Mobile Robot

A mobile robot includes a vehicle having a secondary cell that outputs a first voltage, a first motor driven by the first voltage, and a first circuit that supplies electric power of the secondary cell to the first motor, a robot having a robot arm, a second motor that drives the arm by a second voltage different from the first voltage, and a second circuit that supplies the electric power of the secondary cell to the second motor and supplies regeneration power of the second motor to the secondary cell, and coupled to the vehicle, wherein the second circuit has a voltage conversion unit that mutually converts the first voltage and the second voltage.

The present application is based on, and claims priority from JP Application Serial Number 2019-179569, filed Sep. 30, 2019, the disclosure of which is hereby incorporated by reference herein in its entirety.

BACKGROUND

1. Technical Field

The present disclosure relates to a mobile robot.

2. Related Art

Recently, in factories, due to labor cost rise and labor shortage, work manually performed in the past has been increasingly automated by various robots and robot peripherals. Further, recently, as shown in JP-A-2000-326270, wheeled automated guided vehicles with robots, i.e., mobile robots have autonomously moved and performed work at movement destinations.

The mobile robot shown in JP-A-2000-326270 includes a robot arm, a movement mechanism that moves the robot arm, and a battery that supplies electric power to the movement mechanism and the robot arm. That is, the movement mechanism and the robot arm have configurations driven by the same electrical system. Further, in the mobile robot shown in JP-A-2000-326270, regeneration power when the robot arm is driven is stored in the battery. Thereby, the available time of the battery may be extended.

For example, when increase of the operation speed of the robot is desired or the like, when the drive voltage of the robot arm is set to be higher, the drive voltage of the robot arm and the drive voltage of the movement mechanism may be different. Here, the voltage of the regeneration power of the robot arm and the voltage of the battery are different, and there is a problem that it may be impossible to store the regeneration power of the robot arm in the battery.

SUMMARY

The present disclosure can be implemented as follows.

A mobile robot of an application example includes a vehicle having a secondary cell that outputs a first voltage, a first motor driven by the first voltage, and a first circuit that supplies electric power of the secondary cell to the first motor, a robot having a robot arm, a second motor that drives the arm by a second voltage different from the first voltage, and a second circuit that supplies the electric power of the secondary cell to the second motor and supplies regeneration power of the second motor to the secondary cell, and coupled to the vehicle, wherein the second circuit has a voltage conversion unit that mutually converts the first voltage and the second voltage.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

As below, a mobile robot according to the present disclosure will be explained in detail based on embodiments shown in the accompanying drawings.

First Embodiment

FIG. 1is the side view showing the mobile robot according to the first embodiment.FIG. 2is the block diagram showing details of the mobile robot shown inFIG. 1.

InFIG. 1, for convenience of explanation, an x-axis, a y-axis, and a z-axis are shown as three axes orthogonal to one another. Hereinafter, directions parallel to the x-axis are also referred to as “x-axis directions”, directions parallel to the y-axis are also referred to as “y-axis directions”, and directions parallel to the z-axis are also referred to as “z-axis directions”.

Hereinafter, for convenience of explanation, the +z-axis direction inFIG. 1, i.e., the upside is also referred to as “upper” or “above” and the −z-axis direction, i.e., the downside is also referred to as “lower” or “below”. Further, the z-axis directions inFIG. 1, i.e., upward and downward directions are referred to as “vertical directions” and the x-axis directions and the y-axis directions, i.e., leftward and rightward directions are referred to as “horizontal directions”.

A mobile robot100shown inFIG. 1is an apparatus used for work of e.g. holding, transport, assembly, inspection, etc. of works including electronic components and electronic apparatuses. The mobile robot100includes a robot1and a vehicle2. The vehicle2will be explained as not being contained in the robot1in the embodiment, however, this may be contained in the robot1. That is, the vehicle2may be a component element of the robot1or not.

The robot1shown inFIG. 1is the so-called six-axis vertical articulated robot and has a base110, a robot arm10coupled to the base110, drive units3, a robot control unit4, and a voltage conversion unit5.

