Robot control device, robot, and robot system

A robot control device that controls a robot including a motor, the robot control device comprising: a power converter that is connected to the motor by a power line and converts supplied power to power to be supplied to the motor; a brake that brakes the motor by short-circuiting the power lines, and an inductance element that is provided on the power line and positioned closer to the power converter side than a connection point between the brake and the power line.

BACKGROUND

1. Technical Field

The present invention relates to a robot control device, a robot, and a robot system.

2. Related Art

Research and development of technologies for suppressing noise generated when a robot is controlled by a robot control device are being conducted.

In relation to this technology, there is known a robot which includes a drive unit, a flexible substrate having a power line for transmitting power to the drive unit, and a choke coil connected to the power line and in which a band elimination filter is formed by a parasitic capacitor, which is formed by the power line, and the choke coil (See JP-A-2016-78212).

Here, in a case where such a robot includes a dynamic brake for braking the drive unit by short-circuiting the power lines, a regenerative current generated from the drive unit due to a short circuit between the power lines may cause the choke coil to generate heat, depending on a position where the choke coil is provided. As the size of the choke coil increases, heat resistance of the choke coil increases and a price thereof increases in many cases. For that reason, in a case where an amount of heat generated by the choke coil due to the regenerative current is high, there are cases where the robot has difficulty in miniaturizing the choke coil and suppressing the manufacturing cost.

SUMMARY

An aspect of the invention is directed to a robot control device that controls a robot including a drive unit and includes a power conversion unit that is connected to the drive unit by a power line and converts supplied power to power to be supplied to the drive unit, a braking unit that brakes the drive unit by short-circuiting the power lines, and an inductance element that is provided on the power line and positioned closer to the power conversion unit side than a connection point between the braking unit and the power line.

With this configuration, the robot control device can suppress noise by the inductance element and may suppress heat generation of the inductance element due to a short circuit between the power lines.

In another aspect of the invention, the robot control device may be configured such that the robot control device further includes a detection unit that detects an abnormality and the braking unit short-circuits the power lines in a case where the detection unit detects an abnormality.

With this configuration, the robot control device can suppress heat generation of the inductance element due to the short circuit between the power lines according to detection of the abnormality by the detection unit.

In another aspect of the invention, the robot control device may be configured such that the power conversion unit includes a plurality of switching elements and turns switches of the plurality of switching elements OFF in a case where the detection unit detects an abnormality.

With this configuration, the robot control device can suppress heat generation of the inductance element due to a short circuit between the power lines while suppressing current from flowing into the power conversion unit due to the short circuit between the power lines.

In another aspect of the invention, the robot control device may be configured such that the detection unit is integrated with the power conversion unit.

With this configuration, the robot control device can suppress heat generation of the inductance element due to a short circuit between the power lines according to detection of the abnormality by the detection unit integrated with the power conversion unit.

In another aspect of the invention, the robot control device may be configured such that the power conversion unit, the detection unit, the braking unit, and the inductance element are mounted on the same substrate.

With this configuration, the robot control device can suppress heat generation of the inductance element mounted on the same substrate together with the power conversion unit, the detection unit and the braking unit, and the heat generation of the inductance element is due to a short circuit between the power lines.

In another aspect of the invention, the robot control device may be configured such that the braking unit short-circuits the power lines in a case where a voltage supplied to the braking unit becomes equal to or less than a predetermined value.

With this configuration, the robot control device can suppress heat generation of the inductance element due to a short circuit between the power lines in response to the voltage supplied to the braking unit becoming equal to or less than the predetermined value.

In another aspect of the invention, the robot control device may be configured such that a current detection unit that is provided on the power line and is positioned between the power conversion unit and the inductance element is further included.

With this configuration, the robot control device can suppress heat generation of the inductance element due to a short circuit between the power lines while performing control based on a current flowing in the power line.

In another aspect of the invention, the robot control device may be configured such that the drive unit includes a motor driven by a multi-phase alternating current.

With this configuration, the robot control device can suppress noise by the inductance element, and can suppress heat generation of the inductance element due to a short circuit between the power lines connected to the motor driven by the multi-phase alternating current.

Another aspect of the invention is directed to a robot that is controlled by the robot control device described above.

