Mobile robot

Abstract

This mobile robot comprises: a carriage part; a movement mechanism for turning the carriage part; an arm part including a first joint connected to the carriage part and having a first rotation axis in a vertical direction, a carriage side arm adjustment part including a joint having a first end part and a second end part and having the first end part connected to the first joint and having an orthogonal rotation axis orthogonal to the first rotation axis, an intermediate arm adjustment part having a third end part and a fourth end part and having the third end part connected to the second end part, and a tip-side arm region connected to the fourth end part; and a control part for controlling the movement mechanism and the arm part. The control part controls the first joint so that the orthogonal rotation axis is perpendicular to the traveling direction of the carriage part during turning travel of the carriage part, and controls the intermediate joint included in the intermediate arm adjustment part so that the center-of-gravity position of the tip-side arm region moves in the direction of the turning center more than the center-of-gravity position before the start of turning.

Description

Mobile Robot

[0001] The present disclosure relates to mobile robots.

[0002] WO2021 / 235520 describes a mobile robot equipped with a carriage and a manipulator mounted on the carriage. The manipulator includes a rotating body rotatably supported on a base and a plurality of arms supported on the rotating body.

[0003] A mobile robot comprising a carriage and an arm mounted on the carriage can be used to grasp, manipulate, and transport objects. One suitable basic structure of the arm comprises a first joint connected to the carriage and having a first vertical rotation axis, a carriage-side arm adjustment unit whose lower end is connected to the first joint, and an upper limb extending from the upper end of the carriage-side arm adjustment unit to an end effector. The carriage-side arm adjustment unit may include one joint having an orthogonal rotation axis perpendicular to the first rotation axis, or multiple joints each having multiple orthogonal rotation axes perpendicular to the first rotation axis and parallel to each other. When manipulating an object, the mobile robot extends the upper limb in a generally horizontal direction perpendicular to the orthogonal rotation axis of the carriage-side arm adjustment unit. The direction in the horizontal plane in which the upper limb is extended can be changed by rotating the first rotation axis. When running, the mobile robot extends the upper limb in a generally forward direction. At this time, the orthogonal rotation axis of the carriage-side arm adjustment unit is in a horizontal direction that is approximately perpendicular to the direction of travel.

[0004] Mobile robots need to be prevented from tipping over due to inertial forces generated when accelerating, decelerating, or turning. Tipping over due to inertial forces generated when accelerating or decelerating can be prevented by tilting the arm forward or backward by rotating a joint with an orthogonal rotation axis in the cart-side arm adjustment unit. To prevent tipping over due to inertial forces generated when turning, the center of gravity of the arm must be moved toward the center of rotation, which is to the right or left of the direction of travel. If the arm had a rotation axis parallel to the direction of travel near the cart, the required center of gravity could be shifted by tilting the arm above that rotation axis to the right or left of the direction of travel. However, the arm with the basic structure assumed here does not have a rotation axis parallel to the direction of travel in the cart-side arm adjustment unit, and therefore cannot tilt almost the entire arm to the right or left of the direction of travel.

[0005] The present disclosure aims to prevent a mobile robot from tipping over during a turn in a structure comprising: a cart section; and an arm section mounted on the cart section, the arm section comprising a first joint connected to the cart section and having a first vertical rotation axis; a cart-side arm adjustment section having a lower end connected to the first joint; and an upper limb section extending from the upper end of the cart-side arm adjustment section to an end effector, the cart-side arm adjustment section comprising one joint having an orthogonal rotation axis perpendicular to the first rotation axis, or a plurality of joints each having a plurality of orthogonal rotation axes perpendicular to the first rotation axis and parallel to each other.

[0006] One aspect of the present disclosure provides an arm unit including: a carriage unit; a movement mechanism that causes the carriage unit to swivel; a first joint that is connected to the carriage unit and has a first rotation axis in a vertical direction; a carriage-side arm adjustment unit that has a first end and a second end, with the first end being connected to the first joint; an intermediate arm adjustment unit that has a third end and a fourth end, with the third end being connected to the second end; and a tip-side arm region that is connected to the fourth end; and a control unit that controls the movement mechanism and the arm unit, wherein the carriage-side arm adjustment unit is configured to adjust a rotation axis perpendicular to the first rotation axis by adjusting a rotation axis perpendicular to the first rotation axis, the intermediate arm adjustment unit includes an intermediate joint that moves the center of gravity of the tip-side arm region in an out-of-plane direction of a reference plane that is a plane passing through the first rotation axis and perpendicular to the one or more orthogonal rotation axes, and the control unit controls the first joint so that the reference plane becomes parallel to the traveling direction of the cart unit when the cart unit is rotating and also controls the intermediate joint so that the center of gravity of the tip-side arm region moves in a direction that has a directional component toward the center of rotation relative to the position of the center of gravity before the start of rotation.

