Transport Auxiliary Equipment

Abstract

To realize better assist in moving an object.SOLUTION: A conveyance-assisting device 1 comprises: first and second mecanum wheels 21R,21L; first and second motors 22R,22L; first and second current sensors SW1,SW2 which severally detect induction current flowing through the first and second motors 22R,22L in rotating each of the first and second mecanum wheels 21R,21L; and a controller 4. The controller 4 independently estimates acceleration of each of the first and second mecanum wheels 21R,21L on the basis of detection signals of the first and second current sensors SW1,SW2, determines a moving direction of the bed 10 on the basis of acceleration of each of the first and second mecanum wheels 21R,21L, and severally drives the first and second mecanum wheels 21R,21L via the first and second motors 22R,22L so as to assist movement of the bed 10 along the moving direction.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present disclosure relates to a transport assist device. [Background technology]

[0002] For example, Patent Document 1 discloses an auxiliary propulsion system that uses Mecanum wheels in the drive unit. This auxiliary propulsion system includes a pair of Mecanum wheels connected to a chassis, a motor that drives each Mecanum wheel, and a control system that detects changes in the rotation speed of each motor.

[0003] According to Patent Document 1, when the chassis moves in a predetermined direction, the operator applies a force in the same direction. When each Mecanum wheel rotates due to the applied force, the resulting change in rotation speed is reported to the control system. Based on this report, the control system starts the electric rotation of the motor. This electric rotation assists the movement of the chassis. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2016-525977 Summary of the Invention [Problem to be solved by the invention]

[0005] When using the configuration described in Patent Document 1, it is necessary to properly determine the moving direction of the object in order to achieve better assistance. To make this determination, it is conceivable to attach a force sensor, such as a strain gauge type or a piezoelectric type, to the object, but there is still room for improvement in making a more appropriate determination.

[0006] The technology disclosed herein has been made in consideration of the above points, and its purpose is to provide better assistance when moving an object. [Means for solving the problem]

[0007] A first aspect of the present disclosure relates to a transportation assist device for assisting movement of an object caused by an external force, the transportation assist device including first and second Mecanum wheels attached to the object, first and second motors drivingly connected to the first and second Mecanum wheels, first and second current sensors detecting induced currents flowing through the first and second motors as the first and second Mecanum wheels rotate, respectively, and a controller controlling the first and second motors, wherein the controller estimates accelerations of the first and second Mecanum wheels individually based on detection signals from the first and second current sensors, determines a movement direction of the object based on the accelerations of the first and second Mecanum wheels, and drives the first and second Mecanum wheels via the first and second motors to assist movement of the object along the movement direction.

[0008] According to the first aspect, by detecting the induced current, it is possible to estimate the torque that caused the induced current (the torque that tries to rotate the Mecanum wheel) and, in turn, the acceleration corresponding to that torque. Here, the sign of the induced current corresponds to the sign of the estimated acceleration, and can be related to the rotation direction of each wheel.

[0009] Furthermore, when multiple Mecanum wheels are used, the rotational direction of each wheel can be correlated with the translational direction of the entire transport assist device. The translational direction of the entire transport assist device is considered to be approximately the same as the direction of external force, and therefore the direction of movement of the object. Therefore, the movement direction of the object can be determined from the rotational direction of each wheel. By providing assistance along the determined movement direction, it is possible to achieve better assistance that reflects the actual rotational status of each wheel.

[0010] To detect the acceleration, a six-axis sensor, for example, could be used. However, six-axis sensors are generally susceptible to vibration. Therefore, if the configuration or mounting method of each Mecanum wheel changes, or if a sleeper turns over in bed when using a bed as the target, the sensor's detection value will change significantly, making it difficult to accurately determine direction. In contrast, using induced current as in the present disclosure allows for more accurate direction determination.

[0011] According to a second aspect of the present disclosure, the first Mecanum wheel may include a first wheel body that rotates about a first rotation axis and a plurality of first barrel-shaped rollers arranged along the outer periphery of the first wheel body and each rotating about a first inclined axis inclined with respect to the first rotation axis; and the second Mecanum wheel may include a second wheel body that rotates about a second rotation axis extending parallel to the first rotation axis and a plurality of second barrel-shaped rollers arranged along the outer periphery of the second wheel body and each rotating about a second inclined axis inclined with respect to the second rotation axis in a direction different from the first inclined axis.

[0012] According to the second aspect, the translational direction of the entire transport assist device can be made different when both the first and second Mecanum wheels rotate in the same direction and when one of the first and second Mecanum wheels rotates in a different direction. Because the rotational direction of each wheel is clearly distinguished depending on the translational direction, the movement direction of the object can be determined more accurately. This is advantageous for achieving better assistance when moving the object.

[0013] Furthermore, according to a third aspect of the present disclosure, the first and second rotation axes may both be perpendicular to the front-to-back direction of the object and extend in the left-to-right direction along the conveying surface of the object, and the first inclined axis may be inclined relative to the second inclined axis so as to be linearly symmetrical with respect to the front-to-back direction.

[0014] According to the third aspect, when the first and second Mecanum wheels rotate in the same direction, the entire transport assist device translates in the forward / backward direction. On the other hand, when one of the first and second Mecanum wheels rotates in a different direction, the entire transport assist device translates in the left / right direction. Because the rotation direction of each wheel is clearly distinguished during forward / backward movement and left / right movement, the direction of movement of the object can be determined more accurately. This is advantageous for achieving better assistance when moving the object.

[0015] According to a fourth aspect of the present disclosure, the controller may calculate a difference between the acceleration of the first Mecanum wheel and the acceleration of the second Mecanum wheel, and determine the direction of movement based on the magnitude of the difference.

[0016] According to the fourth aspect, when the first and second Mecanum wheels are both rotating in the same direction (i.e., when they are translating in the front-to-rear direction), the difference is substantially zero. On the other hand, when one of the first and second Mecanum wheels is rotating in a different direction, the difference is significantly greater than zero. Because the magnitude of the difference is clearly distinguished between forward-to-rear movement and left-to-right movement, the movement direction of the object can be determined more accurately. This is advantageous for achieving better assistance when moving the object.