The base110supports the robot arm10. The base110has a housing and, inside of the housing, e.g. a drive device that drives the robot arm10, a communication unit (not shown) for communication with the robot control unit4, etc. are provided. Further, the origin of the robot coordinate system is set in an arbitrary position e.g. the center of gravity of the base110. The origin is a control point of the movement by the vehicle2, which will be described later.

Note that the base110is not limited to the shape as shown in the drawing, but may be formed by e.g. a plate-like member and a plurality of legs as long as the base has the function of supporting the robot arm10.

Or, the base110may be omitted or at least partially provided in the vehicle2.

The robot arm10shown inFIG. 1has a proximal end coupled to the base110and includes an arm11, an arm12, an arm13, an arm14, an arm15, and an arm16as a plurality of arms. These arm11to arm16are sequentially coupled from the proximal end toward the distal end. The respective arm11to arm16are pivotable relative to the adjacent arms or base110.

Further, as shown inFIG. 2, the robot1has the drive units3as drive units that drive the robot arm. The drive units3have a drive unit3A that pivots the arm11relative to the base110, a drive unit3B that pivots the arm12relative to the arm11, a drive unit3C that pivots the arm13relative to the arm12, a drive unit3D that pivots the arm14relative to the arm13, a drive unit3E that pivots the arm15relative to the arm14, and a drive unit3F that pivots the arm16relative to the arm15.

The drive unit3A has a motor31A as a second motor, a motor drive circuit32A, an encoder33A, a reducer (not shown), etc. The drive unit3B has a motor31B as the second motor, a motor drive circuit32B, an encoder33B, a reducer (not shown), etc. The drive unit3C has a motor31C as the second motor, a motor drive circuit32C, an encoder33C, a reducer (not shown), etc. The drive unit3D has a motor31D as the second motor, a motor drive circuit32D, an encoder33D, a reducer (not shown), etc. The drive unit3E has a motor31E as the second motor, a motor drive circuit32E, an encoder33E, a reducer (not shown), etc. The drive unit3F has a motor31F as the second motor, a motor drive circuit32F, an encoder33F, a reducer (not shown), etc.

The motor31A is electrically coupled to a second control section42, which will be described later, via the motor drive circuit32A. The motor31B is electrically coupled to the second control section42via the motor drive circuit32B. The motor31C is electrically coupled to the second control section42via the motor drive circuit32C. The motor31D is electrically coupled to the second control section42via the motor drive circuit32D. The motor31E is electrically coupled to the second control section42via the motor drive circuit32E. The motor31F is electrically coupled to the second control section42via the motor drive circuit32F.

The second control section42respectively independently controls the conduction conditions to the motor drive circuit32A to motor drive circuit32F, and thereby, driving of the motor31A to motor31F is controlled.

The encoder33A to encoder33F are examples as operating state sensors that sense the operating state of the robot arm10. The encoder33A to encoder33F are respectively electrically coupled to the second control section42, and detected position information, i.e., electrical signals corresponding to the sensing results are transmitted to the second control section42. According to the configuration, the second control section42may control driving of the motor31A to motor31F and switch between a first mode and a second mode, which will be described later, based on the sensing results of the encoder33A to encoder33F.

Further, as shown inFIG. 1, an end effector17holding a work object is attached to the distal end of the robot arm10. In the illustrated configuration, the end effector17grips the work object by bringing a plurality of e.g. two fingers closer to each other or away from each other. Note that the end effector17is not limited to the configuration, but may be a suction hand, magnetic hand, or the like.

When the end effector17is driven by a motor, the regeneration power therefor may be supplied to a secondary cell8.

The robot control unit4has a first control section41that controls operation of the voltage conversion unit5, which will be described later, the second control section42that controls driving of the motor drive circuit32A to motor drive circuit32F, and a memory section43.

The first control section41is a control section having a CPU (Central Processing Unit) and reading and executing various programs etc. stored in the memory section43. Switching of the switch of the voltage conversion unit5to be described later is controlled by a command signal generated by the first control section41.

