Mobile robot

Abstract

This mobile robot comprises: a carriage part; a movement mechanism for allowing the carriage part to carry out turning travel; an arm part including a first joint connected to the carriage part, a carriage-side arm adjustment part connected to the first joint, an intermediate arm adjustment part connected to the carriage-side arm adjustment part, and a tip-side arm region connected to the intermediate arm adjustment part; and a control unit. The carriage-side arm adjustment part includes one joint including one orthogonal rotation axis orthogonal to a first rotation axis, or a plurality of joints including a plurality of orthogonal rotation axes orthogonal to the first rotation axis and parallel to each other. During turning travel of the carriage part, the control unit controls the first joint such that the center-of-gravity position of the arm part moves in a direction so as to become closer to the turning center than the center-of-gravity position before the start of turning, and controls the intermediate arm adjustment part such that the tip-side arm region moves in a direction having a component in a direction opposite to the direction of movement of the tip-side arm region resulting from the rotation of the first joint.

Description

Mobile Robot

[0001] The present disclosure relates to mobile robots.

[0002] "Stabilization Control of Vehicle-Mounted Manipulators," Transactions of the Society of Instrument and Control Engineers, Vol. 31, No. 7, 861 / 870 (1995), describes stability for preventing a vehicle-mounted manipulator from tipping over during operation.

[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 turning motion, the mobile robot including a carriage and an arm mounted on the carriage, the arm including a first joint connected to the carriage and having a first vertical rotation axis, a carriage-side arm adjustment unit having a lower end 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 including one joint having an orthogonal rotation axis perpendicular to the first rotation axis, or multiple joints having multiple orthogonal rotation axes perpendicular to the first rotation axis and parallel to each other. Another objective of the present disclosure is to prevent movement of the tip of the arm when the arm is operated to prevent tipping over during turning motion.

[0006] One aspect of the present disclosure provides a control system for controlling a vehicle including a carriage unit, a movement mechanism for rotating the carriage unit, 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, with the first end being connected to the first joint, an intermediate arm adjustment unit having a third end and a fourth end, with 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 is configured to rotate an arm in an orthogonal rotation direction perpendicular to the first rotation axis. the control unit controls the first joint so that, when the carriage unit turns, the center of gravity of the arm unit moves in a direction closer to the center of rotation than the center of gravity position before the turning starts, and controls the intermediate arm adjustment unit so that the tip-side arm region moves in a direction having a component in the opposite direction to the direction of movement of the tip-side arm region due to rotation of the first joint, compared to when the intermediate arm adjustment unit is not operated.

[0007] According to the present disclosure, a mobile robot including a carriage and an arm mounted on the carriage, the arm including 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 including 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 during a turn. Furthermore, when the arm operates to prevent tipping over during a turn, movement of the tip of the arm can be suppressed. This reduces the risk of the tip of the arm coming into contact with a surrounding object during a turn. Furthermore, when an object is held at the tip of the arm, the acceleration of the held object can be suppressed by the operation of the arm to prevent tipping over during a turn.

[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. FIG. 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. FIG. 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. FIG. 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. FIG. 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. FIG. 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. FIG. 9 is a plan view showing the operation of the mobile robot of the embodiment when turning while running.

[0009] An example of an embodiment of the present disclosure will be described below with reference to the drawings. Note that the same or substantially equivalent elements, components, and parts in each drawing are given the same reference numerals. Also, the dimensions and proportions of the drawings are exaggerated for the convenience of explanation and may differ from the actual proportions.

[0010] 1, a mobile robot 26 according to an embodiment includes a cart unit 22 and an arm unit 28. The arm unit 28 is, for example, a robot with 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 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] As shown in Figure 5, the forward, backward, and left-right directions of the mobile robot 26 are defined as follows: Forward direction: The direction along the X-axis determined based on the platform 22, from the driving wheels 24A toward the driven wheels 24B. Rearward direction: The direction opposite to the forward direction. Left-right direction: The direction at a 90-degree angle with the forward direction and the vertical direction (left direction is the left direction when facing forward).

[0043] In the mobile robot 26 of this embodiment, the distal arm region 28C can be moved left and right by rotating the fifth joint 35 or the sixth joint 36.

[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 explaining the movement of the mobile robot 26. The examples shown in Figures 2A to 2C all illustrate 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] 4 and 5 are used as the representative posture of the mobile robot 26 according to this embodiment. This representative posture has the following characteristics: (1) The second, third, and fourth rotational axes J2, J3, and J4 are parallel to the Y axis. (2) The third rotational axis J3 is located behind 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 plan view.

