Transport Auxiliary Equipment

Abstract

To reduce a pushing feeling of an object when assisting movement of the object.SOLUTION: A transfer assist device 1 includes first and second mecanum wheels 21R and 21L to be attached to a bed 10, first and second motors 22R and 22L drivingly connected to the first and second mecanum wheels 21R and 21L, first and second current sensors SW1 and SW2 for detecting induced currents flowing through the first and second motors 22R and 22L when the first and second mecanum wheels 21R and 21L are rotated, and a controller 4. The controller 4 estimates acceleration of the bed 10 based on the detection signals of the first and second current sensors SW1 and SW2, sets command rotational speeds of the first and second motors 22R and 22L based on the estimated acceleration so as to follow the movement of the bed 10, and when an absolute value of the estimated acceleration is equal to or larger than a prescribed value, increases the set command rotational speeds.SELECTED DRAWING: Figure 15

Description

[Technical Field]

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

[0002] For example, in Patent Document 1, wheel The auxiliary propulsion system is disclosed. The auxiliary propulsion system is configured to include a pair of propulsion units connected to a chassis. Wheels (e.g., Mecanum wheels) and each wheel and a control system that senses changes in the rotational 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, when assisting the movement of an object such as a chassis, it is conceivable to set the command rotation speed of the motor so as to follow the movement.

[0006] However, simply having the bed follow the movement of the object lacks the "feeling of assistance" and makes the bed feel heavy for the person carrying it. Further ingenuity is needed to make it feel lighter.

[0007] The technology disclosed herein has been made in consideration of the above points, and its purpose is to make the object feel lighter when assisting its movement. [Means for solving the problem]

[0008] A first aspect of the present disclosure relates to a transportation assist device for assisting the movement of an object caused by an external force, the transportation assist device comprising: a wheel attached to the object, a motor drivingly connected to the wheel, a current sensor detecting an induced current flowing through the motor when the wheel rotates, and a controller controlling the motor, wherein the controller estimates the acceleration of the object based on a detection signal from the current sensor, executes a first control to set a command rotation speed of the motor based on the acceleration so that the motor follows the movement of the object, and executes a second control to increase the command rotation speed set by the first control when the absolute value of the acceleration is equal to or greater than a predetermined value.

[0009] According to the first aspect, by detecting the induced current, it is possible to estimate the torque (torque that tries to rotate the wheel) that caused the induced current. By estimating this torque, it is possible to estimate the acceleration of the object. This acceleration increases according to the external force applied by the operator, so by determining whether the absolute value of the acceleration is equal to or greater than a predetermined value, it is possible to determine whether the object has been pushed.

[0010] By performing the second control in addition to the first control, it is possible not only to make the robot follow the object, but also to reduce the load on the transporter by the amount of the commanded rotation speed increased through the second control. This makes the object easier to push, and provides the transporter with an appropriate "sense of assistance."

[0011] Furthermore, by executing the second control when the absolute value of the acceleration is equal to or greater than a predetermined value, i.e., when the object is pushed, it is possible to synchronize the timing when the transporter pushes the object with the timing when the object becomes easier to push. This allows the transporter to feel just the right amount of assistance. Also, by configuring the second control to be executed only when the object is pushed, it is possible to avoid a situation where the transport assistance device unintentionally starts moving on its own as a result of executing the second control when the object is not being pushed.

[0012] Furthermore, according to a second aspect of the present disclosure, the transport assistance device may be provided with a rotation sensor that detects the rotation speed of the motor, and when the controller increases the command rotation speed, the greater the rotation speed detected by the rotation sensor, the greater the increase in the command rotation speed.

[0013] It is believed that the harder the conveyor pushes the object, the higher the detected value of the rotation speed. According to the second aspect, the harder the conveyor pushes the object, the stronger the thrust force that is used to assist the movement of the object. This makes it possible to provide assistance according to the magnitude of the external force, which is advantageous in making the object easier to push.

[0014] According to a third aspect of the present disclosure, the controller may reduce the command rotation speed after the second control when the absolute value of the acceleration falls below the predetermined value.

[0015] According to the third aspect, when the transporter pushes the object lightly or releases the object, the movement of the object is assisted with a weaker thrust, which makes it possible to realize assistance according to the magnitude of the external force, giving the transporter just the right amount of assistance and preventing the transport assist device from unintentionally moving on its own.

[0016] Furthermore, according to a fourth aspect of the present disclosure, the transport assistance device may be provided with a rotation sensor that detects the rotation speed of the motor, and the controller may allow the wheel to be driven based on the detection signal of the rotation sensor, provided that the rotation speed becomes greater than or equal to a predetermined value.

[0017] According to the fourth aspect, when the rotation speed is less than a predetermined value, the driving of the wheel is limited. This makes it possible to execute the first control and the second control only when the object is actually being transported. This contributes to improving the usability of the transport assist device.

[0018] In addition, according to a fifth aspect of the present disclosure, the transport assistance device includes a rotation sensor that detects the number of rotations of the wheel and an inclination sensor that detects the inclination angle of the transport surface on which the object moves, and the controller determines whether the transport surface is a slope based on the detection signal of the inclination sensor, and if the controller determines that the transport surface is not a slope, it executes both the first control and the second control based on the acceleration obtained by the current sensor, while if the controller determines that the transport surface is a slope, it determines whether the object is climbing along the slope based on the detection signals of the rotation sensor and the inclination sensor, and if it determines that the object is climbing, it increases the acceleration obtained by the current sensor, and executes the first control based on the increased acceleration, and does not execute the second control.

[0019] If the second control is performed when climbing a slope, the sense of assistance improves at the moment when the object begins to be pushed, but the sense of assistance does not improve thereafter (while the object is being climbed). Therefore, according to the fifth aspect, when it is determined that the object is climbing a slope, the acceleration referenced in the first control is increased, and the first control is executed based on the increased acceleration. Increasing the acceleration is equivalent to overestimating the external force acting on the object compared to the actual external force. Overestimating the external force achieves assistance that exerts a thrust force greater than that required to follow the movement of the bed. This process is performed as long as the object continues to climb a slope, so that a good sense of assistance can be continuously exerted while climbing a slope.

