Control system, control method, and program

Abstract

To provide a technology which achieves high speed movement of an autonomous movable body.SOLUTION: A service robot 1 includes: a back drivable robot arm 3; a robot body 4 supporting the robot arm 3; a movable dolly 5 provided at a lower part of the robot body 4; and a control unit 6 which controls the robot arm 3 and the movable dolly 5. The control unit 6 exercises collisional relaxation control if an external force caused by contact with a peripheral object acts on the robot arm 3 when the service robot 1 is moved by using the movable dolly 5. Machine learning may be used in control by the control unit 6.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a control system, a control method, and a program.

Background Art

[0002] Patent Document 1 discloses an autonomous mobile body configured to detect contact with a surrounding object based on a signal output from a contact sensor provided in a plurality of bumpers arranged so as to surround the periphery of a mobile cart.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the configuration of Patent Document 1 described above, it was necessary to keep the moving speed of the autonomous mobile body low so as not to damage the surrounding object when the bumper collided with the surrounding object.

[0005] An object of the present disclosure is to provide a technology for realizing high-speed movement of an autonomous mobile body.

Means for Solving the Problems

[0006] According to a first aspect of the present disclosure, there is provided a control system including an autonomous mobile body including a back-drivable robot arm, a robot body that supports the robot arm, and a mobile cart provided below the robot body, and a control unit that executes collision mitigation control when an external force caused by contact with a surrounding object acts on the robot arm during movement of the autonomous mobile body using the mobile cart. According to the above configuration, high-speed movement of the autonomous mobile body is realized. The collision mitigation control may also be a control that changes the direction of movement of the autonomous mobile body. The collision mitigation control may also be a control that reduces the movement speed of the autonomous mobile body. The control unit may control the robot arm or the mobile cart so that the robot arm is positioned on the side of the autonomous mobile body's direction of movement relative to the robot body while the autonomous mobile body is moving using the mobile cart. With the above configuration, contact between the autonomous mobile body and surrounding objects can be efficiently detected. The control unit may control the robot arm so that, in a plan view, the robot arm protrudes further than the mobile carriage toward the direction of movement of the autonomous mobile body. With the above configuration, contact between the autonomous mobile body and the surrounding objects can be efficiently detected. The control unit may have at least a plurality of sensing modes, including a first sensing mode in which the posture of the robot arm is a first posture, and a second sensing mode in which the posture of the robot arm is a second posture different from the first posture. The control unit may select any one of the plurality of sensing modes and control the posture of the robot arm based on the selected sensing mode. With the above configuration, different sensing ranges can be realized. The autonomous mobile unit further comprises a surrounding environment monitoring unit that monitors the surrounding environment, and the control unit may select one of the plurality of sensing modes based on the surrounding environment. With the above configuration, the optimal sensing mode can be selected according to the surrounding environment. The first posture is one in which the height position of the end effector of the robot arm is a first height position, and the second posture may be one in which the height position of the end effector of the robot arm is a second height position different from the first height position. With the above configuration, it becomes possible to sense different ranges in the vertical direction. The control unit may cause the robot arm to swing in a fan shape while the autonomous mobile body is moving using the mobile trolley. With the above configuration, wide-range sensing can be achieved. The robot arm includes at least two links and a joint connecting the at least two links, and the autonomous mobile body may further include an actuator provided on the robot body for driving the joint and a power transmission mechanism for transmitting power generated by the actuator to the joint. The power transmission mechanism may include a belt or wire. This configuration enables weight reduction of the robot arm. The control unit may also use impedance control to operate the robot arm. With the above configuration, a robot arm capable of backdrivability can be realized with simple control. The system further includes a contact sensor that detects when a surrounding object comes into contact with the mobile cart while the autonomous mobile body is moving using the mobile cart, and the control unit may stop the movement of the autonomous mobile body when it detects that a surrounding object has come into contact with the mobile cart. With the above configuration, the movement of the autonomous mobile body can be stopped when the mobile cart comes into contact with a surrounding object. A second aspect of this disclosure provides a control method for an autonomous mobile body including a backdrivable robot arm, a robot body supporting the robot arm, and a mobile carriage provided at the lower part of the robot body, wherein the autonomous mobile body is moved using the mobile carriage, and if an external force due to contact with a surrounding object acts on the robot arm during the movement of the autonomous mobile body using the mobile carriage, collision mitigation control is performed. The above method enables high-speed movement of the autonomous mobile body. A program is provided that causes a computer to execute the above control method. [Effects of the Invention]

[0007] According to this disclosure, high-speed movement of autonomous mobile vehicles will be realized. [Brief explanation of the drawing]

[0008] [Figure 1] This is a perspective view of a service robot. [Figure 2] This is a side view of the robot arm. [Figure 3] It is a side view of a robot arm. [Figure 4] It is a functional block diagram of a service robot. [Figure 5] It is an explanatory diagram of the first sensing mode. [Figure 6] It is an explanatory diagram of the second sensing mode. [Figure 7] It is an explanatory diagram of the third sensing mode. [Figure 8] It is an explanatory diagram of the fourth sensing mode. [Figure 9] It is the control flow of a service robot. [Figure 10] It is the first modification example and is a plan view of a service robot. [Figure 11] It is the second modification example and is the control flow of a service robot. [Figure 12] It is the third modification example and is a schematic diagram of a control system. [Figure 13] It is an explanatory diagram of back drivability.

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to FIGS. 1 to 9.

[0010] FIG. 1 shows an autonomous mobile service robot 1. The service robot 1 is a specific example of an autonomous mobile body. The service robot 1 provides various services in, for example, medical facilities, nursing facilities, and other facilities. The various services include a transportation service for transporting articles, a patrol service for patrolling within the facility, and other services. FIG. 1 shows a state where the service robot 1 is transporting a beverage container 2.