[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] FIG. 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; however, the first rotational axis J1 may be offset from the center of the carriage unit 22. FIGS. 8A-8H show the change in the rotational position (actual measured value) of each of the first rotational axis J1 through the eighth rotational axis J8 as a function of time when each joint is controlled so that (1) the zero moment point (ZMP) does not reach the edge of the support area SA, (2) the error of the arm unit 28's posture from the representative posture is minimized, and (3) the error of the hand 50's position in the robot coordinate system from the representative posture is minimized. The weights by which the goals (2) and (3) contribute to determining the rotational position of each rotational axis are appropriately set. The time ranges in FIGS. 8A-8H 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] As shown in FIG. 4 , in the representative posture, the center of gravity GP1 of the arm unit 28 is located away from the first rotation axis J1, specifically, forward in the direction of travel of the cart unit 22. In this case, in the mobile robot 26 of this embodiment, as shown in FIG. 9 , at the start of rotation, the control unit 70 rotates the first joint 31 so that the center of gravity GP1 moves leftward toward the rotation center RC. Specifically, as shown in FIG. 8A , the rotation angle of the first joint 31 gradually increases from time T1 at the start of rotation to time T2. From time T2 to time T3, the rotation angle of the first joint 31 reaches an extreme value and begins to decrease. Then, from time T3 to time T4, i.e., with the end of rotation, the rotation angle of the first joint 31 gradually returns to the rotation angle before the start of rotation. The rotation angle of 0 degrees in FIG. 8A is the angle at which the second rotation axis J2, the third rotation axis J3, and the fourth rotation axis J4 are aligned in the Y direction. The control unit 70 controls the first joint 31 in this manner while the mobile robot 26 is turning.

[0051] The control unit 70 further rotates at least one of the fifth joint 35 and the sixth joint 36. As an example, as shown in FIGS. 8E and 8F , from time T1 at the start of rotation to time T2, the rotation angles of the fifth joint 35 and the sixth joint 36 gradually increase with respect to the rotation angle in the representative posture before the start of rotation. From time T2 to time T3, the rotation angle of the fifth joint 35 remains roughly constant. Then, from time T3 to time T4, i.e., with the end of rotation, the rotation angle of the fifth joint 35 gradually returns to the rotation angle before the start of rotation. The rotation directions of the fifth joint 35 and the sixth joint 36 are directions that move the distal arm region 28C so as to have a component in the opposite direction to the movement direction of the distal arm region 28C due to the rotation of the first joint 31. Specifically, during rotation, the fifth joint 35 rotates in a direction that moves the distal arm region 28C away from the rotation center RC in the representative posture of FIG. 4. During the pivoting, the sixth joint 36 rotates so that the position of the hand 50 is lower in the representative posture of Fig. 4. Such rotation of the sixth joint 36 increases the distance of the hand 50 from the fifth rotation axis J5, which has the effect of increasing the amount of movement of the hand 50 in the left-right direction (directions approaching the center of the carriage 22 in the Y direction) due to the rotation of the fifth joint 35.

[0052] In this way, the control unit 70 controls the first joint 31 during the swing travel of the cart unit 22 so that the center of gravity position GP1 of the arm unit 28 moves in a direction closer to the swing center RC than the center of gravity position before the swing started, and controls the intermediate arm adjustment unit 28B so that the tip-side arm region 28C moves in a direction having a component opposite to the direction of movement of the tip-side arm region 28C due to rotation of the first joint 31, compared to when the intermediate arm adjustment unit 28B (fifth joint 35, sixth joint 36) is not operated. This makes it possible to move the center of gravity position GP1 of the arm unit 28 toward the swing center RC while reducing (preferably eliminating) the amount of protrusion of the tip-side arm region 28C (hand 50) from the cart unit 22 in the left-right direction (Y-axis direction). Furthermore, when the hand 50 travels while gripping an object, the acceleration applied to the gripped object due to the rotation of the first joint 31 to prevent tipping during swing can be suppressed.

[0053] There are other ways to combine the rotation of the fifth joint 35 and the sixth joint 36 to move the distal arm region 28C away from the rotation center RC during rotation. In the example shown in FIG. 9 , before starting rotation, the fifth joint 35 is rotated 90 degrees from the representative posture to orient the sixth rotation axis in the Z direction (vertical direction), and the sixth joint 36 is rotated so that the link 43 faces the X direction (forward). When rotation starts, the first joint 31 is rotated counterclockwise in a plan view. This rotation of the first joint 31 acts to move the hand 50 closer to the rotation center RC. At the same time, the sixth joint 36 is rotated in a direction that moves the hand 50 so as to cancel out the movement of the hand 50 caused by the rotation of the first joint 31 (the link 43 is rotated clockwise in a plan view).

