Electric wheelchair

Abstract

To provide an electric wheelchair capable of getting over a step with a simple structure.SOLUTION: The electric wheelchair 10 includes a chair main body provided with a seating part on which an occupant can be seated, main wheels provided on both right and left sides of the chair main body, auxiliary wheels disposed behind the main wheels and movable up and down with respect to the main wheels, and an electric motor provided in a rear part of the chair main body and formed in an elongated shape. And a control unit 60 configured to control the main wheel, the auxiliary wheel, and the support body such that the main wheel is rotated in a state where the auxiliary wheel is grounded until the main wheel is lifted to a predetermined height, and the auxiliary wheel is floated and only the support body is grounded when the main wheel is lifted to the predetermined height.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an electric wheelchair. [Background technology]

[0002] Patent Document 1 discloses an electric wheelchair that can go up and down stairs. Specifically, the electric wheelchair described in Patent Document 1 includes a chair (chair body), main wheels, training wheels, and a support bar that extends rearward beyond the training wheels, and is structured so that when going up stairs, the training wheels are lifted and the chair is supported by the main wheels and the support bar. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-95277 Summary of the Invention [Problem to be solved by the invention]

[0004] The structure described in Patent Document 1 above allows the chair to ascend and descend stairs with a simple structure, but when climbing over steps higher than stairs, the chair body is supported by the main wheels and support rods, which are spaced apart from each other, so the load acting on the main wheels increases. Furthermore, the frictional resistance acting on the support requires the main wheels to exert excessive propulsive force. Therefore, there is room for improvement in climbing over steps with a simple structure.

[0005] An object of the present invention is to provide an electric wheelchair that has a simple structure and is capable of climbing over steps. [Means for solving the problem]

[0006] The electric wheelchair of claim 1 comprises a chair body with a seat on which an occupant can sit, main wheels provided on both the left and right sides of the chair body, auxiliary wheels located rearward of the main wheels and movable up and down relative to the main wheels, a long support provided at the rear of the chair body and movable between a grounding position where it extends rearward from the chair body and touches the ground and a stored position where it extends upward from the chair body, and a control unit that controls the main wheels, the auxiliary wheels, and the support so that the main wheels rotate with the auxiliary wheels on the ground until the main wheels are raised to a predetermined height, and when the main wheels have been raised to the predetermined height, the control unit lifts the auxiliary wheels so that only the support is on the ground.

[0007] In the electric wheelchair according to claim 1, the chair body is provided with a seat on which a passenger can sit. Main wheels are provided on both the left and right sides of the chair body, and auxiliary wheels are located behind the main wheels. A long support is provided at the rear of the chair body. The support is movable between a ground contact position where it extends rearward from the chair body and touches the ground, and a storage position where it extends upward from the chair body. The main wheels, auxiliary wheels, and support are controlled by a controller, which rotates the main wheels with the auxiliary wheels on the ground until the main wheels are raised to a predetermined height. This brings the ground contact position closer to the main wheels, compared to a configuration in which the main wheels and support wheels are on the ground at two points, thereby reducing the load acting on the main wheels. Furthermore, by having the auxiliary wheels on the ground, frictional resistance can be reduced, and the rotation of the main wheels is not hindered, compared to a configuration in which only the support wheels are on the ground behind the main wheels.

[0008] Furthermore, when the main wheels are raised to a predetermined height, the control unit controls the auxiliary wheels to float so that only the supports are in contact with the ground. As a result, when the main wheels are raised to the predetermined height, the load acting on the main wheels increases, improving grip on steps.

[0009] The electric wheelchair of claim 2 is the same as claim 1, and further comprises a height sensor that detects the height between the main wheels and the ground, and the control unit determines that the wheelchair has been raised to a predetermined height based on a signal received from the height sensor.

[0010] In the electric wheelchair according to claim 2, whether or not the switching height for lifting the training wheels has been reached is determined based on the signal received from the height sensor, so that the height from the ground can be determined accurately.

[0011] The electric wheelchair of claim 3 is the same as claim 1, and further comprises an angle sensor that detects the angle of the chair body, and the control unit determines that the chair has been raised to a predetermined height based on a signal received from the angle sensor.

[0012] In the electric wheelchair according to claim 3, whether the switching height has been reached is determined based on the angle of the chair body, so a height sensor that detects the height from the ground is not required. Also, the posture of the occupant can be indirectly detected using an angle sensor.

[0013] The electric wheelchair according to claim 4 is the electric wheelchair according to claim 1, wherein the control unit moves the support body near the ground at a predetermined timing.

