Self-propelled walker

Abstract

To provide a self-propelled walker capable of obtaining stable drive force by reliably grounding right and left drive wheels even in such a case that there are irregularities, steps or rolls on a floor surface.SOLUTION: A self-propelled walker of the present invention includes: a main body that enables a user to stand in the center; drive wheels 14 that are arranged on right and left sides of the main body and that have individual drive motors 16; safety wheels that are arranged before and behind each drive wheel; and a drive wheel grounding mechanism 18 that oscillatably supports each of the drive wheels 14 and that presses the drive wheel against a floor surface by the weight of each of the drive wheels and pressing force of a gas damper 23.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a self-propelled walker that is used by a user standing in the center of the main body and that assists the user in walking. [Background technology]

[0002] The inventors have been continuing to develop a self-propelled walker that can be used by a user standing in the center of the body, and some of the results of this development have already been proposed in Patent Document 1. The self-propelled walker in Patent Document 1 has a body that is U-shaped in plan view so that the user can stand in the center. Drive wheels are located on both the left and right sides of the body, and each drive wheel is equipped with its own drive motor. The self-propelled walker in Patent Document 1 can also read tape on the floor using a camera and propel itself along a predetermined route.

[0003] A self-propelled walker is equipped with training wheels in front of and behind each of its left and right drive wheels to prevent it from tipping over. These four training wheels are firmly attached to the main body so that they can support the weight even if there is a risk of tipping over. When in use, the user puts their weight on the main body, and this force allows the drive wheels to contact the floor and generate driving force. However, if the floor is uneven, has steps, or is undulating, the drive wheel in the center of the training wheels may lift off the floor, losing contact with the floor and spinning freely, preventing the self-propelled walker from generating adequate driving force. If the drive wheels spin freely, not only will driving force be lost, but the number of rotations of the drive wheels will not match the distance traveled, which could result in the self-propelled walker's position not being accurately tracked.

[0004] This problem is common to conveyance devices equipped with auxiliary wheels in front and behind the drive wheels. In this type of conveyance device, the auxiliary wheels support the weight and external forces, so the drive wheels only need to be designed to provide driving force. However, if the floor is not flat and partially recessed, as described above, the drive wheels located between the auxiliary wheels may lift off the floor. Therefore, the traveling device in Patent Document 2 employs a structure in which a pressing mechanism presses the drive wheel located in the center of the drive wheels against the floor. This pressing mechanism has a rotating hinge on the forward direction side of the drive wheels, a drive wheel attached to a link pivotally supported by the rotating hinge, and a compression spring interposed between the link and the main body, which presses the drive wheel against the floor using the compression spring.

[0005] However, with a pressing mechanism using a compression spring, the compression spring is compressed when the drive wheel approaches the body, generating a large repulsive force. Conversely, the compression spring expands and the repulsive force weakens when the drive wheel moves away from the body. This can result in a decrease in ground contact force when maximum driving force is desired, such as when starting to climb a slope. Figure 14 is a conceptual diagram illustrating this situation. When the floor is flat and the front training wheel 1 and rear training wheel 2 are on the same plane, as in (A), the drive wheel 3 is pressed against the floor with a predetermined force by the compression spring 4. However, when the rear training wheel 2 is on a flat surface but the front training wheel 1 is lifted at the start of a slope, as in (B), the compression spring 4 expands, causing the ground contact force of the drive wheel 3 to be lower than in (A).

[0006] Furthermore, the automated guided vehicle in Patent Document 2 has a five-wheel structure with a single drive wheel in the center of the body and auxiliary wheels on the front, back, left, and right to enable tight turning. As a result, the left and right drive wheels cannot be controlled independently. This is not a particular problem for automated guided vehicles that travel on flat floors while carrying cargo, but it is a problem for self-propelled walkers, which are used by physically disabled users and therefore place importance on left-right balance. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2020-99379 [Patent Document 2] Japanese Patent Application Publication No. 11-301486 Summary of the Invention [Problem to be solved by the invention]

[0008] The object of the present invention is to solve the above-mentioned conventional problems and to provide a self-propelled walker which can reliably keep the left and right drive wheels on the ground and obtain a stable driving force even when the floor surface is uneven, has steps, or is undulating. [Means for solving the problem]