The second control section42has a CPU (Central Processing Unit) and reads and executes various programs etc. stored in the memory section43. The robot arm10may execute predetermined work by a command signal generated by the second control section42.

The memory section43stores various programs etc. that can be executed by the first control section41and the second control section42. The memory section43includes e.g. a volatile memory such as a RAM (Random Access Memory), a nonvolatile memory such as a ROM (Read Only Memory), and a detachable external memory device. The coupling between the memory section43and the first control section41and second control section42may be not only wired coupling but also wireless coupling, or coupling by communication via a network such as the Internet.

The vehicle2is configured by an autonomous traveling system and moves the robot1.

The vehicle2has a plurality of wheels, i.e., a pair of front wheels21, a pair of rear wheels22, and a pair of drive wheels23, a vehicle main body20in which these wheels are placed, a vehicle control unit7, the secondary cell8, and drive units9A,9B.

The pair of drive wheels23are examples of movement mechanisms and provided between the pair of front wheels21and the pair of rear wheels22. One drive wheel23is driven by the drive unit9A and the other drive wheel23is driven by the drive unit9B.

The drive unit9A has a motor91A as a first motor, a motor drive circuit92A, an encoder93A, a regeneration resistor part94A, and a reducer (not shown), etc. The drive unit9B has a motor91B as the first motor, a motor drive circuit92B, an encoder93B, a regeneration resistor part94B, and a reducer (not shown), etc.

The motor91A is electrically coupled to a third control section71, which will be described later, via the motor drive circuit92A. The motor91B is electrically coupled to the third control section71via the motor drive circuit92B.

The third control section71respectively independently controls the conduction conditions to the motor drive circuit92A and the motor drive circuit92B, and thereby, driving of the motor91A and the motor91B is controlled.

The encoder93A and the encoder93B are respectively electrically coupled to the third control section71and electrical signals corresponding to the detected position information are transmitted to the third control section71. According to the configuration, the third control section71may control the driving of the motor91A and the motor91B based on the detection results of the encoder93A and the encoder93B.

The regeneration power of the motor91A is supplied to the regeneration resistor part94A via the motor drive circuit92A and the regeneration power of the motor91B is supplied to the regeneration resistor part94B via the motor drive circuit92B. The regeneration resistor part94A and the regeneration resistor part94B are regeneration power absorbing circuits that absorb the regeneration power, respectively have resistors (not shown), and convert the regeneration power into heat and release the heat. That is, the regeneration power of the motor91A and the motor91B is not stored in the secondary cell8.

As described above, the vehicle2has the regeneration resistor part94A and the regeneration resistor part94B that convert the regeneration power of the motor91A and the motor91B as the first motors into heat. Thereby, when the vehicle2urgently stops, supply of the excessive regeneration power generated in the motor91A and the motor91B to the secondary cell8is prevented.

Note that the regeneration resistor part94A and the regeneration resistor part94B may be omitted and the regeneration power of the motor91A and the motor91B may be stored in the secondary cell8.

In the embodiment, the pair of front wheels21and the pair of rear wheels22are driven rollers. However, the pair of front wheels21and the pair of rear wheels22may be coupled to the drive units.

The drive wheels23are respectively configured to be forwardly and backwardly rotatable by the drive unit9A and the drive unit9B. Accordingly, the traveling direction may be changed by adjustment of at least one of the rotation speed or the rotation direction of the respective drive wheels23. Further, in the embodiment, the front wheels21, the rear wheels22, and the drive wheels23are configured not to rotate about the z-axis, however, at least ones of the front wheels21, the rear wheels22, or the drive wheels23may be configured to rotate about the z-axis. In this case, the traveling direction may be changed by adjustment of the amount of rotation about the z-axis.

Note that “movement” in this specification includes not only “linear movement”, “meandering”, and “reciprocation” but also “rotation”. The number of wheels of the vehicle2is not particularly limited. The configuration of the vehicle2is not limited to the above described wheeled type, but may be e.g. a configuration with a caterpillar, a configuration walking with a plurality of legs, or the like.

