Control device for controlling a robot arm and method of controlling the same

Abstract

A control device of a robot arm and a control method thereof are disclosed, which suppresses an increase in power consumption caused by overexcitation control of an electromagnetic brake and effectively performs cooling of the control device. The method of the disclosure includes the following steps: (a) performing overexcitation of the electromagnetic brake; (b) during overexcitation during which the overexcitation is performed, controlling a fan that cools the control device in such a manner that power consumption of the fan is a first power consumption; and (c) after the overexcitation period, controlling the fan in such a manner that the power consumption of the fan is a second power consumption that is higher than the first power consumption.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a control method of a control device that controls a robot arm, and a control device. BACKGROUND

[0002] Patent Document 1 discloses a control device that has a drive circuit that drives a motor of a robot and a fan that cools the drive circuit. The control device is configured to cool the inside of the control device by driving the fan motor using electric energy stored in a smoothing capacitor.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2006-280076

[0004] As a motor of a robot arm, a motor that has an electromagnetic brake of a field weakening type is known, but when energization to such a motor is started, the power consumption of the control device temporarily increases because a field weakening current is applied to the electromagnetic brake to release the brake. However, in the past, there has been a problem that sufficient research has not been made in terms of suppressing an increase in power consumption caused by field weakening of the electromagnetic brake and efficiently cooling the control device. SUMMARY

[0005] According to a first aspect of the present disclosure, there is provided a control method of a control device that controls a robot arm having a motor braked by an electromagnetic brake of a field weakening type, the control method including: (a) performing field weakening of the electromagnetic brake; (b) during a field weakening period in which the field weakening is performed, controlling a fan that cools the control device in such a manner that the power consumption of the fan is a first power consumption; and (c) after the field weakening period, controlling the fan in such a manner that the power consumption of the fan is a second power consumption that is higher than the first power consumption.

[0006] According to a second aspect of the present disclosure, there is provided a computer program for controlling a control device that controls a robot arm having a motor braked by an electromagnetic brake of a field weakening type, the computer program causing a processor to perform: (a) performing field weakening of the electromagnetic brake; (b) during a field weakening period in which the field weakening is performed, controlling a fan that cools the control device in such a manner that the power consumption of the fan is a first power consumption; and (c) after the field weakening period, controlling the fan in such a manner that the power consumption of the fan is a second power consumption that is higher than the first power consumption.

[0007] According to a third aspect of the present disclosure, there is provided a control device that controls a robot arm having a motor braked by an electromagnetic brake of an overexcitation type, the control device including: a motor drive circuit that supplies electric power to the motor; a control power supply that supplies electric power to the electromagnetic brake; a fan that operates with the supply of electric power from the control power supply and cools the control device; and a control section that controls the motor drive circuit and the fan, the control section executing the following processes: (a) overexcitation of the electromagnetic brake is performed; (b) during overexcitation in which the overexcitation is performed, the fan is controlled so that power consumption of the fan is a first power consumption; and (c) after the overexcitation, the fan is controlled so that the power consumption of the fan is a second power consumption that is higher than the first power consumption. BRIEF DESCRIPTION OF DRAWINGS

[0008] Figure 1 is an explanatory diagram showing the configuration of a robot system in an embodiment.

[0009] Figure 2 is a block diagram showing the internal structure of a control device.

[0010] Figure 3 is a timing chart showing a control action in an embodiment.

[0011] Figure 4 is an explanatory diagram showing the state changes of a plurality of electromagnetic brakes in an embodiment.

[0012] Figure 5 is a timing chart showing a control action in a comparative example.

[0013] Figure 6 is an explanatory diagram showing the state changes of a plurality of electromagnetic brakes in another embodiment.

[0014] REFERENCE NUMERALS

[0015] 100 … robot; 110 … base; 120 … robot arm; 122 … arm tip; 150 … end effector; 200 … control device; 210 … frame; 220 … motor drive section; 221 to 226 … motor drive circuits; 230 … control power supply; 240 … control section; 241 … processor; 242 … memory; 250 … cooling fan; 260 … ventilation fan; 300 … information processing device. DETAILED DESCRIPTION

[0016] Figure 1is an explanatory diagram showing an example of a robot system in an embodiment. The robot system is provided with a robot 100, a control device 200 that controls the robot 100, and an information processing device 300. The information processing device 300 is, for example, a personal computer. A user can input an instruction to cause the robot 100 to act using the information processing device 300. The instruction is supplied from the information processing device 300 to the control device 200, and the control device 200 controls the action of the robot 100 in accordance with the instruction. The control device 200 can also accept an instruction from another external device other than the information processing device 300.