[0014] In the electric wheelchair according to claim 4, by moving the support closer to the ground, the support comes into contact with the ground when the chair body tilts backward, and the chair body can be prevented from tipping backward.

[0015] The electric wheelchair according to claim 5 is the same as claim 1, wherein the seating section is provided so as to be slidable in the front-rear direction, and the seating section slides forward as the height of the main wheels increases.

[0016] In the electric wheelchair according to claim 5, the center of gravity moves forward by sliding the seat forward as the height of the main wheels increases, which allows the gripping force of the main wheels to increase after they have overcome a step to some extent. [Effects of the Invention]

[0017] As described above, the electric wheelchair according to the present invention can overcome steps with a simple structure. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic side view showing a main part of an electric wheelchair according to an embodiment. [Figure 2] FIG. 2 is a block diagram showing the hardware configuration of the electric wheelchair. [Figure 3] FIG. 2 is a block diagram showing the functional configuration of the electric wheelchair. [Figure 4] 10 is a flowchart showing an example of a step-crossing process performed by a control unit when the electric wheelchair goes over a step. [Figure 5] FIG. 2 is a schematic side view showing the state of the electric wheelchair during normal driving. [Figure 6] FIG. 1 is a schematic side view showing the initial state of the electric wheelchair going over a step. [Figure 7] FIG. 7 is a schematic side view showing a state in which the main wheels have reached a predetermined height from the state shown in FIG. 6. [Figure 8] 8 is a schematic side view showing a state immediately after going over a step from the state in FIG. 7. FIG. [Figure 9] 9 is a schematic side view showing a state slightly advanced from the state of FIG. 8. FIG. [Figure 10] FIG. 10 is a model diagram for explaining an example of a method for measuring height, showing a state in which a step is in contact. [Figure 11] FIG. 10 is a model diagram for explaining an example of a method for measuring height, showing a state in the middle of climbing over a step. [Figure 12] FIG. 1 is a schematic plan view of an electric wheelchair, showing a state in which one main wheel and two auxiliary wheels are in contact with the ground. [Figure 13] FIG. 10 is a schematic plan view of an electric wheelchair according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0019] An electric wheelchair according to an embodiment will be described with reference to the drawings.

[0020] 1 is a schematic side view showing the main parts of an electric wheelchair 10 according to an embodiment. The arrows FR and UP in the figure respectively indicate the forward and upward directions of the electric wheelchair 10. In the following description, unless otherwise specified, when the front-rear, up-down, and left-right directions are used, they will refer to the front-rear direction of the front-rear, up-down direction of the up-down, and left-right direction (width direction) of the electric wheelchair 10, respectively.

[0021] 1, an electric wheelchair 10 of this embodiment includes a chair body 12, and the chair body 12 is provided with a seating section 14 on which a passenger can sit. Specifically, the chair body 12 is configured to include the seating section 14 and a chair support section 16.

[0022] The seating portion 14 is formed in an approximately L-shape when viewed from the side, and is composed of a seat cushion portion 14A that can support the occupant's buttocks and thighs from below, and a seat back portion 14B that extends upward from the rear end of the seat cushion portion 14A and can support the occupant's back from behind.

[0023] The chair support portion 16 is disposed below the seat cushion portion 14A and is fixed to the underside of the seat cushion portion 14A. The chair support portion 16 supports the seat cushion portion 14A from below.

[0024] A base 18 is disposed below the chair support 16. The base 18 forms the framework of the electric wheelchair 10 and includes a front-to-rear extending portion 18A that extends forward and backward, and a vertical extending portion 18B that is provided at the rear end of the front-to-rear extending portion 18A and extends vertically. A support shaft 20 is rotatably attached to the base 18, and main wheels 22 are fixed to the support shaft 20. The main wheels 22 are provided on both the left and right sides of the chair body 12. For ease of explanation, the main wheels 22 are drawn by imaginary lines in FIG. 1.

[0025] The support shaft 20 is configured to rotate by a drive source such as a motor, and the motor is operated by an occupant to rotate the main wheels 22. In this embodiment, as an example, the support shaft 20 is configured to include a driven pulley 21 provided coaxially with the support shaft 20, a drive pulley 24, and a belt 26 wound around the driven pulley 21 and the drive pulley 24. A motor (not shown) is connected to the drive pulley 24, and when the motor is driven, power is transmitted to the driven pulley 21 via the drive pulley 24 and the belt 26.

[0026] Here, a first actuator 28 is provided between the front-rear extending portion 18A of the base portion 18 and the chair support portion 16. The first actuator 28 is, for example, an electric cylinder type actuator, and includes a first case 28A and a first rod 28B.