[0011] The service robot 1 includes a robot arm 3, a robot body 4, a mobile cart 5 provided below the robot body 4, and a control unit 6 that controls the robot arm 3 and the mobile cart 5.

[0012] In this embodiment, the robot arm 3 is configured as an articulated type. And the robot arm 3 is so-called back-drivable. That the robot arm 3 is back-drivable typically means that when an external force is applied to the robot arm 3, the joint angle of the robot arm 3 changes. Here, the external force does not include the external force due to gravitational acceleration and means the external force resulting from contact with surrounding objects.

[0013] The definition of back-drivability is further described in detail in "Journal of the Robotics Society of Japan, Vol. 31 No. 6, pp.548~551, 2013" (https: / / www.jstage.jst.go.jp / article / jrsj / 31 / 6 / 31_31_548 / _pdf / -char / ja).

[0014] That is, the phenomenon in which the drive system operates by applying an external force to the joint or output shaft of a robot is called backdrive. The concept indicating "ease of backdrive" is backdrivability. When a human arm relaxes (relaxes the muscles), it becomes flabby. Living organisms can easily achieve such high backdrivability, but it is quite difficult for current robots.

[0015] Generally, assuming a drive system composed of an electromagnetic motor and a speed reducer as shown in (a) of FIG. 13, the phenomenon that "the speed reducer and the motor rotate by applying an external torque T to the output shaft" is regarded as backdrive. In this case, since one of the most important factors determining backdrivability is the friction of the speed reducer, this definition will be appropriate when discussing a drive system with less friction from the perspective of mechanical engineering. On the other hand, in robotics, the concept of backdrivability is often used to discuss the characteristics of robots. In such cases, it would be beneficial to interpret backdrive more broadly simply as "the output joint operates due to an external force".

[0016] Broadly speaking, back drive can be implemented in various configurations. Figure 13(b) shows an example where an external force is detected by a torque sensor, and the motor is driven based on this detection signal. This allows back drive to be implemented even in drive systems with high-friction gearboxes. Furthermore, by using encoder information, as shown by the dotted line in Figure 13(b), various resistance forces dependent on rotation angle, speed, and acceleration can be realized. From an even broader perspective, there is also the method of using a clutch or brake on the output shaft, as shown in Figure 13(c). If the clutch is turned off, the driven link becomes loose, and if the brake is used, back drive will not occur. If a viscous damper or elastic body is used instead of a clutch, viscous resistance and compliance can be realized. Here, Figure 13(b) can be called a servo back drive, and Figure 13(c) can be called a mechanical back drive.

[0017] In short, "backdrivable" in a broad sense means that when an external force is applied to the robot arm 3, the joint angle of the robot arm 3 changes. "Backdrivable" in a narrow sense means that the robot arm 3 is configured to change its joint angle when an external force is applied to it, by detecting the application of an external force to the robot arm 3 using some method such as a torque sensor or encoder, and actively controlling the robot arm 3 based on the detection result. In the narrow sense of "backdrivable," for example, it is conceivable to compensate for friction in the drive system of the robot arm 3 by actively treating the external force entering from the output shaft of the robot arm 3 as a control command signal for the robot.

[0018] Furthermore, regardless of the servo motors and gearboxes equipped on the robot arm 3, if an infinitely large external force acts on the robot arm 3, the output shaft of the servo motor will rotate to some extent. Therefore, "backdrivable" in this embodiment can also be defined by the degree of external force that can change the joint angle of the robot arm 3. That is, if the joint angle of the robot arm 3 changes due to contact with a moving object such as a pedestrian or another mobile robot, the robot arm 3 can be defined as backdrivable. Also, if the joint angle of the robot arm 3 changes due to contact with a stationary object such as a wall or furniture, the robot arm 3 can be defined as backdrivable.

[0019] As mentioned above, various known methods can be employed to achieve backdrivability of the robot arm 3.

[0020] Firstly, the reduction ratio of the reduction mechanism provided on the output shaft of the actuator of the robot arm 3 is reduced. In other words, since the biggest factor hindering the backdrivability of the robot arm 3 is friction in the reduction mechanism, reducing this friction is effective in improving backdrivability.

[0021] Secondly, an electromagnetic clutch is used on the output shaft of the actuator of the robot arm 3. That is, by disengaging the electromagnetic clutch, the link driven by the actuator can be temporarily left loose.

[0022] Thirdly, the robot arm 3 is impedance controlled. Impedance control is the process of controlling the robot arm 3 so that its joints behave like springs or dampers. Impedance control can be performed using a torque sensor that directly detects external forces, or it can be performed without using a torque sensor.

[0023] In this embodiment, as an example, the backdrivability of the robot arm 3 is achieved by employing the third method described above. However, the first or second method may be used instead of the third method.

[0024] The robot body 4 supports the robot arm 3 in a cantilevered manner. The robot body 4 includes a rectangular robot base 10 that is elongated in the vertical direction, a sliding mechanism 11 provided on the front surface 10a of the robot base 10, an arm base 12 that is supported by the sliding mechanism 11 so as to be able to move up and down and is connected to the robot arm 3, a lifting actuator 13 that drives the arm base 12 so as to move up and down along the sliding mechanism 11, and a head 14. For example, the entire robot arm 3 can be raised by the lifting actuator 13 raising the arm base 12 along the sliding mechanism 11. Similarly, the entire robot arm 3 can be lowered by the lifting actuator 13 lowering the arm base 12 along the sliding mechanism 11. The lifting actuator 13 is typically a servo motor. Power from the lifting actuator 13 is transmitted to the arm base 12 via an endless belt (not shown). The head 14 is located on top of the robot base 10. The head 14 is equipped with a camera 15 and a Lidar 16 (Light Detection and Ranging). The camera 15 and Lidar 16 are used to acquire the surrounding environment. The camera 15 is a specific example of an image sensor. The camera 15 captures the surrounding environment and outputs the image data obtained to the control unit 6. The Lidar 16 is a specific example of a distance sensor. The Lidar 16 outputs three-dimensional point cloud data obtained by scanning the surrounding environment to the control unit 6. Instead of the Lidar 16, a stereo camera or a pattern projection camera can be used as the distance sensor.