[0020] According to a sixth aspect of the present disclosure, the transport assistance device may include a rotation sensor that detects the number of rotations of the wheel and an inclination sensor that detects the inclination angle of the transport surface along which the object is transported, and the controller may determine whether the transport surface is a slope based on the detection signal of the inclination sensor. If the controller determines that the transport surface is not a slope, the controller may execute both the first control and the second control based on the acceleration obtained by the current sensor. If the controller determines that the transport surface is a slope, the controller may determine whether the object is descending along the slope based on the detection signals of the rotation sensor and the inclination sensor. If the controller determines that the object is descending, the controller may execute the first control based on the acceleration obtained by the current sensor and not execute the second control.

[0021] If the second control is performed when the carrier is descending a slope, the object may be accelerated more than necessary, causing the object to fall out of the carrier's hands. Therefore, according to the sixth aspect, when it is determined that the carrier is descending a slope, only the first control is performed without increasing the acceleration, and the second control is not performed. This allows the carrier to provide a sense of assistance that is appropriate when descending a slope.

[0022] Furthermore, according to a seventh aspect of the present disclosure, during the first control, the controller may maintain the value of the command rotation speed when the command rotation speed is less than a predetermined threshold, and change the command rotation speed to the threshold when the command rotation speed is equal to or greater than the threshold.

[0023] According to the seventh aspect, the command rotation speed value can be maintained at or below the threshold value, thereby further improving the safety of the transport assist device compared to conventional devices.

[0024] According to an eighth aspect of the present disclosure, the object may be a caster bed, and the wheels may be attached to a bottom of the caster bed.

[0025] According to the eighth aspect, the object is a bed with casters. Even when assisting the movement of a heavy object such as a bed with casters, the comfort of pushing the bed with the carrier can be reduced. [Effects of the Invention]

[0026] As described above, according to the present disclosure, when assisting the movement of an object, the pushing sensation by the transporter can be made lighter. [Brief explanation of the drawings]

[0027] [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] FIG. 2 is a control block diagram illustrating a configuration of compliance control. [Figure 12] FIG. 1 is a conceptual diagram for explaining the basic concept of compliance control. [Figure 13] FIG. 10 is a diagram illustrating an example of a change in speed increase amount relative to the rotation speed. [Figure 14] FIG. 10 is a diagram illustrating an example of a command rotation speed obtained by speed increase control. [Figure 15] 10 is a flowchart illustrating compliance control and speed increase control. [Figure 16] 10 is a flowchart illustrating a process relating to ascending / descending a slope. [Figure 17] 10 is a flowchart illustrating a safety limit control. DETAILED DESCRIPTION OF THE INVENTION

[0028] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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).

[0033] 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.

[0034] 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."

[0035] 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).

[0036] The bed 10 is supported by the carrier 100. In the illustrated example, the bed 10 is supported at one end (e.g., the rear end) in the front-to-rear direction. The transport assist device 1 operates to assist the carrier 100 in manually pushing and moving the bed 10.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 1 to 6, the transportation auxiliary device 1 includes a storage box 6, a fixture 7, first and second Mecanum wheels 21R, 21L as wheels, first and second motors 22R, 22L, a controller 4, first and second current sensors SW1, SW2 as current sensors, first and second rotation sensors SW3, SW4 as rotation sensors, and a six-axis sensor SW5 as a tilt sensor (the first and second motors 22R, 22L and the sensors SW1 to SW5 are only shown in FIG. 6). Hereinafter, 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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).

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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).

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] As will be described in detail below, 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).

[0074] 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.

[0075] 8, the six-axis sensor SW5 as an inclination sensor detects the inclination angle of the conveying surface F on which the bed 10 moves. More specifically, the six-axis sensor SW5 is configured to be able to detect at least the angular velocity of the rotation angle (so-called pitch angle θ) around the y-axis extending in the left-right direction.

[0076] More specifically, the six-axis sensor SW5 according to this embodiment can detect not only the angular velocity of the pitch angle θ, but also acceleration in three directions along the x-axis extending in the front-to-back direction, the y-axis extending in the left-to-right direction, and the z-axis extending in the up-to-down direction, the angular velocity of the rotation angle about the x-axis (so-called roll angle φ), and the angular velocity of the rotation angle about the z-axis (so-called yaw angle ψ). The detection signals of the six-axis sensor SW5 are input to the controller 4.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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

[0082] 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.

[0083] 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). 217). 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

[0084] 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, and a rearward thrust can be applied to the entire transport assist device 1. This thrust can assist the rearward movement of the bed 10.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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. On the other hand, by rotating only the first Mecanum wheel 21R forward, the bed 10 can be assisted in moving diagonally forward to the left (not shown).

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] The assistance provided by the controller 4 will be described in detail below with reference to FIG. 9 and other figures.

[0094] Here, FIG. 9 is a flowchart illustrating the main processing performed by the controller 4. FIG. 10 is a flowchart illustrating processing related to determining the direction of movement. FIG. 11 is a control block diagram that schematically illustrates the configuration of compliance control. FIG. 12 is a conceptual diagram for explaining the basic concept of compliance control. FIG. 13 is a diagram illustrating changes in the speed increase amount relative to the rotation speed. FIG. 14 is a diagram illustrating an example of a command rotation speed obtained by speed increase control. FIG. 15 is a flowchart illustrating compliance control and speed increase control.

[0095] Fig. 16 is a flowchart illustrating a process for going uphill / downhill, and Fig. 17 is a flowchart illustrating a safety limit control.

[0096] First, in step S1 of FIG. 9, the controller 4 reads the detection signals of the five sensors SW1 to SW5 described above.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] 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).

[0102] a r =(-1) T r / (R m) …(1) a l=(-1) T l / (R m) …(2)

[0103] 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.