[0009] The self-propelled walker of the present invention, which has been made to solve the above problems, comprises a main body on which a user can stand in the center, drive wheels arranged on the left and right sides of the main body and each equipped with an individual drive motor, auxiliary wheels arranged in front and behind each drive wheel, and each drive wheel is supported so as to be swingable. and a drive wheel grounding mechanism for pressing each drive wheel against the floor surface, the drive wheel grounding mechanism comprising a drive wheel support member whose front end is journalled to the body by a horizontal shaft and whose rear end is fitted with a drive wheel and its drive motor, and a rear end connected to the rear end of the drive wheel support member, Drive and a gas damper that applies a downward rotational moment to the wheel support member. It is characterized by the following.

[0010] In addition, It is preferable that a plurality of mounting holes are formed in the horizontal shaft, and the pressing force of the gas damper on the drive wheels against the floor surface can be adjusted by changing the mounting holes.

[0011] The main body preferably includes a driving calculation processing unit that detects the user's walking state from the current value of each drive motor and assists walking, and a gyro sensor that detects the tilt of the main body.Furthermore, the main body preferably includes a wireless communication unit for remote control, a camera, and an obstacle sensor. [Effects of the Invention]

[0012] The self-propelled walker of the present invention is equipped with a drive wheel contact mechanism that uses the weight of the drive wheels and the pressure of the gas dampers to press the drive wheels against the floor surface. Unlike springs, gas dampers have the characteristic of small changes in pressure across the entire stroke, allowing the drive wheels to be pressed against the floor surface with a nearly constant force whether the drive wheels approach the main body or move away from the main body. This allows the drive wheel contact force to be kept nearly constant even on uneven, stepped, or undulating floor surfaces, thereby providing reliable driving force. Furthermore, because the drive wheels do not spin freely, the position of the self-propelled walker can be accurately determined from the rotation speed. Furthermore, the drive wheel contact mechanism allows the left and right drive wheels to be raised and lowered independently, allowing the self-propelled walker to assist the user without losing balance even on floors where only one side is recessed. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a plan view of a self-propelled walker according to an embodiment. [Figure 2] FIG. 1 is a front view of a self-propelled walker according to an embodiment. [Figure 3] FIG. [Figure 4] FIG. 10 is a front view showing a drive wheel ground contact mechanism in which the mounting angle of the gas damper is changed. [Figure 5] FIG. 10 is a diagram showing the change in ground contact force when the mounting angle of the gas damper is changed. [Figure 6] FIG. 10 is a schematic explanatory diagram showing the advantage of providing independent left and right drive wheel ground contact mechanisms. [Figure 7] FIG. 10 is a schematic explanatory diagram showing the advantages of the drive wheel ground contact mechanism. [Figure 8] FIG. 2 is a block diagram showing a control system for drive wheels. [Figure 9] This is an explanatory diagram of the state when the self-propelled walker approaches the entrance of the flagpole. [Figure 10] 1 is a graph of torque and wheel speed in various driving conditions. [Figure 11]1 is a graph of torque and wheel speed during deceleration and downhill driving conditions. [Figure 12] FIG. 1 is an overall diagram of a control system. [Figure 13] FIG. 1 is an explanatory diagram of a state in which a user is sitting on the toilet seat. [Figure 14] FIG. 1 is an explanatory diagram illustrating a problem with the prior art. DETAILED DESCRIPTION OF THE INVENTION

[0014] Preferred embodiments of the present invention will be described below. Figure 1 is a plan view of a self-propelled walker according to an embodiment, and Figure 2 is its front view. As shown in Figure 1, the main body 10 has a U-shaped or C-shaped planar shape and is designed for use by a user standing in the center. The main body 10 comprises left and right side frames 11 and a front structure 12 connecting their front parts, and arms 13 on the top surfaces of the left and right side frames 11 are provided on which the user places their hands. The left and right side frames 11 are connected only by the front structure 12 so that the user can stand in the center and walk. If the front structure 12 is set at a height of 500 mm or more above the floor, it will be possible for the walker to pass over a toilet seat.