[0017] The robot 100 is provided with a base 110 and a robot arm 120. A robot end effector 150 is installed at a front end of the robot arm 120, that is, an arm tip 122. The robot arm 120 is connected in series through six joints J1 to J6. Among these joints J1 to J6, three joints J2, J3, J5 are bending joints, and the other three joints J1, J4, J6 are twisting joints. In the present embodiment, a six-axis robot is exemplified, but a robot including any robot arm mechanism having one or more joints can be used. In addition, the robot 100 of the present embodiment is a vertical multi-joint robot, but a horizontal multi-joint robot can also be used.

[0018] Figure 2 is a block diagram showing the internal structure of the control device 200. In Figure 2 , a communication line is drawn in a broken line, and a power line is drawn in a solid line. A motor M1 to a motor M6 and an electromagnetic brake B1 to an electromagnetic brake B6 of an overexcitation type are provided at the plurality of joints J1 to J6 of the robot arm 120, respectively. The overexcitation type means that a larger overexcitation current is applied at the time of power-on to switch from a braking action state to a braking release state, and thereafter, the braking release state is maintained with a holding current smaller than the overexcitation current. When the power supply to the electromagnetic brake is stopped, the braking action state is assumed.

[0019] The control device 200 includes a housing 210, a motor drive section 220, a control power supply 230, a control section 240 that controls other constituent elements in the control device 200, a cooling fan 250 that blows air to the motor drive section 220, and an air exchange fan 260 that replaces air inside and outside the housing 210. The motor drive section 220 causes electric current to flow through the motors M1 to M6 of the robot arm 120, thereby driving the motors M1 to M6. The motor drive section 220 has, for example, motor drive circuits 221 to 226 provided corresponding to the respective motors M1 to M6. The motor drive circuits 221 to 226 each have a plurality of switching elements such as transistors or MOSFETs, and control electric current flowing through the motors M1 to M6 by switching the on and off of the switching elements, thereby driving the motors M1 to M6. The control power supply 230 supplies electric power to the control section 240, the cooling fan 250, and the air exchange fan 260, and also supplies electric power to the electromagnetic brakes B1 to B6 of the robot arm 120.

[0020] The housing 210 has a substantially rectangular parallelepiped shape, and houses other constituent elements. The motor drive section 220 has a power semiconductor such as an IPM (Intelligent Power Module), and is a large heat source. The cooling fan 250 cools the motor drive section 220 by blowing air to the motor drive section 220. In addition, the cooling fan 250 also has a function as a circulator that circulates air inside the housing 210. The air exchange fan 260 is installed on a wall of the housing 210, and cools the entire control device 200 by replacing air inside and outside the housing 210. In Figure 2 In the example of FIG. 1, two air exchange fans 260 are provided, but three or more can be provided, or only one can be provided. The cooling fan 250 and the air exchange fan 260 each function as a fan that cools the control device 200, and in particular, function as a fan that cools the motor drive section 220. Note that one of the cooling fan 250 and the air exchange fan 260 can be omitted.

[0021] Electric power of the motors M1 to M6 of the robot arm 120 is supplied from the motor drive section 220 via a first electric power line PL1. Electric power of the electromagnetic brakes B1 to B6 is supplied from the control power supply 230 via a second electric power line PL2. The second electric power line PL2 is connected to the electromagnetic brakes B1 to B6, for example, by a daisy chain connection. Instead of the daisy chain connection, a bus connection can be used. In any case, the plurality of electromagnetic brakes B1 to B6 are preferably connected by the second electric power line PL2 as a common electric power line.

[0022] The electromagnetic brakes B1 to B6 are also connected to the control section 240 via a communication line CL. The control section 240 sends an operation instruction to the electromagnetic brakes B1 to B6 via the communication line CL. Each of the electromagnetic brakes B1 to B6 can also be provided with a brake section BM that performs braking of the joint and a brake drive circuit BD that drives the brake section BM. The brake drive circuit BD controls the operation of the brake section BM in accordance with the operation instruction supplied from the control section 240. Note that the brake drive circuit BD can be omitted, and the brake section BM can be directly controlled by the control section 240.