[0104] 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 and mass are the same for the first Mecanum wheel 21R and the second Mecanum wheel 21L.

[0105] 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.

[0106] 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.

[0107] 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 lThe 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).

[0108] a x =(a r +a l ) / twenty three) a y =(a r -a l ) / twenty four)

[0109] 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.

[0110] 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).

[0111] 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.

[0112] And r x [rpm] is the rotation speed of the first and second motors 22R, 22L in the front-rear direction (hereinafter, also referred to as "vertical rotation speed"), and r yLet [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.

[0113] r x =(r r +r l ) / twenty five) r y =(r r -r l ) / 2 …(6)

[0114] 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 r y By setting r r and r l can be uniquely determined.

[0115] r r =r x +r y …(7) r l =r x -r y …(8)

[0116] Furthermore, by multiplying both sides of the above equations (7) and (8) by a constant (=πR / 30) that depends on the tire radius R and the ratio of the circumference of a circle to its circumference, a similar relational expression can be obtained for the velocity. r Let [m / s] be the velocity of the first Mecanum wheel 21R in the forward / backward direction, and v l Let [m / s] be the velocity of the second Mecanum wheel 21L in the forward / backward direction. And v x [m / s] is the overall speed of the first and second Mecanum wheels 21R, 21L in the longitudinal direction (hereinafter also referred to as the "longitudinal speed"), and v yLet [m / s] be the overall speed of the first and second Mecanum wheels 21R, 21L in the left-right direction (hereinafter also referred to as the "lateral speed"). When the first and second Mecanum wheels 21R, 21L are configured and arranged as in this embodiment, the following equations (9) and (10) hold.

[0117] In this case, "velocity" refers to the translational velocity (tangential velocity) of an object undergoing angular motion.

[0118] v x =(v r +v l ) / 2 …(9) v y =(v r -v l ) / 2 …(10)

[0119] The above equations (9) and (10) can be transformed into the following equations (11) and (12). As shown in the following equations (11) and (12), v x and v y By setting v r and v l can be set uniquely.

[0120] v r =v x +v y …(11) v l =v x -v y …(12)

[0121] In addition, by utilizing the relationship between the equations, for example, the longitudinal velocity v x and / or lateral velocity v y When the command values ​​of are determined, the vertical rotation speed r required to realize those command values ​​is r and lateral rotation speed r l can be uniquely determined, and the vertical rotation speed r r and / or lateral rotation speed r l The first rotation speed r corresponding to r and the second rotation speed r l It is possible to determine the following.

[0122] 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 speed of the first and second Mecanum wheels 21R and 21L becomes equal to or greater than a predetermined value (first threshold value).

[0123] Specifically, in step S4 following step S3, the controller 4 determines whether or not either one of the following relational expressions (13) and (14) is satisfied. Through this determination, it is possible to confirm whether or not the bed 10 is actually being transported (whether or not the bed 10 is actually moving).

[0124] r x ≧T1 …(13) r y ≧T1 …(14)

[0125] In the above equations (13) and (14), 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).

[0126] Here, if both of the above formulas (13) and (14) are not satisfied, the controller 4 determines that the bed 10 is not being transported and does not allow the first and second motors 22R, 22L to be driven (step S4: NO). In this case, the control process proceeds to step S5. In this step S5, the controller 4 sets the command rotation speeds of the first and second motors 22R, 22L to zero.

[0127] If the process proceeds to step S5, the command rotation speeds of the first and second motors 22R, 22L (more specifically, the assist speeds described below) are maintained at zero in the subsequent steps S7 to S9 (steps S7 to S9 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.

[0128] On the other hand, if at least one of the above formulas (13) and (14) is satisfied, the controller 4 determines that the bed 10 is actually 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 speed (assist rotation speed) of each of the first and second motors 22R and 22L to assist the manual movement caused by the external force. This assist rotation speed is determined by the vertical rotation speed r x and horizontal rotation speed r y This corresponds to the command value.

[0129] Steps S11 to S16 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.

[0130] In step S11, the controller 4 calculates the vertical acceleration a estimated in step S3 of FIG. x and lateral acceleration a y Specifically, the controller 4 according to this embodiment determines the direction of movement of the bed 10 based on the vertical acceleration a x and lateral acceleration a y Based on this, it is determined whether the movement direction of the bed 10 is the front-rear direction (whether the bed 10 is moving forward or backward) or the left-right direction.

[0131] More specifically, in step S11, the controller 4 determines whether the following relational expression (15) is satisfied.

[0132] |a y | <T2 …(15)

[0133] In the above equation (15), 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.

[0134] Here, if the above formula (15) is not satisfied, the controller 4 determines that the movement direction of the bed 10 is the left-right direction, and proceeds to step S12 (step S11: NO). Details of the processing when proceeding to step S12 will be described later.

[0135] On the other hand, if the above formula (15) is satisfied, the controller 4 determines that the movement direction of the bed 10 is the front-rear direction, and advances the control process to step S13 (step S11: YES).

[0136] In the following steps S13 and S14, the controller 4 determines whether or not the conveying surface F is a slope based on the detection signal of the six-axis sensor SW5 serving as an inclination sensor.

[0137] Specifically, in step S13, the controller 4 calculates the inclination angle (road surface gradient) θ of the conveying surface F based on the detection signal of the six-axis sensor SW5. s This calculation can be performed based on the angular acceleration around the y-axis shown in FIG.

[0138] Subsequently, in step S14, the controller 4 determines whether the following relational expression (16) is satisfied.

[0139] |θ s |≧T3 …(16)

[0140] In equation (16), T3 is the third threshold value. The magnitude of the third threshold value is stored in advance in the memory of the controller 4, and is read out as needed.

[0141] Here, if the above formula (16) is not satisfied, the controller 4 determines that the conveying surface F is a flat, non-sloping road, and advances the control process to step S15.