With this configuration, the robot can suppress noise by an inductance element, and can suppress heat generation of the inductance element due to a short circuit between power lines.

Another aspect of the invention is directed to a robot system that includes the robot control device described above and the robot.

With this configuration, the robot system can suppress noise by an inductance element, and can suppress heat generation of the inductance element due to a short circuit between power lines.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Embodiment

In the following, embodiments of the invention will be described with reference to the drawings.

Configuration of Robot System

First, a configuration of a robot system1will be described.

FIG. 1is a diagram illustrating an example of a configuration of a robot system1according to the embodiment. The robot system1includes a robot20and a robot control device30. In the robot system1, the robot20and the robot control device30are configured separately, but instead of being separately configured, the robot20and the robot control device30may be integrally configured. In this case, the robot control device30is built in the robot20. Further, in this case, the robot system1includes the robot20configured integrally with the robot control device30.

The robot20is a single arm robot including a movable portion A and a supporting stand B for supporting the movable portion A. The single-arm robot is a robot including one arm like the movable portion A in this example. The robot20may be a multi-arm robot instead of a single-arm robot. The multi-arm robot is a robot including two or more arms (for example, two or more movable portions A). Among the multi-arm robots, a robot including two arms (for example, two movable portions A) is also called a dual arm robot. That is, the robot20may be a dual arm robot including two arms or a multi-arm robot including three or more arms (for example, three or more movable portions A). The robot20may be another robot such as a SCARA robot, an orthogonal coordinate robot, or a cylindrical robot. The orthogonal coordinate robot is, for example, a gantry robot.

The movable portion A includes an end effector E and a manipulator M. The end effector E is an end effector that holds an object. In this example, the end effector E1includes a finger portion, and holds the object by gripping the object by the finger portion. Instead of this, the end effector E may be configured to hold the object by lifting the object with suction of air, magnetic force, another jig, or the like. In this example, “holding” means to bring the object into a state where it is possible to lift the object.

The end effector E is communicably connected to the robot control device30by a cable. With this, the end effector E performs an operation based on a control signal acquired from the robot control device30. Wired communication via a cable is performed according to standards such as Ethernet (registered trademark) and USB, for example. The end effector E may be configured to be connected to the robot control device by wireless communication performed according to a communication standard such as Wi-Fi (registered trademark).

The manipulator M includes six joints of joints J1to J6. Each of the six joints includes a drive unit. For the sake of convenience of explanation, a drive unit included in the joint J1is referred to as a drive unit M1, a drive unit included in the joint J2is referred to as a drive unit M2, a drive unit included in the joint J3is referred to as a drive unit M3, a drive unit included in the joint J4is referred to as a drive unit M4, a drive unit included in the joint J5is referred to as a drive unit M5, and a drive unit included in the joint J6is referred to as a drive unit M6.

Each of the drive units M1to M6is a motor driven by a multi-phase AC. In the following, as an example, a case where each of the drive units M1to M6is a motor driven by a three-phase AC will be described. Each of the drive units M1to M6may be a motor driven by AC of two phases or may be a motor driven by AC of four or more phases.

That is, the movable portion A including the manipulator M is a six-axis vertical articulated arm. The movable portion A performs operation of degree of freedom of six axes by a cooperative operation of the supporting stand B, the end effector E, and each of the drive units M1to M6of the manipulator M. The movable portion A may operate with degree of freedom of five axes or less, or may operate with degree of freedom of seven axes or more.

Each of the drive unit M1to the drive unit M6included in the manipulator M is connected to the robot control device30via a cable so as to communicate with each other. With this, each of the drive units M1to M6operates the manipulator M based on the control signal acquired from the robot control device30. Wired communication via a cable is performed according to standards such as Ethernet (registered trademark) and USB, for example. In addition, some or all of the six actuators included in the manipulator M are configured to be connected to the robot control device30by wireless communication performed according to a communication standard such as Wi-Fi (registered trademark).