[0027] The first case 28A is formed in a generally cylindrical shape, and the rear end of the first case 28A is fixed to a first rear bracket 30 provided on the front-to-rear extending portion 18A. A portion of the first rod 28B is inserted inside the first case 28A and is configured to be slidable relative to the first case 28A. The front end of the first rod 28B is fixed to a first front bracket 32 ​​provided on the underside of the chair support 16. Therefore, when the first rod 28B slides forward and the first actuator 28 extends forward, the chair support 16 and the chair main body 12 slide forward relative to the base 18. Conversely, when the first rod 28B slides rearward from its extended state and the first actuator 28 retracts, the chair support 16 and the chair main body 12 slide rearward relative to the base 18.

[0028] A front flipper 34, auxiliary wheels 36, and a rear flipper 38 serving as a support are rotatably attached to the lower end of the vertically extending portion 18B of the base portion 18.

[0029] The front flipper 34 is disposed between the left and right main wheels 22 and extends in the front-to-rear direction, and the rear end of the front flipper 34 is rotatably supported on the base portion 18. A roller 40 is attached to the front end of the front flipper 34. Furthermore, the front flipper 34 and the front-to-rear extending portion 18A of the base portion 18 are connected by a second actuator 42.

[0030] A second upper bracket 44 is provided at the front end of the front-rear extending portion 18A, and the upper end of the second actuator 42 is connected to this second upper bracket 44. In addition, the lower end of the second actuator 42 is connected to the center portion of the front flipper 34 in the front-rear direction via a second lower bracket 46.

[0031] The second actuator 42 is an electric cylinder type actuator including a second case 42A and a second rod 42B, and is configured so that the front flipper 34 swings up and down as the second rod 42B extends and retracts relative to the second case 42A.

[0032] The auxiliary wheels 36 are disposed rearward of the main wheels 22 and are configured to be movable up and down relative to the main wheels 22. Specifically, the auxiliary wheels 36 are rotatably attached to one end of an elongated arm 48, and the other end of the arm 48 is rotatably supported on the lower end of the vertical extension portion 18B.

[0033] The arm 48 is provided with an actuator (not shown), and by operating this actuator, the arm 48 swings up and down. When the arm 48 is moved downward, the auxiliary wheels 36 and the main wheels 22 come into contact with the ground G. When the arm 48 is moved upward, the chair body 12 tilts as the arm 48 moves. When the arm 48 is moved upward while a rear flipper 38 (described later) is in contact with the ground, the chair body 12 does not tilt, and the auxiliary wheels 36 are lifted off the ground G.

[0034] As an example, the training wheels 36 of this embodiment are so-called omni-wheels, in which a plurality of rollers (not shown) that rotate in a direction perpendicular to the rotation direction of the training wheels 36 are arranged on the outer periphery of the training wheels 36. Therefore, the training wheels 36 can be moved in all directions in a plan view without changing the orientation of the training wheels 36.

[0035] The rear flipper 38 is formed in an elongated shape with a slightly curved tip. The base end of the rear flipper 38 is rotatably supported on the lower end of the vertical extension portion 18B of the base portion 18.

[0036] The rear flipper 38 and the vertical extension 18B of the base 18 are connected by a third actuator 50. The third actuator 50 is an electric cylinder type actuator including a third case 50A and a third rod 50B, and the front end of the third actuator 50 is connected to a third front bracket 52 provided on the vertical extension 18B. In addition, the rear end of the third actuator 50 is connected to a third rear bracket 54 provided on the rear flipper 38.

[0037] The third actuator 50 is configured as described above, and is configured so that the rear flipper 38 swings up and down as the third rod 50B expands and contracts relative to the third case 50A. Specifically, FIG. 1 illustrates the third actuator 50 in a contracted state, in which the rear flipper 38 is in a stored position extending in the vertical direction. Furthermore, as the third rod 50B of the third actuator 50 expands from the state in FIG. 1, the rear flipper 38 extends forward and backward and moves to a ground contact position where it comes into contact with the ground G (see FIG. 7). In other words, the rear flipper 38 is movable between the ground contact position and the stored position.

[0038] Fig. 2 is a block diagram showing the hardware configuration of the electric wheelchair 10. As shown in Fig. 2, the electric wheelchair 10 has a control unit 60 that performs various controls, and the control unit 60 is configured to include a CPU (Central Processing Unit: processor) 62, a ROM (Read Only Memory) 64, a RAM (Random Access Memory) 66, a storage 68, a communication I / F (communication interface) 70, and an input / output I / F (input / output interface) 72. Each component is connected to each other via a bus 61 so that they can communicate with each other.

