Drive system, electric wheelchair, control method, and computer program

Abstract

To more appropriately control battery charging using a current generated by regenerative braking of an electric wheelchair.SOLUTION: A drive system 10 used in an electric wheelchair 1 includes: at least one electric motor 25L and 25R; a battery 7 that supplies power to the at least one electric motors 25L and 25R; a control device 110 that controls an operation of the at least one electric motor 25L and 25R; speed sensors 26L and 26R that output signals related to a traveling speed of the electric wheelchair 1; and a current sensor 115 that outputs signals related to a current flowing through an electrical path between the at least one electric motor 25L and 25R and the battery 7. The control device 110 acquires a current value of a charging current generated by regenerative braking to charge the battery 7 and decelerates the traveling speed of the electric wheelchair 1 on the basis of the current value.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a drive system, an electric wheelchair, a control method and a computer program. [Background technology]

[0002] There is known an electric wheelchair that uses an electric motor as a drive source (see, for example, Patent Document 1). In an electric wheelchair, for example, a user operates an operating device to generate rotation in the electric motor, and the rotation of the electric motor is transmitted to the wheels, thereby allowing the electric wheelchair to move. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 5-095976 Summary of the Invention [Problem to be solved by the invention]

[0004] When an electric wheelchair travels downhill, for example, the regenerative brake generates a braking force to prevent the electric wheelchair from traveling too fast. Also, by charging the battery with the current generated by the regenerative brake, the distance the electric wheelchair can travel can be increased.

[0005] There is a need for better control of the charging of the battery using the current generated by regenerative braking in such electric wheelchairs. [Means for solving the problem]

[0006] This specification discloses a drive system, an electric wheelchair, a control method, and a computer program as described in the following items.

[0007] [Item 1] A drive system for use in an electric wheelchair, comprising: at least one electric motor that generates a driving force for propelling the electric wheelchair; a battery for powering the at least one electric motor; a control device for controlling the operation of the at least one electric motor; a speed sensor that outputs a signal related to the traveling speed of the electric wheelchair; a current sensor that outputs a signal related to a current flowing through an electrical path between the at least one electric motor and the battery; Equipped with The control device A current value of a charging current for charging the battery, which is generated by regenerative braking, is acquired; A drive system that reduces the traveling speed of the electric wheelchair based on the current value.

[0008] According to one embodiment of the present invention, the traveling speed of the electric wheelchair is reduced based on the current value of the charging current generated by regenerative braking, thereby preventing the charging current generated by regenerative braking from becoming too large when traveling downhill, for example.

[0009] [Item 2] The control device determining whether the current value is equal to or greater than a first threshold value; 2. The drive system according to item 1, wherein the driving speed of the electric wheelchair is reduced when it is determined that the current value is equal to or greater than the first threshold value.

[0010] If the current value is equal to or greater than the first threshold, the traveling speed of the electric wheelchair is reduced, thereby preventing the charging current from becoming too large.

[0011] [Item 3] The control device controlling the operation of the electric motor so that the traveling speed of the electric wheelchair is equal to or less than an upper speed limit value that is an upper limit value of the traveling speed; 3. The drive system according to item 1 or 2, wherein the upper speed limit value is reduced based on the current value.

[0012] By reducing the upper speed limit, the traveling speed of the electric wheelchair can be reduced.

[0013] [Item 4] The control device determining whether the current value is equal to or greater than a first threshold value; 4. The drive system according to item 3, wherein the upper speed limit is reduced when it is determined that the current value is equal to or greater than the first threshold value.

[0014] When the current value is equal to or greater than the first threshold, the upper speed limit is reduced to slow down the traveling speed of the electric wheelchair and prevent the charging current from becoming too large.

[0015] [Item 5] 5. The drive system according to item 4, wherein the control device does not reduce the upper speed limit value when it determines that the current value is not equal to or greater than the first threshold value.

[0016] If the current value is less than the first threshold value, the upper speed limit is not reduced, so that the electric wheelchair can be driven at a speed that is in line with the user's intention.

[0017] [Item 6] 6. The drive system according to item 4 or 5, wherein the control device reduces the upper speed limit by a first predetermined value when it determines that the current value is equal to or greater than the first threshold value.

[0018] By reducing the upper speed limit by the first predetermined value, the traveling speed of the electric wheelchair is reduced, and the charging current can be prevented from becoming too large.

[0019] [Item 7] 6. The drive system according to item 4 or 5, wherein the control device, when determining that the current value is equal to or greater than the first threshold value, reduces the upper speed limit value by a first predetermined value every first predetermined time.

[0020] By decreasing the upper speed limit by the first predetermined value every first predetermined time, the traveling speed of the electric wheelchair is reduced, and it is possible to prevent the charging current from becoming too large.

[0021] [Item 8] When the control device determines that the current value is equal to or greater than the first threshold value, The upper speed limit value is reduced by a first predetermined value, Counting the time since the upper speed limit value is reduced by the first predetermined value, 6. The drive system according to item 4 or 5, wherein when the counted time reaches a first predetermined time, the upper speed limit value is further reduced by the first predetermined value.

[0022] By decreasing the upper speed limit by the first predetermined value every first predetermined time, the traveling speed of the electric wheelchair is reduced, and it is possible to prevent the charging current from becoming too large.

[0023] [Item 9] 9. The drive system according to any one of items 4 to 8, wherein the control device determines that the current value is equal to or greater than the first threshold value and reduces the upper speed limit value, and then, when the current value is no longer equal to or greater than the first threshold value, stops the control of reducing the upper speed limit value based on the current value.

[0024] When the charging current becomes small, the control to reduce the upper speed limit is stopped, thereby preventing the traveling speed of the electric wheelchair from becoming too slow.