[0015] A computing device, a battery, etc. are housed inside this front structure 12. As will be described later, this self-propelled walker not only has the function of assisting the user in walking, but also has the function of self-propelling in an unmanned state.

[0016] (Basic configuration) Drive wheels 14 are disposed at the bottom of each of the left and right side frames 11 of the main body 10, and small-diameter auxiliary wheels 15 are disposed in front and behind each drive wheel 14. It is desirable for a self-propelled walker to be able to not only move forward and backward, but also turn around on the spot and suddenly change direction of travel. For this reason, each auxiliary wheel 15 is preferably a swivel wheel that can rotate freely not only forward and backward, but also diagonally and sideways. In this embodiment, swivel wheels commercially available under the name Omniwheel (registered trademark) are used. These auxiliary wheels 15 are attached directly to the bottom of the side frames 11.

[0017] As shown in Figure 3, each drive wheel 14 is equipped with a drive motor 16 and is independently driven and controlled on the left and right sides. The center shaft 17 of each drive wheel 14 is attached to the bottom of the main body 10 by a drive wheel contact mechanism 18. The drive wheel contact mechanism 18 includes a plate-shaped drive wheel support member 19 extending in the front-to-rear direction. The front end of this drive wheel support member 19 is supported by a horizontal shaft 20 on a lower bracket 21 of the side frame 11. The center shaft 17 of each drive wheel 14 is attached to the rear end of the drive wheel support member 19. This allows the drive wheels 14 to swing up and down relative to the side frame 11 around the horizontal shaft 20. In this way, the drive wheels 14 do not move in a linear direction up and down, but rather swing in an arc slightly backward relative to the forward movement, making it easier to follow unevenness in the floor surface. A thrust washer is attached to the horizontal shaft 20 to eliminate lateral wobble of the drive wheels 14 and eliminate backlash in the thrust direction.

[0018] As shown in Figure 3, the drive wheel 14 is equipped with a drive motor 16 and a reducer 22. Therefore, the weight of these components causes a downward rotational moment around a horizontal axis 20 to act on the drive wheel support member 19, pressing the drive wheel 14 against the floor surface. However, in the present invention, a gas damper 23 is incorporated into the drive wheel ground contact mechanism 18 to further increase the ground contact force of the drive wheel 14.

[0019] The gas damper 23 has a cylinder filled with nitrogen gas or the like, and uses gas pressure to push out the piston rod. Unlike a spring, its repulsive force remains constant throughout the entire stroke. The rear end of the gas damper 23 is supported by a shaft 24 at the rear upper end of the drive wheel support member 19. The front end of the gas damper 23 is attached to a mounting plate 25 fixed to the side frame 11. As shown in Figures 3 and 4, the mounting plate 25 has a plurality of mounting holes 26 formed in two rows of arcs centered on the shaft 24. A plate 27 is attached to one of these two rows of mounting holes 26 with bolts, and the front end of the gas damper 23 is attached to the plate 27 by a shaft 28. By changing the mounting position of the plate 27 relative to the mounting hole 26, the position of the shaft 28 at the front end of the gas damper 23 can be adjusted up or down.

[0020] Figure 5 shows the change in ground contact force when the position of the axis 28 of the gas damper 23 is changed. Figure 5 (A) corresponds to Figure 3, and (B) corresponds to Figure 4. O1 is the horizontal axis 20 that serves as the center of rotation of the drive wheel support member 19, and O2 is the central axis 17 of the drive wheel 14. Point P is the axis 24 that supports the rear end of the gas damper 23, and points S1 and S2 indicate the position of the axis 28 at the front end of the gas damper 22. The direction of the pressing force of the gas damper 22 is indicated by S1P and S2P, and the pressing force of the gas damper 22 is assumed to be constant and is represented by the vector PQ.