[0025] The mobile trolley 5 has a trolley body 20 and a bumper 21.

[0026] The trolley body 20, as an example, has two drive wheels 22 and one driven wheel 23, and two trolley motors 24 that drive the two drive wheels 22, respectively. The service robot 1 moves forward or backward when the two trolley motors 24 drive the two drive wheels 22 at the same rotational speed and in the same direction. The service robot 1 turns when the two trolley motors 24 drive the two drive wheels 22 at different rotational speeds and in the same direction. The service robot 1 turns in a pivot position when the two trolley motors 24 drive the two drive wheels 22 in different rotational directions. The bumper 21 is a rigid body provided in an annular shape on the outer circumference of the trolley body 20, protecting the trolley body 20 from collisions with surrounding objects. The bumper 21 is equipped with a bumper sensor 25 that detects when a surrounding object comes into contact with the bumper 21. The bumper sensor 25 is a specific example of a contact sensor. The bumper sensor 25 is typically composed of an acceleration sensor or a strain gauge. However, the configuration of the bumper sensor 25 is not limited to this.

[0027] Figure 2 shows a side view of the robot arm 3. The robot arm 3 of this embodiment employs a structure that simulates a human arm. Specifically, the robot arm 3 has an upper arm link 30, a forearm link 31, a shoulder joint 32, an elbow joint 33, and a wrist joint 34. The upper arm link 30 is connected to the arm base 12 via the shoulder joint 32 so as to be able to rotate both pitch and roll. The forearm link 31 is connected to the upper arm link 30 via the elbow joint 33 so as to be able to rotate pitch. A grip-type end effector 35 is provided at the tip of the forearm link 31. The end effector 35 is connected to the forearm link 31 via the wrist joint 34 so as to be able to rotate pitch.

[0028] The arm base 12 of the service robot 1 includes a shoulder joint actuator 40 that drives the shoulder joint 32, an elbow joint actuator 41 that drives the elbow joint 33, and a wrist joint actuator 42 that drives the wrist joint 34. In other words, the shoulder joint actuator 40, the elbow joint actuator 41, and the wrist joint actuator 42 are located on the arm base 12 of the service robot 1. This allows for a reduction in the weight of the robot arm 3 compared to, for example, a direct drive system where the elbow joint actuator 41 is located on the elbow joint 33. The reduced weight of the robot arm 3 reduces the damage inflicted on surrounding objects when the robot arm 3 comes into contact with them. In other words, the reduced weight of the robot arm 3 allows for a high level of backdrivability of the robot arm 3.

[0029] The shoulder joint actuator 40, elbow joint actuator 41, and wrist joint actuator 42 are typically servo motors. The output shaft of the shoulder joint actuator 40 is connected to the shoulder joint pulley 40b via a reduction mechanism 40a. Similarly, the output shaft of the elbow joint actuator 41 is connected to the elbow joint pulley 41b via a reduction mechanism 41a. Similarly, the output shaft of the wrist joint actuator 42 is connected to the wrist joint pulley 42b via a reduction mechanism 42a.

[0030] The shoulder joint pulley 40b is connected to the upper arm link pulley 30a, which is located on the shoulder joint 32 (the pitch pivot axis of the upper arm link 30), via an endless belt 30b. The upper arm link pulley 30a is fixed to the upper arm link 30 in a way that prevents rotation. Therefore, the endless belt 30b transmits the power generated by the shoulder joint actuator 40 to the shoulder joint 32. The endless belt 30b is a specific example of a power transmission mechanism. A similar configuration is provided for the roll rotation of the upper arm link 30.

[0031] The elbow joint pulley 41b is connected to the forearm link pulley 31a, which is located at the elbow joint 33 (the pitch pivot axis of the forearm link 31), via an endless belt 31b. The forearm link pulley 31a is fixed to the forearm link 31 in a way that prevents rotation. Therefore, the endless belt 31b transmits the power generated by the elbow joint actuator 41 to the elbow joint 33. The endless belt 31b is a specific example of a power transmission mechanism.

[0032] The wrist joint pulley 42b is connected to the end effector pulley 35a, which is located on the wrist joint 34, the pitch pivot axis of the end effector 35, via two wires 35b. One end of each wire 35b is fixed to the outer circumference of the wrist joint pulley 42b, and the other end is fixed to the outer circumference of the end effector pulley 35a. Thus, the two wires 35b transmit the power generated by the wrist joint actuator 42 to the wrist joint 34. The two wires 35b are a concrete example of a power transmission mechanism.

[0033] The power transmission mechanism is not limited to the above. For example, as shown in Figure 3, a pinion gear 45 may be provided on the output shaft of the elbow joint actuator 41 via a reduction mechanism 41a, and a pinion gear 46 may be provided on the elbow joint 33 that is fixed to the forearm link 31 so as not to rotate, and the pinion gear 45 and pinion gear 46 may be linked via a drive shaft 47. That is, a worm gear 48 that meshes with the pinion gear 45 may be provided at one end of the drive shaft 47, and a worm gear 49 that meshes with the pinion gear 46 may be provided at the other end. A universal joint 50 may be provided on the drive shaft 47 so that the drive shaft 47 can be bent at the shoulder joint 32.

[0034] Next, the electrical configuration of service robot 1 will be explained with reference to Figure 4.

[0035] The control unit 6 includes a CPU 60 (Central Processing Unit), RAM 61 (Random Access Memory), ROM 62 (Read Only Memory), HDD 63 (Hard Disk Drive), and a communication interface 64. The HDD 63 stores map data 65 of the service environment. The CPU 60 reads and executes the control program stored in the HDD 63, which in turn causes the CPU 60 and other hardware to function as a destination setting unit 70, a self-position estimation unit 71, a route generation unit 72, and an autonomous movement control unit 73.