[0007] According to the present disclosure, a mobile robot having a structure comprising a cart unit and an arm unit mounted on the cart unit, the arm unit comprising a first joint connected to the cart unit and having a first vertical rotation axis, a cart-side arm adjustment unit having a lower end connected to the first joint, and an upper limb unit extending from the upper end of the cart-side arm adjustment unit to an end effector, wherein the cart-side arm adjustment unit has one joint having an orthogonal rotation axis perpendicular to the first rotation axis, or multiple joints each having multiple orthogonal rotation axes perpendicular to the first rotation axis and parallel to each other, can be prevented from tipping over when turning.

[0008] FIG. 1 is a perspective view of a mobile robot according to an embodiment. FIG. 2 is a block diagram of a control unit of a mobile robot according to an embodiment. FIG. 3A is an explanatory diagram showing the movement of a joint of a mobile robot according to an embodiment. FIG. 3B is an explanatory diagram showing the movement of a joint of a mobile robot according to an embodiment. FIG. 3C is an explanatory diagram showing the movement of a joint of a mobile robot according to an embodiment. FIG. 3D is an explanatory diagram showing the notation of joints and links according to the JIS standard. FIG. 4 is a side view showing a representative posture of a mobile robot according to an embodiment. FIG. 5 is a plan view showing a representative posture of a mobile robot according to an embodiment. FIG. 6 is a rear view showing the zero moment point in the representative posture of a mobile robot according to an embodiment. FIG. 7 is a plan view showing the turning motion of a mobile robot according to an embodiment. FIG. 8A is a graph showing the time change in the rotation angle of a first joint during turning motion of a mobile robot according to an embodiment. FIG. 8B is a graph showing the time change in the rotation angle of a second joint during turning motion of a mobile robot according to an embodiment. FIG. 8C is a graph showing the time change in the rotation angle of a third joint during turning motion of a mobile robot according to an embodiment. Figure 8D is a graph showing the change over time in the rotation angle of the fourth joint when the mobile robot of the embodiment turns while running in a turning motion. Figure 8E is a graph showing the change over time in the rotation angle of the fifth joint when the mobile robot of the embodiment turns while running in a turning motion. Figure 8F is a graph showing the change over time in the rotation angle of the sixth joint when the mobile robot of the embodiment turns while running in a turning motion. Figure 8G is a graph showing the change over time in the rotation angle of the seventh joint when the mobile robot of the embodiment turns while running in a turning motion. Figure 8H is a graph showing the change over time in the rotation angle of the eighth joint when the mobile robot of the embodiment turns while running in a turning motion.

[0009] An example of an embodiment of the present disclosure will be described below with reference to the drawings. In each drawing, the same or substantially equivalent elements, components, and parts are designated by the same reference numerals. Furthermore, the dimensions and proportions of the drawings are exaggerated for the sake of explanation and may differ from the actual proportions.

[0010] 1, a mobile robot 26 according to this embodiment includes a platform unit 22 and an arm unit 28. The arm unit 28 has, for example, eight degrees of freedom.

[0011] In the example shown in Fig. 1, the bogie unit 22 has a substantially rectangular parallelepiped shape. In the following, an X-axis, a Y-axis, and a Z-axis are set as the coordinate system of the bogie unit 22. The X-axis direction is the front-rear direction of the bogie unit 22, the Y-axis is the left-right direction of the bogie unit 22, and the Z-axis is the height direction of the bogie unit 22. This left-right direction is also the width direction of the bogie unit 22. In the following, an example will be described in which the height direction of the bogie unit 22 coincides with the vertical direction.

[0012] The carriage unit 22 is provided with a movement mechanism 24 and a control unit 70. The control unit 70 controls the operation of the movement mechanism 24 and the arm unit 28. The movement mechanism 24 has two drive wheels 24A, two driven wheels 24B, and two rotational drive sources (motors, not shown) that independently drive the two drive wheels 24A. The two drive wheels 24A are provided on the carriage unit 22 at a distance from each other in the left-right direction, and the two driven wheels 24B are also provided on the carriage unit 22 at a distance from each other in the left-right direction. The drive wheels 24A are provided relatively toward the rear of the vehicle, and the driven wheels 24B are provided relatively toward the front of the vehicle. The drive wheels 24A and the driven wheels 24B support the mobile robot 26. The drive wheels 24A and the driven wheels 24B may be collectively referred to as wheels.

[0013] 4 and 6, the drive wheels 24A and the driven wheels 24B are in contact with the floor surface LF, thereby supporting the mobile robot 26. The square connecting the four points of the drive wheels 24A and the driven wheels 24B is the support area SA.