[0017] According to a fifth aspect of the present disclosure, the controller may determine whether the direction of movement is the forward / backward direction based on the acceleration of each of the first and second mecanum wheels, and if it determines that the direction of movement is the forward / backward direction, set each command rotation speed to rotate both the first and second mecanum wheels forward or backward, and during this setting, set the absolute values ​​of the command rotation speeds of the first mecanum wheel and the second mecanum wheel to the same value.

[0018] According to the fifth aspect, by making the absolute value of the command rotation speed equal during forward and backward movement, it is possible to realize more stable forward and backward movement regardless of the posture of the object, which is advantageous in realizing better assistance during movement of the object.

[0019] According to a sixth aspect of the present disclosure, the controller may determine whether the direction of movement is the left-right direction based on the acceleration of each of the first and second Mecanum wheels, and if it determines that the direction of movement is the left-right direction, set command rotation speeds to rotate one of the first and second Mecanum wheels forward and the other backward, and when setting the command rotation speeds, make the absolute values ​​of the command rotation speeds of the first Mecanum wheel and the second Mecanum wheel equal.

[0020] According to the sixth aspect, by making the absolute value of the command rotation speed equal during left and right movement, it is possible to achieve more stable left and right movement regardless of the posture of the object, which is advantageous in achieving better assistance during movement of the object.

[0021] According to a seventh aspect of the present disclosure, the object may be a caster bed, and the first and second Mecanum wheels may be attached to a lower portion of the caster bed.

[0022] According to the seventh aspect, the object is a bed with casters. The present disclosure can provide good assistance even when moving a heavy object such as a bed with casters. [Effects of the Invention]

[0023] As described above, according to the present disclosure, better assistance can be achieved when moving an object. [Brief explanation of the drawings]

[0024] [Figure 1]1 is a side view illustrating an example of the overall configuration of a transport assist device and a bed with casters. FIG. [Figure 2] 1 is a bottom view illustrating an example of the overall configuration of a transport assist device and a bed with casters. FIG. [Figure 3] FIG. 2 is a perspective view illustrating the configuration of a transport assist device. [Figure 4] FIG. 2 is a plan view illustrating the configuration of a transport assist device. [Figure 5] FIG. 2 is a side view illustrating the configuration of a transport assist device. [Figure 6] FIG. 2 is a block diagram illustrating the configuration of a control system of the transport assist device. [Figure 7] 10A and 10B are diagrams for explaining the operation of the first and second Mecanum wheels. [Figure 8] FIG. 2 is a diagram for explaining a detection target of a six-axis sensor. [Figure 9] 4 is a flowchart illustrating main processing performed by a controller. [Figure 10] 10 is a flowchart illustrating a process related to determination of a movement direction. [Figure 11] 10 is a flowchart illustrating a safety limit control. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0026] FIG. 1 is a side view illustrating the overall configuration of a transport assistance device 1 and a bed with casters 10, and FIG. 2 is a bottom view illustrating the overall configuration of the transport assistance device 1 and a bed with casters 10. As shown in FIG.

[0027] 3 is a perspective view illustrating the configuration of the transport auxiliary device 1, FIG. 4 is a plan view illustrating the configuration of the transport auxiliary device 1, and FIG. 5 is a side view illustrating the configuration of the transport auxiliary device 1.

[0028] Fig. 6 is a block diagram illustrating the configuration of the control system of the transport assist device 1, Fig. 7 is a diagram for explaining the operation of the first and second Mecanum wheels 21R, 21L, and Fig. 8 is a diagram for explaining the detection target of the six-axis sensor SW5.

[0029] The transport assist device 1 is attached to a predetermined object. The transport assist device 1 is a device for assisting the movement of the object by an external force (for example, an external force applied by the transporter 100).

[0030] 1 and 2, the object according to this embodiment is a bed with casters (hereinafter simply referred to as a "bed") 10. This bed 10 is equipped with a plurality of casters 14 including front wheels 14F and rear wheels 14B, and is intended to be used as, for example, a medical bed.

[0031] Hereinafter, the longitudinal direction of bed 10, i.e., the direction in which a person lies on bed 10, will be referred to as the "front-to-back direction" or "longitudinal direction," the direction toward the feet along the front-to-back direction will be referred to as the "front," and the direction toward the pillow will be referred to as the "rear."

[0032] Similarly, the short direction of the bed 10, that is, the direction perpendicular to the front-to-back direction on a horizontal plane, is defined as the "left-to-right direction" or "lateral direction," and the direction along this left-to-right direction toward the depth of the paper in FIG. 1 is defined as the "right," and the direction along this left-to-right direction toward the front of the paper in FIG. 1 is defined as the "left" (see FIG. 2 for details). Note that the "left-to-right direction" here refers to the left-to-right direction when viewed from the rear to the front. In the following description, "lateral movement" refers to movement along this left-to-right direction. The left-to-right direction (lateral direction) can also be defined as the direction perpendicular to the front-to-back direction and extending along the transport surface F (the floor surface along which the bed 10 travels).

[0033] The bed 10 is supported at one end in the front-rear direction (the rear end in the illustrated example) by the carrier 100. The transport assist device 1 operates to assist the carrier 100 in manually pushing and moving the bed 10 supported by the carrier 100.

[0034] 1, the bed 10 includes a bed body 11 on which a mattress (not shown) is placed, a frame 12 that supports the bed body 11 from below, a lifting unit 13 that raises and lowers the bed body 11 relative to the frame 12, and a plurality of casters 14 (four in the illustrated example) arranged on the underside of the bed 10. When used as a medical bed, the bed 10 weighs, for example, between 60 kg and 300 kg.

[0035] Here, the bed body 11 has a headboard 11h arranged at the rear end side of the bed 10, a footboard 11f arranged at the front end side opposite the rear end side in the front-to-rear direction, and side rails 11s arranged on both the left and right sides of the bed 10.

[0036] Of these, the headboard 11h is supported from the rear by the carrier 100 to manually move the bed 10. The headboard 11h functions as a support part to which the carrier 100 applies force. A handle, a grip, or other member may be attached to the headboard 11h or integrated with the headboard 11h, thereby making these members the support part. The footboard 11f, the side rails 11s, etc. may also be supported.

[0037] As shown in FIG. 2, the frame 12 is configured in a rectangular frame shape, and its four sides are formed by a front frame 12F, a right frame 12R, a left frame 12L, and a rear frame 12B.