[0039] The CPU 62 is a central processing unit that executes various programs and controls each part. That is, the CPU 62 reads programs from the ROM 64 or the storage 68 and executes the programs using the RAM 66 as a work area. The CPU 62 controls each of the above components and performs various arithmetic processing in accordance with the programs recorded in the ROM 64 or the storage 68.

[0040] The ROM 64 stores various programs and various data. The RAM 66 temporarily stores programs or data as a working area. The storage 68 is configured with an HDD (Hard Disk Drive) or an SSD (Solid State Drive) and stores various programs including an operating system and various data. In this embodiment, the ROM 64 or the storage 68 stores programs and various data for performing information registration processing, information update processing, etc.

[0041] The communication I / F 70 is an interface that allows the control unit 60 to communicate with other devices, and uses standards such as CAN (Controller Area Network), Ethernet (registered trademark), LTE (Long Term Evolution), FDDI (Fiber Distributed Data Interface), and Wi-Fi (registered trademark).

[0042] The input / output I / F 72 is electrically connected to the first actuator 28, the second actuator 42, the third actuator 50, the fourth actuator 74, an angle sensor 76, and a forward sensor 78.

[0043] By sending a predetermined signal from the control unit 60 to the motor of the first actuator 28, the first rod 28B slides relative to the first case 28A, and the first actuator 28 expands or contracts. Similarly, by sending a predetermined signal from the control unit 60 to the motors that respectively constitute the second actuator 42, the third actuator 50, and the fourth actuator 74, the second actuator 42, the third actuator 50, and the fourth actuator 74 expand or contract. Note that the fourth actuator 74 is an actuator for raising or lowering the arm 48 of the training wheel 36.

[0044] The angle sensor 76 is attached to, for example, the chair body 12 and is a sensor that detects the angle of the chair body 12. The control unit 60 is configured to acquire a signal from the angle sensor 76, thereby detecting the angle of the chair body 12 relative to the horizontal or the angle relative to the initial angle.

[0045] The forward sensor 78 is provided, for example, at the front of the chair body 12, and is a sensor for detecting obstacles and the like in front of the electric wheelchair 10. The forward sensor 78 is configured using, for example, an optical camera, radar, and lidar (LIDAR: Light Detection and Ranging or Laser Imaging Detection and Ranging), etc.

[0046] (Functional configuration of electric wheelchair 10) The electric wheelchair 10 uses the above hardware resources to realize various functions. The functional configuration realized by the electric wheelchair 10 will be described with reference to FIG.

[0047] 3, the electric wheelchair 10 is configured to include, as functional components, a first actuator control unit 82, a second actuator control unit 84, a third actuator control unit 86, a fourth actuator control unit 88, a target attitude angle calculation unit 90, and a flat ground determination unit 92. Each functional component is realized by the CPU 62 reading and executing a program stored in the ROM 64 or storage 68.

[0048] The first actuator control unit 82 controls the first actuator 28 to slide the chair support unit 16 and the chair body 12 in the front-rear direction relative to the base unit 18 to a predetermined position (see FIG. 1). The first actuator control unit 82 also stores the amount of movement of the chair support unit 16 relative to the base unit 18.

[0049] The second actuator control unit 84 controls the second actuator 42 to swing the front flipper 34 up and down (see FIG. 1). The second actuator control unit 84 also stores the amount of movement of the front flipper 34 relative to a reference position.

[0050] The third actuator control unit 86 controls the third actuator 50 to swing the rear flipper 38 up and down (see FIG. 1). The third actuator control unit 86 also stores the amount of movement of the rear flipper 38 relative to a reference position.

[0051] The fourth actuator control unit 88 controls the fourth actuator 74 to swing the arm 48 of the training wheel 36 up and down (see FIG. 1). The fourth actuator control unit 88 also stores the amount of movement of the arm 48 relative to a reference position.

[0052] The target posture angle calculation unit 90 calculates the timing for switching the rear contact point when going over a step, based on the height of the step in front of the electric wheelchair 10 detected by the front sensor 78. This switching timing is calculated as a target value for the angle of the chair body 12.

[0053] The flat ground determination unit 92 determines whether the electric wheelchair 10 has completely cleared the step. The determination by the flat ground determination unit 92 is made based on the amount of rotation (rotation speed) of the main wheels 22 and the angle of the chair body 12.

[0054] The electric wheelchair 10 of this embodiment is configured as described above, and switches the rear contact points while going over a step to prevent slippage of the main wheels 22. Specifically, the main wheels 22 are rotated with the auxiliary wheels 36 in contact with the ground until the main wheels 22 are raised to a predetermined height, and when the main wheels 22 have been raised to the predetermined height, the auxiliary wheels 36 are lifted and the main wheels 22, auxiliary wheels 36, and rear flippers 38 are controlled so that only the rear flippers 38 are in contact with the ground.