[0036] The destination setting unit 70 sets the destination of the service robot 1 based on external input via the communication interface 64.

[0037] The self-position estimation unit 71 estimates the current position of the service robot 1 by comparing the image data output from the camera 15 with the map data 65. Typically, a particle filter is used as the self-position estimation method, but it is not limited to this.

[0038] The route generation unit 72 generates a route from the service robot 1's current location to the destination.

[0039] The autonomous movement control unit 73 controls the robot arm 3 and the mobile carriage 5. Specifically, the autonomous movement control unit 73 controls the mobile carriage 5 so that the service robot 1 moves according to the path generated by the path generation unit 72. In this embodiment, the autonomous movement control unit 73 is also configured to use the robot arm 3 to detect contact between the service robot 1 and surrounding objects while the service robot 1 is moving. Therefore, as illustrated in Figures 5 to 7, the autonomous movement control unit 73 controls the robot arm 3 or the mobile carriage 5 so that at least a part or all of the robot arm 3 is positioned on the side of the service robot 1's movement direction when viewed from the robot body 4 while the service robot 1 is moving using the mobile carriage 5. More specifically, the autonomous movement control unit 73 controls the robot arm 3 so that, in a plan view, at least a part or all of the robot arm 3 protrudes further than the mobile carriage 5 on the side of the service robot 1's movement direction.

[0040] Returning to Figure 4, the autonomous mobile control unit 73 has multiple sensing modes. These multiple sensing modes include a first sensing mode 80, a second sensing mode 81, a third sensing mode 82, and a fourth sensing mode 83. The autonomous mobile control unit 73 then selects one of the multiple sensing modes based on the image data output from the camera 15 and the three-dimensional point cloud data output from the Lidar 16, and controls the posture of the robot arm 3 based on the selected sensing mode.

[0041] The first sensing mode 80 is a sensing mode that controls the posture of the robot arm 3 so that the end effector 35 of the robot arm 3 is positioned above the upper end 4a of the robot body 4, as shown in Figure 5. The upper arm link 30 extends diagonally upward from the arm base 12, and the forearm link 31 extends upward along the vertical direction. For example, when a drone-type delivery robot is flying in a service environment, there is a risk that the drone-type delivery robot may come into contact with the head 14 of the service robot 1. Therefore, in such a case, it is necessary to protect the head 14 of the service robot 1, so the autonomous mobile control unit 73 selects the first sensing mode 80 and controls the posture of the robot arm 3 based on the first sensing mode 80 so that the posture of the robot arm 3 becomes the posture shown in Figure 5. The posture of the robot arm 3 shown in Figure 5 is a specific example of the first posture.

[0042] As shown in Figure 5, in the first sensing mode 80, the height position of the end effector 35 is the first height position H1. As mentioned above, the first height position H1 is higher than the upper end 4a of the robot body 4. In the first sensing mode 80, the forearm link 31 extends vertically. Therefore, when the first sensing mode 80 is selected, the sensing range SR1 corresponds to the link length of the forearm link 31 in the vertical direction.

[0043] The second sensing mode 81 is a sensing mode that controls the posture of the robot arm 3 so that the end effector 35 of the robot arm 3 is positioned slightly below the upper end 4a of the robot body 4, as shown in Figure 6. The upper arm link 30 extends diagonally downward from the arm base 12, and the forearm link 31 extends upward along the vertical direction. For example, if there are many pedestrians in the service environment, there is a risk that pedestrians may come into contact with the service robot 1. In such cases, the autonomous mobile control unit 73 selects the second sensing mode 81 to prevent the robot arm 3 from coming into contact with the heads of pedestrians, and controls the posture of the robot arm 3 based on the second sensing mode 81 so that the posture of the robot arm 3 becomes the posture shown in Figure 6. The posture of the robot arm 3 shown in Figure 6 is a specific example of the second posture.

[0044] As shown in Figure 6, in the second sensing mode 81, the height position of the end effector 35 is the second height position H2. The second height position H2 is lower than the first height position H1. As mentioned above, the second height position H2 is slightly lower than the upper end 4a of the robot body 4. In the second sensing mode 81, the forearm link 31 extends vertically. Therefore, when the second sensing mode 81 is selected, the sensing range SR2 corresponds to the link length of the forearm link 31 in the vertical direction.

[0045] The third sensing mode 82 is a sensing mode that controls the posture of the robot arm 3 so that the end effector 35 of the robot arm 3 is located near the road surface F of the service environment, as shown in Figure 7. The upper arm link 30 extends diagonally downward from the arm base 12, and the forearm link 31 extends downward along the vertical direction. For example, when an autonomous mobile cleaning robot is moving in a service environment, there is a risk that the autonomous mobile cleaning robot may come into contact with the mobile cart 5 of the service robot 1. Therefore, in such a case, in order to reduce the chance of the service robot 1 coming to an emergency stop due to the autonomous mobile cleaning robot coming into contact with the mobile cart 5, the autonomous mobile control unit 73 selects the third sensing mode 82 and controls the posture of the robot arm 3 based on the third sensing mode 82 so that the posture of the robot arm 3 is as shown in Figure 7.

[0046] As shown in Figure 7, in the third sensing mode 82, the height position of the end effector 35 is the third height position H3. The third height position H3 is lower than the first height position H1 and the second height position H2. As mentioned above, the third height position H3 is near the road surface F. In the third sensing mode 82, the forearm link 31 extends vertically. Therefore, when the third sensing mode 82 is selected, the sensing range SR3 corresponds to the link length of the forearm link 31 in the vertical direction.