In this example, the robot control device30is a controller that controls (operates) the robot20. The robot control device30specifies one or more teaching points in the order indicated by an operation program, based on the operation program stored in advance in a memory (not illustrated inFIG. 1) included in the robot control device30. The teaching point is a virtual point which is a target for making a control point of the robot20coincide with the teaching point. The position and orientation are correlated with each teaching point. Here, the control point of the robot20is a virtual point which is set in the robot20that moves together with the robot20, and is, for example, a tool center point (TCP) of the robot20. The control point may be another virtual point which is set in the robot20instead of the TCP. In a case where the control point is made to coincide with a certain teaching point, the position and orientation of the control point coincide with the position and orientation of the teaching point. The robot control device30calculates the rotation angle of each of the joints J1to J6, based on the specified teaching point and inverse kinematics, in a case where the control point coincides with the teaching point. The robot control device30generates control signals for respectively driving the drive units M1to M6, based on the calculated rotation angle. The robot control device30drives the drive unit M1to the drive unit M6based on the generated control signal to make the control point coincide with the teaching point. With this, the robot control device30can operate the robot20, and as a result, the robot20can perform the operation indicated by the operation program.

Here, a configuration of the robot control device30will be described referring toFIG. 2.FIG. 2is a diagram illustrating an example of the configuration of the robot control device30. In the following, as an example, a case where the robot control device30drives the drive unit M1will be described. For that reason, inFIG. 2, in order to simplify the drawing, a configuration for driving the drive unit M1in the configuration of the robot control device30is illustrated. That is, inFIG. 2, a configuration for driving each of the drive units M2to M6in the configuration of the robot control device30is omitted. The configuration for driving each of the drive units M2to M6in the configuration of the robot control device30may be the same as the configuration for driving the drive unit M1in the configuration of the robot control device30or may be different from that for driving the drive unit M1in the configuration of the robot control device30. In the following, as an example, description will be made on a case where the configuration for driving each of the drive units M2to M6in the configuration of the robot control device30is the same as the configuration for driving the drive unit M1in the configuration of the robot control device30.

In the configuration for driving the drive unit M1among the configuration of the robot control device30, a processor31, a memory32, a gate driver33, a power conversion unit (for example, a power converter)34, a braking unit (for example, a brake)35, an inductance element C1, an inductance element C2, an inductance element C3, a current detection unit (for example, a current detector) I1, and a current detection unit (for example, a current detector) I2are included.

The processor31controls the entire robot control device30. The processor31is, for example, a central processing unit (CPU). The processor31may be another processor such as a field programmable gate array (FPGA). The processor31specifies one or more teaching points in the order indicated by the operation program, based on the operation program stored in advance in the memory32. Based on the specified teaching point and the inverse kinematics, the processor31calculates the rotation angle of each of the joints J1to J6in a case where the control point coincides with the teaching point. The processor31generates a control signal for driving the drive unit M1based on the rotation angle for rotating the joint J1among the calculated rotation angles. The processor31outputs the generated control signal to the gate driver33.

The memory32includes, for example, a hard disk drive (HDD), a solid state drive (SSD), an electrically erasable programmable read-only memory (EEPROM), a read-only memory (ROM), a random access memory (RAM), and the like. The memory32may be an external storage device connected by a digital input/output port such as a USB, instead of the built-in memory of the robot control device30. The memory32stores various pieces of information to be processed by the robot control device30, the operation program described above, and the like.

The gate driver33includes, for example, an amplification unit331, a control unit332, and a detection unit333. These functional units of the gate driver33are hardware functional units such as a large scale integration (LSI) and an application specific integrated circuit (ASIC). Some or all of the functional units may be software functional units. The gate driver33may be configured to include another functional unit instead of these functional units.

The amplification unit331acquires a control signal for driving the drive unit M1from the processor31. The amplification unit331amplifies the acquired control signal.

The control unit332controls the power conversion unit34based on the control signal amplified by the amplification unit331and causes the power conversion unit34to drive the drive unit M1. Here, the power conversion unit34will be described.

The power conversion unit34is connected to the drive unit M1by a power line. In this example, since the drive unit M1is a motor driven by three-phase AC, the power conversion unit34is connected to the drive unit M1by a power line L1, a power line L2, and a power line L3, which are three power lines. In the following, for convenience of explanation, each of the three phases will be referred to as a U-phase, a V-phase, and a W-phase. The power line L1is a power line that supplies electric power to a U-phase electromagnet of the drive unit M1. The power line L2is a power line that supplies electric power to a V-phase electromagnet of the drive unit M1. The power line L3is a power line that supplies electric power to a W-phase electromagnet of the drive unit M1.