[0038] Here, the front frame 12F is disposed on the front side of the bed 10 and extends in the left-right direction. The right frame 12R is disposed on the right side of the bed 10 and extends in the front-rear direction. The left frame 12L is disposed on the left side of the bed 10 and extends in the front-rear direction. The rear frame 12B is disposed on the rear side of the bed 10 and extends in the left-right direction.

[0039] 1 and 2, the front wheels 14F and rear wheels 14B that make up the plurality of casters 14 are arranged at the four corners of the underside of the bed 10. Two front wheels 14F and two rear wheels 14B are provided along the left-right direction. The plurality of casters 14 support the frame 12, the lifting section 13, and the bed body 11 on the conveyance surface F.

[0040] Each caster 14 is a so-called free caster and includes a mounting portion 14a fixed to the underside of the bed 10, a fork portion 14b that can rotate about a rotation axis Oc relative to the mounting portion 14a, and a wheel 14c that is rotatably supported by the fork portion 14b. The rotation axis Oc of each fork portion 14b extends in the vertical direction (the height direction of the bed 10). The rotation axis of each wheel 14c extends along a horizontal plane. This rotation axis is tilted in the left-right direction as the fork portion 14b rotates relative to the mounting portion 14a.

[0041] The transport auxiliary device 1 is disposed so as to bridge between a midpoint in the front-to-rear direction of the right frame 12R and a midpoint in the front-to-rear direction of the left frame L. The transport auxiliary device 1 is disposed between the front wheels 14F and the rear wheels 14B in the front-to-rear direction, and is disposed in the center of the bed 10 in the left-to-right direction.

[0042] 1 to 6, the transportation auxiliary device 1 includes a storage box 6, a fixture 7, first and second Mecanum wheels 21R, 21L, first and second motors 22R, 22L, a controller 4, first and second current sensors SW1, SW2, first and second rotation sensors SW3, SW4, and a six-axis sensor SW5 (the first and second motors 22R, 22L and the sensors SW1 to SW5 are only shown in FIG. 6). In the following, of the first and second Mecanum wheels 21R, 21L, the first Mecanum wheel 21R is assumed to be located on the right side, and the second Mecanum wheel 21L is assumed to be located on the left side.

[0043] Of these elements, the controller 4 and the six-axis sensor SW5 are housed in the housing box 6, while the mounting fixture 7, the first and second Mecanum wheels 21R, 21L, the first and second motors 22R, 22L, the first and second current sensors SW1, SW2, and the first and second rotation sensors SW3, SW4 are located outside the housing box 6.

[0044] As described above, the storage box 6 stores the controller 4. The storage box 6 is disposed between the first Mecanum wheel 21R and the second Mecanum wheel 21L in the left-right direction.

[0045] The storage box 6 is attached to a fixture 7 together with the first and second Mecanum wheels 21R, 21L, and is attached to the bottom of the bed 10 via this fixture 7. The fixture 7 is detachable from the bottom of the bed 10. In other words, the transport assistance device 1 according to this embodiment can be retrofitted to the bed 10 and can be detached as needed.

[0046] More specifically, as shown in Figures 2 to 5, the mounting fixture 7 according to this embodiment has a front rail member 71f, a rear rail member 71b, and first and second arm members 72R and 72L that rotatably support the first and second Mecanum wheels 21R and 21L, respectively.

[0047] The front rail member 71f and the rear rail member 71b are spaced apart in the front-to-rear direction and span the front-to-rear center of the right frame 12R and the front-to-rear center of the left frame 12L, respectively. The front rail member 71f and the rear rail member 71b are detachable from the right frame 12R and the left frame 12L. The first and second Mecanum wheels 21R, 21L and the storage box 6 are arranged between the front rail member 71f and the rear rail member 71b in the front-to-rear direction.

[0048] 3 and 4, the first arm member 72R is swingably supported by the rear rail member 71b. The front end of the first arm member 72R rotatably supports the first Mecanum wheel 21R. The first arm member 72R is positioned between the first Mecanum wheel 21R and the storage box 6 in the left-right direction.

[0049] One end of a first tension spring 75R is anchored to the upper end of the first arm member 72R, and the other end of the first tension spring 75R is anchored to a first bracket 76R fixed to the front rail member 71f.

[0050] 3 and 4, the second arm member 72L is swingably supported by the rear rail member 71b, similar to the first arm member 72R. The front end of the second arm member 72L rotatably supports the second Mecanum wheel 21L. The second arm member 72L is positioned between the second Mecanum wheel 21L and the storage box 6 in the left-right direction.

[0051] One end of a second tension spring 75L is secured to the upper end of the second arm member 72L, and the other end of the second tension spring 75L is secured to a second bracket 76L fixed to the front rail member 71f (see also FIG. 5).

[0052] As shown in FIGS. 1 and 2, the first and second Mecanum wheels 21R, 21L are attached to the lower part (bottom) of the bed 10. The first and second Mecanum wheels 21R, 21L are in contact with the conveying surface F of the bed 10. The conveying surface F is only shown in FIG. 1. The first and second Mecanum wheels 21R, 21L are disposed rearward of the front wheels 14F and in front of the rear wheels 14B. In this embodiment, the first and second Mecanum wheels 21R, 21L are disposed side by side in the left-right direction, which is the short side direction, as shown in FIG. 2.

[0053] In detail, as shown in Figures 3 to 5, the first Mecanum wheel 21R has a first wheel body 211R that rotates around a first rotation axis Oy1, and a plurality of first barrel-shaped rollers 212R that are arranged along the outer periphery of the first wheel body 211R and each rotates around a first inclined axis Or that is inclined with respect to the first rotation axis Oy1.

[0054] On the other hand, the second Mecanum wheel 21L has a second wheel body 211L that rotates around a second rotation axis Oy2, and a plurality of second barrel-shaped rollers 212L that are arranged along the outer periphery of the second wheel body 211L and each rotate around a second inclined axis Ol that is inclined in a direction different from the first inclined axis Or relative to the second rotation axis Oy2.

