage circuit section 70 are all in the ''energized'' state. That is, since the output level of the interruption signal from the stage circuit section 70 becomes ''H'', the opening / closing portions 78a to 78c of the power cut-off device 54 are all in the ''closed'' state (that is, ''no interruption''). As a result, only the desired excitation coil 24a is in the energized state, so the operation of the electromagnetic brake 22a is released.

[0051] Second, the state where a short circuit occurs between the wirings L2a and L2b (the "J2-J3 short circuit" in FIG. 4) will be described. Under this short circuit state, the output levels of the brake release signals at the J2 axis, J3 axis, and J5 axis become "H", "H", and "L", respectively. Then, the first stage 71, the second stage 72, and the third stage 73 of the step circuit section 70 become a "non-energized" state, an "energized" state, and an "energized" state, respectively. That is, since the output level of the cutoff signal from the step circuit section 70 becomes "L", all of the opening / closing sections 78a to 78c of the power cutoff device 54 become an "open" state (that is, "cutoff exists"). As a result, the energization of the desired excitation coil 24a is stopped, so the operation of the electromagnetic brake 22a is maintained.

[0052] Third, the state where a short circuit occurs between the wirings L2a and L2c (the "J2-J5 short circuit" in FIG. 4) will be described. Under this short circuit state, the output levels of the brake release signals at the J2 axis, J3 axis, and J5 axis become "H", "L", and "H", respectively. Then, the first stage 71, the second stage 72, and the third stage 73 of the step circuit section 70 become an "energized" state, an "energized" state, and a "non-energized" state, respectively. That is, since the output level of the cutoff signal from the step circuit section 70 becomes "L", all of the opening / closing sections 78a to 78c of the power cutoff device 54 become an "open" state (that is, "cutoff exists"). As a result, the energization of the desired excitation coil 24a is stopped, so the operation of the electromagnetic brake 22a is maintained.

[0053] Fourth, the state where a short circuit occurs between the wirings 50b and 50c (the "J3-J5 short circuit" in FIG. 4) will be described. Under this short circuit state, the output levels of the brake release signals at the J2 axis, J3 axis, and J5 axis become "H", "L", and "L", respectively. Then, all of the first stage 71, the second stage 72, and the third stage 73 of the step circuit section 70 become an "energized" state. That is, since the output level of the cutoff signal from the step circuit section 70 becomes "H", all of the opening / closing sections 78a to 78c of the power cutoff device 54 become a "closed" state (that is, "no cutoff"). As a result, only the desired excitation coil 24a becomes energized, so the operation of the electromagnetic brake 22a is released.

[0054] Hereinafter, the operator sequentially releases the operation of the electromagnetic brake 22 by repeating the operation of inserting the first plug PLG1 into another connector 40. The operator can grasp at a glance the presence or absence of a short circuit between the operating wirings by visually recognizing the light emission state of the light emitting element 80.

[0055] [Another Configuration Example] By the way, the circuit configuration of the brake release circuit 30 is not limited to the example of FIG. 3. Hereinafter, a brake release circuit 100, which is another configuration example of the brake release circuit 30, will be described. As shown in FIG. 2, the brake release circuit 100 is basically the same as the configuration of the brake release circuit 30, except that only the circuit configurations of the short circuit detector 102 and the energization cut-off device 104 are different.

[0056] FIG. 5 is a diagram showing another example of the circuit configuration of the short circuit detector 102 and the energization cut-off device 104 in FIG. 2. The description of the components similar to those in FIG. 3 will be omitted.

[0057] The short circuit detector 102 includes three relays 110a, 110b, and 110c, which are contact relays or non-contact relays. The relay 110a is connected to a branch point P3a on the wiring L2a corresponding to the J2 axis. The relay 110b is connected to a branch point P3b on the wiring L2b corresponding to the J3 axis. The relay 110c is connected to a branch point P3c on the wiring L2c corresponding to the J5 axis.

[0058] The relay 110a includes a detection unit 112a that detects the energization state of the wiring L2a, and two opening / closing units 114a and 116a that open and close according to the energization state detected by the detection unit 112a. In the example of FIG. 5, the opening / closing units 114a and 116a are normally open (or A-contact) type switches that are in the "open" state when the wiring L2a is in a non-energized state.