[0047] As shown in Figures 5 to 7, the sensing range SR1 in the first sensing mode 80, the sensing range SR2 in the second sensing mode 81, and the sensing range SR3 in the third sensing mode 82 are set to different heights. In this way, in this embodiment, the appropriate sensing range can be flexibly set according to the surrounding environment.

[0048] The fourth sensing mode 83 is a sensing mode in which the robot arm 3 swings from side to side in a fan shape in front of the service robot 1, as shown in Figure 8. By swinging the robot arm 3 in this way, the autonomous movement control unit 73 can detect contact with surrounding objects over a wide range in the direction of movement of the service robot 1. In the example in Figure 8, the autonomous movement control unit 73 swings the robot arm 3 below the arm base 12. However, instead, the autonomous movement control unit 73 may swing the robot arm 3 above the arm base 12.

[0049] The autonomous movement control unit 73 then performs collision mitigation control when an external force is applied to the robot arm 3 due to contact with a surrounding object while the service robot 1 is moving using the mobile trolley 5. Specifically, the autonomous movement control unit 73 can detect the above-mentioned external force as an external force torque by monitoring the current values ​​of the shoulder joint actuator 40, elbow joint actuator 41, and wrist joint actuator 42. Alternatively, the autonomous movement control unit 73 may detect that the above-mentioned external force has been applied based on the output values ​​of encoders provided on the shoulder joint actuator 40, elbow joint actuator 41, and wrist joint actuator 42. In addition, the autonomous movement control unit 73 may attach strain gauges to the upper arm link 30 and the forearm link 31 and detect that the above-mentioned external force has been applied based on the output values ​​of the strain gauges.

[0050] The collision mitigation control described above typically involves reducing the movement speed of the service robot 1 or changing the direction of movement of the service robot 1. The collision mitigation control may also involve reducing the movement speed of the service robot 1 while changing the direction of movement of the service robot 1. In this embodiment, the collision mitigation control is a control that changes the direction of movement of the service robot 1.

[0051] Next, the operation of the service robot 1 will be explained with reference to Figure 9.

[0052] First, the destination setting unit 70 sets the destination (S100). Next, the self-position estimation unit 71 estimates the current position of the service robot 1 (S110). Next, the path generation unit 72 generates a path from the current position of the service robot 1 to the destination (S120). Next, the autonomous movement control unit 73 acquires image data output from the camera 15 and three-dimensional point cloud data output from the Lidar 16 as environmental information (S130). Next, the autonomous movement control unit 73 selects a sensing mode based on the environmental information (S140). Specifically, if the autonomous movement control unit 73 detects a drone-type delivery robot based on the environmental information, it selects the first sensing mode 80. If the autonomous movement control unit 73 detects a pedestrian based on the environmental information, it selects the second sensing mode 81. If the autonomous movement control unit 73 detects an autonomous cleaning robot based on the environmental information, it selects the third sensing mode 82. In other cases, the autonomous movement control unit 73 selects the fourth sensing mode 83.

[0053] Next, the autonomous movement control unit 73 starts autonomous movement according to the path generated by the path generation unit 72 and controls the posture of the robot arm 3 based on the selected sensing mode (S150). Next, the self-position estimation unit 71 estimates the current position of the service robot 1 (S160). Next, the autonomous movement control unit 73 acquires image data output from the camera 15 and three-dimensional point cloud data output from the Lidar 16 as environmental information (S170). Next, the autonomous movement control unit 73 selects a sensing mode based on the environmental information (S180). The autonomous movement control unit 73 may also select a sensing mode using a trained neural network that outputs a sensing mode when environmental information is input. Next, if the sensing mode selected in step S180 is different from the sensing mode currently being executed, the autonomous movement control unit 73 switches the sensing mode to be executed from then on to the sensing mode selected in step S180 (S190).

[0054] Next, the autonomous movement control unit 73 determines whether or not an external force acting on the robot arm 3 due to contact with a surrounding object occurred while the service robot 1 was moving using the mobile trolley 5 (S200). If the autonomous movement control unit 73 determines that an external force was acting, the autonomous movement control unit 73 proceeds to S210. On the other hand, if the autonomous movement control unit 73 determines that no external force was acting, the autonomous movement control unit 73 proceeds to S230.

[0055] Next, the autonomous movement control unit 73 changes the direction of movement of the service robot 1 (S210). For example, while maintaining the movement speed of the service robot 1, the autonomous movement control unit 73 changes the direction of movement of the service robot 1 by approximately 5 to 45 degrees to the left or right in a plan view. Since the robot arm 3 is backdrivable, the damage to surrounding objects is inherently small. Therefore, in this embodiment, the direction of movement of the service robot 1 is simply changed slightly without stopping the service robot 1. This allows the service robot 1 to arrive at its destination earlier.

[0056] Next, the path generation unit 72 updates the path (S220). That is, as described above, the movement path of the service robot 1 deviates from the previously generated path, so the path generation unit 72 generates a new path from the current position of the service robot 1 to the destination.

[0057] Next, the autonomous movement control unit 73 determines whether or not an external force acting on the mobile carriage 5 due to contact with a surrounding object occurred while the service robot 1 was moving using the mobile carriage 5 (S230). If the autonomous movement control unit 73 determines that an external force has acted, the autonomous movement control unit 73 immediately stops the movement of the service robot 1 (S240). On the other hand, if the autonomous movement control unit 73 determines that no external force has acted, the autonomous movement control unit 73 proceeds to S250.

[0058] Next, the autonomous mobile control unit 73 determines whether the service robot 1 has arrived at its destination (S250). If the autonomous mobile control unit 73 determines that the service robot 1 has arrived at its destination, the autonomous mobile control unit 73 terminates processing. If the autonomous mobile control unit 73 determines that the service robot 1 has not arrived at its destination, the autonomous mobile control unit 73 returns processing to S160.