[0055] Here, both the first and second rotation axes Oy1 and Oy2 extend in the left-right direction. The first tilt axis Or is tilted with respect to the second tilt axis Ol so as to be symmetrical with respect to the front-to-rear direction (see the axis of symmetry Os in FIG. 4). In other words, if a plane extending in the up-down and front-to-rear directions is taken as a mirror plane, the first tilt axis Or and the second tilt axis Ol extend so as to be mirror-symmetrical with respect to the mirror plane.

[0056] Furthermore, when viewed from above (when viewed from a plane) as in Figure 4, the first and second inclined axes Or, Ol each extend from the inside to the outside in the left-right direction (from the center in the left-right direction to the right or left) as they move from the rear to the front along the fore-and-aft direction.

[0057] Specifically, the first inclined axis Or extends from the center to the right in the front-rear direction, while the second inclined axis Ol extends from the center to the left in the front-rear direction.

[0058] More specifically, the tilt angle θr of the first tilt axis Or relative to the first rotation axis Oy1 is set to 45° in plan view. Similarly, the tilt angle θl of the second tilt axis Ol relative to the second rotation axis Oy2 is also set to 45° in plan view. Note that the tilt direction and tilt angle of each barrel-shaped roller 212R, 212L are not limited to these examples. For example, the entire conveyance auxiliary device 1 may be rearranged from the state illustrated in FIG. 2 to a state rotated a predetermined angle around the z-axis extending in the vertical direction.

[0059] As described above, the first and second Mecanum wheels 21R, 21L are connected to each other via the front rail member 71f and the rear rail member 71b shown in Fig. 3 etc. Therefore, the first and second Mecanum wheels 21R, 21L move together in the front-rear and left-right directions and rotate together around a rotation axis perpendicular to the horizontal plane.

[0060] The first and second motors 22R, 22L are drivingly connected to the first and second Mecanum wheels 21R, 21L, respectively. Specifically, the first and second motors 22R, 22L are each configured as a so-called three-phase DC brushless motor. Both the first and second motors 22R, 22L are electrically connected to the controller 4 and are controlled by the controller 4.

[0061] The first and second motors 22R, 22L are supplied with motor currents corresponding to the torque loads during their respective rotations. The motor currents can be used to switch the rotation speeds of the first and second motors 22R, 22L and their rotation directions between forward and reverse.

[0062] The first motor 22R is connected to the first Mecanum wheel 21R so as to transmit a driving force (torque). The second motor 22L is connected to the second Mecanum wheel 21L so as to transmit a driving force (torque).

[0063] When the first motor 22R rotates, its driving force is transmitted to rotate the first Mecanum wheel 21R. Similarly, when the second motor 22L rotates, its driving force is transmitted to rotate the second Mecanum wheel 21L.

[0064] In this embodiment, the first Mecanum wheel 21R is configured to rotate forward by rotating the first motor 22R in the normal direction, and the first Mecanum wheel 21R is configured to rotate backward by rotating the first motor 22R in the reverse direction. Similarly, in this embodiment, the second Mecanum wheel 21L is configured to rotate forward by rotating the second motor 22L in the normal direction, and the second Mecanum wheel 21L is configured to rotate backward by rotating the second motor 22L in the reverse direction.

[0065] The first motor 22R is built into the first Mecanum wheel 21R, and the second motor 22L is built into the second Mecanum wheel 21L. By building the first and second motors 22R and 22L into the wheels in this way, the entire transport auxiliary device 1 can be simplified and made compact.

[0066] The first current sensor SW1 detects the induced current flowing through the first motor 22R when the first Mecanum wheel 21R rotates. That is, when the first Mecanum wheel 21R rotates due to an external force, the rotor and stator of the first motor 22R rotate relative to each other, generating an induced current. The induced current detected by the first current sensor SW1 corresponds to the q-axis current.

[0067] Here, the magnitude of the induced current is proportional to the torque acting on the first Mecanum wheel 21R when the first Mecanum wheel 21R rotates due to an external force. The magnitude of this torque is related to the magnitude of the external force received by the bed 10 and, ultimately, the amount of change in speed of the bed 10 due to the external force. The sign of the induced current is related to the direction of rotation of the first Mecanum wheel 21R when the first Mecanum wheel 21R rotates due to an external force. The sign of the induced current is opposite to the sign of the motor current that flows when the first motor 22R is driven.

[0068] The second current sensor SW2 detects the induced current flowing through the second motor 22L when the second Mecanum wheel 21L rotates. In other words, when the second Mecanum wheel 21L rotates due to an external force, the rotor and stator of the second motor 22L rotate relative to each other, generating an induced current. The induced current detected by the second current sensor SW2 corresponds to the q-axis current.

[0069] Here, the magnitude of the induced current is proportional to the torque acting on the second Mecanum wheel 21L when the second Mecanum wheel 21L rotates due to an external force. The magnitude of this torque is related to the magnitude of the external force received by the bed 10 and, ultimately, the amount of change in speed of the bed 10 due to the external force. The sign of the induced current is related to the direction of rotation of the second Mecanum wheel 21L when the second Mecanum wheel 21L rotates due to an external force. The sign of the induced current is opposite to the sign of the motor current that flows when the second motor 22L is driven.

[0070] For example, if an external force causes the first Mecanum wheel 21R to rotate forward and the second Mecanum wheel 21L to rotate backward at the same time, the first current sensor SW1 will detect an induced current with the same sign as when the first motor 22R is rotated in the reverse direction, and the second current sensor SW2 will detect an induced current with the same sign as when the second motor 22L is rotated in the forward direction.

[0071] The controller 4 according to this embodiment is configured to provide assistance in the forward direction, i.e., in the direction of action of the external force, by feeding back the torque related to the induced current (more specifically, by rotating the first and second motors 22R, 22L at a command rotation speed corresponding to the torque).

[0072] Furthermore, the first and second rotation sensors SW3 and SW4 detect the rotation speeds of the first and second motors 22R and 22L, respectively. Specifically, the first and second rotation sensors SW3 and SW4 according to this embodiment are each configured as encoders. The first rotation sensor SW3, which functions as an encoder, detects the rotation speed and rotation angle of the first motor 22R, and the second rotation sensor SW4, which also functions as an encoder, detects the rotation speed and rotation angle of the second motor 22L.