[0025] [Item 10] The control device determining whether the current value is equal to or greater than a second threshold value that is greater than the first threshold value; When it is determined that the current value is equal to or greater than the second threshold value, the speed upper limit value is reduced by a second predetermined value; 7. The drive system according to item 6, wherein the second threshold value is greater than the first threshold value, and the second predetermined value is greater than the first predetermined value.

[0026] If the current value is equal to or greater than the second threshold, the pace at which the traveling speed of the electric wheelchair is decelerated can be increased to quickly reach a state where the charging current is small.

[0027] [Item 11] 11. The drive system according to any one of items 2 and 4 to 10, wherein the first threshold value is smaller than a maximum charging current value set for the battery.

[0028] By setting the first threshold value to be smaller than the maximum charging current value, even if the charging current temporarily increases during the process of slowing down the traveling speed of the electric wheelchair, the current value of the charging current can be prevented from exceeding the maximum charging current value.

[0029] [Item 12] Item 11. The drive system according to item 10, wherein the second threshold value is smaller than a maximum charging current value set for the battery.

[0030] Because the second threshold value is smaller than the maximum charging current value, even if the charging current temporarily increases during the process of slowing down the electric wheelchair's traveling speed, the current value of the charging current can be prevented from exceeding the maximum charging current value.

[0031] [Item 13] further comprising a user interface for accepting user operations; The control device starting control to reduce the traveling speed of the electric wheelchair based on an operation of the user on the user interface; 13. The drive system according to any one of items 1 to 12, wherein the pace at which the traveling speed of the electric wheelchair is decelerated is changed based on the current value.

[0032] This makes it possible to prevent the charging current generated by regenerative braking from becoming too large when the traveling speed is reduced in response to a user operation.

[0033] [Item 14] 14. The drive system according to any one of items 4 to 13, wherein the control device determines that the current value is equal to or greater than the first threshold value and reduces the upper speed limit value, and then increases the upper speed limit value when it determines that the current value has become equal to or less than a third threshold value that is smaller than the first threshold value.

[0034] When the charging current becomes sufficiently small, the upper speed limit can be increased to prevent the driving speed from being continuously limited to a low value, for example, even after moving from a downhill slope to a flat road.

[0035] [Item 15] When the control device determines that the current value is equal to or less than the third threshold value, Counting the time since it is determined that the current value is equal to or less than the third threshold value; Item 15. The drive system according to item 14, wherein when the counted time reaches a second predetermined time, the upper speed limit value is increased by a third predetermined value.

[0036] By increasing the upper speed limit after the second predetermined time has elapsed since it was determined that the current value is equal to or less than the third threshold, it is possible to prevent the running speed from increasing when the charging current temporarily decreases. Also, it is possible to smoothly transition from deceleration to acceleration.

[0037] [Item 16] Item 16. The drive system described in item 15, wherein the control device increases the upper speed limit value by the third predetermined value every second predetermined time after the counted time reaches a second predetermined time and increases the upper speed limit value by the third predetermined value every second predetermined time.

[0038] By increasing the upper speed limit by the third predetermined value every second predetermined time, the traveling speed can be increased gradually.

[0039] [Item 17] 17. The drive system according to any one of items 14 to 16, wherein, when the upper speed limit value reaches a predetermined maximum value, the control device stops control for increasing the upper speed limit value and maintains the upper speed limit value at the maximum value.

[0040] When the upper speed limit value reaches a predetermined maximum value, the control for increasing the upper speed limit value is stopped, thereby preventing the traveling speed of the electric wheelchair from exceeding the maximum value.

[0041] [Item 18] 17. The drive system according to any one of items 14 to 16, wherein the control device determines that the current value is equal to or less than the third threshold and increases the upper speed limit value, and then, if the control device determines that the current value is greater than the third threshold value, stops the control to increase the upper speed limit value and maintains the current upper speed limit value.

[0042] When the charging current becomes large, the control for increasing the upper speed limit value is stopped, thereby preventing the charging current from becoming too large.

[0043] [Item 19] 19. The drive system according to any one of items 1 to 18, wherein the control device reduces the traveling speed of the electric wheelchair by at least the regenerative braking.

[0044] By charging the battery with the current generated by regenerative braking, the travel distance of the electric wheelchair can be increased.

[0045] [Item 20] 20. The drive system according to item 19, wherein the control device reduces the traveling speed of the electric wheelchair by increasing the braking force generated by the regenerative brake based on the current value.

[0046] Increasing the braking force generated by the regenerative brake can temporarily increase the charging current, but as the traveling speed decreases, the regenerative current decreases, allowing the charging current to be reduced.

[0047] [Item 21] An electric wheelchair equipped with a drive system according to any one of items 1 to 20.

[0048] It is possible to realize an electric wheelchair that can prevent the charging current generated by regenerative braking from becoming too large.

[0049] [Item 22] A computer-implemented control method for controlling a charging current for charging a battery of an electric wheelchair, comprising: the battery supplies power to at least one electric motor that generates a driving force for propelling the electric wheelchair; The control method includes: Obtaining a current value of a charging current generated by regenerative braking for charging the battery; reducing the traveling speed of the electric wheelchair based on the current value; A control method comprising:

[0050] According to one embodiment of the present invention, the traveling speed of the electric wheelchair is reduced based on the current value of the charging current generated by regenerative braking, thereby preventing the charging current generated by regenerative braking from becoming too large when traveling downhill, for example.