[0023] The control section 240 is provided with a processor 241 and a memory 242, and controls the other constituent elements in the control device 200 by executing a computer program stored in the memory. The computer program can also be recorded in a non-transitory recording medium such as a hard disk or an optical disk. Alternatively, the functions of the control section 240 can be realized by a hardware circuit.

[0024] Figure 3 is a timing chart that shows the control operation in the embodiment. The control operation is performed by the control section 240. In Figure 3 the following changes are plotted. Note that in Figure 3 one of the motor drive circuits 221 to 226 is exemplified, but the temperature Td of any one of the motor drive circuits is the same graph.

[0025] (1) The excited / non-excited state of the motors M1 to M6.

[0026] (2) The OFF / over-excited / hold-excited state of the electromagnetic brakes B1 to B6.

[0027] (3) The ON / OFF state of the cooling fan 250.

[0028] (4) The ON / OFF state of the ventilation fan 260.

[0029] (5) The temperature Td of the motor drive circuits 221 to 226.

[0030] (6) The power consumption Wc of the control power supply 230.

[0031] Figure 3 The horizontal axis of shows time, which is divided into the following five periods. The states of the electromagnetic brakes B1 to B6, the cooling fan 250, and the ventilation fan 260 in each period are as follows.

[0032] <Period P1>

[0033] Period P1 is a period in which the motors M1 to M6 are in a non-excited state, i.e., a state in which no power is supplied.

[0034] • The electromagnetic brakes B1 to B6 are in a non-energized braking state, i.e., a braking operation state.

[0035] • The cooling fan 250 is in an OFF state.

[0036] • The ventilation fan 260 is in an ON state.

[0037] The reason for making the ventilation fan 260 in an ON state is to prevent the control section 240 from being heated. During this period P1, the control section 240 also monitors the state of the robot 100 and stands by to accept an input from the outside. During the period P1, since the amount of heat generated in the control device 200 is less than during the period P3 in which the robot arm 120 is operated, it is preferable to reduce the cooling capacity of the ventilation fan 260 as compared with the period P3, thereby reducing power consumption. Specifically, at least one of the plurality of ventilation fans 260 can be turned on, or all of the ventilation fans 260 can be turned on with a reduced rotational speed as compared with the period P3.

[0038] <Period P2>

[0039] The period P2 is a period after the excitation of the motors M1 to M6 has just started, and is a period in which the electromagnetic brakes B1 to B6 are over-excited. The length of this period P2 is, for example, about 0.4 seconds to about 1.2 seconds.

[0040] • The electromagnetic brakes B1 to B6 are in a non-energized braking state, i.e., a braking operation state.

[0041] • The cooling fan 250 is maintained in an OFF state.

[0042] • The ventilation fan 260 is switched to an OFF state.

[0043] The reason for making the cooling fan 250 and the ventilation fan 260 in an OFF state is to prevent the power consumption of the control power supply 230 from excessively increasing when a large over-excitation current is generated due to over-excitation of the electromagnetic brakes B1 to B6. During the period P2, the cooling fan 250 and the ventilation fan 260 can be made in an OFF state, but instead, their power consumption can be reduced as compared with the period P3. For example, only a part of the cooling fan 250 and the ventilation fan 260 can be made in an ON state, or the rotational speed can be reduced. The power consumption of the cooling fan 250 and the ventilation fan 260 during the period P2 is referred to as "first power consumption". The first power consumption is preferably zero, but can also be a value other than zero.

[0044] At the start time t1 of the period P2, when the control section 240 receives the instruction to actuate the robot arm 120 from the information processing apparatus 300, the control section 240 sends the motor drive circuits 221 to 226 the instructions to excite the motors M1 to M6 in accordance with the instruction, and sends the instructions to de-excite the electromagnetic brakes B1 to B6 that are in the braking state. In Figure 3 In the example, the times at which the electromagnetic brakes B1 to B6 are de-excited are staggered from each other. In this way, since the power consumption based on the de-excitation is equalized, the power peak can be suppressed.

[0045] <Period P3>

[0046] The period P3 is a period in which the electromagnetic brakes B1 to B6 become the braking release state, and the motors M1 to M6 are excited so that the robot arm 120 can actuate.

[0047] • All of the electromagnetic brakes B1 to B6 are in the braking release state.

[0048] • The cooling fan 250 is switched to the ON state.

[0049] • All of the ventilation fans 260 are switched to the ON state.