[0054] The expression "the control unit 70 controls the joints so that the mobile robot 26 is in a certain state when turning" (e.g., "the first joint 31 is rotated so that the center of gravity GP1 moves to the left, where the turning center RC is located") does not necessarily imply rule-based control, such as controlling the joints to a predetermined angle in response to a condition, such as turning. This expression also implies calculating the angle each joint of the arm unit 28 should assume at each time in order to move along a specified trajectory without tipping over, and then controlling the joints as described. Figures 8A-8H show the angle changes of each joint as a result of this calculation; these angle change curves are not pre-programmed.

[0055] From the viewpoint of reducing the amount of protrusion of the tip-side arm region 28C, it is not necessary to rotate both the fifth joint 35 and the sixth joint 36, and it may be sufficient to rotate either one of them. In any case, by rotating the joint included in the intermediate arm adjustment unit 28B, it is possible to reduce the amount of protrusion of the tip-side arm region 28C.

[0056] In the mobile robot 26 of this embodiment, the control unit 70 also rotates the eighth joint 38, as shown in FIG. 8H . Rotation of the eighth joint 38 adjusts the posture of the hand 50. For example, if rotation of the fifth joint 35 causes the hand 50 to tilt left or right (which causes the posture of the object being grasped by the hand 50 to tilt left or right), rotation of the eighth joint 38 can bring the posture of the hand 50 closer to the posture before the fifth joint 35 was rotated.

[0057] Note that, from the viewpoint of moving the center of gravity GP1 of the arm unit 28 toward the rotation center RC and moving the distal arm region 28C in the opposite direction, the control unit 70 does not need to perform control to rotate any joint other than the first joint 31, the fifth joint 35, and the sixth joint 36. In fact, in Figure 8, the changes in the rotation angles of the second joint 32 (Figure 8B), the third joint 33 (Figure 8C), the fourth joint 34 (Figure 8D), and the seventh joint 37 (Figure 8G) are small. However, other joints may be rotated during the swing travel as long as they do not interfere with the prevention of tipping over and the prevention of protrusion of the distal arm region 28C.

[0058] The above example shows a case where the center of gravity GP1 of the arm unit 28 is located forward of the first rotation axis J1 in the direction of travel of the carriage unit 22. In this case, the control unit 70 controls the first joint 31 so that, with the center of gravity GP1 of the arm unit 28 located forward of the first rotation axis J1 in the direction of travel of the carriage unit 22, the center of gravity GP1 of the arm unit 28 moves in a direction closer to the center of rotation than the center of gravity position before the start of rotation, and controls the intermediate arm adjustment unit 28B so that the tip-side arm region 28C moves in a direction away from the center of rotation RC compared to when the intermediate arm adjustment unit 28B (fifth joint 35, sixth joint 36) is not operated. Such a forward-leaning posture of the arm unit 28 has the effect of preventing the zero moment point ZMP from approaching the rear end of the support area SA during accelerated travel, which generates a rearward inertial force.

[0059] Conversely, the center of gravity GP1 of the arm unit 28 may be located rearward of the first rotation axis J1 in the direction of travel of the carriage unit 22. In this case, the control unit 70 controls the first joint 31 so that, with the center of gravity GP1 of the arm unit 28 located rearward of the first rotation axis J1 in the direction of travel of the carriage unit, the center of gravity GP1 of the arm unit 28 moves in a direction closer to the rotation center RC than the center of gravity position before the start of rotation, and controls the intermediate arm adjustment unit 28B so that the tip-side arm region 28C moves in a direction closer to the rotation center RC compared to when the intermediate arm adjustment unit 28B (fifth joint 35, sixth joint 36) is not operated. Such a rearward tilting posture of the arm unit 28 has the effect of preventing the zero moment point ZMP from approaching the front end of the support area SA during deceleration travel, which generates a forward inertial force.

[0060] When the arm unit 28 is in a backward tilt position, the control unit 70 rotates the first joint 31 in the opposite direction to when the arm unit 28 is in a forward tilt position. This causes the center of gravity GP1 of the arm unit 28 to move more toward the rotation center RC than it did before the start of rotation. This prevents the zero moment point ZMP from approaching the edge of the support area SA in the opposite direction from the rotation center RC, preventing the mobile robot 26 from tipping over.