[0021] In the case of (A) in FIG. 5, the pressing force of the gas damper 23 acts on point P at an angle close to horizontal, and the component force in the rotational direction of the drive wheel support member 19 is PR1. Note that PR1 is perpendicular to O1P and is a vector that indicates the magnitude of the rotational force. In the case of (B), the pressing force of the gas damper 23 acts on point P at an angle greater than horizontal, and the component force in the rotational direction of the drive wheel support member 19 is PR2. Since PR2 is greater than PR1 and a greater rotational moment is applied to the drive wheel support member 19, the drive wheel 14 is pressed against the floor surface with a greater force than in the case of (A). In this way, by changing the mounting position of the shaft 28 at the front end of the gas damper 23, the ground contact force of the drive wheel 14 can be changed, making it possible to adjust the ground contact force according to the user's weight and age.

[0022] FIG. 6 is a schematic diagram illustrating the advantages of providing independent drive wheel ground contact mechanisms 18 on the left and right. The left side shows the conventional structure of Patent Document 2, and the right side shows the structure of the present invention. When the floor is inclined left or right relative to the direction of travel, the conventional structure on the left causes the vehicle body to tilt left or right. However, in the present invention on the right, the drive wheel 14 on the lower floor side moves downward, thereby preventing the vehicle body from tilting left or right. FIG. 7 is a schematic diagram illustrating the advantages of the drive wheel ground contact mechanism 18. In a conventional structure without a drive wheel ground contact mechanism, the drive wheels 14 lift up and reduce ground contact force at the beginning of a slope when maximum drive force is required. In contrast, in the structure of the present invention, the drive wheels 14 are constantly pressed against the floor with a constant force, preventing a reduction in drive force.

[0023] (Control of assist force) The self-propelled walker of the present invention has a function of assisting the user in walking, which will be described in detail below. As shown in the control system diagram in Figure 8, the drive motors 16 of the left and right drive wheels 14 each have an encoder 50 and an amplifier 51 built in. In Figure 8, these are abbreviated as left wheel, left motor, left encoder, right wheel, right motor, right encoder, etc. Reference numeral 52 denotes a driving measurement processing unit, which is connected to a driving calculation processing unit 53. Reference numeral 54 denotes a power supply, and 55 denotes a gyro sensor attached to the main body 10. The driving calculation processing unit 53 and power supply 54 are housed in the front structure 12 described above.

[0024] The left and right wheels are driven by the left and right motors in response to a driving command from the driving calculation processor 53. The rotation of these motors is detected by the built-in encoder 50 and converted into a speed signal by the driving measurement processor 52, which is then sent to the driving calculation processor 53. The torque of these motors is also detected by the current value and sent to the driving calculation processor 53. When moving forward, the left and right wheels rotate at the same speed, assisting the user in walking forward. If an error occurs in the diameter of the left and right wheels for some reason, the direction of travel of the self-propelled walker will change if left as is. However, if the user applies force to the main body 10 in an attempt to continue moving forward without changing the direction of travel, the rotation speed of the left and right wheels and the torque of the motors will change, and the driving calculation processor 53 will be able to read the user's intention and change the rotation speed of the left and right wheels to maintain straight travel.

[0025] Furthermore, when the user applies force to main body 10 in an attempt to turn left or right, a difference in speed occurs between the left and right wheels, causing a change in the current value. Traveling calculation processor 53 reads the user's intention from the torque and speed signals of the left and right wheels, and changes the rotation speed of the left and right wheels to change the direction of travel. Furthermore, when the user applies force to main body 10 in an attempt to turn around on the spot, a forward rotational force is applied to one wheel and a backward rotational force is applied to the other wheel. Traveling calculation processor 53 reads the user's intention and reverses the rotational direction of the left and right wheels, causing main body 10 to turn around on the spot. In this way, the self-propelled walker of the present invention detects the force with which the user pushes or pulls main body 10 from the rotation of the left and right wheels and the current value, and provides assistance in accordance with the user's intention.

[0026] Next, we will explain the control of the assist force using the output of the gyro sensor 55. The gyro sensor 55 is a chip-shaped angular velocity sensor, and can be attached to the main body 10 to detect its inclination.