The vehicle control unit7has the third control section71that controls the driving of the motor drive circuit92A and the motor drive circuit92B and a memory section72.

The third control section71has e.g. a CPU (Central Processing Unit) and reads and executes various programs etc. stored in the memory section72. The vehicle2may travel on a predetermined route by a command signal generated in the third control section71.

The memory section72stores various programs etc. that can be executed by the third control section71. The memory section72includes e.g. a volatile memory such as a RAM (Random Access Memory), a nonvolatile memory such as a ROM (Read Only Memory), and a detachable external memory device. The coupling between the memory section72and the third control section71may be not only wired coupling but also wireless coupling, or coupling by communication via a network such as the Internet.

As shown inFIG. 1, the secondary cell8outputs a first voltage V1and is provided inside of the vehicle main body20. The secondary cell8can be repeatedly charged and discharged and supplies electric power to the respective parts of the mobile robot100. That is, the secondary cell8is electrically coupled to the motor drive circuit32A to motor drive circuit32F and robot control unit4of the robot1and the vehicle control unit7and drive unit9A and drive unit9B of the vehicle2, and supplies electric power to those. Note that the secondary cell is also generally called “storage battery”, “rechargeable battery”, or “battery”. The secondary cell refers to a battery that stores electricity by charging for use as a battery and can be repeatedly used.

When the stored electric charge is lost, the secondary cell8is charged from an external power supply (not shown) for use. The secondary cell8is not particularly limited to, but includes e.g. a nickel-cadmium battery, nickel-hydrogen battery, sodium battery, magnesium battery, lithium-ion battery, and lead storage battery as long as the battery can be repeatedly charged and discharged.

Here, circuits of the mobile robot100shown inFIG. 2have a first circuit100A at the vehicle2side and a second circuit100B at the robot1side.

The first circuit100A is a circuit that supplies electric power to the motor91A and the motor91B as the first motors. That is, the first circuit100A includes electric wiring containing the motor drive circuit92A between the secondary cell8and the motor91A and electric wiring containing the motor drive circuit92B between the secondary cell8and the motor91B.

The second circuit100B is a circuit that supplies the electric power of the secondary cell8to the motor31A to motor31F as the second motors and supplies the regeneration power of the motor31A to motor31F to the secondary cell8. That is, the second circuit100B includes electric wiring containing the voltage conversion unit5between the secondary cell8and the motor31A to motor31F and the motor drive circuit32A to motor drive circuit32F and the voltage conversion unit5. The regeneration power of the motor31A to motor31F is supplied to the secondary cell8respectively via the motor drive circuit32A to motor drive circuit32F and the voltage conversion unit5.

The above described first circuit100A and second circuit100B are provided, and thereby, the respective parts of the mobile robot100are driven by the electric power from the secondary cell8. In other words, the robot1and the vehicle2have the secondary cell8as the single power supply in common and the respective parts of the robot1and the respective parts of the vehicle2are driven by the electric power from the secondary cell8.

The motor91A and the motor91B of the vehicle2are driven by the first voltage V1. On the other hand, the motor31A to motor31F of the robot arm10are driven by a second voltage V2different from the first voltage V1. As below, as an example, a case where the second voltage V2is larger than the first voltage V1will be explained. Note that these motor91A, motor91B, and motor31A to motor31F are driven by alternating-current voltages and the first voltage V1and the second voltage V2refer to the maximum values of the amplitude of the voltage waveforms.

Here, converters such as DC/DC converters may be provided between the secondary cell8and the motor drive circuit92A and motor drive circuit92B. The output voltage of the secondary cell8may be unstable depending on the state of charge, remaining charge, or the like. The converters are provided, and thereby, the voltages supplied from the secondary cell8to the motor91A and the motor91B may be stabilized for stable operation of the control circuits, and adjustment to raise the absolute maximum rating of the motor91A and motor91B, the encoder93A and encoder93B, etc. or the like may be unnecessary. Further, the converters are provided, and thereby, the distances between the motor drive circuit92A and motor drive circuit92B and the secondary cell8may be made longer and, when the voltage supply from the secondary cell8is turned off, the data evacuation time can be secured.