[0073] 8, the six-axis sensor SW5 can detect acceleration in three directions, namely, along the x-axis extending in the front-rear direction, the y-axis extending in the left-right direction, and the z-axis extending in the up-down direction, as well as the angular velocity of the rotation angle around the x-axis (so-called roll angle φ), the angular velocity of the rotation angle around the y-axis (so-called pitch angle θ), and the angular velocity of the rotation angle around the z-axis (so-called yaw angle ψ). The detection signals of the six-axis sensor SW5 are input to the controller 4.

[0074] The controller 4 controls the first and second motors 22R, 22L based on electrical signals input from the various sensors SW1 to SW5. The controller 4 has a CPU, a memory, and an input / output bus, and is configured by, for example, a control board.

[0075] Specifically, the controller 4 according to this embodiment sets the command rotation speeds of the first and second motors 22R, 22L based on the detection signals input from the various sensors SW1 to SW5. The controller 4 inputs motor currents corresponding to the set command rotation speeds to the first and second motors 22R, 22L. As a result, the first and second motors 22R, 22L rotate at the command rotation speeds set by the controller 4.

[0076] At this time, the first Mecanum wheel 21R rotates at the same rotation speed as the first motor 22R, and the second Mecanum wheel 21L rotates at the same rotation speed as the second motor 22L. In other words, setting the command rotation speeds of the first and second motors 22R and 22L is equivalent to setting the command rotation speeds of the first and second Mecanum wheels 21R and 21L.

[0077] Furthermore, by changing the sign of each command rotation speed, the rotation direction of the first motor 22R and the second motor 22L can be changed individually. By changing the rotation direction of each motor 22R, 22L, the corresponding Mecanum wheels 21R, 21L can be switched between forward rotation and backward rotation.

[0078] In this embodiment, when the first Mecanum wheel 21R located on the right side is rotated forward, a thrust force can be applied to the transport auxiliary device 1 and the bed 10 diagonally forward to the left (arrow A in FIG. 7). 11 7). On the other hand, when the second Mecanum wheel 21L located on the left side is rotated forward, the transport assist device 1 can apply a thrust force to the bed 10 diagonally forward to the right (see arrow A in FIG. 7). 12 (See

[0079] 7, for example, when both the first and second Mecanum wheels 21R and 21L are rotated forward, the leftward thrust applied by rotating the first Mecanum wheel 21R forward and the rightward thrust applied by rotating the second Mecanum wheel 21L forward cancel each other out, and a forward thrust can be applied to the entire transport assist device 1. This thrust can assist the forward movement of the bed 10.

[0080] Similarly, when the first Mecanum wheel 21R located on the right side is rotated backward, a thrust force can be applied to the transport auxiliary device 1 and the bed 10 obliquely backward to the right (arrow A in FIG. 7). 21 7). On the other hand, when the second Mecanum wheel 21L located on the left side is rotated backward, the transport assist device 1 can apply a thrust force to the bed 10 obliquely backward to the left (see arrow A in FIG. 7).22 (See

[0081] 7, for example, when both the first and second Mecanum wheels 21R, 21L are rotated backward, the rightward thrust applied by rotating the first Mecanum wheel 21R backward and the leftward thrust applied by rotating the second Mecanum wheel 21L backward cancel each other out, allowing the entire transport assist device 1 to exert a backward thrust. This thrust can assist the backward movement of the bed 10.

[0082] On the other hand, when one of the first and second Mecanum wheels 21R, 21L is rotated forward and the other is rotated backward, the transport auxiliary device 1 applies a thrust to the bed 10 in the left and right directions.

[0083] In the example shown in the lower left of FIG. 7, a thrust in the right direction is applied to the bed 10 by rotating the first Mecanum wheel 21R backward and rotating the second Mecanum wheel 21L forward.

[0084] Furthermore, when only one of the first and second Mecanum wheels 21R, 21L is rotated forward or backward, the transport auxiliary device 1 applies a thrust to the bed 10 in an oblique direction.

[0085] In the example shown in the lower right of Figure 7, by rotating only the second Mecanum wheel 21L forward, the bed 10 can be propelled diagonally forward to the right. This can assist the diagonal movement of the bed 10. On the other hand, by rotating only the first Mecanum wheel 21R forward, it can assist the movement of the bed 10 diagonally forward to the left (not shown).

[0086] The transport assistance device 1 is configured to assist the transporter 100 in transporting the bed 10 through the thrust applied as described above by operating the first and second motors 22R, 22L based on the detection signals of various sensors SW1 to SW5.

[0087] To achieve such assistance, the controller 4 according to this embodiment determines the direction in which the external force acts (hereinafter simply referred to as the "direction of action") based on the detection signals of the various sensors SW1 to SW5, and operates the first and second motors 22R, 22L to exert a thrust along the direction of action.

[0088] For example, if it is determined that an external force is acting from the rear toward the front as a result of the headboard 11h being pushed forward from the rear, the controller 4 rotates both the first and second motors 22R, 22L forward, thereby rotating both the first and second Mecanum wheels 21R, 21L forward, which makes it possible to assist the forward movement of the bed 10 as shown in the upper left of FIG.

[0089] Furthermore, the first and second Mecanum wheels 21R, 21L are allowed to rotate forward and backward even when the corresponding motors 22R, 22L are not driven, which reduces wobbling when the bed 10 is manually pushed and stabilizes the transport of the bed 10.

[0090] The assistance provided by the controller 4 will be described in detail below with reference to FIG. 9 and other figures.

[0091] Here, Fig. 9 is a flowchart illustrating an example of main processing performed by the controller 4. Fig. 10 is a flowchart illustrating processing related to determination of the movement direction. Fig. 11 is a flowchart illustrating safety limit control.

[0092] First, in step S1 of FIG. 9, the controller 4 reads the detection signals of the five sensors SW1 to SW5 described above.

[0093] In the following step S2, the controller 4 estimates the accelerations of the first and second Mecanum wheels 21R, 21L individually based on the detection signals of the first and second current sensors SW1, SW2.

[0094] Hereinafter, the acceleration of the first Mecanum wheel 21R will be referred to as the “first acceleration,” and the acceleration of the second Mecanum wheel 21R will be referred to as the “second acceleration.” Both the first and second accelerations are the time derivatives of the translational velocity, that is, so-called tangential accelerations.