The power conversion unit34includes a wiring UV to which a predetermined voltage is applied from a power supply (not illustrated) included in the robot control device30, a wiring DV which is grounded to the ground, and a plurality of switching elements.

The wiring UV and the wiring DV are connected by a wiring SL1. The wiring SL1has a connection point P11between the wiring UV and the wiring DV. The connection point P11is connected to the power line L1. In the wiring SL1, a switching element SU1is provided between the connection point P11and the wiring UV. In the wiring SL1, a switching element SU2is provided between the connection point P11and the wiring DV. Here, each of the switching element SU1and the switching element SU2is one of the plurality of switching elements of the power conversion unit34.

The wiring UV and the wiring DV are connected by a wiring SL2. The wiring SL2has a connection point P12between the wiring UV and the wiring DV. The connection point P12is connected to the power line L2. In the wiring SL2, a switching element SU3is provided between the connection point P12and the wiring UV. In the wiring SL2, a switching element SU4is provided between the connection point P12and the wiring DV. Here, each of the switching element SU3and the switching element SD4is one of the plurality of switching elements of the power conversion unit34.

The wiring UV and the wiring DV are connected by a wiring SL3. The wiring SL3has a connection point P13between the wiring UV and the wiring DV. The connection point P13is connected to the power line L3. In the wiring SL3, a switching element SU5is provided between the connection point P13and the wiring UV. In the wiring SL3, a switching element SU6is provided between the connection point P13and the wiring DV. Here, each of the switching element SU5and the switching element SU6is one of the plurality of switching elements of the power conversion unit34.

The switching element SU1is a semiconductor element that switches ON/OFF (that is, switching) of a switch included in the switching element SU1and is, for example, a field effect transistor (FET). The switching element SU1may be another semiconductor element which switches ON/OFF of the switch, such as a gate turn off thyristor (GTO), or insulated gate bipolar transistor (IGBT), instead of the FET, or may be another element that switches ON/OFF of the switch instead of the semiconductor element.

A configuration of each of the switching elements SU2to SU6is the same as the configuration of the switching element SU1, and thus the description thereof will be omitted.

Here, the control unit332turns each of the switching elements SU1to SU6included in the power conversion unit34ON/OFF, based on the control signal which is amplified by the amplification unit321and is for driving the drive unit M1. With this, the control unit332causes the power conversion unit34to convert power (namely, voltage applied to the wiring UV), which is supplied from a power supply (not illustrated) of the robot control device30to the power conversion unit34, into power to be supplied to the drive unit M1. The power converted by the power conversion unit34is supplied to the drive unit M1. More specifically, the control unit332switches ON/OFF of each of the switching elements SU1to SU6included in the power conversion unit34based on the control signal, thereby causing the power conversion unit34to perform switching control of the drive unit M1(For example, pulse width modulation (PWM) control).

Description returns to the functional units of the gate driver33. The detection unit333detects an abnormality of the robot control device30. The abnormality includes, for example, occurrence of an overcurrent in the robot control device30, a decrease in the voltage supplied to the robot control device30, occurrence of overheating in the robot control device30, and the like. In a case where the abnormality is detected, the detection unit333outputs information indicating the detected abnormality to the processor31. In this case, the processor31controls the braking unit35to brake the drive unit M1. Here, the braking unit35will be described.

The braking unit35brakes the drive unit M1by short-circuiting the power lines connecting the robot control device30and the drive unit M1(that is, between the power line L1, the power line L2, and the power line L3). The braking unit35is a dynamic brake configured with by a relay switch which includes a switch RS1, a switch RS2, and a switch RS3and is a normally-on relay switch.

The switch RS1is a switch connecting a connection point P31and a connection point P32. The connection point P31is connected to the connection point P21which is a connection point included on the power line L1and is positioned between the drive unit M1and the power conversion unit34by a wiring. The connection point P32is connected to a connection point P22which is a connection point included on the power line L2and is positioned between the drive unit M1and the power conversion unit34by a wiring.

The switch RS2is a switch connecting the connection point P32described above and a connection point P33. The connection point P33is connected to a connection point P23which is a connection point included on the power line L3and is positioned between the drive unit M1and the power conversion unit34by a wiring.