[0050] As a method of generating the instruction to start driving the cooling fan 250 and the ventilation fans 260 at the start time t2 of the period P3, for example, the following two methods can be considered. The first method is a method in which the control section 240 measures the time using a timer from the start time t1 of the period P2, and generates the driving instruction of the cooling fan 250 and the ventilation fans 260 after a prescribed time elapses. The second method is a method in which the driving instruction of the cooling fan 250 and the ventilation fans 260 is generated almost at the same time as the control section 240 sends the instruction to stop de-exciting the electromagnetic brake B1 that was last de-excited.

[0051] The power consumption of the cooling fan 250 and the ventilation fans 260 in the period P3 is referred to as "second power consumption". The second power consumption is greater than the power consumption of the cooling fan 250 and the ventilation fans 260 in the period P2, that is, the first power consumption.

[0052] <Period P4>

[0053] The period P4 is a period after the motors M1 to M6 are switched to the non-excitation state at the time t3. The length of this period P4 is, for example, about 1 minute to about 5 minutes.

[0054] • All of the electromagnetic brakes B1 to B6 are switched to the braking action state of the non-excitation.

[0055] • The cooling fan 250 is maintained in the ON state.

[0056] • All of the ventilation fans 260 are maintained in the ON state.

[0057] The reason why the cooling fan 250 and the ventilation fan 260 are maintained in the ON state is that the temperatures Td of the motor drive circuits 221 to 226 are high after the motors Ml to M6 are switched to the non-field application.

[0058] <Period P5>

[0059] The period P5 is a period in which the motors Ml to M6 are in a state of non-field application, i.e., a state of not being supplied with electric power, and is the same state as the period PI.

[0060] • The electromagnetic brakes Bl to B6 are in a non-energized braking state, i.e., a braking operation state.

[0061] • The cooling fan 250 is in an OFF state.

[0062] • The ventilation fan 260 is in an ON state.

[0063] The start time t4 of the period P5 is a point in time at which the temperatures Td of the motor drive circuits 221 to 226 are sufficiently reduced. This time t4 can be determined by the control section 240 using the temperature sensor to measure the temperatures Td of the motor drive circuits 221 to 226, or can be determined by counting up from the start time t3 of the period P4 using a timer. At the initial stage of the period P5, the temperatures Td of the motor drive circuits 221 to 226 slightly increase due to the cooling fan 250 being switched to the OFF state, but the increase is sufficiently small and does not become a problem.

[0064] The temperatures Td of the motor drive circuits 221 to 226 become maximum values in the period P3, but in order to prevent the temperatures Td from becoming excessively high, cooling is performed by the cooling fan 250 and the ventilation fan 260. The power consumption Wc of the control power supply 230 becomes a maximum value Wc maxl in the period P3, and is suppressed to be smaller than the period P3 in the period P2 of overexcitation. This will be further described later.

[0065] Figure 4 is a diagram showing the state changes of the plurality of electromagnetic brakes in the period P2 of Figure 3 Figure 3 ​As described above, in the present embodiment, the timings at which the electromagnetic brakes B1 to B6 are over-excited are staggered from each other. More specifically, the individual over-excitation periods PP at which each of the electromagnetic brakes is over-excited are staggered in a manner not to coincide with each other. As a result, an increase in power consumption due to the individual over-excitation periods PP of the plurality of electromagnetic brakes coinciding with each other can be prevented. In this example, the electromagnetic brake B6 located at the most fingertip side of the robot arm 120 is over-excited first, and the electromagnetic brake Bl located at the most base 110 side is over-excited last. In this way, the power consumption caused by over-excitation can be further equalized.

[0066] Figure 5 is a timing chart showing the control operation in the comparative example. The difference from the control operation in the embodiment shown in Figure 3 is that the cooling fan 250 and the ventilation fan 260 are maintained in the on state during all periods, and the other operations are the same as in the embodiment shown in Figure 3 In this comparative example, since the cooling fan 250 and the ventilation fan 260 are also maintained in the on state during the over-excitation period P2, the power consumption Wc of the control power supply 230 becomes larger compared to the period P3, and the power consumption Wc becomes the maximum value Wc_max2 during the over-excitation period P2. This maximum value Wc_max2 is larger than the maximum value Wc_maxl in the embodiment shown in Figure 3 .