[0095] The magnitude of the induced current detected by each of the first and second current sensors SW1 and SW2 is proportional to the torque (particularly the torque caused by the reaction force) acting on the first and second Mecanum wheels 21R and 21L as they rotate. Based on this proportional relationship, the controller 4 individually estimates the first torque acting on the first Mecanum wheel 21R and the second torque acting on the second Mecanum wheel 21L. In this case, a proportionality coefficient pre-stored in the controller 4 can be used to convert the induced current to torque.

[0096] The controller 4 according to this embodiment assists the movement of the bed 10 by driving the first and second motors 22R and 22L against the reaction forces corresponding to the first and second torques.

[0097] In order to realize such an assist, the controller 4 estimates a first acceleration corresponding to the first torque and a second acceleration corresponding to the second torque based on the following equations (1) and (2).

[0098] a r =(-1) T r / (R m) …(1) a l =(-1) T l / (R m) …(2) In the above equations (1) and (2), T r [Nm] is the first torque, T l [Nm] is the second torque. r [m / s 2 ] is the first acceleration corresponding to the first torque, and a l [m / s 2 ] is the second acceleration corresponding to the second torque.

[0099] Additionally, R [m] is the tire radius of each of the first and second Mecanum wheels 21R, 21L, and m [kg] is the mass of each of the first and second Mecanum wheels 21R, 21L. In this embodiment, the tire radius R and mass m are the same for the first Mecanum wheel 21R and the second Mecanum wheel 21L.

[0100] In the following step S3, the controller 4 estimates the translational acceleration of the first and second Mecanum wheels 21R, 21L based on the detection signals of the first and second current sensors SW1, SW2.

[0101] Specifically, the controller 4 estimates the first and second accelerations a based on the detection signals of the first and second current sensors SW1 and SW2. r ,a l are used to estimate the vertical acceleration indicating the translational acceleration of the first and second Mecanum wheels 21R, 21L in the front-to-rear direction, and the lateral acceleration indicating the translational acceleration of the first and second Mecanum wheels 21R, 21L in the lateral direction.

[0102] More specifically, when the first and second Mecanum wheels 21R and 21L are configured as shown in FIGS. 3 to 5, the controller 4 controls the first acceleration a r and the second acceleration a l The vertical acceleration is estimated by adding the first acceleration a r and the second acceleration a l The lateral acceleration is estimated by calculating the difference between the calculated values. The details of these calculations are shown in the following equations (3) and (4).

[0103] a x =(a r +a l ) / twenty three) a y =(a l -a r ) / twenty four) In the above equations (3) and (4), a x [m / s 2 ] is the vertical acceleration, and a y [m / s 2] is the lateral acceleration. The sign of equation (3) is defined as positive for the front and negative for the rear. The sign may be reversed between the front and rear. Similarly, the sign of equation (4) is defined as positive for the left and negative for the right. The sign may be reversed between the left and right.

[0104] Note that the relational expressions such as equations (3) and (4) also hold true for the rotation speeds of the first and second motors 22R and 22L (that is, the rotation speeds of the first and second Mecanum wheels 21R and 21L).

[0105] where r r [rpm] is the rotation speed of the first motor 22R in the front-rear direction (hereinafter also referred to as "first rotation speed"), and r l [rpm] is the rotation speed of the second motor 22L in the front-rear direction (hereinafter also referred to as the "second rotation speed"). r is the rotation speed detected by the first rotation sensor SW3, and the second rotation speed r l is the rotation speed detected by the second rotation sensor SW4.

[0106] And r x [rpm] is the rotation speed of the first and second motors 22R, 22L as a whole in the front-rear direction (hereinafter, this will also be referred to as the "vertical rotation speed"), and r y Let [rpm] be the total rotation speed of the first and second motors 22R, 22L in the left-right direction (hereinafter also referred to as the "horizontal rotation speed"). When the first and second Mecanum wheels 21R, 21L are configured and arranged as in this embodiment, the following equations (5) and (6) hold.

[0107] r x =(r r +r l ) / twenty five) r y =(r r -r l ) / 2 …(6) The above equations (5) and (6) can be transformed into the following equations (7) and (8). As shown in the following equations (7) and (8), r x and ry By setting r r and r l can be uniquely determined.

[0108] r r =r x +r y …(7) r l =r x -r y …(8) Next, based on the detection signals of the first and second rotation sensors SW3 and SW4, the controller 4 allows the first and second Mecanum wheels 21R and 21L to be driven on the condition that the rotation speeds of the first and second Mecanum wheels 21R and 21L are equal to or greater than a predetermined first threshold value.

[0109] More specifically, in step S4 following step S3, the controller 4 determines whether or not either one of the following relational expressions (5) and (6) is satisfied. Through this determination, it is possible to confirm whether or not the bed 10 is actually being transported (transportation confirmation).

[0110] r x ≧T1 …(9) r y ≧T1 …(10) In the above equations (9) and (10), T1 [1 / s] is the first threshold value. The magnitude of the first threshold value is stored in advance in the memory of the controller 4, and is set to be equal in the above equations (13) and (14).

[0111] If neither of the above formulas (9) nor (10) is satisfied, the controller 4 determines that the bed 10 is not being transported by an external force and does not allow the first and second motors 22R and 22L to be driven (step S4: NO). In this case, the control process proceeds to step S5. In step S5, the controller 4 sets the command rotation speeds of the first and second motors 22R and 22L to zero.

[0112] If the process proceeds to step S5, the command rotation speeds of the first and second motors 22R, 22L are set to zero in the subsequent steps S7 and S8 (steps S7 and S8 will be described in detail later). In this case, the controller 4 ends the flow shown in FIG. 9 without driving the first and second motors 22R, 22L.

[0113] On the other hand, if at least one of the above formulas (9) and (10) is satisfied, the controller 4 determines that the bed 10 is being transported by an external force and allows the first and second motors 22R and 22L to be driven (step S4: YES). In this case, the control process proceeds to step S6. In this step S6, the controller 4 sets the command rotation speeds of the first and second motors 22R and 22L to assist the manual movement caused by the external force.

[0114] Steps S11 to S15 in Fig. 10 each illustrate the processing executed in step S6 in Fig. 9. That is, when the control process proceeds to step S6, the controller 4 starts step S11 in Fig. 10.