[0142] The case where the process proceeds to step S15 corresponds to the case where it is determined that the bed 10 is moving forward or backward and not ascending or descending a slope. In this case, the controller 4 performs the following steps to assist the manual movement of the bed 10 in the forward and backward directions, thereby detecting the longitudinal acceleration a obtained by the first and second current sensors SW1 and SW2. x and lateral acceleration a y Based on this, both the compliance control as the first control and the speed increase control as the second control are executed.

[0143] On the other hand, if the above formula (16) is satisfied, the controller 4 determines that the conveying surface F is a slope, and advances the control process to step S16.

[0144] The case where the process proceeds to step S16 corresponds to the case where it is determined that the bed 10 is moving forward or backward and also going uphill or downhill. In this case, the controller 4 executes control to assist the manual pushing of the bed 10 in the forward and backward directions, and in particular, executes control optimized for going uphill or downhill.

[0145] The processes performed in steps S12 and S15, and the process performed in step S16 will be described below in order. When proceeding to these steps, the controller 4 drives the first and second Mecanum wheels 21R, 21L via the first and second motors 22R, 22L based on the movement direction determined in step S11 so as to assist the movement of the bed 10 along that movement direction. During this process, the controller 4 according to this embodiment executes compliance control as a first control and speed increase control as a second control.

[0146] Compliance control is a process in which the controller 4 controls the acceleration estimated in step S3 (i.e., the vertical acceleration a x and lateral acceleration a yIn this compliance control, the controller 4 controls the movement of the bed 10 as an object based on a velocity command in the front-rear direction or the left-right direction, that is, a vertical velocity v x and lateral velocity v y Set the command value.

[0147] As explained in relation to equations (9)-(12), the longitudinal velocity v x and lateral velocity v y By setting the command value of the first rotation speed r r and the second rotation speed r l The command value is uniquely determined.

[0148] Below, the vertical velocity v x and lateral velocity v y The command values ​​of the vertical speed command V x and lateral speed command V y The first rotation speed r of each of the motors 22R and 22L is called r and the second rotation speed r l The command values ​​of the first command speed R r and second command rotation speed R l It is called.

[0149] In this embodiment, the longitudinal speed command V x and lateral speed command V y and the first command rotation speed R is set to follow the movement of the bed 10. r and second command rotation speed R l is equivalent to setting

[0150] On the other hand, the speed increase control is executed by the controller 4 based on the acceleration estimated in step S3 and the command rotation speed set in the compliance control. In this speed increase control, when the absolute value of the acceleration referred to in the compliance control is equal to or greater than a predetermined value (a fourth threshold T4 described later), the controller 4 increases the longitudinal speed command V set in the compliance control. x and lateral speed command V y (Especially, each speed command Vx ,V y (absolute value of

[0151] In this embodiment, the vertical speed command V x and lateral speed command V y Increasing the first command speed R r and second command rotation speed R l (Especially, each command rotation speed R r ,R l is equivalent to increasing the absolute value of

[0152] First, a case where the control process proceeds to step S12 or step S15 will be described. Here, steps S31 to S37 in Fig. 15 exemplify the processing executed in step S12 or S15 in Fig. 10, respectively. That is, when the control process proceeds to step S12 or S15, the controller 4 executes each step in order starting from step S31 in Fig. 15.

[0153] For example, when the process proceeds from step S12 to the flow of FIG. 15, that is, when it is determined that the "movement direction=left / right direction", the controller 4 calculates the lateral acceleration a y and performs compliance control based on the lateral velocity command V y The speed increase control is performed based on the above.

[0154] On the other hand, when the process proceeds from step S15 to the flow of FIG. 15, that is, when it is determined that the "movement direction=front-rear direction", the controller 4 calculates the vertical acceleration a x and performs compliance control based on the longitudinal velocity command V x The speed increase control is performed based on the above.

[0155] The following will describe in detail the case where the process proceeds from step S15 to the flow of Fig. 15. In the flow of Fig. 15, step S31 relates to compliance control, and steps S32 to S34 relate to speed increase control.

[0156] First, in step S31, the controller 4 inputs the longitudinal acceleration a x Enter the vertical velocity v x The command value of the input vertical acceleration a x is estimated based on the detection signals of the first and second current sensors SW1 and SW2, and the longitudinal acceleration a x This corresponds to the estimated value (measured value) of

[0157] In this control block, s is a Laplace operator, and M represents the inertia of the bed 10 and the transport assist device 1. Furthermore, D is a damping coefficient between the support position of the bed 10 (e.g., the headboard 11h) of the transporter 100 and the first and second Mecanum wheels 21R, 21L, and K is a spring multiplier between the support position and the first and second Mecanum wheels 21R, 21L. The values ​​of M, D, and K are set in advance and stored in the controller 4.

[0158] If the transport auxiliary device 1, the bed 10, and the transported person 100 are considered to be rigid bodies, the vertical velocity v generated when the first and second Mecanum wheels 21R and 21L rotate due to the application of an external force will be x changes in synchronization with the moving speed of the bed 10 and the conveyed person 100 in the forward and backward direction, and the magnitudes thereof also match each other. In this case, the vertical acceleration a x By integrating the measured value of , the vertical speed command V that follows the manual push movement of the bed 10 is obtained. x This will be obtained.

[0159] However, in reality, the frame 12 of the bed 10, the mounting fixture 7 of the transport auxiliary device 1, etc. are interposed between the support position of the bed 10 and the first and second Mecanum wheels 21R, 21L. Due to the deflection of the frame 12, etc., the actual vertical speed v x will change with a delay from the moving speed of the bed 10 and the person being carried 100, or a deviation in value will occur between the moving speed and the moving speed.

[0160] The control block shown in Figure 11 is a model of the effects of such delays and deviations. This control block calculates the physical quantity corresponding to the force (longitudinal acceleration a x , lateral acceleration a y ) is used as input, and the speed command (longitudinal speed command V x , lateral speed command V y ) is the output of compliance control.