[0059] Relay 110b includes a detection unit 112b that detects the energization state of wiring L2b, and two switching units 114b and 116b that open and close according to the energization state detected by the detection unit 112b. In the example of FIG. 5, the switching units 114b and 116b are normally open (or A-contact) type switches that are in the "open" state when the wiring L2b is in a non-energized state.

[0060] Relay 110c includes a detection unit 112c that detects the energization state of wiring L2c, and two switching units 114c and 116c that open and close according to the energization state detected by the detection unit 112c. In the example of FIG. 5, the switching units 114c and 116c are normally open (or A-contact) type switches that are in the "open" state when the wiring L2c is in a non-energized state.

[0061] By combining the six switching units 114a to 114c and 116a to 116c described above, a stage circuit unit 120 that outputs a signal (i.e., a cutoff signal) for cutting off the power supply to the excitation coils 24a to 24c is configured. The stage circuit unit 120 is provided between the emergency power supply 36 and the power cutoff device 104. Specifically, the stage circuit unit 120 has a circuit configuration in which a first stage 121, a second stage 122, and a third stage 123 are connected in parallel. The first stage 121 is formed by connecting the switching unit 114a and the switching unit 114b in series. The second stage 122 is formed by connecting the switching unit 116b and the switching unit 114c in series. The third stage 123 is formed by connecting the switching unit 116a and the switching unit 116c in series.

[0062] The energization breaker 104 switches the connection state of the wirings L2a to L2c so as to connect the wirings L2a to L2c while the cutoff signal is not output by the short-circuit detector 102 and not to connect the wirings L2a to L2c while the cutoff signal is output. The energization breaker 104 is composed of, for example, a contact relay or a non-contact relay. Specifically, the energization breaker 104 includes a detection unit 126 that detects a cutoff signal from the short-circuit detector 102 (more specifically, the stage circuit unit 120), and three opening / closing units 128a, 128b, and 128c that open and close according to the detection result by the detection unit 126. In the example of FIG. 5, the opening / closing units 128a to 128c are normally closed (or B-contact) type switches that are in the "closed" state when the cutoff signal is "L" (that is, the detection unit 126 is de-energized).

[0063] Note that, similar to the cases of FIGS. 1 to 3, the relationship among the number of relays 110, the number of opening / closing units 114 and 116, and the number of stages of the stage circuit unit 120 can be generalized. Let N be the total number of exciting coils 24, n be the number of combinations of the exciting coils 24, and m be the number of relays 110. In this case, the number of opening / closing units of the relay 110 is COMBIN(m - 1, n - 1), the number of connections of the opening / closing units for each stage of the stage circuit unit 70 is n, and the number of stages of the stage circuit unit 70 is COMBIN(m, n).

[0064] The brake release circuit 100 is configured as described above. Subsequently, the operation of the brake release circuit 100 will be described while comparing with FIG. 4. Here, the cases where the short-circuit states of the wirings L2a to L2c are "no short circuit" and "J2 - J3 short circuit" will be described as examples.

[0065] First, a state where there is no short circuit between wirings L2a to L2c (''no short circuit'' in FIG. 4) will be described. Under this non-short circuit state, the output levels of the brake release signals on the J2 axis, J3 axis, and J5 axis are ''H'', ''L'', and ''L'', respectively. Then, the first stage 121, the second stage 122, and the third stage 123 of the step circuit section 120 are all in the ''non-energized'' state. That is, since the output level of the cutoff signal from the step circuit section 120 becomes ''L'', the opening / closing sections 128a to 128c of the power cutoff device 104 are all in the ''closed'' state (that is, ''no cutoff''). As a result, only the desired excitation coil 24a is in the energized state, so the operation of the electromagnetic brake 22a is released.