[0014] The drive wheels 24A are rotationally driven by a rotary drive source (not shown). For example, by rotating the two drive wheels 24A at a constant rotation speed, the carriage unit 22 can be moved linearly. Furthermore, by differentiating the rotation speeds of the two drive wheels 24A (left and right) (differential rotation), the carriage unit 22 can be rotated. In contrast, the driven wheels 24B are not rotationally driven by a rotary drive source and can rotate freely. Furthermore, the rotation axis of the driven wheels 24B can freely change direction within a horizontal plane. In other words, the driven wheels 24B are swivel casters (swivel casters).

[0015] The arm portion 28 has eight joints (first joint 31, second joint 32, third joint 33, fourth joint 34, fifth joint 35, sixth joint 36, seventh joint 37 and eighth joint 38), three links (first link 41, second link 42 and third link 43), and a hand 50.

[0016] The first joint 31 has a first rotation axis J1 that is oriented in a specific direction relative to the cart unit 22. In this embodiment, the specific direction is a normal direction to the top surface 22A of the cart unit 22. In the illustrated example, the top surface 22A of the cart unit 22 is parallel to the floor surface LF of the mobile robot 26. Therefore, the normal direction to the top surface 22A of the cart unit 22 is also a normal direction to the floor surface LF. When the floor surface LF is horizontal, the direction of the first rotation axis J1 is vertical.

[0017] The second joint 32 is connected to the first joint 31 without any other joint therebetween. The second joint 32 has a second rotation axis J2 that is perpendicular to the first rotation axis J1.

[0018] One end 41A of the first link 41 is connected to the second joint 32. The first link 41 has a length extending from the one end 41A in a direction perpendicular to the second rotation axis J2.

[0019] The third joint 33 is provided at the other end 41B of the first link 41. The third joint 33 has a third rotation axis J3 that is parallel to the second rotation axis J2.

[0020] One end 42A of the second link 42 is connected to the third joint 33. The second link 42 has a length extending from the one end 42A in a direction perpendicular to the third rotation axis J3.

[0021] The fourth joint 34 is connected to the other end 42B of the second link 42. The fourth joint 34 has a fourth rotation axis J4 that is parallel to the third rotation axis J3.

[0022] As shown in FIG. 4 , in the arm unit 28, the bogie-side arm adjustment unit 28A is a portion including a second joint 32, a first link 41, a third joint 33, a second link 42, and a fourth joint 34. The second joint 32 is a first end 28A1 of the bogie-side arm adjustment unit 28A and is connected to the first joint 31. The fourth joint 34 is a second end 28A2 of the bogie-side arm adjustment unit 28A. The second rotation axis J2, the third rotation axis J3, and the fourth rotation axis J4 are orthogonal to the first rotation axis J1 when viewed in the Z-axis direction and are examples of orthogonal rotation axes. The number of joints included in the bogie-side arm adjustment unit 28A and having orthogonal rotation axes orthogonal to the first rotation axis J1 is not limited to three, and may be one, two, four, or more.

[0023] The fifth joint 35 is connected to the fourth joint 34, i.e., the second end 28A2 of the bogie-side arm adjustment unit 28A. The fifth joint 35 has a fifth rotation axis J5 that is perpendicular to the fourth rotation axis J4.

[0024] The sixth joint 36 is connected to the fifth joint 35. The sixth joint 36 has a sixth rotation axis J6 that is perpendicular to the fifth rotation axis J5, and is connected to the fifth joint 35. A link having a length may be interposed between the fourth joint 34 and the fifth joint 35. A link having a length may be interposed between the fifth joint 35 and the sixth joint 36. In other words, the fifth joint 35 and the sixth joint 36 are included in the intermediate arm adjustment unit 28B, and the sixth joint 36 is located on the opposite side of the fifth joint 35 from the bogie-side arm adjustment unit 28A.

[0025] 4, in the arm unit 28, the intermediate arm adjustment unit 28B is a portion that includes a fifth joint 35 and a sixth joint 36. The fifth joint 35 is a third end 28B3 of the intermediate arm adjustment unit 28B, and is connected to a second end 28A2 of the bogie-side arm adjustment unit 28A. The sixth joint 36 is a fourth end 28B4 of the intermediate arm adjustment unit 28B.

[0026] One end of the third link 43 is connected to the fourth end 28B4 of the intermediate arm adjustment part 28B, i.e., the sixth joint 36. A seventh joint 37 having a seventh rotation axis J7 is connected to the other end of the third link 43. In the illustrated example, the seventh rotation axis J7 is parallel to the sixth rotation axis J6.