[0067] During the over-excitation period P2, since the amount of heat generated by the motor drive circuits 221 to 226 is small, even if the cooling fan 250 and the ventilation fan 260 are stopped, the influence of the heat on the motor drive circuits 221 to 226 is small. Therefore, in the embodiment shown in Figure 3 , the cooling capacity of the cooling fan 250 and the ventilation fan 260 is reduced compared to the period P3 during the over-excitation period P2, and thus the power consumption is reduced. As a result, reduction in the power supply capacity of the control power supply 230 and cooling of the motor drive circuits 221 to 226 can be achieved at the same time.

[0068] As described above, in the above embodiment, since the power consumption of the fan of the cooling control device 200 is set to the first power consumption lower than the second power consumption during the period P3 after the over-excitation period P2 during the over-excitation period P2, an excessive increase in the power consumption during the over-excitation period P2 can be prevented. As a result, the control power supply 230 can be miniaturized and reduced in cost.

[0069] In the above embodiment, the control device 200 controls the operations of the plurality of motors M1 to M6 and the plurality of electromagnetic brakes B1 to B6, but the number of motors and electromagnetic brakes as control targets can be one or more as appropriate.

[0070] Figure 6This is an explanatory diagram showing the state changes of multiple electromagnetic brakes in other embodiments. (and...) Figure 4 The only difference in the illustrated implementation is that the PP portions partially overlap during the individual overexcitation periods of the electromagnetic brakes. More specifically, the timing of the overexcitation of electromagnetic brakes B1 to B6 is staggered. Figure 4 Same, but Figure 6 In this example, the PP during a single overexcitation period is staggered by half from each of the other adjacent single overexcitation periods. This prevents increased power consumption caused by the overlap of all single overexcitation periods. Furthermore, in this example, the overall length of P2 during the overexcitation period is... Figure 4 The overexcitation period P2 is half the length, thus enabling the robotic arm 120 to move earlier.

[0071] exist Figure 4 and Figure 6 In the various embodiments shown, the effect of suppressing the power consumption of the control power supply 230 during the overexcitation period P2 is achieved by (i) a first feature of setting the power consumption of the cooling control device 200 fan to be lower than the second power consumption of the period P3 following the overexcitation period P2, and (ii) a second feature of staggering the individual overexcitation periods PP from each other. The second feature can be omitted. That is, it can also be set so that the individual overexcitation periods PP for multiple electromagnetic brakes coincide. However, employing both the first and second features further enhances the effect of suppressing the power consumption of the control power supply 230.

[0072] Other methods:

[0073] This disclosure is not limited to the embodiments described above, and can be implemented in various ways without departing from its spirit. For example, this disclosure can also be implemented in the following aspects. In order to solve part or all of the technical problems of this disclosure, or to achieve part or all of the effects of this disclosure, the technical features in the above embodiments corresponding to the technical features described in the following aspects can be appropriately replaced or combined. In addition, if a technical feature is not described as an essential feature in this specification, it can be appropriately deleted.

[0074] (1) According to a first aspect of the present disclosure, a control method is provided, which is a control method for a control device for a robotic arm, the robotic arm having a motor braked by an electromagnetic brake in an overexcitation manner, the control method comprising the following steps: (a) performing overexcitation of the electromagnetic brake; (b) during the overexcitation period, controlling the fan such that the power consumption of a fan cooling the control device is a first power consumption; and (c) after the overexcitation period, controlling the fan such that the power consumption of the fan is a second power consumption higher than the first power consumption.

[0075] According to the control method, since the power consumption of the fan is set to the first power consumption lower than the second power consumption after the period of field weakening, it is possible to prevent the power consumption from excessively increasing during the period of field weakening.

[0076] (2) In the above control method, the mechanical arm can also have a plurality of the electromagnetic brakes and the motors, and the timing at which each electromagnetic brake is subjected to field weakening can be staggered.

[0077] According to the control method, since the power consumption of field weakening is balanced, it is possible to suppress the power peak.

[0078] (3) In the above control method, the plurality of electromagnetic brakes can be connected through a common power supply line, and the plurality of electromagnetic brakes can be subjected to field weakening in order from the electromagnetic brake on the most fingertip side of the mechanical arm.

[0079] According to the control method, since the power consumption of field weakening is further balanced, it is possible to suppress the power peak.

[0080] (4) In the above control method, the fan can include a ventilation fan that replaces air inside and outside the control device, and the ventilation fan can start operating after the control device receives an instruction from the outside to operate the mechanical arm.