[0051] [Item 23] A computer program that causes a computer to execute a process for controlling a charging current for charging a battery of an electric wheelchair, the battery supplies power to at least one electric motor that generates a driving force for propelling the electric wheelchair; The computer program comprises: Obtaining a current value of a charging current generated by regenerative braking for charging the battery; reducing the traveling speed of the electric wheelchair based on the current value; A computer program that causes the computer to execute the above.

[0052] According to one embodiment of the present invention, the traveling speed of the electric wheelchair is reduced based on the current value of the charging current generated by regenerative braking, thereby preventing the charging current generated by regenerative braking from becoming too large when traveling downhill, for example. [Effects of the Invention]

[0053] According to one embodiment of the present invention, the traveling speed of the electric wheelchair is reduced based on the current value of the charging current generated by regenerative braking, thereby preventing the charging current generated by regenerative braking from becoming too large when traveling downhill, for example. [Brief explanation of the drawings]

[0054] [Figure 1] 1 is a right side view showing an electric wheelchair 1 according to an embodiment. [Figure 2] 1 is a perspective view showing an electric wheelchair 1 according to an embodiment. [Figure 3] 1 is a block diagram showing a drive unit 10 provided in an electric wheelchair 1 according to an embodiment. [Figure 4] 1 is a block diagram showing a current path between a battery 7, drive circuits 114L and 114R, and electric motors 25L and 25R according to the embodiment. FIG. [Figure 5] 10 is a flowchart showing an example of a process for reducing the traveling speed of the electric wheelchair 1 based on the value of a charging current generated by regenerative braking according to the embodiment. [Figure 6] FIG. 10 is a diagram illustrating an example of a relationship between an upper speed limit value and time according to the embodiment. [Figure 7] FIG. 4 is a diagram illustrating an example of the relationship between traveling speed, charging current, and time according to the embodiment. [Figure 8] 10 is a flowchart showing another example of the process of decelerating the traveling speed of the electric wheelchair 1 based on the value of the charging current generated by the regenerative brake according to the embodiment. [Figure 9] 10 is a flowchart showing another example of the process of decelerating the traveling speed of the electric wheelchair 1 based on the value of the charging current generated by the regenerative brake according to the embodiment. [Figure 10] FIG. 10 is a diagram illustrating another example of the relationship between the upper speed limit value and time according to the embodiment. [Figure 11] 10 is a flowchart illustrating an example of a process for increasing an upper speed limit value according to the embodiment. [Figure 12] 10 is a flowchart illustrating an example of a process for increasing an upper speed limit value according to the embodiment. [Figure 13] FIG. 10 is a diagram illustrating yet another example of the relationship between the upper speed limit value and time according to the embodiment. [Figure 14] 10 is a flowchart illustrating another example of the process of increasing the upper speed limit value according to the embodiment. [Figure 15] 10 is a flowchart illustrating another example of the process of increasing the upper speed limit value according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0055] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Similar components will be assigned similar reference symbols, and overlapping descriptions will be omitted. The symbols F, Re, L, R, U, and D in the drawings represent front, rear, left, right, top, and bottom, respectively. Front, rear, left, right, top, and bottom refer to the front, rear, left, right, top, and bottom as seen by a user seated in the seat of the electric wheelchair.

[0056] The electric wheelchair exemplified below is an electric wheelchair that can travel using only the driving force generated by an electric motor, but the electric wheelchair according to the embodiment is not limited to this. The electric wheelchair according to the embodiment may also be a power-assisted wheelchair that uses an electric motor to assist the force exerted by a person manually on hand rims. The electric wheelchair according to the embodiment may also be a handle-type electric wheelchair. The following embodiment is merely an example, and the present invention is not limited to the following embodiment.

[0057] (Electric wheelchair) Fig. 1 is a right side view showing an electric wheelchair 1 according to an embodiment, and Fig. 2 is a perspective view showing the electric wheelchair 1 as seen from diagonally rear left.

[0058] The electric wheelchair 1 includes a body frame 4 formed of metal pipes or the like. A pair of left and right wheels 2L and 2R and a pair of left and right casters 5L and 5R are rotatably supported on the body frame 4. The body frame 4 includes a pair of left and right seat frames 41, a pair of left and right armrest frames 42, a pair of left and right base frames 43, a pair of left and right under frames 44, and a pair of left and right back frames 45.

[0059] A seat 6 on which a person sits is provided between a pair of left and right seat frames 41. The front portion of the seat frame 41 is bent downward, and a footrest 47 is provided at the lower end of the front portion of the seat frame 41. The rear end of the seat frame 41 is connected to a back frame 45. The back frame 45 extends in the vertical direction. A backrest 9 is provided between the pair of left and right back frames 45. In Figure 1, the backrest 9 is not shown in order to clearly show the shape of the back frame 45.

[0060] The back frame 45 has a handle bar 45a that bends and extends rearward at its upper portion. The handle bar 45a is provided with hand grips 46 that the caregiver can hold with their hands.

[0061] A base frame 43 and an underframe 44 are disposed below the seat frame 41. An armrest frame 42 is disposed above the seat frame 41. An armrest 8 is provided on the armrest frame 42, on which a person seated in the seat 6 places their arms.

[0062] The wheel 2L is provided with a hand rim 3L for manually driving the wheel 2L. The wheel 2R is provided with a hand rim 3R for manually driving the wheel 2R. Each of the wheels 2L and 2R has a wheel hub 21, an outer periphery 23 surrounding the wheel hub 21, and a plurality of spokes 22. The plurality of spokes 22 connect the wheel hub 21 and the outer periphery 23. The outer periphery 23 includes a rim to which the spokes 22 are connected, and a tire attached to the rim. The hand rims 3L and 3R are connected to a plurality of connecting members 24 extending from the outer periphery 23 of the wheels 2L and 2R.