[0027] The eighth joint 38 has an eighth rotation axis J8 that is perpendicular to the seventh rotation axis J7 and is connected to the seventh joint 37. The seventh joint 37 and the eighth joint 38 are joints that correspond to a wrist. While it is not essential to have a joint that corresponds to a wrist, from the perspective of object manipulation, it is preferable to have two joints whose rotation axes are oriented perpendicular to each other. The directions of the rotation axes of the two joints may be different from the directions of the seventh rotation axis J7 and the eighth rotation axis J8.

[0028] The hand 50 is connected to the eighth joint 38. The hand 50 is an element that performs a predetermined operation or processing on an object, and is an example of an end effector. The specific structure of the hand 50 is not limited as long as it is capable of performing such a predetermined operation or processing on an object. For example, the hand 50 is configured to be able to grasp an object.

[0029] As shown in FIG. 4 , in the arm section 28 , the distal arm region 28C is a portion including the third link 43 , the seventh joint 37 , the eighth joint 38 , and the hand 50 .

[0030] The arm portion 28 is provided with an imaging device 60. The imaging device 60 is provided near the fourth joint 34. The imaging device 60 may be a type that captures still images or a type that captures moving images.

[0031] FIG. 2 is a block diagram showing the hardware configuration of the control unit 70 that controls the operation of the mobile robot 26.

[0032] The control unit 70 includes a computer 140. The computer 140 includes a processor 142, a memory 144, a storage 146, an input device 148, an output device 150, a storage medium reader 152, and a communication I / F (Interface) 154. These elements are connected to each other via a bus 156 so as to be able to communicate with each other.

[0033] The storage 146 stores a control program 158 for controlling the mobile robot 26. The processor 142 can execute various programs and control each element. Specifically, the processor 142 reads the program from the storage 146 and executes the program using the memory 144 as a work area. That is, the processor 142 controls each element and performs various arithmetic operations in accordance with the program stored in the storage 146.

[0034] The memory 144 can temporarily store programs and various data as a working area.

[0035] The storage 146 is, for example, a read-only memory (ROM), a hard disk drive (HDD), or a solid state drive (SSD), and stores various programs and data. These programs include not only application programs such as the control program described above, but also an operating system.

[0036] The input device 148 is a device for performing various inputs to the computer 140. The input device 148 includes operation switches, operation buttons, etc., and may also include pointing devices such as a keyboard and a mouse used in a personal computer, etc.

[0037] The output device 150 is a device for outputting various types of information from the computer 140, and includes, for example, a display, an indicator lamp, a speaker, etc. A touch panel display can also be used as the output device 150, in which case the touch panel display also functions as the input device 148.

[0038] The input device 148 and the output device 150 may be detachable when the mobile robot 26 is in operation. Instead of providing the input device 148 and the output device 150, operation commands and other information for the mobile robot 26 may be input and the operation status and other information for the mobile robot 26 may be output via wireless communication via the communication I / F 154.

[0039] The storage medium reader 152 is a device that reads data stored in various storage media and writes data to the storage media, such as a CD (Compact Disc)-ROM, a DVD (Digital Versatile Disc)-ROM, a Blu-ray Disc, and a USB (Universal Serial Bus) memory.

[0040] The communication I / F 154 is an interface for communicating with other devices, and is compliant with standards such as Ethernet (registered trademark) and FDDI (Fiber Distributed Data Interface).

[0041] The above-described joints, hand 50, and drive wheel 24A are controlled by the control unit 70. Specifically, for example, each joint rotates about its own rotation axis as a result of a drive source (not shown) being controlled by the control unit 70. Similarly, the hand 50 also has a drive source (not shown) controlled by the control unit 70 to perform a predetermined operation or processing on an object. The drive wheel 24A rotates as a rotation drive source (not shown) is controlled by the control unit 70.

[0042] Hereinafter, as shown in Figure 5, the reference plane SL is defined as a plane that passes through the first rotation axis J1 and is perpendicular to the second rotation axis J2 (with the second rotation axis J2 as its normal). The forward, backward, and left-right directions of the mobile robot 26 are defined as follows: Forward direction: A direction along the X-axis determined based on the carriage unit 22, from the driving wheels 24A toward the driven wheels 24B. Rearward direction: A direction opposite to the forward direction. Left-right direction: A direction that forms an angle of 90 degrees with the forward direction and the vertical direction (the left direction is the direction to the left when facing forward).

[0043] In the mobile robot 26 of this embodiment, the center of gravity GP2 (see FIGS. 4 and 5 ) of the distal arm region 28C can be moved out of the plane of the reference plane SL by rotating the fifth joint 35 or the sixth joint 36. A joint that moves the center of gravity GP2 of the distal arm region 28C out of the plane of the reference plane SL in this manner is an example of an “intermediate joint” of the disclosed technology.