[0161] In Figure 11, first, the vertical acceleration a x The actual measured value of the vertical acceleration a is input to the first block B1 after passing through the subtractor P2. x The measured value of is time-integrated. The output of the first block B1 is the vertical acceleration a x The longitudinal speed command V x The controller 4 calculates the current longitudinal speed command V x By adding or integrating the correction amount ΔV to the vertical speed command V x Set.

[0162] The output from block B1 is multiplied by D / M in second block B2, and then input to subtractor P2 via adder P1. The multiplied value input to subtractor P2 is the vertical acceleration a x This feedback is subtracted from the actual measured value of the longitudinal speed command V x (particularly, damping occurring between the support position of the bed 10 and the first and second Mecanum wheels 21R, 21L).

[0163] The output from block B1 is also input to the third block B3. In this third block B3, the correction amount ΔV is further integrated over time. The output from the third block B3 is multiplied by K / M in the fourth block B4, and then input to the subtractor P2 via the adder P1. The multiplied value input to the subtractor P2 is multiplied by the vertical acceleration a in the same way as the multiplied value via the second block B2. xThis feedback is intended to incorporate a restoring force proportional to the amount of displacement (particularly, a restoring force caused by the deflection between the support position of the bed 10 and the first and second Mecanum wheels 21R, 21L).

[0164] Vertical acceleration a x By reflecting these two feedbacks in the above, the acceleration of the bed 10 (particularly the acceleration at the support position of the person 100) is estimated, taking into account deflection, damping, etc. The acceleration is integrated over time in the first block B1 to obtain a speed that follows the movement of the bed 10.

[0165] Furthermore, signal processing (for example, processing using a delay operator) may be performed on the way from the adder P1 to the subtractor P2 to compensate for the time lag caused by feedback.

[0166] For example, as shown in the upper diagram of Fig. 12, when the transport assistance device 1, the bed 10, and the transported person 100 are moving at a constant speed, the acceleration estimated by the first and second current sensors SW1 and SW2 is zero. Figure 11 The vertical acceleration a input to the control block x becomes zero, and the correction amount ΔV output from the control block also becomes zero. In this case, the transport auxiliary device 1 does not accelerate or decelerate.

[0167] On the other hand, as shown in the center diagram of Fig. 12, when the person 100 is moving faster than the transportation assistance device 1, the acceleration estimated by the first and second current sensors SW1 and SW2 is positive. In this case, an external force is being applied to the bed 10 to push it down (see arrow F1). In this case, Figure 11 The vertical acceleration a input to the control block x becomes positive, and the correction amount ΔV output from the control block also becomes positive. At this time, the restoring force related to the fourth block B4 acts in a direction that increases the correction amount ΔV (see arrow F3). As a result, the transport assistance device 1 accelerates with a delay after the application of the external force so that the speed becomes equal to that of the bed 10 and the transported person 100.

[0168] On the other hand, as shown in the lower diagram of Fig. 12, when the person 100 is moving behind the transportation assistance device 1, the acceleration estimated by the first and second current sensors SW1 and SW2 becomes negative. In this case, an external force that pulls the bed 10 in is being applied (see arrow F2). In this case, Figure 11 The vertical acceleration a input to the control block x becomes negative, and the correction amount ΔV output from that control block also becomes negative. At that time, the restoring force related to the fourth block B4 acts in a direction to reduce the correction amount ΔV (see arrow F4). As a result, the transport assistance device 1 decelerates with a delay after the application of the external force so as to be at the same speed as the bed 10 and the transported person 100.

[0169] In the following steps S32 to S34, the controller 4 executes the above-mentioned speed increase control. When executing this speed increase control, the controller 4 increases the speed command value by a larger amount as the rotation speeds detected by the first and second rotation sensors SW3 and SW4 increase (see FIG. 13).

[0170] Specifically, in step S32, the controller 4 calculates the longitudinal velocity v x The larger the velocity increment v off Set the vertical velocity v x Instead of the vertical rotation speed r x The larger the velocity increment v off may be set.

[0171] Also, if the flow proceeds from step S12 to the flow of FIG. 15, the vertical speed v x Instead of the lateral velocity v y That is, the controller 4 determines the velocity increase amount v based on the moving direction determined in step S11 of FIG. off The following settings are made:

[0172] In the following step S33, the controller 4 determines whether the following relational expression (17) is satisfied:x is equal to or greater than a predetermined value. Through this determination, it is possible to detect whether the bed 10 is being pushed in the direction of movement (detecting the pushing force).

[0173] |a x |≧T4 …(17)

[0174] In the above equation (17), T4 [m / s 2 ] is a fourth threshold value (predetermined value). The magnitude of the fourth threshold value T4 as a predetermined value is stored in advance in the memory of the controller 4, and is read out as needed.

[0175] If the flow of FIG. 15 is proceeded from step S12, the vertical acceleration a x Instead of lateral acceleration a y is compared. That is, the controller 4 determines whether or not the acceleration in the movement direction determined in step S11 of FIG.

[0176] Here, if the above equation (17) is satisfied (i.e., the vertical acceleration a x is equal to or greater than a predetermined value), the controller 4 determines that the bed 10 is being pressed, and advances the control process to step S34 (step S33: YES).

[0177] In step S34, the controller 4 calculates the speed command (vertical speed command V x ) with a speed increase of v off The controller 4 uses the added value thus obtained as the final speed command (assist speed) (step S36). The assist speed in the longitudinal direction is calculated by adding the above-mentioned longitudinal speed command V x The assist speed in the left and right direction is calculated by the above-mentioned lateral speed command V x is.

[0178] In addition, the speed increase amount v offInstead of calculating and adding it to the speed command, it is also possible to calculate an increase magnification (>1) that increases as the number of rotations detected by the first and second rotation sensors SW3 and SW4 increases, and multiply the speed command by the increase magnification to perform speed increase control.

[0179] On the other hand, if the above equation (17) is not satisfied (i.e., the vertical acceleration a x is less than the predetermined value), the controller 4 determines that the bed 10 is not being pushed, and proceeds to step S35 (step S33: NO).

[0180] In step S35, the controller 4 executes the third control to reduce the speed command after the second control.