[0027] FIG. 9 shows the state in which the self-propelled walker of the present invention approaches the start of the climb and the state in which it is maintaining the climb. First, when it approaches the start of the climb, the torque of the left and right drive motors increases, as shown in the torque graph in the upper part of FIG. 9. Also, as shown in the graph in the middle, the rotational speed of the wheels decreases. Furthermore, as shown in the graph in the lower part, the gyro sensor 55 detects the inclination of the main body 10. From these signals, the travel calculation processing unit 53 determines that the main body 10 has approached the start of the climb, and applies a larger current to the left and right wheels to assist the walker in the climb. Note that when it enters the state in which it is maintaining the climb, these signals become constant.

[0028] Figures 10 and 11 show graphs of torque and wheel rotation speed under various driving conditions. When driving at a constant speed as shown in Figure 10, the torque and rotation speed of the left and right wheels are constant. If the user pushes the main body 10 forward to increase the driving speed, the wheels are forced to rotate, temporarily increasing the torque. After the acceleration ends after time c1, the torque becomes constant. The wheel rotation speed also continues to increase. Thresholds and speed limits are set for these torque fluctuations and wheel rotation speed. This is because if the self-propelled walker's driving speed becomes too fast, the user will not be able to keep up. The self-propelled walker of the present invention is intended for use in facilities for the disabled and hospitals, and is not intended for use by an unspecified number of users. For this reason, it is preferable to preset the maximum speed and various thresholds according to the user's age, gender, weight, degree of disability, etc.

[0029] The forward tipping shown in Figure 10 occurs when the user trips and begins to tip forward. At this time, the main body is suddenly pushed forward, and the torque and wheel rotation speed exceed the threshold value indicated by c2 within a short period of time, and the wheel rotation speed also exceeds the speed limit value indicated by c2 within a short period of time. When such a sudden change is detected, the driving calculation processing unit 53 determines that an abnormality has occurred and brings the wheels to an emergency stop. The user can prevent a tipping accident by holding on to the stopped main body. The same applies to a backward tipping. When going over a step, the torque temporarily increases and the wheel rotation speed decreases. The gyro sensor 55 detects the tilt of the main body 10 due to the step and increases the assist force. After passing the step, the main body returns to traveling at a constant speed.

[0030] In the case of deceleration shown in Figure 11, a counter torque is generated as the user tries to restrain the body from moving forward, and the driving calculation processing unit 53 reduces the wheel rotation speed. When it is determined from torque fluctuations that the body has decelerated to the speed desired by the user, the driving calculation processing unit 53 assists the body to maintain that speed. When going down a slope, the torque driving the wheels decreases and the wheel rotation speed tends to increase. When the gyro sensor 55 detects that the body is approaching a downhill slope, the driving calculation processing unit 53 controls the wheels in a braking direction to maintain a constant speed. In this way, changes in the floor surface and the user's behavior are detected, and control is performed to exert an assist force in line with the user's intentions.

[0031] (The entire control system) Figure 12 is an overall diagram of the control system. The remote control / display unit 60 at the bottom left is a portable terminal operated by the user, but the remaining units, such as the power supply unit 61, sensor unit 62, integrated management unit 63, and driving calculation processing unit 53, are all mounted on the main body 10. In addition to the gyro sensor 55 mentioned above, the sensor unit 62 includes a light 64, an assist load changeover switch 65, an obstacle sensor 66, a camera 67, etc.

[0032] A light 64 is attached to the bottom of the main body and illuminates the user's feet. A camera 67 also photographs the floor surface under the user's feet, and if the user's feet disappear from view, an emergency signal is sent to the travel calculation processing unit 53 to stop the main body 10, as there is a possibility of the user falling.

[0033] Furthermore, when there is no user present, the camera 67 photographs tape affixed to the floor, the image processor 68 reads the direction, and the driving calculation processor 53 controls the rotation of the left and right wheels to drive the main body 10 unmanned. If the user is an inpatient, and tape is affixed to the floor, the unmanned vehicle can be driven by itself from an outside waiting area to the user's bed and called.