[0081] According to the control method, it is possible to operate the ventilation fan when ventilation is required, and it is possible to suppress the power peak.

[0082] (5) In the above control method, the control device can have a plurality of ventilation fans, and at least some of the ventilation fans can be stopped in the process (b).

[0083] According to the control method, it is possible to further reduce the power peak.

[0084] (6) In the above control method, all of the ventilation fans can be stopped in the process (b).

[0085] According to the control method, it is possible to further reduce the power peak.

[0086] (7) In the above control method, the control device can have a motor drive circuit that supplies power to the motor, and the fan can include a cooling fan that blows air to the motor drive circuit, and the cooling fan can be stopped in the process (b).

[0087] According to the control method, since the temperature of the motor drive circuit does not excessively increase even when the cooling fan is stopped during field weakening, it is possible to suppress the power peak.

[0088] (8) According to a second aspect of the present disclosure, there is provided a computer program for controlling a control device that controls a robot arm having a motor braked by an electromagnetic brake of an overexcitation type. The computer program causes a processor to execute: (a) switching from a braking operation state to a braking release state by performing overexcitation of the electromagnetic brake; (b) controlling a fan that cools the control device in such a manner that power consumption of the fan is a first power consumption during overexcitation of the overexcitation; and (c) controlling the fan in such a manner that the power consumption of the fan is a second power consumption higher than the first power consumption after the overexcitation.

[0089] (9) According to a third aspect of the present disclosure, there is provided a control device that controls a robot arm having a motor braked by an electromagnetic brake of an overexcitation type. The control device includes: a motor drive circuit that supplies electric power to the motor; a control power supply that supplies electric power to the electromagnetic brake; a fan that operates from the electric power supplied from the control power supply and cools the control device; and a control section that controls the motor drive circuit and the fan. The control section executes: (a) overexcitation of the electromagnetic brake; (b) control of the fan in such a manner that power consumption of the fan is a first power consumption during overexcitation of the overexcitation; and (c) control of the fan in such a manner that the power consumption of the fan is a second power consumption higher than the first power consumption after the overexcitation.

[0090] The present disclosure can also be realized in various ways other than the above. For example, it can be realized in the form of a robot system that includes a robot and a control device, a computer program for realizing the functions of the control device, a non-transitory storage medium in which the computer program is recorded, and the like.

Claims

1. A control method characterized by, A control method of a control device that controls a robot arm having a motor braked by an electromagnetic brake of an overexcitation type, the control method including: (a) performing overexcitation of the electromagnetic brake; (b) during overexcitation of the overexcitation, controlling a cooling fan that blows air to a drive section of the motor and a ventilation fan that ventilates air between the inside and outside of the control device in such a manner that power consumption is a first power consumption; and (c) after the overexcitation, controlling the cooling fan and the ventilation fan in such a manner that power consumption is a second power consumption higher than the first power consumption. Before the process (a), the cooling fan is in an off state and the ventilation fan is in an on state.

2. The control method according to claim 1, wherein the robot arm has a plurality of the electromagnetic brakes and the motors, respectively, overexcitation of the electromagnetic brakes is performed at times staggered with respect to each other.

3. The control method according to claim 2, wherein the plurality of the electromagnetic brakes are connected by a common power supply line, the plurality of the electromagnetic brakes are overexcited in order from the electromagnetic brake on the most distal side of the robot arm.

4. The control method according to any one of claims 1 to 3, wherein the ventilation fan starts operating after the control device receives an instruction from the outside to operate the robot arm. A control device that controls a robot arm having a motor braked by an electromagnetic brake of an overexcitation type, the control device comprising:

5. A control device characterized by comprising: a motor drive section that supplies electric power to the motor; a control power supply that supplies electric power to the electromagnetic brake; a cooling fan that operates by receiving electric power supply from the control power supply and blows air to the motor drive section; a ventilation fan that ventilates air between the inside and outside of the control device; and a control section that controls the motor drive section, the cooling fan, and the ventilation fan, the control section performs the following processes: (a) performing overexcitation of the electromagnetic brake; (b) during overexcitation of the overexcitation, controlling the cooling fan and the ventilation fan in such a manner that power consumption is a first power consumption; and (c) after the overexcitation, controlling the cooling fan and the ventilation fan in such a manner that power consumption is a second power consumption higher than the first power consumption. Before the process (a), the cooling fan is in an off state and the ventilation fan is in an on state. ​ ​

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