[0181] Specifically, in step S35, the controller 4 calculates the speed increase amount v off After subtracting Δv2 from the value at that time, the control process proceeds to step S34. off The subtraction amount Δv2 may be constant. When the subtraction amount Δv2 is set to a constant, if the state where the bed 10 is not pushed is repeated, the speed increase amount v off will gradually decrease. Also, during this subtraction, the speed increase v off is configured not to become less than zero. This ensures that the assist speed is fast enough to follow the movement of the bed 10.

[0182] For example, when the process proceeds from step S33 to step S34 in the n-th loop, the longitudinal speed command V x is the longitudinal velocity v x The speed increase v according to off After that, when the process proceeds from step S33 to step S35 in the n+1th loop, the speed increase amount v off is subtracted from the value at the nth loop. After that, when the situation in which the process proceeds from step S33 to step S35 is repeated, the longitudinal speed command V x will decrease towards the value calculated in step S31.

[0183] FIG. 14 is a diagram comparing the assist rotation speed (dashed line) when compliance control is executed and speed increase control is not executed, and the assist rotation speed (solid line) when both compliance control and speed increase control are executed. The circles in FIG. 14 indicate the timings (the timings when the determination in step S33 becomes YES) at which it is determined that the bed 10 has been pushed, respectively.

[0184] When only compliance control is executed, the assist rotation speed rises after a delay from the movement of the bed 10 and then changes to a value that follows the movement.

[0185] On the other hand, when both compliance control and speed increase control are executed, each time it is determined that the bed 10 has been pushed, the assist rotation speed rises steeply (see, for example, t = t1, t2, t3). On the other hand, if the period during which it is determined that the bed 10 is not being pushed continues, the assist rotation speed after rising will gradually decrease over time (see, for example, t1 < t < t2, t2 < t < t3).

[0186] Then, when the process according to step S36 is completed, the control process ends the flows of FIGS. 10 and 15 and proceeds to step S7 of FIG. 9.

[0187] Note that the description regarding FIG. 15 is the same when the flow of FIG. 15 is entered from step S12. In that case, in the above description, the word "vertical" may be replaced with the word "horizontal", and the word "front - rear" may be replaced with the word "left - right". The same applies to various mathematical formulas. At that time, a predetermined value such as the fourth threshold value T4 may be the same in the front - rear direction and the left - right direction, or may be different.

[0188] Subsequently, the case where the process proceeds to step S16 in FIG. 10 will be described. In this case, steps S41 to S44 in FIG. 16 are performed in order.

[0189] First, in step S41, the controller 4 determines whether or not the bed 10 is moving up a slope, i.e., whether or not the bed 10 is climbing, based on the detection signals of the first and second rotation sensors SW3, SW4 and the six-axis sensor SW5.

[0190] The determination in step S41 is made based on the road surface gradient θ s is increasing and the direction of movement is forward (vertical rotation speed r x or vertical velocity v x > 0), or when the road gradient θ s is decreasing and the movement direction is backward (vertical rotation speed r x or vertical velocity v x <0), the answer is YES.

[0191] On the other hand, the determination in step S41 is made based on the road surface gradient θ s is increasing and the direction of movement is backward, or the road gradient θ s The answer is NO when the value is decreasing and the direction of movement is forward.

[0192] The road surface gradient θ referred to in the determination of step S41 s The value calculated in step S13 can be used for .

[0193] When the controller 4 determines that the bed 10 is moving uphill (step S41: YES), the controller 4 calculates the vertical acceleration a obtained by the first and second current sensors SW1 and SW2. x After increasing the vertical acceleration a x ', compliance control is executed, and speed increase control is not executed.

[0194] Specifically, in step S42, which follows when the determination in step S41 is YES, the controller 4 calculates the longitudinal acceleration a obtained by the first and second current sensors SW1 and SW2. x The increase amount Δa x For example, the road gradient θs It may be set so that the larger the value, the larger the value.

[0195] Then, in step S43 following step S42, the controller 4 calculates the increased vertical acceleration a x The compliance control in the longitudinal direction is performed based on the increased longitudinal acceleration a'. x The content of step S31 is the same as that of step S31 for the front-rear direction, except for whether or not "'" is used.

[0196] On the other hand, when it is determined that the bed 10 is descending along a slope (step S41: NO), the controller 4 calculates the vertical acceleration a obtained by the first and second current sensors SW1 and SW2. x without increasing its longitudinal acceleration a x The compliance control is executed based on the above, and the speed increase control is not executed.

[0197] Specifically, in step S45 that follows when the determination in step S41 is NO, the controller 4 calculates the longitudinal acceleration a obtained by the first and second current sensors SW1 and SW2. x Set the increase to zero and the vertical acceleration a x Maintain the value of

[0198] Then, in step S43 following step S45, the controller 4 calculates the non-increased vertical acceleration a x '(=a x ) and executes compliance control in the front-rear direction. The details of step S43 are the same as those of step S31 described above.

[0199] Thereafter, in step S44 following step S43, the controller 4 determines the final assist speed in the longitudinal direction, similar to the above-mentioned step S36.

[0200] When climbing a slope, as shown in steps S41 and S42 of FIG. 16, the vertical acceleration a xOn the other hand, as explained with reference to FIG. 14, the assist rotation speed rises in the speed increase control as the longitudinal acceleration a x becomes equal to or greater than a predetermined value, that is, is approximately synchronized with the timing at which an external force acts on the bed 10.

[0201] Therefore, in other words, the processing related to uphill driving, the controller 4 according to this embodiment determines whether the vehicle is traveling on flat ground or in an uphill driving state, and based on the determination result, when traveling on flat ground, it intermittently increases the command rotation speed of the motors (first and second motors 22R, 22L) so as to synchronize with the timing at which an external force acts, and when traveling uphill, it maintains the increase in the command rotation speed as long as the uphill driving state continues.