The switch RS3is connected to the processor31and is turned ON in a case where a voltage is supplied from the processor31, and is turned OFF in a case where the voltage supplied from the processor31becomes equal to or less than a predetermined value.

Here, the switches RS1and RS2are switched ON/OFF in conjunction with ON/OFF of the switch RS3. As described above, the braking unit35is a normally-on relay switch. For that reason, the switches RS1and RS2are respectively turned OFF when the switch RS3is turned ON. The switches RS1and RS2are respectively turned ON when the switch RS3is turned OFF. With this, as illustrated inFIG. 3, the braking unit35can short-circuit the three power lines of the power line L1to the power line L3.FIG. 3is a diagram illustrating an example of a state in which the three power lines of the power line L1to the power line L3are short-circuited.

In a case where the braking unit35short-circuits the three power lines of the power line L1to the power line L3, a regenerative current generated by driving the drive unit M1flows in each of the three power lines. Due to this regenerative current, the braking unit35brakes the drive unit M1.

Return to the description of the detection unit333. As described above, in a case where an abnormality is detected, the detection unit333outputs information indicating the detected abnormality to the processor31. In this case, the processor31turns the switch RS3of the braking unit35OFF, thereby short-circuiting the three power lines of the power line L1to the power line L3and braking the drive unit M1.

As described above, the switch RS3is turned OFF when the voltage supplied from the processor31becomes equal to or less than a predetermined value. For that reason, even if the processor31stops operating in the case where supply of power to the robot control device30is interrupted for some reason, the braking unit35can short-circuit the three power lines of the power line L1to the power line L3to brake the drive unit M1.

As described above, the robot control device30includes the gate driver33, the power conversion unit34, and the braking unit35. Here, in a case where the control unit332of the gate driver33causes the power conversion unit34to perform switching control of the drive unit M1, high-frequency noise is generated in each of the three power lines of the power line L1to the power line L3. In a case where the noise is not suppressed, the robot control device30makes it difficult to cause the robot20to perform work with high accuracy. Accordingly, the robot control device30in this example includes the inductance element C1to the inductance element C3, in addition to the gate driver33, the power conversion unit34, and the braking unit35.

The inductance element C1is an element having inductance, and is, for example, a choke coil. The inductance element C may be another element having inductance such as a flux gate sensor, instead of the choke coil.

The inductance element C1is provided on the power line L1. More specifically, the inductance element C1is provided closer to the power conversion unit34than the connection point P21included on the power line L1. In the example illustrated inFIG. 2, the inductance element C1is positioned between the connection point P21and the connection point P11. With this, no regenerative current flows from the drive unit M1to the inductance element C1even in a case where the braking unit35short-circuits the three power lines of the power line L1to the power line L3. As a result, the robot control device30can suppress high-frequency noise generated in the power line L1and can suppress the inductance element C1from generating heat due to the regenerative current.

Since the configuration of the inductance element C2is the same as the configuration of the inductance element C1, description thereof will be omitted. The inductance element C2is provided on the power line L2. More specifically, the inductance element C2is provided closer to the power conversion unit34than the connection point P22included on the power line L2. In the example illustrated inFIG. 2, the inductance element C2is positioned between the connection point P22and the connection point P12. With this, no regenerative current flows from the drive unit M1to the inductance element C2even in a case where the braking unit35short-circuits the three power lines of the power line L1to the power line L3. As a result, the robot control device30can suppress high-frequency noise generated in the power line L2and can suppress the inductance element C2from generating heat due to the regenerative current.

Since the configuration of the inductance element C3is the same as the configuration of the inductance element C1, description thereof will be omitted. The inductance element C3is provided on the power line L3. More specifically, the inductance element C3is provided closer to the power conversion unit34than the connection point P23included on the power line L3. In the example illustrated inFIG. 2, the inductance element C3is positioned between the connection point P23and the connection point P13. With this, no regenerative current flows from the drive unit M1to the inductance element C3even in a case where the braking unit35short-circuits the three power lines of the power line L1to the power line L3. As a result, the robot control device30can suppress high-frequency noise generated in the power line L3and can suppress the inductance element C3from generating heat due to the regenerative current.