[0066] Second, a state where there is a short circuit between wirings L2a and L2b (''J2-J3 short circuit'' in FIG. 4) will be described. Under this short circuit state, the output levels of the brake release signals on the J2 axis, J3 axis, and J5 axis are ''H'', ''H'', and ''L'', respectively. Then, the first stage 121, the second stage 122, and the third stage 123 of the step circuit section 120 are in the ''energized'' state, the ''non-energized'' state, and the ''non-energized'' state, respectively. That is, since the output level of the cutoff signal from the step circuit section 120 becomes ''H'', the opening / closing sections 128a to 128c of the power cutoff device 104 are all in the ''open'' state (that is, ''cutoff''). As a result, the energization of the desired excitation coil 24a is stopped, so the operation of the electromagnetic brake 22a is maintained. In this way, the brake release circuit 100 exhibits the same function as the brake release circuit 30 in FIG. 3.

[0067] [Summary of Embodiment] As described above, the brake release circuit 30 in this embodiment detects a short circuit between the operation wirings (here, wirings L2a to L2c) corresponding to the combination of n excitation coils 24 out of the N excitation coil groups 24G, and when a short circuit is detected, at least cuts off the energization to the n excitation coils 24. Thereby, when selectively releasing the electromagnetic brake 22 from among the electromagnetic brake groups 22G, even when the wirings L2a to L2c for energizing the excitation coil 24 of the electromagnetic brake 22 are short-circuited, it is possible to suppress the simultaneous release of the operations of the plurality of electromagnetic brakes 22.

[0068] Further, the short - circuit detector 52(102) includes m operating wirings of the wiring group 50 (here, m relays 60a - 60c (110a - 110c) connected to L2a - L2c), and outputs a cutoff signal to the power cutoff device 54(104) while a short - circuit is detected. The power cutoff device 54(104) may switch the connection state of the wirings 50a - 50c so as to connect the wirings L2a - L2c while the cutoff signal is not being output, and to disconnect the wirings L2a - L2c while the cutoff signal is being output.

[0069] Also, the m relays 60a - 60c each have a detection unit 62a - 62c for detecting the energization state of the wirings L2a - L2c, and a plurality of opening / closing units 64a - 64c, 66a - 66c that open and close according to the energization state detected by the detection units 62a - 62c. In this case, the power cutoff device 54 may output a cutoff signal via a stage circuit unit 70 in which each stage (first stage 71, second stage 72, third stage 73) in which a combination of n opening / closing units 64a - 64c, 66a - 66c are connected in parallel is connected in series. Thereby, a short - circuit detection function and a power cutoff function can be realized with a relatively simple circuit configuration.

[0070] Also, the m relays 110a - 110c each have a detection unit 112a - 112c for detecting the energization state of the wirings L2a - L2c, and a plurality of opening / closing units 124a - 124c, 126a - 126c that open and close according to the energization state detected by the detection units 112a - 112c. In this case, the power cutoff device 104 may output a cutoff signal via a stage circuit unit 120 in which each stage (first stage 121, second stage 122, third stage 123) in which a combination of n opening / closing units 124a - 124c, 126a - 126c are connected in series is connected in parallel. Thereby, a short - circuit detection function and a power cutoff function can be realized with a relatively simple circuit configuration.

[0071] Furthermore, when the robot 12 has an arm unit 16 formed by connecting a plurality of links in series, the above combination may include excitation coils 24a to 24c of electromagnetic brakes 22a to 22c attached to joint axes 18 (here, J2, J3, and J5 axes) for changing the angle between adjacent links. In particular, the J2, J3, and J5 axes tend to be easily subjected to loads due to gravity, so the release suppression effect is more pronounced accordingly.

[0072] The above combination may include a first excitation coil (e.g., excitation coil 24a) that is energized when a predetermined operation is performed by an operator, and a second excitation coil (e.g., excitation coils 24b, 24c) that is kept de-energized even by the predetermined operation. During the operation to release the electromagnetic brake 22a, the operator tends to become less aware of the other electromagnetic brakes 22b, 22c, so that the effect of suppressing the release becomes more noticeable.

[0073] [Variations] The present invention is not limited to the above-described embodiment, and can be freely modified without departing from the spirit and scope of the present invention. Alternatively, the respective configurations may be arbitrarily combined without causing any technical contradiction.