[0063] An electric motor 25L is provided on the wheel hub 21 of the wheel 2L. An electric motor 25R is provided on the wheel hub 21 of the wheel 2R. The electric motors 25L and 25R are, for example, hub motors. The wheel hub 21 includes an axle, a first housing located on the inside in the left-right direction of the electric wheelchair 1, and a second housing located on the outside. The first housing on the inside is fixed to the axle, and the second housing on the outside is rotatable about the axle. The stators of the electric motors 25L and 25R are fixed to the first housing and the axle, and the rotors of the electric motors 25L and 25R are fixed to the second housing. The spokes 22 are connected to the second housing.

[0064] The axle of the wheel hub 21 is fixed to the body frame 4. The axle of the wheel hub 21 is fixed to, for example, the back frame 45. The axle of the wheel hub 21 may be fixed to the body frame 4 via a bracket provided between the seat frame 41 and the underframe 44. The wheels 2L and 2R rotate as the second housing rotates relative to the axle and the first housing fixed to the body frame 4.

[0065] The electric wheelchair 1 is equipped with a battery 7 for supplying power to the electric motors 25L and 25R. When power is supplied to the electric motors 25L and 25R, a rotor fixed to the second housing rotates relative to a stator fixed to the first housing, causing the wheels 2L and 2R to rotate.

[0066] The electric motors 25L and 25R are not limited to hub motors, and may be provided outside the wheel hub 21. In this case, the rotation generated by the electric motors 25L and 25R can be transmitted to the wheel hub 21 via a reducer.

[0067] An operating device 15 is provided in front of the armrest 8 to allow a user seated in the seat 6 to operate the electric wheelchair 1. The operating device 15 is an example of a user interface that accepts user operations. The operating device 15 has a stick 16, and when the stick 16 of the operating device 15 is tilted by hand, the electric motors 25L and 25R generate rotation, causing the electric wheelchair 1 to travel. The traveling speed can be adjusted by adjusting the degree to which the stick 16 is tilted. When the stick 16 is returned to the neutral position, the drive of the electric motors 25L and 25R stops, and the electric wheelchair 1 can be stopped.

[0068] An operating device for operating the electric wheelchair 1 by an attendant may be provided on the handlebar 45a of the back frame 45.

[0069] (Drive unit) Next, the drive unit provided in the electric wheelchair 1 will be described.

[0070] 3 is a block diagram showing the drive unit 10 provided in the electric wheelchair 1. The drive unit 10 is a drive system that supplies current to the electric motors 25L and 25R to drive them, and charges the battery 7 using regenerative current generated by the electric motors 25L and 25R. The drive unit 10 includes a control device 110, an operation device 15, a battery 7, electric motors 25L and 25R, speed sensors 26L and 26R, and wheels 2L and 2R. The drive unit 10 causes the electric motors 25L and 25R to generate drive force corresponding to the operation of the operation device 15, causing the electric wheelchair 1 to travel.

[0071] The control device 110 includes a processor 111, recording media such as a read-only memory (ROM) 112 and a random access memory (RAM) 113, and drive circuits 114L and 114R. The ROM 112 pre-stores a computer program (or firmware) for causing the processor 111 to execute various processes. The computer program may be provided to the drive unit 10 via a storage medium (e.g., a semiconductor memory) or a telecommunications line (e.g., the Internet). Such a computer program may be sold as commercial software.

[0072] The processor 111 is a semiconductor integrated circuit and includes, for example, a central processing unit (CPU). The processor 111 can be realized by a microprocessor or a microcontroller. The processor 111 sequentially executes a computer program (a computer program stored in the ROM 112) that describes a group of instructions for executing various processes, thereby realizing desired processing.

[0073] The processor 111 may be a field programmable gate array (FPGA) equipped with a CPU, a graphics processing unit (GPU), an application specific integrated circuit (ASIC), an application specific standard product (ASSP), or a combination of two or more circuits selected from these circuits.

[0074] ROM 112 is, for example, a writable memory (e.g., PROM), a rewritable memory (e.g., flash memory), or a read-only memory. ROM 112 does not have to be a single recording medium, but may be a collection of multiple recording media. RAM 113 provides a working area for temporarily loading computer programs stored in ROM 112 at boot time. RAM 113 does not have to be a single recording medium, but may be a collection of multiple recording media.

[0075] FIG. 4 is a block diagram showing current paths between the battery 7, the drive circuits 114L and 114R, and the electric motors 25L and 25R.

[0076] The drive circuits 114L and 114R are, for example, bidirectional converters. When supplying current to drive the electric motors 25L and 25R, the drive circuits 114L and 114R operate as inverters that convert the direct current output from the battery 7 into alternating current. The drive circuits 114L and 114R generate drive currents according to the current command values ​​output from the processor 111 and supply them to the electric motors 25L and 25R.

[0077] When the battery 7 is charged using regenerative current generated by the electric motors 25L and 25R due to regenerative braking, the drive circuits 114L and 114R operate as converters that convert the AC current output from the electric motors 25L and 25R into DC current. The DC current output from the drive circuits 114L and 114R is supplied to the battery 7 as a charging current, thereby charging the battery 7.

[0078] The current sensor 115 detects the current value of the output current of the battery 7 and the value of the charging current for charging the battery 7, which is generated by regenerative braking.

[0079] The speed sensors 26L and 26R output signals related to the traveling speed of the electric wheelchair 1. In this embodiment, the speed sensors 26L and 26R detect the rotation angles of the electric motors 25L and 25R. The traveling speed of the electric wheelchair 1 can be calculated from the rotation angles of the electric motors 25L and 25R.