[0115] In steps S11 to S13 described below, the controller 4 calculates the first and second accelerations a estimated in step S2 of FIG. r ,a l In detail, the controller 4 according to this embodiment determines the moving direction of the bed 10 based on the first and second accelerations a r ,a l Based on this, it is determined whether the movement direction of the bed 10 is the forward / backward direction, and Left and right direction and determining whether or not the

[0116] More specifically, the controller 4 according to this embodiment calculates the first acceleration a calculated in step S3 in the figure. r and the second acceleration a l The difference between the lateral acceleration a y ) based on the magnitude of the difference, the direction of movement of the bed 10 is determined.

[0117] Specifically, in step S11 of FIG. 10, the controller 4 determines whether the following relational expression (11) is satisfied.

[0118] |a y | <T2 …(11) In the above equation (11), T2 [m / s 2 ] is the second threshold. The magnitude of the second threshold is stored in advance in the memory of the controller 4, and is read out as needed.

[0119] If the above formula (11) is satisfied (step S11: YES), the controller 4 advances the control step to step S12. In step S12, the controller 4 determines that "movement direction=front-rear direction".

[0120] In step S12, the controller 4 also calculates the vertical acceleration a x Based on the sign of x >0) or backward (a x <0). Once this determination is complete, the controller 4 advances the control process to step S13.

[0121] On the other hand, if the above formula (7) is not satisfied (step S11: NO), the controller 4 advances the control step to step S14. In step S14, the controller 4 determines that "movement direction=left / right direction".

[0122] In step S14, the controller 4 also calculates the lateral acceleration a y Based on the sign of y >0) or right (a y <0). Once this determination is complete, the controller 4 advances the control process to step S15.

[0123] In steps S13 and S15, the controller 4 sets the command rotation speeds of the first and second motors 22R, 22L, respectively, based on the determination made in step S12 or step S14, so as to assist the movement of the bed 10 along the movement direction.

[0124] Specifically, in step S13, which is reached when it is determined that the movement direction is the forward / backward direction, the controller 4 sets the command rotation speeds for the first and second motors 22R, 22L so that both the first and second Mecanum wheels 21R, 21L rotate forward or backward. In setting these speeds, the controller 4 sets the absolute values ​​of the command rotation speeds for the first motor 22R and the second motor 22L to be equal. The sign of each command rotation speed is defined to be positive when the motor rotates forward and negative when the motor rotates reverse.

[0125] Therefore, the command rotation speed of the first motor 22R (hereinafter also referred to as the first command rotation speed) is set to R r The command rotation speed of the second motor 22L (hereinafter also referred to as the second command rotation speed) is R r Then, in the transport auxiliary device 1 according to this embodiment, the following formula (12) is satisfied when the moving direction is forward, and the following formula (13) is satisfied when the moving direction is backward.

[0126] R r =R l >0 …(12) R r =R l <0 …(13) On the other hand, in step S15, which is reached when it is determined that the movement direction is left-right, the controller 4 sets the command rotation speeds of the first and second motors 22R, 22L so that one of the first and second Mecanum wheels 21R, 21L rotates forward and the other rotates backward. When setting these speeds, the controller 4 sets the absolute values ​​of the command rotation speeds of the first motor 22R and the second motor 22L to be equal.

[0127] Therefore, in the transport auxiliary device 1 according to this embodiment, the following formula (14) is satisfied when the moving direction is leftward, and the following formula (15) is satisfied when the moving direction is rightward.

[0128] R r =-R l >0 …(14) R l =-R r >0 …(15) When the processing of steps S13 and S15 in Fig. 10 is completed, the control process proceeds to step S7 in Fig. 9. In step S7, the controller 4 executes safety control processing. Details of this processing are shown in steps S31 and S32 in Fig. 11.

[0129] In step S31, the controller 4 calculates the command rotation speed R set through the flow of FIG. r ,R l It is determined whether the absolute value of is equal to or greater than a predetermined third threshold T3. Here, the magnitude of the third threshold T3 is stored in advance in the memory of the controller 4, and is read out as needed.

[0130] If the determination in step S31 is YES, the controller 4 advances the control process to step S32. In step S32, the controller 4 calculates each command rotation speed R r ,R l is changed to the third threshold T3.

[0131] On the other hand, if the determination in step S32 is NO, the controller 4 skips step S32 and returns. r ,R l The magnitude of remains below the third threshold T3.

[0132] 9, the controller 4 drives the first and second Mecanum wheels 21R and 21L via the first and second motors 22R and 22L, respectively, to assist the movement of the bed 10 along the movement direction. At this time, the command rotation speed R determined through the above-mentioned steps S5, S6, and S7 is used. r ,R l The first and second motors 22R and 22L are driven so as to realize the above. This realizes assistance along the movement direction of the bed 10.

[0133] As described above, by using two Mecanum wheels 21R, 21L, the rotation direction of each Mecanum wheel 21R, 21L can be associated with the translation direction on the xy plane (see FIG. 7). Furthermore, the translation direction of the transport assist device 1 itself is considered to be approximately the same as the direction of action of the external force, and therefore the movement direction of the bed 10. Therefore, the movement direction of the entire bed 10 can be determined based on the rotation direction of each Mecanum wheel 21R, 21L. By providing assistance along the determined movement direction, it is possible to achieve better assistance that reflects the actual rotation status of each Mecanum wheel 21R, 21L.

[0134] 7, the translation direction of the entire transport assist device 1 can be made different when both the first and second Mecanum wheels 21R, 21L rotate in the same direction and when one of the first and second Mecanum wheels 21R, 21L rotates in a different direction. Because the rotation direction of each Mecanum wheel 21R, 21L is clearly distinguished depending on the translation direction, the movement direction of the bed 10 can be determined more accurately. This is advantageous for achieving better assistance when moving the bed 10.

[0135] 7, when the first and second Mecanum wheels 21R, 21L are both rotating in the same direction, the entire transport assistance device 1 translates in the front-to-back direction. On the other hand, when one of the first and second Mecanum wheels 21R, 21L is rotating in a different direction, the entire transport assistance device 1 translates in the left-to-right direction. Because the rotation direction of each Mecanum wheel 21R, 21L is clearly distinguished between when moving forward and backward and when moving left and right, the direction of movement of the bed 10 can be determined more accurately. This is advantageous for achieving better assistance when moving the bed 10.