[0044] Next, the movement and action of the mobile robot 26 of this embodiment will be described. The symbols shown in Figures 3A to 3C are used in the drawings that explain the movement of the mobile robot 26. Each of the examples shown in Figures 3A to 3C illustrates a joint 30 and a link 40 as representative of various joints and links. Each symbol indicates that the link 40 rotates in the direction of arrow R1 around the joint 30.

[0045] Figure 3D is a representation of the joint 30 and link 40 corresponding to Figure 3C in accordance with the JIS standard. As shown in Figure 3D, in the JIS standard, the line segment of the link 40 extending in a direction perpendicular to the rotation axis of the joint 30 is represented by connecting it to a short line segment indicating the rotation axis via a broken line. This is simplified in Figure 3C, where the line segment of the link 40 is connected to the outline of the graphic of the joint 30.

[0046] In Figures 4 and 5, the mobile robot 26 is represented using the joint and link diagrams shown in Figures 3A to 3C. In Figures 4 and 5, the connection order of each joint and link, the direction of each joint's rotation axis, and the direction of each link are accurately depicted. However, the three-dimensional position of each joint and link is not necessarily accurately depicted. For example, referring to Figure 1, it can be seen that links 41 and 42 are separated from each other in the Y direction and are not on the same plane. However, in Figure 5, links 41 and 42 are depicted as if they are on the same plane. Furthermore, if two joints are connected without a line segment representing the link, the three-dimensional relative positional relationship between the two joints is not specified. For example, in Figure 4, the three-dimensional positional relationship between the fourth joint 34 and the fifth joint 35 may be such that the fifth joint 35 is in the X direction, the Y direction, or the Z direction relative to the fourth joint 34. Regardless of the positional relationship, the direction of the rotation axis J5 of the fifth joint 35 rotates in the XZ plane in accordance with the rotation of the fourth joint 34.

[0047] In this embodiment, the mobile robot 26 is considered to have the representative posture shown in FIGS. 4 and 5 . This representative posture has the following characteristics: (1) The second rotational axis J2, the third rotational axis J3, and the fourth rotational axis J4 are parallel to the Y-axis. (2) The third rotational axis J3 is located rearward of the second rotational axis J2 in the X-axis direction, and the distal arm region 28C is located forward. The center of gravity GP1 of the mobile robot 26 is located forward of the center of the platform unit 22 (on the first rotational axis J1) in a planar view. (The representative posture may also be a state in which the center of gravity GP1 of the mobile robot 26 is located at the center of the platform unit 22 (on the first rotational axis J1) in a planar view, or a state in which the center of gravity GP1 is located rearward of the center of the platform unit 22 (on the first rotational axis J1) in a planar view.) (3) The fifth rotational axis J5 is parallel to the X-axis. (4) The center of gravity GP2 of the distal arm region 28C is located below the fifth rotational axis J5 (away from the fifth rotational axis J5).

[0048] As shown in Figure 6, gravity F1 and inertial force F2 act on the center of gravity GP1 of the mobile robot 26. The inertial force F2 is the resultant of the inertial force associated with the forward / backward acceleration of the mobile robot 26, the centrifugal force associated with turning, and the inertial force associated with the movement of the arm 28 due to the drive of each of the first joint 31 through the eighth joint 38. The point where the direction of the resultant force F3 of gravity F1 and inertial force F2 intersects with the floor LF is called the zero moment point (ZMP). If the inertial force F2 becomes large enough that the zero moment point ZMP reaches the edge of the support area SA, one of the wheels of the mobile robot 26 will leave the floor LF, causing the mobile robot 26 to begin to tip over.

[0049] Figure 7 shows the trajectory TL of the center of the carriage unit 22 as the mobile robot 26 turns. In this example, the position of the first rotational axis J1 coincides with the center of the carriage unit 22, but the first rotational axis J1 may be offset from the center of the carriage unit 22. Figures 8A to 8H show the change in the rotational position (actual measured value) of each of the first rotational axis J1 to the eighth rotational axis J8 as a function of time when each joint is controlled so that the zero moment point (ZMP) does not reach the edge of the support area SA and so that the error of the arm unit 28 from the representative posture is minimized. The time ranges are divided as follows: - Up to time T1: Traveling in a straight line - From time T1 to T2: Traveling around a corner with a gradually decreasing turning radius - From time T2 to T3: Traveling around a corner with a constant turning radius - From time T3 to T4: Traveling around a corner with a gradually increasing turning radius - From time T4: Traveling in a straight line In each time range, the forward velocity component is constant.