[0080] The speed sensor 26L is provided on the electric motor 25L. The speed sensor 26R is provided on the electric motor 25R. The speed sensors 26L and 25R are, for example, encoders. The speed sensor 26L detects the rotation angle of the rotor of the electric motor 25L and outputs a signal corresponding to the rotation angle to the control device 110. The speed sensor 26R detects the rotation angle of the rotor of the electric motor 25R and outputs a signal corresponding to the rotation angle to the control device 110.

[0081] The control device 110 may be provided in the wheel hub 21 of the wheel 2L or the wheel 2R. The components of the control device 110 may be distributed between the wheel hub 21 of the wheel 2L and the wheel hub 21 of the wheel 2R. For example, the drive circuit 114L may be provided in the wheel hub 21 of the wheel 2L, and the drive circuit 114R may be provided in the wheel hub 21 of the wheel 2R. The control device 110 may be provided independently of the wheel hub 21. The processor 111 of the control device 110 calculates the rotational speeds of the electric motors 25L and 25R from the output signals of the speed sensors 26L and 26R. The tire sizes of the wheels 2L and 2R are known in advance, and the processor 111 can calculate the traveling speed of the electric wheelchair 1 from the rotational speeds of the electric motors 25L and 25R. If the rotation of the electric motors 25L and 25R is transmitted to the wheels 2L and 2R via reducers, the processor 111 also uses information about the reduction ratio of the reducers to calculate the traveling speed of the electric wheelchair 1. In this way, the traveling speed of the electric wheelchair 1 can be calculated using the output signals of the speed sensors 26L and 26R.

[0082] The speed sensors 26L and 26R may be provided on the wheel hubs 21, outer peripheries 23, or spokes 22 of the wheels 2L and 2R. The speed sensors 26L and 26R may output signals corresponding to the rotation of the parts on which they are provided.

[0083] The operation device 15 outputs a signal to the control device 110 in response to the operation of the stick 16 by the user seated on the seat 6. The processor 111 calculates target values ​​for the rotational speeds of the electric motors 25L and 25R based on the output signal from the operation device 15. The processor 111 calculates the target values ​​for the rotational speeds by, for example, referring to a map that shows the relationship between the operation amount of the stick 16 of the operation device 15 and the rotational speeds of the electric motors 25L and 25R.

[0084] The processor 111 calculates the current rotation speeds of the electric motors 25L and 25R from the output signals of the speed sensors 26L and 26R, and calculates a current command value to reduce the deviation between the current rotation speed and a target value.

[0085] The processor 111 outputs the calculated current command value to the drive circuits 114L and 114R. The drive circuits 114L and 114R generate drive currents according to the current command values ​​and supply them to the electric motors 25L and 25R. The electric motors 25L and 25R rotate when the drive current is supplied. By performing feedback control to reduce the deviation between the current rotation speed of the electric motors 25L and 25R and the target value, the electric wheelchair 1 can be driven at a speed according to the amount of operation of the operation device 15. The drive unit 10 may be detachable from the body frame 4 of the electric wheelchair 1. The drive unit 10 may also be detachable from a body frame other than the body frame 4. For example, by removing the wheels from the body frame of a general wheelchair and attaching the drive unit 10 to the body frame, the general wheelchair can be used as the electric wheelchair 1.

[0086] The drive unit 10 does not have to include wheels 2L and 2R. In this case, the drive unit 10 can be attached to a wheelchair that has wheels and hand rims. The drive unit 10 does not have to include an operating device 15. In this case, the drive unit 10 can be attached to a wheelchair that has an operating device. The drive unit 10 does not have to include a battery 7. In this case, power can be supplied to the drive unit 10 from a battery that is provided separately from the drive unit 10.

[0087] (battery charging control) Next, the control of charging the battery using the current generated by regenerative braking will be described.

[0088] As described above, the processor 111 of the control device 110 causes the electric wheelchair 1 to travel at a traveling speed that corresponds to the amount of operation of the user on the operation device 15. For example, the traveling speed is increased in proportion to the angle at which the stick 16 of the operation device 15 is tilted.

[0089] When the user returns the stick 16 to the neutral position while the electric wheelchair 1 is moving, the processor 111 reduces the traveling speed so as to stop the electric wheelchair 1. The reduction in traveling speed is achieved by activating the regenerative brake.

[0090] The electric wheelchair 1 is equipped with an electromagnetic brake mechanism. After the electric wheelchair 1 has decelerated and stopped by regenerative braking, the processor 111 activates the electromagnetic brake to maintain the electric wheelchair 1 in a stopped state.

[0091] Furthermore, when the user eases up on the operation of the stick 16 while the electric wheelchair 1 is traveling and the angle of tilt of the stick 16 decreases, the processor 111 slows down the traveling speed to a traveling speed corresponding to the decreased angle. At this time, the traveling speed may be slowed down by activating the regenerative brake. Furthermore, when traveling downhill, for example, by operating the regenerative brake while traveling the electric wheelchair 1, it is possible to maintain a traveling speed according to the amount of operation of the stick 16 and to prevent the traveling speed from exceeding the upper speed limit.

[0092] When the regenerative braking is activated as described above, the battery 7 is charged with the charging current generated by the regenerative braking, thereby increasing the distance that the electric wheelchair 1 can travel.

[0093] A maximum charging current value, which is the maximum value of the recommended charging current, is preset for the battery 7. The maximum charging current value is preset, for example, by the manufacturer of the battery 7. It is desirable that the value of the charging current generated by regenerative braking does not exceed this maximum charging current value.

[0094] In this embodiment, the traveling speed of the electric wheelchair 1 is reduced based on the value of the charging current generated by the regenerative braking. This prevents the charging current generated by the regenerative braking from becoming too large when traveling downhill, for example.