[0136] In addition, when both the first and second Mecanum wheels 21R and 21L are rotating in the same direction (i.e., when they are moving in the forward and backward directions), the lateral acceleration a y On the other hand, when one of the first and second Mecanum wheels 21R and 21L rotates in a different direction, the lateral acceleration a y becomes significantly larger than zero. Since the magnitude of the difference is clearly distinguished between forward and backward movement and left and right movement, the movement direction of the bed 10 can be determined more accurately, as exemplified in steps S11, S12, and S14 of FIG. 10. This is advantageous in realizing better assistance when moving the bed 10.

[0137] 10, by making the absolute values ​​of the command rotation speeds equal on the left and right sides during forward and backward movement, more stable forward and backward movement can be achieved regardless of the posture of the bed 10. This is advantageous in realizing better assistance when moving the bed 10.

[0138] 10, by making the absolute values ​​of the command rotation speeds equal on the left and right during left and right movement, more stable left and right movement can be achieved regardless of the posture of the bed 10. This is advantageous in achieving better assistance during movement of the bed 10.

[0139] Furthermore, the transport assist device 1 according to this embodiment can provide good assistance when moving a heavy object such as a bed with casters.

[0140] <Other embodiments> Although the above embodiment illustrates a configuration including a pair of Mecanum wheels, the present disclosure is not limited to such a configuration. For example, a configuration may be adopted in which multiple Mecanum wheels, such as third and fourth Mecanum wheels, are provided in addition to the first and second Mecanum wheels 21R and 21L that can be used to determine the direction of movement of the bed 10.

[0141] In addition, in the above embodiment, it is determined whether the direction of movement of the bed 10 is the front-rear direction or the left-right direction, but the present disclosure is not limited to such a configuration. For example, x and lateral acceleration a y If both of these are equal to or greater than a predetermined value, it may be determined that the movement direction of the bed 10 is a diagonal direction. As shown in the example at the bottom right of Figure 7, it is also possible to use the thrust generated by rotating one of the first and second Mecanum wheels 21R, 21L forward or backward to assist the movement in the diagonal direction.

[0142] When making a determination regarding the diagonal direction, for example, it is sufficient to determine whether or not the following formula (16) is satisfied between step S11 and step S14 in FIG.

[0143] |a x | <T2 …(16) If the determination in the above equation (16) is YES, the controller 4 determines that the movement direction of the bed 10 is left or right, and proceeds to step S14 to execute the above-mentioned processing. Also, if the determination in the above equation (16) is NO, the controller 4 determines that the movement of the bed 10 is diagonal, and executes processing to rotate one of the first and second Mecanum wheels 21R, 21L forward or backward as described above.

[0144] Furthermore, when assisting in a diagonal direction, it is sufficient to determine whether at least one of the formulas (9) and (10) is satisfied, rather than just one of the formulas (9) and (10), in step S4 of Fig. 9. For example, when the bed 10 is moving in a diagonal direction, both the formulas (9) and (10) are satisfied. [Explanation of symbols]

[0145] 1. Transport auxiliary equipment 4 Controller 10 Bed (object) 14 Caster 14F front wheel 14B rear wheel 21R 1st Mecanum Wheel 211R 1st wheel body 212R No. 1 barrel roller 21L 2nd Mecanum Wheel 211L Second wheel body 212L No. 2 barrel roller 22R 1st motor 22L Second motor Oy1 First rotation axis Oy2 Second rotation axis Or 1st tilt axis Ol 2nd tilt axis SW1 First current sensor SW2 Second current sensor

Claims

1. A transport assist device for assisting the movement of an object by an external force, first and second Mecanum wheels attached to the object; first and second motors drivingly connected to the first and second Mecanum wheels, respectively; first and second current sensors for detecting induced currents flowing in the first and second motors when the first and second Mecanum wheels rotate, respectively; a controller that controls the first and second motors, If the acceleration of the first Mecanum wheel is referred to as a first acceleration and the acceleration of the second Mecanum wheel is referred to as a second acceleration, The controller Estimating the first and second accelerations individually based on detection signals of the first and second current sensors; determining a moving direction of the object based on the sum of the first and second accelerations and the subtraction of the first and second accelerations; The first and second Mecanum wheels are driven via the first and second motors, respectively, so as to exert a thrust along the movement direction. A transport auxiliary device characterized by:

2. 2. The transport assist device according to claim 1, The first Mecanum wheel is a first wheel body that rotates about a first rotation axis; a plurality of first barrel-shaped rollers arranged along the outer periphery of the first wheel body, each rotating around a first inclined axis inclined with respect to the first rotation axis; The second Mecanum wheel is a second wheel body that rotates about a second rotation axis that extends parallel to the first rotation axis; a plurality of second barrel-shaped rollers arranged along the outer periphery of the second wheel body, each rotating around a second inclined axis inclined relative to the second rotation axis in a direction different from that of the first inclined axis; A transport auxiliary device characterized by:

3. 3. The transport assist device according to claim 2, the first and second rotation axes are both perpendicular to the front-rear direction of the object and extend in the left-right direction along the conveyance surface of the object; The first tilt axis is tilted to be line-symmetrical with respect to the second tilt axis with respect to the front-rear direction. A transport auxiliary device characterized by:

4. 4. The transport assist device according to claim 3, The controller determining whether the movement direction is the forward / backward direction based on the first and second accelerations; When it is determined that the movement direction is the forward / backward direction, the command rotation speeds of the first and second motors are set so that both the first and second Mecanum wheels rotate forward or backward, and in this setting, the absolute values ​​of the command rotation speeds of the first motor and the second motor are made equal. A transport auxiliary device characterized by:

5. 4. The transport assist device according to claim 3, The controller determining whether the movement direction is the left-right direction based on the first and second accelerations; When it is determined that the movement direction is the left-right direction, the command rotation speeds of the first and second motors are set so that one of the first and second Mecanum wheels rotates forward and the other rotates backward, and in this setting, the absolute values ​​of the command rotation speeds of the first motor and the second motor are made equal. A transport auxiliary device characterized by:

6. 6. The transport assist device according to claim 1, the object is a caster bed, The first and second Mecanum wheels are respectively attached to the bottom of the caster bed. A transport auxiliary device characterized by:

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