[0061] The control unit 70 further rotates the fifth joint 35 and the sixth joint 36. The direction of rotation of the fifth joint 35 and the sixth joint 36 when the arm unit 28 is in the backward tilting posture is also the same as when the arm unit 28 is in the forward tilting posture in that, compared to when the fifth joint 35 and the sixth joint 36 are not rotated, the distal arm region 28C moves in a direction having a component opposite to the direction of movement of the distal arm region 28C due to rotation of the first joint 31. However, since this direction is a direction approaching the rotation center RC, from this point of view, it is the opposite direction to the direction of movement of the distal arm region 28C when the arm unit 28 is in the forward tilting posture.

[0062] The position of the arm portion 28 during turning travel, whether the center of gravity GP1 is in front of or behind the first rotation axis J1, may be selected depending on whether acceleration travel or deceleration travel is expected before, during, or after turning travel.

[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 including one orthogonal rotation axis perpendicular to the first rotation axis (J1), or multiple joints (32, 33, 34) each including multiple orthogonal rotation axes (J2, J3, J4) perpendicular to the first rotation axis and parallel to one another, and the control unit (70) controls the first joint (31) during the rotational travel of the carriage unit (22) so that the center of gravity position (GP1) of the arm unit (28) moves in a direction closer to the rotation center (RC) than the center of gravity position before the start of rotation, and controls the intermediate arm adjustment unit (28B) so that the tip-side arm region (28C) moves in a direction having a component in the opposite direction to the direction of movement of the tip-side arm region (28C) due to rotation of the first joint (31) compared to when the intermediate arm adjustment unit (28B) is not operated. (Supplementary Note 2) The mobile robot (26) according to Supplementary Note 1, wherein the control unit (70) controls the first joint (31) so that, while the center of gravity (GP1) of the arm unit (28) is located forward of the first rotation axis (J1) in the direction of travel of the carriage unit (22), the center of gravity (GP1) of the arm unit (28) moves in a direction closer to the center of rotation than the center of gravity position before the start of rotation, and controls the intermediate arm adjustment unit (28B) so that the tip-side arm region (28C) moves in a direction away from the center of rotation compared to when the intermediate arm adjustment unit (28B) is not operated.(Supplementary Note 3) The mobile robot (26) according to Supplementary Note 1, wherein the control unit (70) controls the first joint (31) so that, with the center of gravity (GP1) of the arm unit (28) located rearward of the first rotation axis (J1) in the direction of travel of the carriage unit (22), the center of gravity (GP1) of the arm unit (28) moves closer to the center of rotation (RC) than the center of gravity position before the start of rotation, and controls the intermediate arm adjustment unit (28B) so that the tip-side arm region (28C) moves closer to the center of rotation compared to when the intermediate arm adjustment unit (28B) is not operated. (Appendix 4) The mobile robot (26) of any one of Appendices 1 to 3, wherein 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 (28A) from the fifth joint (35). (Supplementary Note 5) The mobile robot (26) according to any one of Supplementary Notes 1 to 4, 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. 2023-170787, 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 moving 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 moving mechanism and the arm unit, wherein the carriage-side arm adjustment unit includes one joint including an orthogonal rotation axis perpendicular to the first rotation axis, or a plurality of joints each including a plurality of orthogonal rotation axes perpendicular to the first rotation axis and parallel to each other, and the control unit a control unit for controlling the first joint so that, during a turning motion of the carriage unit, the center of gravity of the arm unit moves in a direction closer to a center of turning than the center of gravity position before turning begins, and a control unit for controlling the intermediate arm adjustment unit so that the tip-side arm region moves in a direction having a component opposite to the direction of movement of the tip-side arm region due to rotation of the first joint, compared to a case in which the intermediate arm adjustment unit is not operated.

2. A mobile robot as described in claim 1, wherein the control unit controls the first joint so that, with the center of gravity of the arm unit being forward in the direction of travel of the cart unit relative to the first rotation axis, the center of gravity of the arm unit moves in a direction closer to the center of rotation than the center of gravity position before the start of rotation, and controls the intermediate arm adjustment unit so that the tip arm region moves in a direction away from the center of rotation compared to when the intermediate arm adjustment unit is not operated.

3. A mobile robot as described in claim 1, wherein the control unit controls the first joint so that, with the center of gravity of the arm unit being located rearward of the carriage unit in the direction of travel relative to the first rotation axis, the center of gravity of the arm unit moves in a direction closer to the center of rotation than the center of gravity position before the start of rotation, and controls the intermediate arm adjustment unit so that the tip arm region moves toward the center of rotation compared to when the intermediate arm adjustment unit is not operated.

4. A mobile robot as described in 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.

5. 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 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 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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