[0050] In the mobile robot 26 of this embodiment, the first joint 31 is controlled to rotate so that the reference plane SL is parallel to the traveling direction of the carriage unit 22. As shown in FIG. 8A , which shows the rotation angle of the first joint 31, the rotation angle of the first joint 31 is maintained at approximately 0 degrees. Here, 0 degrees is the angle that makes the reference plane parallel to the X-axis direction, i.e., the traveling direction of the carriage unit 22. If the angle between the reference plane SL and the traveling direction of the carriage unit 22 is within approximately 10 degrees, the reference plane SL and the traveling direction of the carriage unit 22 may be considered to be substantially parallel. During rotation, the control unit 70 controls the fifth joint 35 so that the center of gravity GP2 of the distal arm region 28C moves in a direction that has a directional component toward the center of rotation relative to the center of gravity GP2 before the start of rotation. Rotating the fifth joint 35 in this manner is an example of using the fifth joint 35 as an intermediate joint in the disclosed technology.

[0051] The expression "the control unit 70 controls the joints so that the mobile robot 26 is in a certain state when turning" (e.g., "when turning, the control unit 70 controls the first joint 31 so that the reference plane SL is parallel to the traveling direction of the carriage unit 22") does not necessarily mean that rule-based control is being performed, such as controlling the joints to a predetermined angle in response to a condition, such as turning. This expression also includes calculating the angle that each joint of the arm unit 28 should assume at each time in order to travel along a specified trajectory without tipping over, and then controlling the joints as described in the expression. Figures 8A to 8H show the angle changes of each joint as a result of such calculations; these angle change curves are not pre-programmed.

[0052] 8E, which shows the rotation angle of the fifth joint 35, indicates that during turning, the fifth joint 35 rotates significantly from the rotation angle before the start of turning. The rotation angle in the positive direction in Fig. 8E is the angle at which the distal arm region 28C moves to the left, where the center of turning is, in the representative posture.

[0053] 8E , the rotation angle of the fifth joint 35 gradually increases from time T1 when the turning starts to time T2, and the rotation angle of the fifth joint 35 remains roughly constant from time T2 to time T3. Then, from time T3 to time T4, that is, as the turning ends, the rotation angle of the fifth joint 35 gradually decreases.

[0054] As shown in Figure 7, while the mobile robot 26 is turning, an inertial force F2, including a centrifugal force, acts in the opposite direction from the center of rotation RC. When a resultant force F3 of gravity F1 and the inertial force F2 acts on the center of gravity of the arm unit 28, the zero moment point ZMP moves in the opposite direction from the center of rotation RC. As a result, when the zero moment point ZMP reaches the edge of the support area SA, the mobile robot 26 begins to tip over.

[0055] However, in the mobile robot 26 of this embodiment, the center of gravity GP2 of the distal arm section 28C is moved toward the center of rotation RC, which causes the center of gravity GP1 of the entire mobile robot 26 to also move toward the center of rotation RC. This prevents the zero moment point ZMP from approaching the edge of the support area SA.

[0056] From the viewpoint of moving the center of gravity position GP2 of the distal arm region 28C toward the rotation center RC, the control unit 70 does not need to perform control to rotate any joint other than the fifth joint 35. In fact, in Figure 8, the rotation angles of the joints other than the fifth joint 35 are small. However, other joints may be rotated during turning travel within a range that does not interfere with the prevention of tipping over.

[0057] In order to move the center of gravity GP2 of the distal arm region 28C in the left-right direction by rotating the fifth joint 35, the center of gravity GP2 of the distal arm region 28C needs to be located away from an extension of the fifth rotation axis J5. ("A position away from an extension of the rotation axis" is also expressed as "a position away from the rotation axis.") In the representative posture, the center of gravity GP2 of the distal arm region 28C is located below, not on, the extension of the fifth rotation axis J5. In this embodiment, by rotating the sixth joint 36 so that the third link 43 forms a relatively large angle (e.g., 30 degrees or more) with the fifth rotation axis J5, the center of gravity GP2 of the distal arm region 28C can be located away from an extension of the fifth rotation axis J5. In order to move the center of gravity position GP2 of the tip-side arm region 28C in the left-right direction by rotating the fifth joint 35, it is not necessary for the fifth rotation axis J5 to be horizontal; for example, the fifth rotation axis J5 may be at an angle other than horizontal by rotating the fourth joint 34.

[0058] In the disclosed technology, the state in which the center of gravity position GP2 of the distal arm region 28C is not on an extension of the fifth rotation axis J5 may be realized as part of the structure of the arm section 28, without relying on the rotation of the sixth joint 36. For example, this state may be realized by not including the sixth joint 36, and by having a link structure beyond the fifth joint 35 having a shape that extends in a direction that forms an angle with the fifth rotation axis J5.