[0095] FIG. 5 is a flowchart showing an example of a process for reducing the traveling speed of the electric wheelchair 1 based on the value of the charging current generated by regenerative braking.

[0096] The electric wheelchair 1 is preset with an upper speed limit, which is the upper limit of the traveling speed. As an example, the upper speed limit is 6 km / h, but is not limited to this value. For example, when the user operates the operation device 15 at a maximum, the processor 111 controls the operation of the electric motors 25L and 25R so that the traveling speed is 6 km / h. The processor 111 controls the operation of the electric motors 25L and 25R so that the traveling speed of the electric wheelchair 1 does not exceed the upper speed limit.

[0097] For example, when the electric wheelchair 1 traveling at 6 km / h or slightly slower than 6 km / h enters a downhill slope from a flat road, gravity acts on the electric wheelchair 1 to accelerate it forward. If the slope angle of the downhill slope is relatively large, the force of gravity that accelerates it forward becomes large. The processor 111 controls the operation of the electric motors 25L and 25R so that the traveling speed of the electric wheelchair 1 does not exceed the upper speed limit.

[0098] For example, the processor 111 stops the supply of drive current to the electric motors 25L and 25R and operates the drive circuits 114L and 114R as converters to generate braking force through regenerative braking. At this time, the drive circuits 114L and 114R convert the AC current output from the electric motors 25L and 25R into DC current and supply it to the battery 7 as a charging current, thereby charging the battery 7. As described above, a maximum charging current value is set in advance for the battery 7. The processor 111 controls charging so that the value of the charging current generated by the regenerative braking does not exceed the maximum charging current value. Here, the maximum charging current value is set to 18 A as an example, but the maximum charging current value is not limited to this value.

[0099] The processor 111 detects the value of the charging current generated by regenerative braking for charging the battery 7 from the output signal of the current sensor 115 (step S101). The processor 111 determines whether the detected current value is equal to or greater than a first threshold value (step S102). The first threshold value is smaller than the maximum charging current value set for the battery 7. Here, the first threshold value is set to 12 A as an example, but the first threshold value is not limited to this value.

[0100] When processor 111 determines that the detected current value is not equal to or greater than the first threshold, it does not perform processing to reduce the upper speed limit value, which will be described later, and maintains the current upper speed limit value (step S111).

[0101] When the processor 111 determines that the detected current value is equal to or greater than the first threshold, it determines whether the deceleration mode is on (step S103). In this embodiment, the "deceleration mode" means an operation mode in which the upper speed limit is reduced so that the value of the charging current generated by regenerative braking does not exceed the maximum charging current value.

[0102] If processor 111 determines that the deceleration mode is not on, it turns on the deceleration mode and reduces the upper speed limit by a first predetermined value (steps S104 and S105). Here, as an example, the first predetermined value is 1 km / h, but the first predetermined value is not limited to this value. For example, if the upper speed limit is 6 km / h, processor 111 reduces the upper speed limit to 5 km / h.

[0103] The processor 111 reduces the traveling speed by controlling the magnitude of the braking force of the regenerative brake so that the traveling speed of the electric wheelchair 1 does not exceed the reduced upper speed limit. For example, the processor 111 increases the regenerative current and the braking force by adjusting the duty ratio in the PWM control of the drive circuits 114L and 114R. This allows the traveling speed to be reduced.

[0104] Processor 111 starts counting the time since the upper speed limit value was reduced by the first predetermined value (step S106), and returns to the process of step S101.

[0105] When processor 111 determines that the detected current value is equal to or greater than the first threshold, processor 111 determines whether the deceleration mode is on (steps S102 and S103). When processor 111 determines that the deceleration mode is on, processor 111 proceeds to the process of step S107.

[0106] In step S107, processor 111 determines whether the counted time is equal to or greater than a first predetermined time. As an example, the first predetermined time is one second, but the first predetermined time is not limited to this value.

[0107] When the processor 111 determines that the counted time has reached or exceeded the first predetermined time, it further reduces the upper speed limit by the first predetermined value (step S108). For example, if the upper speed limit is 5 km / h, the processor 111 reduces the upper speed limit to 4 km / h. The processor 111 controls the magnitude of the braking force of the regenerative brake so that the traveling speed of the electric wheelchair 1 does not exceed the further reduced upper speed limit, thereby reducing the traveling speed.

[0108] Processor 111 resets the counted time, starts counting the time since the upper speed limit value was further reduced by the first predetermined value in step S108 (steps S109 and S110), and returns to the process of step S101.

[0109] As the traveling speed of the electric wheelchair 1 gradually decreases, the charging current generated by regenerative braking also gradually decreases. If the processor 111 determines in step S102 that the detected current value is not equal to or greater than the first threshold, it maintains the current upper speed limit (step S111). That is, it stops the process of decreasing the upper speed limit. If it has been counting time, it resets the counted time (step S112).

[0110] In this embodiment, when it is determined that the value of the charging current is equal to or greater than the first threshold, the upper speed limit value is reduced to slow down the traveling speed of the electric wheelchair 1. This prevents the charging current from becoming too large. When slowing down the traveling speed, the upper speed limit value is reduced by a first predetermined value every first predetermined time, so that the traveling speed can be slowly slowed down.

[0111] When the value of the charging current is no longer equal to or greater than the first threshold, the process of reducing the upper speed limit is stopped, thereby preventing the traveling speed of the electric wheelchair 1 from becoming too slow.