[0202] When the flow relating to step S12, step S15, and step S16 in Fig. 10 is completed, the control process proceeds to step S7 in Fig. 9. In this step S7, the controller 4 adjusts the longitudinal speed command V x or lateral speed command V y The first command rotation speed R is calculated using the following equations (18) and (19), which are defined in the same way as the above equations (5) and (6). r and the second command speed R l Convert to and.

[0203] R r =60*(V x +V y ) / (2π·R) …(18) R l =60*(V x -V y ) / (2π·R) …(19)

[0204] In the above equations (18) and (19), "R" is the tire radius. In this embodiment, when assisting in the longitudinal direction, V x ≠0 and V y = 0, and when assisting left and right, V x =0 and V y ≠0.

[0205] For example, when the controller 4 determines that the moving direction of the bed 10 is the forward / backward direction (when the process has gone through step S15), the controller 4 controls the first and second command rotation speeds R so that both the first and second Mecanum wheels 21R and 21L rotate forward or backward, as illustrated in the upper left and upper right of FIG. r ,R l In addition, when setting, the absolute values ​​of the command rotation speeds of the first Mecanum wheel 21R and the second Mecanum wheel 21L are made equal (R r =R l ).

[0206] First and second command rotation speeds R r ,R l By making the absolute values ​​of equal, movement along the front-to-rear direction can be stabilized regardless of the orientation of each caster 14.

[0207] Furthermore, when the controller 4 determines that the moving direction of the bed 10 is the left-right direction (when the process has gone through step S12), it controls the first and second command rotation speeds R to rotate one of the first and second Mecanum wheels 21R, 21L forward and the other backward, as illustrated in the lower left of FIG. r ,R l In addition, when setting the rotation speed, the absolute values ​​of the command rotation speeds of the first Mecanum wheel 21R and the second Mecanum wheel 21L are set to be equal (R r =-R l ).

[0208] First and second command rotation speeds R r ,R l By making the absolute values ​​of equal, movement along the left-right direction can be stabilized regardless of the orientation of each caster 14.

[0209] Thereafter, in step S8 following step S7, the controller 4 executes safety control processing. Details of this processing are as shown in steps S51 and S52 in FIG.

[0210] First, in step S51, the controller 4 calculates the command rotation speed R set through the flow of FIG. r ,R l is equal to or greater than a predetermined fifth threshold T5. Here, the magnitude of the fifth threshold T5 is stored in advance in the memory of the controller 4, and is read out as needed.

[0211] If the determination in step S51 is YES, the controller 4 advances the control process to step S52. In step S52, the controller 4 calculates each command rotation speed R r ,R l is changed to the fifth threshold T5.

[0212] On the other hand, if the determination in step S51 is NO, the controller 4 skips step S52 and returns. r ,R l The magnitude of remains below the fifth threshold T5.

[0213] In this way, the controller 4 according to this embodiment controls the first and second command rotational speeds R after the speed increase control as the second control. r ,R l is less than the predetermined threshold value (fifth threshold value T5) (step S51: NO), the first and second command rotation speeds R r ,R l and maintain the value of the first and second command speeds R r ,R l is equal to or greater than the fifth threshold T5 (step S51: YES), the first and second command rotation speeds R r ,R l to a fifth threshold T5.

[0214] 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, thereby realizing assistance along the movement direction.

[0215] As described above, according to this embodiment, the torque (torque that tries to rotate the wheel) that caused the induced current can be estimated by detecting the induced current using the first and second current sensors SW1 and SW2. As a result, as illustrated in step S3 of FIG. 9, the acceleration a x ,a y Each acceleration a x ,a y increases according to the external force applied by the conveyor 100. Therefore, as shown in step S33 of FIG. 15, each acceleration a x ,a y By determining whether or not is equal to or greater than a predetermined value, it is possible to determine whether or not the bed 10 has been pushed.

[0216] 15, by performing the speed increase control as the second control in addition to the compliance control as the first control, it is possible not only to make the bed 10 follow the bed 10 but also to reduce the load on the person 100 by the amount of the increase in the command rotation speed through the speed increase control. This makes it possible to lighten the feeling of pushing the bed 10 and provide the person 100 with an appropriate "feeling of assistance."

[0217] Furthermore, as shown in step S33 of FIG. 15, the acceleration a x ,a yis equal to or greater than the fourth threshold, that is, when the bed 10 is pushed, the speed increase control is executed, thereby synchronizing the timing when the person 100 pushes the bed 10 with the timing when the feeling of pushing the bed 10 becomes lighter. This allows the person 100 to be given a sense of assistance that is neither too much nor too little. Furthermore, by configuring the speed increase control to be executed on the condition that the bed 10 is pushed, it is possible to avoid a situation in which the transportation assistance device 1 unintentionally moves on its own as a result of the speed increase control being executed when the bed 10 is not being pushed.

[0218] It is also considered that the harder the person 100 pushes the bed 10, the higher the detection values ​​of the first and second rotation sensors SW3 and SW4. In this embodiment, as shown in steps S32 to S34 in Figures 13 and 15, the higher the detected value of the rotation speed, the stronger the thrust force that assists the movement of the bed 10. This makes it possible to realize assistance according to the magnitude of the external force, which is advantageous in making the bed 10 easier to push.

[0219] 15, when the person being conveyed 100 lightly pushes the bed 10 or releases his / her hands from the bed 10, the movement of the bed 10 is assisted with a weaker thrust. This makes it possible to realize assistance according to the magnitude of the external force, giving the person being conveyed just the right amount of assistance, and preventing unintended self-propulsion of the conveyance assistance device 1.

[0220] 9, when the rotation speed is less than the first threshold T1, the driving of the first and second Mecanum wheels 21R, 21L as wheels is limited. This makes it possible to execute compliance control and speed increase control only when the bed 10 is actually being transported. This contributes to improving the usability of the transport assistance device 1.