[0059] While the above is an example in which the fifth joint 35 functions as the "intermediate joint" of the disclosed technology, the sixth joint 36 may instead be controlled to function as the "intermediate joint" of the disclosed technology. That is, when the center of gravity GP2 of the distal arm region 28C is moved toward the center of rotation RC during the mobile robot 26's turning motion, the controller 70 rotates the sixth joint 36. By moving the center of gravity GP2 of the distal arm region 28C toward the center of rotation RC from the center of gravity GP2 before the start of turning, it is possible to prevent the mobile robot 26 from tipping over.

[0060] In this case, if the direction of the sixth rotation axis J6 is perpendicular to the fourth rotation axis J4 (e.g., vertically), the effect of moving the center of gravity GP2 of the distal arm region 28C toward the rotation center RC by rotating the sixth joint 36 is enhanced. On the other hand, if the direction of the sixth rotation axis J6 is parallel to the fourth rotation axis J4 (horizontally), rotating the sixth joint 36 does not result in movement of the center of gravity GP2 of the distal arm region 28C toward the rotation center RC. In order to move the center of gravity GP2 of the distal arm region 28C in the left-right direction by rotating the sixth joint 36, the direction of the sixth rotation axis J6 needs to be a direction having a component perpendicular to the fourth rotation axis J4 (the “orthogonal axis” in the disclosed technology). When the sixth joint 36 is to function as an “intermediate joint,” the fifth joint 35 is controlled so that the direction of the sixth rotation axis J6 is a direction having a component perpendicular to the “orthogonal axis.” In order to move the center of gravity GP2 of the tip-end arm region 28C in the left-right direction by rotating the sixth joint 36, it is necessary for the center of gravity GP2 of the tip-end arm region 28C to be located away from the extension line of the sixth rotation axis J6, just as in the case where the fifth joint 35 acts as an ``intermediate joint.''

[0061] It is also possible to move the center of gravity GP2 of the distal arm region 28C toward the rotation center RC by combining the rotation of the fifth joint 35 and the sixth joint 36. In this case, the fifth joint 35 and the sixth joint 36 both function as "intermediate joints." In another embodiment, the sixth joint 36 may not be provided, and the third link 43 may be connected to the fifth joint 35 perpendicular to the fifth rotation axis J5.

[0062] The center of gravity GP1 of the entire mobile robot 26 can be moved left or right by rotating the first joint 31. However, rotating the fifth joint 35 or the sixth joint 36 to move the center of gravity requires less movement and less energy to prevent the mobile robot from tipping over. This also reduces the change in the imaging direction of the imaging device 60.

[0063] The following are supplementary notes related to the present disclosure: (Supplementary Note 1) A vehicle (22) comprising: a moving mechanism (24) that causes the vehicle (22) to rotate; a first joint (31) connected to the vehicle (22) and having a first rotation axis (J1) in a vertical direction; a vehicle-side arm adjustment unit (28A) having a first end (28A1) and a second end (28A2), with the first end (28A1) connected to the first joint (31); an intermediate arm adjustment unit (28B) having a third end (28B3) and a fourth end (28B4), with the third end (28B3) connected to the second end (28A2); and a tip-side arm region (28C) connected to the fourth end (28B4); and a control unit (70) that controls the moving mechanism (24) and the arm unit (28). the carriage-side arm adjustment unit (28A) includes one joint having one orthogonal rotation axis perpendicular to the first rotation axis (J1), or multiple joints (32, 33, 34) each having multiple orthogonal rotation axes (J2, J3, J4) perpendicular to the first rotation axis and parallel to one another, the intermediate arm adjustment unit (28B) includes an intermediate joint that moves the center of gravity position (GP2) of the tip-side arm region (28C) in an out-of-plane direction of a reference plane (SL), which is a plane passing through the first rotation axis (J1) and perpendicular to the one or more orthogonal rotation axes (J2, J3, J4), and the control unit (70) The mobile robot (26) controls the first joint (31) so that the reference plane (SL) is parallel to the traveling direction of the cart unit (22) when the cart unit (22) is turning, and controls the intermediate joint so that the center of gravity position (GP2) of the tip-side arm region (28C) moves in a direction having a directional component toward the center of rotation (RC) from the center of gravity position before the start of turning.(Supplementary Note 2) The mobile robot (26) according to Supplementary Note 1, wherein the intermediate joint is a fifth joint (35) having a fifth rotation axis (J5) perpendicular to the orthogonal rotation axes (J2, J3, J4), and the control unit (70) controls the fifth joint (35) so that, when the carriage unit (22) is rotating and the center of gravity (GP2) of the tip-side arm region (28C) is located away from the fifth rotation axis (J5), the center of gravity (GP2) of the tip-side arm region (28C) moves in a direction having a directional component toward the rotation center (RC). (Supplementary Note 3) The intermediate arm adjustment unit (28B) includes a fifth joint (35) having a fifth rotation axis (J5) perpendicular to the orthogonal rotation axes (J2, J3, J4), and a sixth joint (36) having a sixth rotation axis (J6) perpendicular to the fifth rotation axis (J5) and located on the opposite side of the bogie-side arm adjustment unit from the fifth joint (35), and the intermediate joint is the sixth joint (36), 2. The mobile robot (26) of claim 1, wherein the control unit (70) controls the fifth joint (35) so that the direction of the sixth rotation axis (J6) is a direction having a component perpendicular to the orthogonal rotation axes (J2, J3, J4) when the carriage unit (22) is turning, and controls the sixth joint (36) so that the center of gravity position (GP2) of the tip-side arm region (28C) moves in a direction having a directional component toward the center of rotation (RC) when the center of gravity position (GP2) of the tip-side arm region (28C) is away from the sixth rotation axis (J6).(Supplementary Note 4) The mobile robot (26) according to any one of Supplementary Notes 1 to 3, wherein the bogie-side arm adjustment unit (28A) includes: a second joint (32) connected to the first joint (31) without any other joint therebetween and having a second rotation axis (J2) perpendicular to the first rotation axis (J1); a first link (41) having one end connected to the second joint (32) and a length perpendicular to the second rotation axis (J2); a third joint (33) provided at the other end of the first link (41) and having a third rotation axis (J3) parallel to the second rotation axis (J2); a second link (42) having one end connected to the third joint (33) and a length perpendicular to the third rotation axis (J3); and a fourth joint (34) provided at the other end of the second link (42) and having a fourth rotation axis (J4) parallel to the third rotation axis (J3).