[0112] Fig. 6 is a diagram showing an example of the relationship between the upper speed limit and time. Fig. 7 is a diagram showing an example of the relationship between the running speed, charging current, and time. In Fig. 7, the solid line indicates the running speed, and the dotted line indicates the charging current.

[0113] In the example shown in Figure 6, the upper speed limit is reduced from 6 km / h to 5 km / h at the 5-second mark. Also, the upper speed limit is reduced from 5 km / h to 4 km / h at the 6-second mark. In this way, for example, by reducing the upper speed limit by 1 km / h every second, the traveling speed of the electric wheelchair 1 can be gradually reduced.

[0114] Increasing the braking force generated by the regenerative brake to slow down the running speed can temporarily increase the charging current, as shown in Figure 7. However, as the running speed decreases, the regenerative current decreases, allowing the charging current to be reduced.

[0115] Because the above-mentioned first threshold is smaller than the maximum charging current value, even if the charging current temporarily increases in the process of decelerating the traveling speed, the charging current value can be prevented from exceeding the maximum charging current value.

[0116] Next, another example of the process of decelerating the traveling speed of the electric wheelchair 1 based on the value of the charging current generated by regenerative braking will be described.

[0117] Figures 8 and 9 are flowcharts showing another example of the process of decelerating the traveling speed of the electric wheelchair 1 based on the value of the charging current generated by regenerative braking. Figure 10 is a diagram showing another example of the relationship between the upper speed limit and time. In the examples shown in Figures 8 to 10, when the value of the charging current is equal to or greater than a second threshold value that is greater than the first threshold value, the pace at which the traveling speed of the electric wheelchair 1 is decelerated is increased, thereby quickly reaching a state where the charging current becomes small.

[0118] The processes of steps S101 to S104, S111, and S112 shown in FIG. 8 are the same as the processes of steps S101 to S104, S111, and S112 shown in FIG.

[0119] If processor 111 determines in step S103 shown in FIG. 8 that the deceleration mode is not on, it turns on the deceleration mode (step S104). Processor 111 determines whether the detected charging current value is equal to or greater than a second threshold (step S121). The second threshold is greater than the first threshold and less than the maximum charging current value. Here, as an example, the second threshold is set to 15 A, but the second threshold is not limited to this value.

[0120] If the processor 111 determines that the detected current value is not equal to or greater than the second threshold, it reduces the upper speed limit by a first predetermined value (step S122). For example, if the upper speed limit is 6 km / h, the processor 111 reduces the upper speed limit to 5 km / h. If the processor 111 determines that the detected current value is equal to or greater than the second threshold, it reduces the upper speed limit by a second predetermined value (step S123). Here, as an example, the second predetermined value is 2 km / h, but the second predetermined value is not limited to this value. For example, if the upper speed limit is 6 km / h, the processor 111 reduces the upper speed limit to 4 km / h. The processor 111 reduces the traveling speed of the electric wheelchair 1 by controlling the magnitude of the braking force of the regenerative brake so that the traveling speed does not exceed the reduced upper speed limit.

[0121] Processor 111 starts counting the time since the upper speed limit value is reduced by the first predetermined value or the second predetermined value (step S124), and returns to the process of step S101 in FIG.

[0122] When processor 111 determines that the detected current value is equal to or greater than the first threshold, it determines whether or not the deceleration mode is on (steps S102 and S103). In the example shown in Figures 8 and 9, when the deceleration mode is on, the process proceeds to step S125.

[0123] In step S125, processor 111 determines whether the counted time has reached or exceeded a first predetermined time.

[0124] When processor 111 determines that the counted time is equal to or greater than the first predetermined time, processor 111 determines whether the detected current value is equal to or greater than a second threshold value (step S126).

[0125] If the processor 111 determines that the detected current value is not equal to or greater than the second threshold, it further reduces the upper speed limit by a first predetermined value (step S127). For example, if the upper speed limit is 4 km / h, the processor 111 reduces the upper speed limit to 3 km / h. If the processor 111 determines that the detected current value is equal to or greater than the second threshold, it further reduces the upper speed limit by a second predetermined value (step S128). For example, if the upper speed limit is 4 km / h, the processor 111 reduces the upper speed limit to 2 km / h. The processor 111 reduces the traveling speed of the electric wheelchair 1 by controlling the magnitude of the braking force of the regenerative brake so that the traveling speed does not exceed the reduced upper speed limit.

[0126] Processor 111 resets the counted time (step S129). Processor 111 starts counting the time after further reducing the upper speed limit value by the first predetermined value or the second predetermined value (step S130), and returns to the processing of step S101 in FIG. 8.

[0127] In the example shown in Figure 10, at 5 seconds, it is determined that the charging current value is equal to or greater than the second threshold, and the upper speed limit is reduced from 6 km / h to 4 km / h. At 6 seconds, it is determined that the charging current value is equal to or greater than the first threshold and less than the second threshold, and the upper speed limit is reduced from 4 km / h to 3 km / h. If the charging current value is equal to or greater than the second threshold, the pace at which the traveling speed of the electric wheelchair 1 is decelerated can be increased to quickly reach a state where the charging current is reduced.

[0128] Because the above-mentioned second threshold is smaller than the maximum charging current value, even if the charging current temporarily increases in the process of decelerating the traveling speed, the charging current value can be prevented from exceeding the maximum charging current value.

[0129] Next, the process of increasing the upper speed limit will be described.

[0130] As described above, after the process of reducing the upper speed limit is performed, if the charging current becomes sufficiently small, the upper speed limit is increased. This prevents the traveling speed from being continuously limited to a low value. For example, it prevents the traveling speed from being continuously limited to a low value even after the electric wheelchair 1 moves from a downhill slope to a flat road.