[0059] As described above, if the autonomous movement control unit 73 causes an emergency stop to the movement of the service robot 1 (S240), the autonomous movement control unit 73 notifies the operator that the service robot 1 has made an emergency stop. The operator rushes to the service robot 1 and determines whether the service robot 1 can continue moving. If the operator determines that it can continue, the operator restarts the movement of the service robot 1.

[0060] The embodiments of the present disclosure have been described above, and these embodiments have the following features.

[0061] As shown in Figures 1, 4, and 9, the service robot 1 (autonomous mobile unit) includes a backdrivable robot arm 3, a robot body 4 that supports the robot arm 3, a mobile carriage 5 provided at the bottom of the robot body 4, and a control unit 6 that controls the robot arm 3 and the mobile carriage 5. The control unit 6 performs collision mitigation control when an external force caused by contact with a surrounding object acts on the robot arm 3 while the service robot 1 is moving using the mobile carriage 5. With this configuration, collision detection is performed using the backdrivable robot arm 3, which does not cause significant damage to surrounding objects when it comes into contact with them. Therefore, the service robot 1 can be moved at a higher speed compared to when collision detection is performed using the bumper 21. In addition, since no significant damage is caused to surrounding objects, the constraints on generating the movement path of the service robot 1 are reduced, such as not having to select a long, roundabout route with extremely few pedestrians.

[0062] Furthermore, as shown in Figure 9, the collision mitigation control is a control (S210) that changes the direction of movement of the service robot 1. With the above configuration, the service robot 1 can avoid surrounding objects without reducing its movement speed.

[0063] Furthermore, as shown in Figure 5, for example, the control unit 6 controls the robot arm 3 and the mobile cart 5 so that the robot arm 3 is positioned on the side of the direction of movement of the service robot 1 when viewed from the robot body 4 while the service robot 1 is moving using the mobile cart 5. With the above configuration, contact between the service robot 1 and surrounding objects can be efficiently detected.

[0064] Furthermore, as shown in Figure 5, for example, the control unit 6 controls the robot arm 3 so that, in a plan view, the robot arm 3 protrudes further than the mobile carriage 5 in the direction of movement of the service robot 1. With this configuration, contact between the service robot 1 and surrounding objects can be efficiently detected.

[0065] Furthermore, as shown in Figures 5 to 7, for example, the control unit 6 has multiple sensing modes, including a first sensing mode 80 in which the posture of the robot arm 3 is the first posture shown in Figure 5, and a second sensing mode 81 in which the posture of the robot arm 3 is the second posture shown in Figure 6, which is different from the first posture shown in Figure 5. The control unit 6 selects one of the multiple sensing modes. The control unit 6 controls the posture of the robot arm 3 based on the selected sensing mode. With the above configuration, different sensing ranges can be realized.

[0066] Furthermore, as shown in Figures 4 and 9, the service robot 1 is further equipped with a camera 15 and a Lidar 16 (surrounding environment monitoring unit) to monitor the surrounding environment. The control unit 6 selects one of several sensing modes based on the surrounding environment (S130, S140, S170, S180, S190). With this configuration, the optimal sensing mode can be selected according to the surrounding environment.

[0067] The first posture shown in Figure 5 is when the height position of the end effector 35 of the robot arm 3 is the first height position H1. The second posture shown in Figure 6 is when the height position of the end effector 35 of the robot arm 3 is the second height position H2, which is different from the first height position H1. With this configuration, it becomes possible to sense different ranges in the vertical direction.

[0068] Furthermore, as shown in Figure 8, for example, the control unit 6 may swing the robot arm 3 in a fan shape while the service robot 1 is moving using the mobile cart 5. With the above configuration, wide-range sensing can be achieved.

[0069] Furthermore, as shown in Figure 2, for example, the robot arm 3 includes an upper arm link 30 and a forearm link 31 (at least two links), and an elbow joint 33 (joint) connecting the upper arm link 30 and the forearm link 31. The service robot 1 further includes an elbow joint actuator 41 (actuator) provided on the arm base 12 of the robot body 4 to drive the elbow joint 33, and an endless belt 31b (power transmission mechanism) that transmits the power generated by the elbow joint actuator 41 to the elbow joint 33. With this configuration, the weight of the robot arm is reduced. Therefore, when the robot arm 3 of the service robot 1 comes into contact with a surrounding object, it does not cause significant damage to the surrounding object. In addition, with this configuration, the backdrivability of the robot arm 3 is achieved at a high level.

[0070] Furthermore, as the power transmission mechanism, for example, an endless belt 31b or a wire 35b may be used. With the above configuration, a high degree of weight reduction of the robot arm 3 can be achieved.

[0071] Furthermore, the control unit 6 controls the robot arm 3 using impedance control. With this configuration, a robot arm 3 that can be back-driven can be realized with simple control.

[0072] Furthermore, as shown in Figures 4 and 9, the service robot 1 is further equipped with a bumper sensor 25 (contact sensor) that detects when a surrounding object comes into contact with the mobile cart 5 while the service robot 1 is moving using the mobile cart 5. The control unit 6 may stop the movement of the service robot 1 when it detects that a surrounding object has come into contact with the mobile cart 5 (S240). With the above configuration, the movement of the service robot 1 can be stopped when the mobile cart 5 comes into contact with a surrounding object.

[0073] Furthermore, as shown in Figure 9, the control method for the service robot 1 includes initiating autonomous movement of the service robot 1 using the mobile cart 5 (S150), and executing collision mitigation control when an external force due to contact with a surrounding object acts on the robot arm 3 during movement of the service robot 1 using the mobile cart 5 (S210). By this method, high-speed movement of the service robot 1 is realized.

[0074] (First variation) Next, the first modified example will be described with reference to Figure 10. The following description will focus on the differences between this modified example and the above embodiment, omitting any redundant explanations.