Here, in this example, as the size of the inductance element C1to the inductance element C3, which are the choke coils, increases, the heat resistance of the inductance element C1to the inductance element C3and the price thereof increase in many cases. For that reason, in a case where heat generation of the inductance element C1to the inductance element C3due to the regenerative current is suppressed, the robot control device30can achieve miniaturization of the inductance element C1to the inductance element C3(then, miniaturization of the robot control device30accompanying the miniaturization of the inductance element C1to the inductance element C3) and suppression of the manufacturing cost.

FIG. 4is a graph illustrating an example of high-frequency noise generated from the three power lines of the power line L1to the power line L3in a case where the robot control device30does not include the inductance element C1to the inductance element C3.FIG. 5is a graph illustrating an example of high-frequency noise generated from the three power lines of the power line L1to the power line L3in a case where the robot control device30includes the inductance element C1to the inductance element C3as illustrated inFIG. 2. Each of the horizontal axes of the graphs illustrated inFIGS. 4 and 5indicates a frequency of noise. Each of the vertical axes of the graphs indicates magnitude of the noise of the frequency indicated by each of the horizontal axes of the graphs. In the graphs illustrated inFIGS. 4 and 5, a value TH indicates an upper limit value of noise that can be allowed in the control of the robot20by the robot control device30. In the graph illustrated inFIG. 4, high-frequency noise generated from the three power lines exceeds the value TH in a portion of a frequency band of 7 MHz or more. On the other hand, in the graph illustrated inFIG. 5, the noise does not exceed the value TH in any frequency band. That is, in a case where the robot control device30includes the inductance element C1to the inductance element C3, it is understood that the noise is suppressed. That is, in a case where the robot control device30includes the inductance element C1to the inductance element C3as illustrated inFIG. 2, the robot control device30can suppress the noise by the inductance element C1to the inductance element C3and suppress heat generation of each of the inductance elements C1to C3due to the short circuit between the three power lines L1to L3.

In the example illustrated inFIG. 2, the robot control device30includes, the current detection unit I1and the current detection unit I2, in addition to the gate driver33, the power conversion unit34, the braking unit35, and the inductance element C1to the inductance element C3.

The current detection unit I1includes a shunt resistor and detects a current corresponding to a potential difference between both ends of the shunt resistor. The current detection unit I1is provided between the connection point P21and the connection point P11(more specifically, between inductance element C1and connection point P11) described above. That is, the current detection unit I1detects the current flowing through the power line L1. Since the current detection unit I1is positioned between the connection point P21and the connection point P11, the regenerative current does not flow to the current detection unit I1even in a case where the braking unit35short-circuits the three power lines of the power line L1to the power line L3. For that reason, an inexpensive sensor having low heat resistance can be used for the current detection unit I1. As a result, the robot control device30can suppress the manufacturing cost. The current detection unit I1may be any sensor as long as it can detect the current. Further, the current detection unit I1may be configured to include a Hall element, a flux gate sensor, or the like, instead of the shunt resistor.

A configuration of the current detection unit I2is the same as the configuration of the current detection unit I1, and thus the description thereof will be omitted. The current detection unit I2is provided between the connection point P22and the connection point P12(more specifically, between inductance element C2and connection point P12). That is, the current detection unit I2detects the current flowing through the power line L2. Since the current detection unit I2is positioned between the connection point P22and the connection point P12, the regenerative current does not flow to the current detection unit I2even in a case where the braking unit35short-circuits the three power lines of the power lines L1to L3. For that reason, an inexpensive sensor having low heat resistance can be used for the current detection unit I2. As a result, the robot control device30can suppress the manufacturing cost. The current detection unit I2may be any sensor as long as it can detect the current.

Here, in a case where a current flowing through each of the power line L1and the power line L2is detected, the current flowing in the power line L3can be calculated by Kirchhoff's laws. For that reason, in the example illustrated inFIG. 2, the robot control device30does not include a current detection unit provided on the power line L3.

Since the current detection unit I1and the current detection unit I2are included, the control unit332of the gate driver33can perform vector control when controlling the drive unit M1via the power conversion unit34. The control unit332acquires information indicating the current detected by the current detection unit I1and information indicating the current detected by the current detection unit I2each time a predetermined time elapses. The control unit332specifies the currents flowing through the power lines L1to L3, respectively, based on the pieces of acquired information. The control unit332performs vector control of the drive unit M1via the power conversion unit34based on the specified current. The vector control may be realized by a known control method or may be realized by a control method developed from now.