[0074] In the above embodiment, the robot 12 is described as a vertical articulated robot, but the type of industrial robot is not limited to this. For example, the robot may be a horizontal articulated robot, a parallel link robot, or an orthogonal robot.

[0075] In the above embodiment, the short circuit detectors 52, 102 are connected to the y point side (i.e., the low potential side) of the excitation coil 24. However, the short circuit detectors 52, 102 may be connected to the x point side (i.e., the high potential side) of the excitation coil 24.

[0076] In the above-described embodiment, the energization cut-off devices 54 and 104 are described by taking as an example the case where, when two of the three wirings L2a to L2c are short-circuited, the energization to all the excitation coils 24a to 24c is cut off simultaneously. However, the present invention is not limited to this example. Specifically, the energization cut-off device may selectively cut off the energization only to the excitation coils 24a and 24b corresponding to the short-circuited wirings L2a and L2b.

Explanation of Signs

[0077] 10…Robot system, 12…Robot, 14…Control system, 20…Robot control device, 22, 22a, 22b, 22c…Electromagnetic brake, 22G…Electromagnetic brake group, 24, 24a, 24b, 24c…Excitation coil, 24G…Excitation coil group, 30, 100…Brake release circuit, 50x, 50y…Wiring group, 52, 102…Short-circuit detector, 54, 104…Energization cut-off device, 60a to 60c, 110a to 110c…Relay, 62a to 62c, 112a to 112c…Detection unit, 64a to 64c, 66a to 66c, 114a to 114c, 116a to 116c…Opening / closing unit, 70, 120…Step circuit unit

Claims

1. A brake release circuit for releasing the operation of a non-excitation operation type electromagnetic brake group attached to a robot, A wiring group including an operation wiring for energizing an excitation coil group which is an aggregate of N excitation coils respectively possessed by N electromagnetic brakes which are integers of 3 or more constituting the electromagnetic brake group, A short-circuit detector for detecting a short circuit between the operation wirings corresponding to a combination of n excitation coils which are integers of 2 or more and N or less among the excitation coil group, When the short circuit is detected by the short-circuit detector, at least a power cut-off device for cutting off the power supply to the n excitation coils, A brake release circuit characterized by comprising.

2. The short-circuit detector includes m relays connected to m operation wirings which are integers of n or more and N or less among the wiring group, and outputs a cut-off signal to the power cut-off device while the short circuit is not detected by the m relays, The power cut-off device connects the operation wiring while the cut-off signal is not output by the short-circuit detector, and switches the connection state of the operation wiring so as to disconnect the operation wiring while the cut-off signal is output. The brake release circuit according to claim 1.

3. Each of the m relays has a detection unit for detecting the energization state of the operation wiring, and a plurality of opening / closing units for opening and closing according to the energization state detected by the detection unit, The power cut-off device outputs the cut-off signal through a stage circuit unit in which each stage in which the combinations of the n opening / closing units are connected in parallel is connected in series. The brake release circuit according to claim 2.

4. Each of the m relays has a detection unit for detecting the energization state of the operation wiring, and a plurality of opening / closing units for opening and closing according to the energization state detected by the detection unit, The power cut-off device outputs the cut-off signal through a stage circuit unit in which each stage in which the combinations of the n opening / closing units are connected in series is connected in parallel. The brake release circuit according to claim 2.

5. A brake release method for releasing the operation of a non-excitation operation type electromagnetic brake group attached to a robot, The brake release circuit is, A wiring group including an operating wiring for energizing an exciting coil group, which is an aggregate of N exciting coils respectively provided in N electromagnetic brakes that are integers of 3 or more constituting the electromagnetic brake group, is provided, and a short circuit between the operating wirings corresponding to a combination of n exciting coils, which is an integer of 2 or more and N or less among the exciting coil group, is detected, and when the short circuit is detected by the short circuit detector, at least the energization to the n exciting coils is cut off. A brake release method characterized by this.

6. The electromagnetic brake group according to any one of Claims 1 to 4, and A robot control device configured to include the brake release circuit according to any one of Claims 1 to 4, and A control system characterized by comprising.

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