[0075] Figure 10 shows a plan view of the service robot 1. As shown in Figure 10, the robot arm 3 is located on the side of the service robot 1's direction of movement when viewed from the robot body 4. In the plan view of Figure 10, the forearm link 31 of the robot arm 3 is located on the side of the service robot 1's direction of movement when viewed from the mobile carriage 5. The forearm link 31 extends in a direction perpendicular to the direction of movement of the service robot 1 in the plan view, and is in a horizontally extending position. With this configuration, the sensing range can be extended in the width direction of the service robot 1. Also, as shown in Figure 10, the link length of the forearm link 31 may be greater than the diameter of the mobile carriage 5. With this configuration, a wide sensing range can be achieved in the width direction of the service robot 1.

[0076] (Second variation) Next, a second modified example will be described with reference to Figure 11. The following description will focus on the differences between this modified example and the above embodiment, omitting any redundant explanations.

[0077] As shown in Figure 11, steps S100 to S200 are the same as in the above embodiment, so their explanation will be omitted.

[0078] The autonomous mobile control unit 73 determines whether an external force caused by contact with a surrounding object has acted on the robot arm 3 while the service robot 1 is moving using the mobile cart 5 (S200). If the autonomous mobile control unit 73 determines that an external force has acted, the autonomous mobile control unit 73 proceeds to S300. In step S300, the autonomous mobile control unit 73 reduces the movement speed of the service robot 1 (S300). When the service robot 1 slows down in this way, the surrounding object may move away from the direction of travel of the service robot 1 even while in contact with it, potentially resolving the contact. Therefore, compared to the case where the service robot 1 is brought to an emergency stop, the movement speed of the service robot 1 can be maintained to some extent, thereby enabling the service robot 1 to arrive at its destination earlier.

[0079] In the second modified example described above, if the autonomous movement control unit 73 determines that an external force has been applied (S200), the autonomous movement control unit 73 may temporarily reduce the movement speed of the service robot 1. Temporarily reducing the movement speed of the service robot 1 means returning the movement speed to its pre-reduction speed after a predetermined time has elapsed since the reduction, or when predetermined conditions have been met since the reduction in the service robot 1's movement speed.

[0080] In the second modified example described above, if the autonomous mobile control unit 73 determines that an external force has been applied (S200), the autonomous mobile control unit 73 may non-temporarily reduce the movement speed of the service robot 1. Non-temporarily reducing the movement speed of the service robot 1 means that, in principle, the movement speed of the service robot 1 will not be returned to the speed before the reduction after the reduction. That is, since it has been found that the environment in which the service robot 1 is currently moving is an environment in which there is a risk that surrounding objects may come into contact with the robot arm 3 while the service robot 1 is moving using the mobile cart 5, after the above determination, it is conceivable to operate the service robot 1 with its movement speed reduced by a predetermined amount, regardless of whether an external force has been applied or not.

[0081] The first and second modified examples have been described above, but further modifications can be made as follows.

[0082] For example, the control unit 6 may change the control parameters of the impedance control of the robot arm 3 according to the movement speed of the service robot 1. Here, the control parameters of impedance control typically refer to the coefficient of inertia, the viscosity coefficient, and the stiffness coefficient.

[0083] Furthermore, instead of the mechanism exemplified in Figures 2 and 3, a link mechanism may be used as the power transmission mechanism that transmits the power generated by the elbow joint actuator 41 to the elbow joint 33.

[0084] (Third variation) Next, a third modified example will be described with reference to Figure 12. The following description will focus on the differences between this modified example and the above embodiment, omitting any redundant explanations.

[0085] In the above embodiment, as shown in Figure 1, the service robot 1 is equipped with a control unit 6. That is, the control system 100, which includes the service robot 1 and the control unit 6, is realized by the service robot 1 alone.

[0086] In contrast, in this modified example, the control system 300 includes a service robot 1 and a control device 200. The service robot 1 and the control system 200 are configured as separate entities. The service robot 1 and the control system 200 are configured to communicate bidirectionally. The control system 200 performs some or all of the functions of the control unit 6 shown in Figure 4. That is, the control unit 6 shown in Figure 4 is realized by distributed processing by the service robot 1 and the control system 200. In this case, for example, the control unit 6 of the service robot 1 determines whether or not an external force caused by contact with a surrounding object is acting on the robot arm 3 while the service robot 1 is moving using the mobile cart 5, and the control unit 6 of the service robot 1 transmits the determination result to the control system 200. Based on the determination result received from the service robot 1, the control system 200 determines whether or not collision mitigation control is necessary. If the control system 200 determines that collision mitigation control is necessary, the control system 200 transmits a collision mitigation control command to the service robot 1. When the control unit 6 of the service robot 1 receives a collision mitigation control command from the control system 200, it executes a predetermined collision mitigation control.

[0087] In the above modified example, the control unit 6 of the service robot 1 determines whether or not an external force caused by contact with a surrounding object acts on the robot arm 3 while the service robot 1 is moving using the mobile cart 5, but the system is not limited to this. The sensor signals from various sensors of the service robot 1 may be transmitted to the control system 200 in real time, and the control system 200 may determine whether or not an external force caused by contact with a surrounding object acts on the robot arm 3 while the service robot 1 is moving using the mobile cart 5 based on the sensor signals received.

[0088] (Fourth variation) Next, a fourth modified example will be described. The following description will focus on the differences between this modified example and the above embodiment, omitting any redundant explanations.

[0089] In the above embodiment, collision mitigation control was defined as, for example, reducing the movement speed of the service robot 1 or changing the direction of movement of the service robot 1. However, collision mitigation control is not limited to these.

[0090] For example, collision mitigation control may involve stopping the movement of the service robot 1.