Further, the robot control device30may be configured not to include the current detection unit I1and the current detection unit I2. In this case, the control unit332does not perform vector control of the drive unit M1via the power conversion unit34.

Some or all of the functional units (amplification unit331, control unit332, and detecting unit333) included in the gate driver33described above may be integrated with the power conversion unit34, or may be configured separately.

Some or all of the functional units (amplification unit331, control unit332, and detecting unit333) included in the gate driver33described above, the power conversion unit34, the braking unit35, and the inductance elements C1to C3may be mounted on the same substrate (a single substrate), or may be respectively mounted on a plurality of substrates.

Further, in a case where the braking unit35short-circuits the three power lines of the power line L1to the power line L3, the control unit332included in the gate driver33described above may be configured to turn each of the switching elements SU1to SU6OFF. With this, the robot control device30can suppress the regenerative current generated in the drive unit M1from flowing to the gate driver33and the processor31via the power conversion unit34.

As described above, the robot control device30includes a power conversion unit (power conversion unit34in the example described above) which is connected to a drive unit (drive unit M1in the example described above) by a power line (power line L1to the power line L3in the example described above) and converts the supplied power to power to be supplied to the drive unit, a braking unit (braking unit35in the example described above) for braking the drive unit by short-circuiting the power lines, and an inductance element (in the example described above, inductance element C1to the inductance element C3) provided in the power line and positioned closer to the power conversion unit side than a connection point between the braking unit and the power line (in the example described above, connection points P21to P23). With this, the robot control device30can suppress noise by the inductance element and can suppress heat generation of the inductance element due to a short circuit between the power lines.

The robot control device30includes a detection unit (in the example described above, detection unit333) for detecting an abnormality, and short-circuits the power lines in a case where the detection unit detects the abnormality. With this, the robot control device30can suppress heat generation of the inductance element due to the short circuit between the power lines according to detection of the abnormality by the detection unit.

In the robot control device30, the power conversion unit includes a plurality of switching elements (switching elements SU1to SU6in the example described above), and turns switches of the plurality of switching elements OFF in a case where the detection unit detects an abnormality. With this, the robot control device30can suppress heat generation of the inductance element due to a short circuit between the power lines while suppressing the current from flowing into the power conversion unit due to the short circuit between the power lines.

In the robot control device30, the detection unit is integrated with the power conversion unit. With this, the robot control device30can suppress heat generation of the inductance element due to the short circuit between the power lines according to the detection of the abnormality by the detection unit integrated with the power conversion unit.

In the robot control device30, the power conversion unit, the detection unit, the braking unit, and the inductance element are mounted on the same substrate. With this, the robot control device30can suppress heat generation of the inductance elements mounted on the same substrate together with the power conversion unit, the detection unit, and the braking unit, and the heat generation of the inductance element is due to a short circuit between the power lines.

In the robot control device30, in a case where the voltage supplied to the braking unit becomes equal to or less than a predetermined value, the braking unit short-circuits the power lines. With this, the robot control device30can suppress heat generation of the inductance element due to the short circuit between the power lines in response to the voltage supplied to the braking unit becoming a predetermined value or less.

In the robot control device30, a current detection unit provided on the power line and positioned between the power conversion unit and the inductance element is further included. With this, the robot control device30can suppress heat generation of the inductance element due to the short circuit between the power lines while performing control based on the current flowing in the power line (vector control in the example described above).

Further, in the robot control device30, the drive unit includes a motor driven by a multi-phase alternating current. With this, the robot control device30can suppress noise by the inductance element, and can suppress heat generation of the inductance element due to a short circuit between the power lines connected to the motor driven by the multi-phase alternating current.

Although the embodiment of the invention has been described in detail with reference to the drawings, a specific configuration is not limited to this embodiment, and various modifications, substitutions, deletions, and the like may be made thereto without departing from the spirit of the invention.

The entire disclosure of Japanese Patent Application No. 2017-186230, filed Sep. 27, 2017 is expressly incorporated by reference herein.