[0064] The disclosure of Japanese Patent Application No. 2023-170786, filed on September 29, 2023, is incorporated herein by reference in its entirety.

[0065] All publications, patent applications, and technical standards mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent application, or technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A device comprising: a carriage unit; a movement mechanism for rotating the carriage unit; an arm unit including a first joint connected to the carriage unit and having a first rotation axis in a vertical direction, a carriage-side arm adjustment unit having a first end and a second end, the first end being connected to the first joint, an intermediate arm adjustment unit having a third end and a fourth end, the third end being connected to the second end, and a tip-side arm region connected to the fourth end; and a control unit for controlling the movement mechanism and the arm unit, wherein the carriage-side arm adjustment unit includes one joint having an orthogonal rotation axis perpendicular to the first rotation axis, or a plurality of joints each having a plurality of orthogonal rotation axes perpendicular to the first rotation axis and parallel to each other, and the intermediate arm adjustment unit includes an intermediate joint for moving the center of gravity position of the tip-side arm region in an out-of-plane direction of a reference plane, which is a plane passing through the first rotation axis and perpendicular to the one or more orthogonal rotation axes, and the control unit a control unit that controls the first joint so that the reference plane is parallel to a traveling direction of the cart unit when the cart unit is rotating, and controls the intermediate joint so that the position of the center of gravity of the tip-side arm region moves in a direction having a directional component toward a rotation center from the position of the center of gravity before start of rotation.

2. The mobile robot of claim 1, wherein the intermediate joint is a fifth joint having a fifth rotation axis perpendicular to the orthogonal rotation axis, and the control unit controls the fifth joint so that, when the cart unit is rotating, the center of gravity of the tip-side arm region is located away from the fifth rotation axis, the center of gravity of the tip-side arm region moves in a direction having a directional component toward the center of rotation.

3. The mobile robot of claim 1, wherein the intermediate arm adjustment unit includes a fifth joint having a fifth rotation axis perpendicular to the orthogonal rotation axis and a sixth joint having a sixth rotation axis perpendicular to the fifth rotation axis and located on the opposite side of the cart-side arm adjustment unit from the fifth joint, and the intermediate joint is the sixth joint, and the control unit controls the fifth joint so that the direction of the sixth rotation axis is a direction having a component perpendicular to the orthogonal rotation axis when the cart unit is rotating, and controls the sixth joint so that the position of the center of gravity of the tip-side arm region moves in a direction having a directional component toward the center of rotation when the tip-side arm region is away from the sixth rotation axis.

4. The mobile robot described in claim 1, wherein the cart-side arm adjustment unit includes: a second joint connected to the first joint without any other joint therebetween, and having a second rotation axis perpendicular to the first rotation axis; a first link having one end connected to the second joint and having a length in a direction perpendicular to the second rotation axis; a third joint provided at the other end of the first link, and having a third rotation axis parallel to the second rotation axis; a second link having one end connected to the third joint and having a length in a direction perpendicular to the third rotation axis; and a fourth joint provided at the other end of the second link, and having a fourth rotation axis parallel to the third rotation axis.

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