[0034] The obstacle sensor 66 detects obstacles in front of and to the sides of the main body, and upon detection, sends a detection signal to the integrated processing unit 69 of the integrated management unit 63. The reason why an emergency stop is not immediately initiated when an obstacle is detected is because the self-propelled walker of the present invention may be used in a toilet. Since the user stands at the center of the main body 10 when using the self-propelled walker of the present invention, the walker may be driven up to the position of a toilet seat 80, as shown in FIG. 13. In this case, the integrated processing unit 69 determines not to recognize the toilet seat 80 as an obstacle. This requires the integrated processing unit 69 to know the position of the self-propelled walker. If an obstacle is detected during automatic travel, the self-propelled walker is immediately brought to an emergency stop. As mentioned above, the self-propelled walker of the present invention is capable of passing over a toilet seat 80 by setting the front structure 12 at a height of 500 mm or more above the floor.

[0035] The assist load changeover switch 65 is a switch for changing the threshold value and setting the assist force according to the user's age, sex, weight, degree of disability, etc.

[0036] The overall management unit 63 includes a wireless communication unit 71, a status display LED 72, and a mode switching unit 73. The wireless communication unit 71 communicates wirelessly with the remote control and display unit 60, and can notify the current location of the self-propelled walker and make the self-propelled walker move along the tape on the floor. In addition, when a fall or other abnormal event is detected, an emergency signal can be sent to a monitoring room or the like.

[0037] The status display LED 72 indicates whether the self-propelled walker is in a manual state, an automatic running state, or an abnormal state. The mode switching unit 73 switches between the manual state and the automatic running state.

[0038] As explained above, the self-propelled walker of the present invention can reliably keep the left and right drive wheels 14 in contact with the ground even on uneven, step-like, or undulating floors, providing stable driving force and assisting the user's walking according to the walking conditions. Furthermore, because the drive wheels do not spin freely, the traveled distance can be accurately calculated from the number of rotations, and the current position on the map can be accurately determined at all times. Therefore, in the event of an emergency, such as a fall, rescue can be immediately dispatched from a monitoring room or other location. [Explanation of symbols]

[0039] 1. Front training wheels (prior art) 2 Rear training wheels 3 drive wheels 4 is a compression spring 10 Main body (embodiment) 11 Side frame 12 Front structure 13 Arm 14 drive wheels 15 Training wheels 16 Drive motor 17 Center axis 18 Drive wheel ground contact mechanism 19 Drive wheel support member 20 horizontal axis 21 Lower bracket 22 Reducer 23 Gas damper 24 axes 25 Mounting plate 26 Mounting hole 27 board 28 axes 50 Encoder 51 Amplifier 52 Driving measurement processing unit 53 Driving calculation processing unit 54 Power supply 55 Gyro sensor 60 Remote control and display unit 61 Power supply section 62 Sensor section 63 General Management Department 64 Lighting 65 Assist load changeover switch 66 Obstacle Sensor 67 Camera 71 Radio Communication Department 72 Status indicator LED 73 Mode switching section 80 toilet seats

Claims

1. The main body in the center where the user can stand, Drive wheels arranged on the left and right sides of the body and each equipped with an individual drive motor; Auxiliary wheels are arranged in front and behind each drive wheel; a drive wheel ground contact mechanism that supports each drive wheel so that the drive wheel can swing and presses the drive wheel against a floor surface, The drive wheel ground contact mechanism is characterized in that it comprises a drive wheel support member whose front end is journalled to the main body by a horizontal shaft and whose rear end has a drive wheel and its drive motor attached, and a gas damper whose rear end is connected to the rear end of the drive wheel support member and which applies a downward rotational moment to the drive wheel support member.

2. A self-propelled walker as described in claim 1, in which multiple mounting holes for the horizontal axis are formed in the main body, and the pressing force of the drive wheels against the floor surface by the gas damper can be adjusted by changing the mounting holes.

3. A self-propelled walker as described in claim 1 or 2, characterized in that the main body is equipped with a running calculation processing unit that detects the user's walking state from the current value of each drive motor and assists the walking, and a gyro sensor that detects the inclination of the main body.

4. A self-propelled walker described in any one of claims 1 to 3, characterized in that the main body is equipped with a wireless communication unit for remote control.

5. A self-propelled walker described in any one of claims 1 to 4, characterized in that the main body is equipped with a camera and an obstacle sensor.

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