[0091] Furthermore, the control unit 6 may execute collision mitigation control on the condition that it determines a predetermined number of times that an external force caused by contact with a surrounding object has acted on the robot arm 3 while the service robot 1 is moving using the mobile carriage 5. With the above configuration, the frequency of executing collision mitigation control can be reduced, and the movement of the service robot 1 can be prioritized. Thus, the timing of executing collision mitigation control is not limited to the time when it is determined that an external force caused by contact with a surrounding object has acted on the robot arm 3 while the service robot 1 is moving using the mobile carriage 5, but may be at a later time. The reason why collision mitigation control does not need to be executed immediately when it is determined that an external force caused by contact with a surrounding object has acted on the robot arm 3 while the service robot 1 is moving using the mobile carriage 5 is simply because the robot arm 3 is configured to be backdrivable.

[0092] In the above example, the program can be stored and supplied to the computer using various types of non-transitory computer-readable medium. Non-transitory computer-readable medium includes various types of tangible storage medium. Examples of non-transitory computer-readable medium include magnetic storage media (e.g., flexible disks, magnetic tapes, hard disk drives) and magneto-optical storage media (e.g., magneto-optical disks). Examples of non-transitory computer-readable medium further include CD-ROM (Read Only Memory), CD-R, CD-R / W, and semiconductor memory (e.g., mask ROM; examples of non-transitory computer-readable medium further include PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, and RAM (random access memory)). Alternatively, the program may be supplied to the computer by various types of transient computer-readable medium. Examples of transient computer-readable medium include electrical signals, optical signals, and electromagnetic waves. Temporary computer-readable media can supply programs to a computer via wired communication channels such as electric wires and optical fibers, or via wireless communication channels. [Explanation of Symbols]

[0093] 1 Service Robot 2 Beverage containers 3. Robot Arm 4. Robot body 4a top edge 5. Mobile cart 6 Control Unit 10 Robot Base 10a front 11. Slide mechanism 12 Arm Base 13 Lifting Actuator 14 heads 15 Cameras 16 Lidar 20 Bogie Body 21 Bumper 22 drive wheels 23 Driven wheels 24 Bogie Motors 25 Bumper Sensor 30 Upper Arm Links 30a Upper arm link pulley 30b Endless belt 31 Forearm Link 31a Forearm link pulley 31b Endless belt 32 Shoulder joint 33. Elbow joint 34. Wrist joint 35 End Effector 35a End Effector Pulley 35b Wire 40 Shoulder joint actuator 40a reduction mechanism 40b Shoulder joint pulley 41 Elbow joint actuator 41a Reduction mechanism 41b Elbow joint pulley 42 Wrist joint actuator 42a Reduction mechanism 42b Wrist joint pulley 45 Pinion Gear 46 Pinion Gear 47 Drive shaft 48 Worm gear 49 Worm gear 50 Universal Joint 64 Communication Interfaces 65 Map Data 70 Destination setting section 71 Self-position estimation part 72 Route generation unit 73 Autonomous Mobile Control Unit 80 First Sensing Mode 81 Second Sensing Mode 82 Third Sensing Mode 83. Fourth Sensing Mode 100 control systems 200 Control device 300 Control Systems H1 First height position H2 Second height position H3 Third height position SR1 Sensing Range SR2 Sensing Range SR3 Sensing Range F road surface

Claims

1. A robotic arm that can be driven backward, A robot body that supports the robot arm, A mobile platform is provided at the lower part of the robot body, The surrounding environment monitoring unit monitors the surrounding environment, Autonomous mobile vehicles including, When an external force due to contact with a surrounding object acts on the robot arm while the autonomous mobile body is moving using the aforementioned mobile trolley, a control unit performs collision mitigation control. Includes, The robot arm has an upper arm link connected to the robot body via a shoulder joint, and a forearm link connected to the upper arm link via an elbow joint. The mobile trolley comprises a trolley body, a bumper provided in an annular shape on the outer circumference of the trolley body, and a bumper sensor for detecting when the surrounding object comes into contact with the bumper. When the control unit detects that the surrounding object has come into contact with the bumper, it will bring the autonomous mobile unit to an emergency stop. When the control unit detects an autonomous cleaning robot autonomously moving in the service environment based on the monitoring results from the surrounding environment monitoring unit, it controls the robot arm so that, while the autonomous mobile body is moving using the mobile cart, the robot arm protrudes in a plan view from the mobile cart toward the direction of movement of the autonomous mobile body, the upper arm link extends diagonally downward from the robot body, and the forearm link extends vertically downward, so that the end effector attached to the robot arm is positioned near the road surface of the service environment. Control system.

2. The collision mitigation control is a control that changes the direction of movement of the autonomous mobile body. The control system according to claim 1.

3. The collision mitigation control is a control that reduces the movement speed of the autonomous mobile body. The control system according to claim 1.

4. A robot arm that can be back-driven, A robot body that supports the robot arm, A mobile platform is provided at the lower part of the robot body, The surrounding environment monitoring unit monitors the surrounding environment, Autonomous mobile vehicles including, When an external force due to contact with a surrounding object acts on the robot arm while the autonomous mobile body is moving using the aforementioned mobile trolley, a control unit performs collision mitigation control. including, A control method in a control system, The robot arm has an upper arm link connected to the robot body via a shoulder joint, and a forearm link connected to the upper arm link via an elbow joint. The mobile trolley comprises a trolley body, a bumper provided in an annular shape on the outer circumference of the trolley body, and a bumper sensor for detecting when the surrounding object comes into contact with the bumper. When the control unit detects that the surrounding object has come into contact with the bumper, it will bring the autonomous mobile unit to an emergency stop. When the control unit detects an autonomous cleaning robot autonomously moving in the service environment based on the monitoring results from the surrounding environment monitoring unit, it controls the robot arm so that, while the autonomous mobile body is moving using the mobile cart, the robot arm protrudes in a plan view from the mobile cart toward the direction of movement of the autonomous mobile body, the upper arm link extends diagonally downward from the robot body, and the forearm link extends vertically downward, so that the end effector attached to the robot arm is positioned near the road surface of the service environment. Control method.

5. A program that causes a computer to execute the control method described in claim 4.

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