Next, the voltage conversion unit5will be explained.

The voltage conversion unit5is a circuit that may mutually convert the first voltage V1and the second voltage V2. As the voltage conversion unit5, e.g. an isolated or non-isolated DC/DC bidirectional converter may be used, and the isolated DC/DC bidirectional converter is preferably used. Thereby, the voltage range for conversion may be increased for the better versatility.

The robot arm10has the arm11to arm16as the plurality of arms and the motor31A to motor31F as the plurality of second motors that drive the arms11to16, respectively. The respective motor31A to motor31F are electrically coupled to the same voltage conversion unit5. Thereby, as will be described later, whether the electric power is supplied to the motor31A to motor31F or the regeneration power is supplied to the secondary cell8may be collectively changed by a simple operation of switching the single voltage conversion unit5. Therefore, control of switching between the first mode and the second mode to be described later may be easily performed.

As shownFIG. 1, the robot1has the base110supporting the robot arm10, and the voltage conversion unit5is placed within the base110. That is, in the embodiment, the robot control unit4and the voltage conversion unit5are collectively provided inside of the base110. Thereby, the configuration of the robot1may be simplified.

The voltage conversion unit5has a switch (not shown) and the switch is switched by the first control section41. By the switching, the first mode and the second mode to be described later are switched.

The first mode is a state in which the electric power of the secondary cell8is supplied to the motor31A to motor31F as the second motors. In the first mode, the first voltage V1supplied from the secondary cell8is converted into the second voltage V2and respectively output to the motor drive circuit32A to motor drive circuit32F. Thereby, the motor31A to motor31F driven by the second voltage V2may be driven by the electric power of the secondary cell8outputting the first voltage V1.

On the other hand, the second mode is a state in which the regeneration power of the motor31A to motor31F as the second motors is supplied to the secondary cell8. In the second mode, the regeneration power of the motor31A to motor31F as the second voltage V2is converted into the first voltage V1and output to the secondary cell8. Thereby, the regeneration power as the second voltage V2, which is converted into heat and released in the related art, may be converted into the first voltage V1and stored in the secondary cell8. Therefore, the time to drive the mobile robot100on a single charge may be extended.

In a case where the operation speed of the robot arm10is increased or the like, the power consumption increases with the increase of the second voltage V2. The regeneration power of the motor31A to motor31F is supplied to the secondary cell8, and thereby, reduction of the remaining power of the secondary cell8may be suppressed. Accordingly, when the second voltage V2is increased, the above described effects are more remarkable and effective.

As described above, the voltage conversion unit5converts from the first voltage V1into the second voltage V2in the first mode in which the electric power of the secondary cell8is supplied to the motor31A to motor31F as the second motors, and converts from the second voltage V2into the first voltage V1in the second mode in which the regeneration power of the motor31A to motor31F is supplied to the secondary cell8. Thereby, the regeneration power of the motor31A to motor31F may be stored in the secondary cell8. Therefore, the time to drive the mobile robot100on a single charge may be extended.

The robot1has the first control section41as the control section that controls the operation of the voltage conversion unit5to switch between the first mode and the second mode. Thereby, for example, the first mode and the second mode may be switched appropriately at the following times.

The regeneration power is generated when the motor31A to motor31F make decelerated motion, and the first control section41controls the operation of the voltage conversion unit5to set the second mode when the motor31A to motor31F make decelerated motion and set the first mode when the motor31A to motor31F make accelerated motion and uniform motion.

Specifically, the first control section41specifies the operating state of the robot arm10, i.e., one state of the decelerated motion, the accelerated motion, and the uniform motion based on the encoder values transmitted from the encoder33A to encoder33F as needed. Then, the switch of the voltage conversion unit5is switched according to the result and the first mode and the second mode are switched.