[0221] Furthermore, if speed increase control is performed when climbing a slope, the feeling of assistance improves at the moment when the bed 1 starts to be pushed, but the feeling of assistance does not improve thereafter (while climbing the slope). Therefore, as shown in steps S41 to S44 in FIG. 16, when it is determined that the bed 1 is climbing a slope, the vertical acceleration a x After increasing, the vertical acceleration a x Compliance control is performed based on the longitudinal acceleration a x Increasing this is equivalent to overestimating the external force acting on the bed 10 compared to the actual external force. Overestimating the external force achieves assistance that exerts a thrust force greater than that required to follow the movement of the bed 10. This process is continued as long as the climb continues, so a good sense of assistance can be continuously exerted while climbing a slope.

[0222] Furthermore, if speed increase control is performed when going down a slope, the bed 10 may be accelerated more than necessary, which may cause the bed 10 to slip out of the hands of the person 100. Therefore, as shown in steps S41 to S45 of FIG. 16, the vertical acceleration a x In this case, only compliance control is performed without increasing the speed, and the speed increase control is not performed. This allows the driver to feel an appropriate assist when going down a slope.

[0223] 17, the command rotation speed value can be maintained at or below the fifth threshold value T5, thereby further improving the safety of the transportation assist device 1 compared to conventional devices.

[0224] Furthermore, the transport assist device 1 according to this embodiment can make the pushing feel by the transporter 100 lighter even when assisting in the movement of a heavy object such as the caster-equipped bed 10 illustrated in FIGS.

[0225] <Other embodiments> In the above embodiment, a configuration using first and second Mecanum wheels 21R, 21L is disclosed, but such a configuration is not essential. The present disclosure can also be applied to wheels other than Mecanum wheels, such as omni-wheels. The number of wheels is also not limited to two. For example, if Mecanum wheels are used as in the present embodiment, the number may be four, and if omni-wheels are used, the number may be three or four. Furthermore, the number of motors may be changed depending on the number of wheels.

[0226] Furthermore, in the above embodiment, the speed command (translation speed command value) is increased by the speed increase control, but such a configuration is not essential.

[0227] For example, in steps S32 to S34, a process for increasing the command rotation speed may be executed instead of the process related to the speed command. In this case, a process for converting the speed command into the command rotation speed is provided between steps S31 and S32. [Explanation of symbols]

[0228] 1. Transport auxiliary equipment 4 Controller 10 Bed (object, caster bed) 14 Caster 14F front wheel 14B rear wheel 21R 1st Mecanum Wheel (Wheel) 211R 1st wheel body 212R No. 1 barrel roller 21L 2nd Mecanum Wheel (Wheel) 211L Second wheel body 212L No. 2 barrel roller 22R 1st motor (motor) 22L Second motor (motor) SW1 First current sensor (current sensor) SW2 Second current sensor (current sensor) SW3 1st rotation sensor (rotation sensor) SW4 Second rotation sensor (rotation sensor) SW5 6-axis sensor (tilt sensor)

Claims

1. A transport assist device for assisting the movement of an object by an external force, a wheel attached to the object, in contact with a conveying surface of the object, and rotating forward or backward in response to the external force; a motor drivingly connected to the wheel for rotating the wheel forward or backward; a current sensor that detects an induced current flowing through the motor when the wheel rotates; a controller for controlling the motor, The controller estimating the acceleration of the object based on the detection signal of the current sensor; executes a first control to set a command rotation speed of the motor so as to follow the movement of the object based on the acceleration; When the absolute value of the acceleration is equal to or greater than a predetermined value, a second control is executed to increase the command rotation speed set in the first control. A transport auxiliary device characterized by:

2. 2. The transport assist device according to claim 1, a rotation sensor for detecting the number of rotations of the wheel; When the controller increases the command rotation speed, the greater the rotation speed detected by the rotation sensor, the greater the increase in the command rotation speed. A transport auxiliary device characterized by:

3. 2. The transport assist device according to claim 1, The controller reduces the command rotation speed after the second control when the absolute value of the acceleration falls below the predetermined value. A transport auxiliary device characterized by:

4. 2. The transport assist device according to claim 1, a rotation sensor for detecting the number of rotations of the motor; The controller allows the wheel to be driven on the condition that the number of rotations reaches or exceeds a predetermined number based on the detection signal of the rotation sensor. A transport auxiliary device characterized by:

5. 2. The transport assist device according to claim 1, a rotation sensor for detecting the number of rotations of the motor; an inclination sensor for detecting an inclination angle of a conveyance surface on which the object moves; The controller determines whether the conveying surface is a slope based on the detection signal of the inclination sensor; The controller When it is determined that the conveying surface is not a slope, both the first control and the second control are executed based on the acceleration obtained by the current sensor, When it is determined that the conveying surface is a slope, it is determined whether the object is ascending along the slope based on the detection signals of the rotation sensor and the inclination sensor, and when it is determined that the object is ascending, the acceleration obtained by the current sensor is increased, and the first control is executed based on the increased acceleration, and the second control is not executed. A transport auxiliary device characterized by:

6. 2. The transport assist device according to claim 1, a rotation sensor for detecting the number of rotations of the wheel; an inclination sensor that detects the inclination angle of a conveyance surface on which the object is conveyed; The controller determines whether the conveying surface is a slope based on the detection signal of the inclination sensor; The controller When it is determined that the conveying surface is not a slope, both the first control and the second control are executed based on the acceleration obtained by the current sensor, When it is determined that the conveying surface is a slope, it is determined whether or not the object is descending along the slope based on the detection signals of the rotation sensor and the inclination sensor, and when it is determined that the object is descending, the first control is executed based on the acceleration obtained by the current sensor, and the second control is not executed. A transport auxiliary device characterized by:

7. 2. The transport assist device according to claim 1, After the second control, the controller If the commanded rotation speed is less than a predetermined threshold value, the value of the commanded rotation speed is maintained; If the commanded rotation speed is equal to or greater than the threshold value, the commanded rotation speed is changed to the threshold value. A transport auxiliary device characterized by:

8. 8. The transport assist device according to claim 1, the object is a caster bed, The wheels are attached to the bottom of the caster bed. A transport auxiliary device characterized by:

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