[0055] (Step overrun processing) Fig. 4 is a flowchart showing an example of the flow of processing by the electric wheelchair 10 in this embodiment. The step climbing processing will be described with reference to the flowchart of Fig. 4 and the drawings shown in Figs. 5 to 11.

[0056] 5, when the electric wheelchair 10 of this embodiment is traveling on normal flat ground, the rear flipper 38 moves to the vicinity of the ground G. Specifically, the third actuator 50 is controlled by the function of the third actuator control unit 86, and the rear flipper 38 swings downward to the vicinity of the ground G.

[0057] Furthermore, if the rear flipper 38 is brought into contact with the ground G, the frictional resistance generated between the ground and the rear flipper 38 will hinder the movement of the electric wheelchair 10, so it is preferable to maintain the rear flipper 38 at a height that does not contact the ground G.

[0058] By moving the rear flipper 38 near the ground, when an external force that causes the chair body 12 to roll backward is suddenly applied to the chair body 12 or when the chair body 12 travels on an uneven road surface that makes the posture of the chair body 12 unstable, the rear flipper 38 comes into contact with the ground G and the electric wheelchair 10 is prevented from rolling backward.

[0059] In the state shown in Fig. 5, if there is a step ahead of the electric wheelchair 10, the electric wheelchair 10 switches to the climbing mode. The switch to the climbing mode may be performed automatically by the control unit 60, or may be performed by the occupant operating an operation unit (not shown). In this embodiment, as an example, the occupant operates the operation unit to switch to the climbing mode.

[0060] 4, the CPU 62 of the control unit 60 determines whether the climbing mode has been activated. If the climbing mode has not been activated, the step climbing process is not performed, and therefore this process is terminated. If the climbing mode has been activated by an operation by the occupant or the like, the determination in step S102 is affirmative, and the CPU 62 proceeds to the process of step S104.

[0061] In step S104, the CPU 62 shifts to the climbing-over posture. Specifically, as shown in Fig. 6, the CPU 62 controls the second actuator 42 by the function of the second actuator control unit 84 to swing the front flipper 34 upward so that the front flipper 34 does not interfere with the step S.

[0062] In addition, the CPU 62 controls the fourth actuator 74 using the function of the fourth actuator control unit 88 to move the arm 48 so as to maintain the auxiliary wheel 36 in a grounded state, while rotating the main wheel 22 to climb up the step S.

[0063] 4, the CPU 62 calculates the target posture angle using the function of the target posture angle calculation unit 90. Specifically, the CPU 62 detects the height of the step S based on the signal acquired from the front sensor 78, and calculates the angle of the chair body 12 corresponding to the height at which the rear ground contact point is switched based on the height of the step S.

[0064] The CPU 62 determines whether the target posture angle has been reached in step S108. Here, an example of a method for calculating the height between the main wheels 22 and the ground G from the angle of the chair body 12 will be described with reference to Figs. 10 and 11.

[0065] Fig. 10 is a model diagram for explaining an example of a method for measuring height, showing the electric wheelchair 10 in contact with a step S. Fig. 11 is a model diagram for explaining an example of a method for measuring height, showing the electric wheelchair 10 in the middle of going over the step S. For ease of explanation, Figs. 10 and 11 only schematically depict the seat 14, main wheels 22, and training wheels 36. In Figs. 10 and 11, the arrows indicate the direction of travel.

[0066] 10, when the radius of the main wheels 22 is R, the radius of the auxiliary wheels 36 is r, and the height of the step S is h, immediately after the main wheels 22 come into contact with the step S, the main wheels 22 are not lifted up, so the height from the center of the main wheels 22 to the upper surface of the step S is Rh. The height h of the step S is detected by the front sensor 78.

[0067] In this state, the angle formed by the vertical line and an imaginary line connecting the contact point between the step S and the main wheel 22 and the center of the main wheel 22 is defined as θ0. Furthermore, in this state, the angle formed by the vertical line and a line connecting the center of the main wheel 22 and the center of the auxiliary wheel 36 is defined as φ0.

[0068] As shown in Figure 11, when the electric wheelchair 10 is in the middle of climbing over a step S, the main wheels 22 are floating by a distance z above the ground G. Furthermore, due to the rotation of the main wheels 22, the angle θ0 changes by dθ to become angle θ, and the angle φ0 changes by dφ to become angle φ.