As described above, the robot1has the encoder33A to encoder33F as the operating state sensors that sense the operating state of the robot arm10. Further, the first control section41as the control section controls the operation of the voltage conversion unit5based on the sensing results of the encoder33A to encoder33F. Thereby, switching between the first mode and the second mode may be performed at proper times.

Note that the switching between the first mode and the second mode is not limited to that described above, but may be performed based on an operation program, for example. That is, for execution of the operation program, when the state of the robot arm10is known as one state of the decelerated motion, the accelerated motion, and the uniform motion, the first mode and the second mode may be switched based on an elapsed time or the like.

As described above, the mobile robot100includes the vehicle2having the secondary cell8that outputs the first voltage V1, the motor91A and the motor91B as the first motors driven by the first voltage V1, and the first circuit100A that supplies the electric power of the secondary cell8to the motor91A and the motor91B, and the robot1having the robot arm10, the motor31A to motor31F as the second motors that drive the arm11to arm16by the second voltage V2different from the first voltage V1, and the second circuit100B that supplies the electric power of the secondary cell8to the motor31A to motor31F and supplies the regeneration power of the motor31A to motor31F to the secondary cell8and coupled to the vehicle2. Further, the second circuit100B has the voltage conversion unit5that may mutually convert the first voltage V1and the second voltage V2. Thereby, the regeneration power as the second voltage V2, which is converted into heat and released in the related art, may be converted into the first voltage V1and stored in the secondary cell8. Therefore, the time to drive the mobile robot100on a single charge may be extended.

According to the configuration, when the operation of the robot1is stopped, a user moves the robot arm10by applying an external force to the robot arm10, and thereby, the regeneration power may be generated from the motor31A to motor31F and the secondary cell8may be charged.

Second Embodiment

FIG. 3is the block diagram showing details of the mobile robot according to the second embodiment.

As below, the second embodiment of the mobile robot according to the present disclosure will be explained with reference toFIG. 3, and the explanation will be made with a focus on differences from the above described first embodiment and the explanation of the same items will be omitted.

As shown inFIG. 3, in the embodiment, six of the voltage conversion units5are provided. That is, one voltage conversion unit5is provided for each of the drive units3A to3F. Further, the first control section41respectively independently controls the six voltage conversion units5.

The robot arm10has the arm11to arm16as the plurality of arms and the motor31A to motor31F as the plurality of second motors that drive the arms11to16, respectively. The plurality of, i.e., six voltage conversion units5are respectively provided for the motor31A to motor31F. Thereby, the first mode and the second mode may be switched for each of the voltage conversion units5, and the operation of the motor31A to motor31F may be varied more widely.

Third Embodiment

FIG. 4is the side view showing the mobile robot according to the third embodiment.

As below, the third embodiment of the mobile robot according to the present disclosure will be explained with reference toFIG. 4, and the explanation will be made with a focus on differences from the above described first embodiment and the explanation of the same items will be omitted.

As shown inFIG. 4, the robot1has a casing18provided outside of the base110. Inside of the casing18, the robot control unit4and the voltage conversion unit5are provided. Further, the casing18and the base110are coupled via a junction cable19. The junction cable19contains a part of the wiring of the second circuit100B.

As described above, the robot1has the base110supporting the robot arm10. Further, the voltage conversion unit5is placed outside of the base110. Thereby, for example, maintenance of the voltage conversion unit5may be easily performed.

As above, the mobile robot according to the present disclosure is explained based on the illustrated embodiments, however, the present disclosure is not limited to those. The configurations of the respective parts may be replaced by arbitrary configurations having the same functions. Further, another arbitrary configuration may be added to the present disclosure. The robots of the mobile robots according to the above described embodiments are of the systems including the six-axis vertical articulated robots, however, the number of axes of the vertical articulated robot may be five or less, seven, or more. Or, horizontal articulated robots may be used in place of the vertical articulated robots.