[0069] In the state of Figure 11, the height from the center of the main wheel 22 to the upper surface of the step S is R + zh. When expressed using the angle θ, it becomes Rcos θ. Therefore, z is expressed by the following equation (1).

[0070]

number

[0071] On the other hand, if the distance between the center of the main wheel 22 and the center of the auxiliary wheel 36 is L, the following formula (2) holds.

[0072]

number

[0073] Here, the amount of change dφ in the angle φ is the difference between φ0 and φ, so Lcosφ is expressed as Lcos(φ0-dφ). φ0 is expressed by the following equation (3).

[0074]

number

[0075] From the formulas (2) and (3), the height between the main wheels 22 and the ground G is expressed by the following formula (4).

[0076]

number

[0077] In this way, if the height h of the step S can be detected based on the signal from the front sensor 78, the height z can be calculated from the formula (1). If the height h cannot be detected, the height z can be calculated from the formula (4) based on the signal from the angle sensor 76.

[0078] Alternatively, a height sensor may be provided in the electric wheelchair 10, and the height between the main wheels 22 and the ground G may be measured directly based on a signal received from the height sensor. For example, a laser reflection sensor may be provided on the underside of the base 18, and this laser reflection sensor may be used as the height sensor. Alternatively, radar, ultrasonic sensors, lidar, etc. may be used as the height sensor.

[0079] 4, if the CPU 62 determines that the target attitude angle has been reached, the process proceeds to step S110. The CPU 62 switches the attitude in step S110, thereby switching the rear ground contact point.

[0080] Specifically, the CPU 62 operates the third actuator 50 through the function of the third actuator control section 86 to cause the rear flipper 38 to touch the ground. Meanwhile, the CPU 62 operates the fourth actuator 74 through the function of the fourth actuator control section 88 to move the training wheels 36 upward, thereby lifting the training wheels 36 off the ground G.

[0081] FIG. 7 is a schematic side view showing a state in which the main wheels 22 have reached a predetermined height from the state shown in FIG. 6 , and shows a state in which the switching of the rear contact point has been completed. As shown in FIG. 7 , when the chair body 12 reaches the target attitude angle, the auxiliary wheels 36 are lifted and the rear flippers 38 are brought into contact with the ground, so that the electric wheelchair 10 is supported at a position further rearward from the chair body 12 than when it was supported by the auxiliary wheels 36. In this state, the load acting on the main wheels 22 increases, and the gripping force of the main wheels 22 is improved. Note that, in this embodiment, a case is described in which the step S is overcome by rotating the main wheels 22 after the switching of the rear contact point has been completed. However, the present invention is not limited to this. After the switching of the rear contact point has been completed, the rear flippers 38 may be controlled to push up the chair body 12, thereby enabling the step S to be overcome without the main wheels 22 rotating at all or almost without any rotation.

[0082] Fig. 8 is a schematic side view showing the electric wheelchair 10 immediately after going over the step S from the state in Fig. 7. As shown in Fig. 8, immediately after going over the step S, the rear flipper 38 remains in contact with the ground G, thereby preventing the electric wheelchair 10 from rolling backward.

[0083] 4, the CPU 62 determines whether or not the electric wheelchair 10 has completed climbing over the step S. Specifically, the CPU 62 performs this determination based on the amount of rotation (rotation speed) of the main wheels 22 and the angle of the chair body 12 using the function of the flat ground determination unit 92.

[0084] If the CPU 62 determines in step S112 that the electric wheelchair 10 has gone over the step S, the process proceeds to step S114. In step S114, the CPU 62 transitions the electric wheelchair 10 to the normal posture, and then ends the step going over process.

[0085] Figure 9 is a schematic side view showing the electric wheelchair 10 in a state where it has moved slightly forward from the state shown in Figure 8. In the state shown in Figure 9, the rear flippers 38 are in contact with the ground G, and the training wheels 36 are off the ground. From this state, the fourth actuator 74 is operated to bring the training wheels 36 into contact with the ground, thereby transitioning to the normal posture. During normal travel, the state can be freely switched between a state where the rear flippers 38 are lowered and a state where the rear flippers 38 are retracted as shown in Figure 1.

[0086] (action) Next, the operation of the electric wheelchair 10 according to this embodiment will be described.

[0087] As shown in Figure 1, in an electric wheelchair 10 according to this embodiment, a chair body 12 is provided with a seat 14 on which a passenger can sit. Main wheels 22 are provided on both the left and right sides of the chair body 12, and auxiliary wheels 36 are arranged behind the main wheels 22. A rear flipper 38 is also provided at the rear of the chair body 12. The rear flipper 38 is movable between a grounding position where it extends rearward from the chair body 12 and touches the ground, and a retracted position where it extends upward from the chair body 12.

[0088] Furthermore, the main wheels 22, auxiliary wheels 36, and rear flippers 38 are controlled by the control unit 60, and the main wheels 22 are rotated with the auxiliary wheels 36 on the ground until the main wheels 22 are raised to a predetermined height. This brings the contact point closer to the main wheels 22, reducing the load acting on the main wheels 22, compared to a state in which only the main wheels 22 and rear flippers 38 are on the ground. Furthermore, by having the auxiliary wheels 36 on the ground, frictional resistance can be reduced and the rotation of the main wheels 22 is not hindered, compared to a configuration in which only the rear flippers 38 are on the ground behind the main wheels 22.

[0089] Furthermore, when the main wheels 22 are raised to a predetermined height, the control unit 60 controls the auxiliary wheels 36 to be raised so that only the rear flippers 38 are in contact with the ground. As a result, as shown in Fig. 7, when the main wheels 22 are raised to a predetermined height, the load acting on the main wheels 22 increases, improving the grip force on the step S. In this way, the electric wheelchair 10 of this embodiment can overcome the step S with a simple structure.

[0090] Furthermore, in this embodiment, the angle of the chair body 12 is detected based on a signal from the angle sensor 76 shown in Fig. 2, and whether or not the switching height has been reached is determined based on this angle, so there is no need for a height sensor that detects the height from the ground G. Also, the angle sensor 76 can be used to indirectly detect the posture of the occupant.

[0091] If a height sensor is provided, it is possible to accurately determine the height from the ground G because it is determined based on the signal received from the height sensor whether the switching height for lifting the training wheels 36 has been reached. However, since a dedicated part is required, a structure without a height sensor is preferable from the viewpoint of reducing the number of parts.

[0092] Furthermore, in this embodiment, as shown in FIG. 5, by moving rear flipper 38 closer to the ground during normal travel, rear flipper 38 touches the ground when chair body 12 tilts backward, thereby preventing chair body 12 from tipping backward.

[0093] Although the electric wheelchair according to the present invention has been described above, it goes without saying that it can be embodied in various forms without departing from the spirit of the present invention. For example, in the above embodiment, the first actuator 28 is not activated when going over a step, but the present invention is not limited to this, and the first actuator 28 may be activated at a predetermined timing to slide the seat 14.

[0094] Specifically, by controlling the first actuator 28 so that the seating section 14 slides forward relative to the base section 18 as the height of the main wheels 22 increases, it becomes possible to overcome steps more easily. In other words, by sliding the seating section 14 forward as the height of the main wheels 22 increases, the center of gravity of the electric wheelchair 10 including the occupant moves forward, and therefore the grip force of the main wheels 22 can be increased after the main wheels 22 have overcome the step S to some extent.

[0095] In the above embodiment, a pair of left and right auxiliary wheels 36 are provided and spaced apart in the width direction as shown in Fig. 12, but this is not limiting. For example, the auxiliary wheels 36 may be arranged close to each other as shown in Fig. 13.

[0096] 12, with the main wheels 22 in contact with the step S, one of the main wheels 22 may be lifted up, resulting in the electric wheelchair 10 being supported by one main wheel 22 and two auxiliary wheels 36. In such a case, the triangle connecting the three contact points in a plan view may deviate from the center of gravity VG of the electric wheelchair 10, which may cause the posture of the electric wheelchair 10 to become unstable.

[0097] In contrast to this, as shown in Figure 13, by bringing the training wheels 36 closer together, they can be regarded as a single training wheel, and the situation where one of the main wheels 22 is lifted up can be effectively prevented. As a result, the posture of the electric wheelchair 10 can be stabilized. Note that since the pair of left and right training wheels 36 are each omni-wheels, they may be moved closer to each other when going over a step S. Also, a configuration with only one training wheel 36 may be used.

[0098] Furthermore, the posture of the electric wheelchair 10 may be stabilized by changing the control method without changing the auxiliary wheels 36. Specifically, the torque of the main wheels 22 may be detected, and if the main wheels 22 spin, the main wheels 22 that are not spinning may be rotated in the opposite direction to suppress spin.

[0099] Furthermore, in the above embodiment, the control unit 60 controls the auxiliary wheels 36 to be lifted and only the rear flippers 38 to be in contact with the ground when the main wheels 22 are raised to a predetermined height, but this is not limiting. For example, the control unit 60 may control the auxiliary wheels 36 to be gradually lifted as the main wheels 22 are raised. In this case, the load acting on the auxiliary wheels 36 decreases over time, and instead the load acting on the rear flippers 38 increases, thereby ensuring a longer period of time in which both the auxiliary wheels 36 and the rear flippers 38 are in contact with the ground, and enabling smooth switching of the rear ground contact point.

[0100] Furthermore, in the above embodiment, the configuration is one in which the front flipper 34 is provided, but the present invention is not limited to this and may be applied to an electric wheelchair that does not have the front flipper 34. In this case, the configuration is one in which the front flipper 34 and the second actuator 42 are omitted.

[0101] In the above embodiment, the first actuator 28, the second actuator 42, the third actuator 50, and the fourth actuator 74 are each an electric cylinder type actuator, but this is not limiting and other types of actuators may be used. For example, the first actuator 28 may be a slider type actuator.

[0102] Furthermore, in the above embodiment, the control when climbing over a step has been described, but the opposite control can be applied when descending a step. Specifically, when descending a step, the rear flipper 38 is first lowered and brought into contact with the ground below the step. Then, the main wheels 22 are rotated to descend the step. Here, when the wheelchair has descended to a predetermined height, the auxiliary wheels 36 are brought into contact with the ground and the rear flippers 38 are lifted off the ground, thereby switching the rear contact point. By switching the rear contact point at a predetermined height in this way, the load acting on the main wheels 22 can be reduced, and slippage of the main wheels 22 can be suppressed. Note that, by positioning the rear flippers 38 near the ground when switching the rear contact point, the power wheelchair 10 can be prevented from rolling backward.

[0103] The following notes are provided regarding the above embodiment.

[0104] (Appendix 1) a chair body having a seating portion on which an occupant can sit; Main wheels provided on both the left and right sides of the chair body; auxiliary wheels that are disposed rearward of the main wheels and are movable up and down relative to the main wheels; a support provided at the rear of the chair body, formed in an elongated shape, and movable between a grounding position extending rearward from the chair body and grounding the chair, and a storage position extending upward from the chair body; a control unit that rotates the main wheels with the auxiliary wheels in a state where they are in contact with the ground until the main wheels are raised to a predetermined height, and controls the main wheels, the auxiliary wheels, and the support body so that, when the main wheels are raised to the predetermined height, the auxiliary wheels are lifted and only the support body is in contact with the ground; An electric wheelchair having: (Appendix 2) a height sensor for detecting the height between the main wheel and the ground; The electric wheelchair of claim 1, wherein the control unit determines that the electric wheelchair has been raised to a predetermined height based on a signal received from the height sensor. (Appendix 3) an angle sensor for detecting the angle of the chair body; The electric wheelchair of claim 1, wherein the control unit determines that the electric wheelchair has been raised to a predetermined height based on a signal received from the angle sensor. (Appendix 4) 2. The electric wheelchair of claim 1, wherein the control unit moves the support body near the ground at a predetermined timing. (Appendix 5) The seating portion is provided so as to be slidable in the front-rear direction, 2. The electric wheelchair of claim 1, wherein the seat slides forward as the height of the main wheels increases. [Explanation of symbols]

[0105] 10 Electric wheelchair 12 Chair body 22 Main wheel 36 Training wheels 38 Rear flipper (support) 60 Control Unit 76 Angle Sensor

Claims

1. a chair body having a seating portion on which an occupant can sit; Main wheels provided on both the left and right sides of the chair body; auxiliary wheels that are disposed rearward of the main wheels and are movable up and down relative to the main wheels; a support provided at a rear portion of the chair body, formed in an elongated shape, and movable between a grounding position extending rearward from the chair body and grounding the chair, and a storage position extending upward from the chair body; a control unit that rotates the main wheels with the auxiliary wheels in a state where they are in contact with the ground until the main wheels are raised to a predetermined height, and controls the main wheels, the auxiliary wheels, and the support body so that, when the main wheels are raised to the predetermined height, the auxiliary wheels are lifted and only the support body is in contact with the ground; An electric wheelchair having:

2. a height sensor for detecting the height between the main wheel and the ground; The electric wheelchair according to claim 1 , wherein the control unit determines that the electric wheelchair has been raised to a predetermined height based on a signal received from the height sensor.

3. an angle sensor for detecting the angle of the chair body; The electric wheelchair according to claim 1 , wherein the control unit determines that the electric wheelchair has been raised to a predetermined height based on a signal received from the angle sensor.

4. The electric wheelchair according to claim 1 , wherein the control unit moves the support body near the ground at a predetermined timing.

5. The seating portion is provided so as to be slidable in the front-rear direction, The electric wheelchair according to claim 1, wherein the seating section slides forward as the height of the main wheels increases.

Images