[0131] 11 and 12 are flowcharts showing an example of a process for increasing the upper speed limit.

[0132] The processor 111 determines whether the current upper speed limit is the maximum value (step S141). The maximum value of the upper speed limit is preset in the electric wheelchair 1. As an example, the maximum value is 6 km / h, but is not limited to this value.

[0133] When processor 111 determines that the current upper speed limit is the maximum value, it does not perform the speed increase process described later (step S147).

[0134] After the process of reducing the upper speed limit has been performed as described above, the upper speed limit is smaller than the maximum value. If the processor 111 determines that the current upper speed limit is not the maximum value, it determines whether the electric wheelchair 1 is decelerating (step S142). If the processor 111 determines that the electric wheelchair 1 is decelerating, it does not perform the speed increase process (step S147).

[0135] If the processor 111 determines that the electric wheelchair 1 is not decelerating, it determines whether the value of the charging current is equal to or less than a third threshold (step S143). The third threshold is smaller than the first threshold. Here, the third threshold is set to 6 A as an example, but the third threshold is not limited to this value. If the processor 111 determines that the value of the charging current is not equal to or less than the third threshold, it does not perform the acceleration process (step S147).

[0136] When the processor 111 determines that the value of the charging current is equal to or less than the third threshold, it determines whether or not the speed increase process is permitted (step S144). In this embodiment, the "speed increase process" means "a process of increasing the upper speed limit value that was reduced in the deceleration mode."

[0137] If processor 111 determines that the speed-up process is not permitted, it permits the speed-up process (step S145). Processor 111 starts counting the time since the speed-up process was permitted (step S146), and returns to the process of step S141. Because the processes of steps S141 to S146 are performed in a short time, it is assumed here that the "time since the speed-up process was permitted" and the "time since it was determined that the value of the charging current is equal to or less than the third threshold" are substantially the same.

[0138] After the processes of steps S141-S143, processor 111 determines whether or not the speed-up process is permitted (step S144). If the speed-up process is permitted, the process proceeds to the process of step S151 (FIG. 12).

[0139] In step S151, processor 111 determines whether the counted time is equal to or greater than a second predetermined time. As an example, the second predetermined time is one second, but the second predetermined time is not limited to this value.

[0140] When processor 111 determines that the counted time has reached or exceeded the second predetermined time, it increases the upper speed limit by a third predetermined value (step S152). Here, as an example, the third predetermined value is 1 km / h, but the third predetermined value is not limited to this value. For example, if the upper speed limit is 4 km / h, processor 111 increases the upper speed limit to 5 km / h.

[0141] Processor 111 resets the counted time, starts counting the time since the upper speed limit value was increased by the third predetermined value in step S152 (steps S153 and S154), and returns to the process of step S141.

[0142] If processor 111 determines after the processes of steps S141-S144 that the counted time has reached or exceeded the second predetermined time, it further increases the upper speed limit by a third predetermined value (steps S151, S152).

[0143] In this way, processor 111 increases the upper speed limit by the third predetermined value every second predetermined time. For example, the upper speed limit is increased by 1 km / h every second. By increasing the upper speed limit by the third predetermined value every second predetermined time, the traveling speed can be increased gradually.

[0144] If the value of the charging current becomes greater than the third threshold after increasing the upper speed limit, processor 111 stops the process of increasing the upper speed limit and maintains the current upper speed limit (steps S143, S147). If time has been counted, the counted time is reset (step S148). By stopping the process of increasing the upper speed limit when the charging current becomes large, it is possible to prevent the charging current from becoming too large.

[0145] When the upper speed limit value reaches the maximum value, the processor 111 stops the process of increasing the upper speed limit value and maintains the upper speed limit value at the maximum value (steps S141, S147). If the time was being counted, the counted time is reset (step S148). When the upper speed limit value reaches the maximum value, the process of increasing the upper speed limit value is stopped, thereby preventing the traveling speed of the electric wheelchair 1 from exceeding the maximum value.

[0146] In this embodiment, when it is determined in step S143 that the charging current value is equal to or less than the third threshold, the upper speed limit is not immediately increased, but is increased after the second predetermined time has elapsed since counting began in step S146. By increasing the upper speed limit after the second predetermined time has elapsed since it was determined that the charging current value is equal to or less than the third threshold, it is possible to prevent the traveling speed from increasing when the charging current temporarily decreases. Furthermore, it is possible to smoothly transition from deceleration to acceleration.

[0147] Fig. 13 is a diagram showing an example of the relationship between the upper speed limit and time in the speed increase process. In the example shown in Fig. 13, the upper speed limit is increased from 4 km / h to 5 km / h at the time of 5 seconds. Furthermore, the upper speed limit is increased from 5 km / h to 6 km / h at the time of 6 seconds. In this way, for example, by increasing the upper speed limit by 1 km / h every second, the traveling speed of the electric wheelchair 1 can be increased gradually.

[0148] Next, another example of the process for increasing the upper speed limit will be described.

[0149] 14 and 15 are flowcharts showing another example of the process of increasing the upper speed limit. The processes of steps S141-S145, S147, and S148 shown in FIG. 14 are the same as the processes of steps S141-S145, S147, and S148 shown in FIG. 11. In the example shown in FIGS. 14 and 15, if the speed increase process is permitted in the process of step S145, the upper speed limit is immediately increased by a third predetermined value without waiting for the second predetermined time to elapse. For example, if the upper speed limit is 4 km / h, processor 111 increases the upper speed limit to 5 km / h.

[0150] 14, when processor 111 determines in the process of step S144 that the speed increase process is not permitted, processor 111 permits the speed increase process and increases the upper speed limit by a third predetermined value (steps S145 and S161). Processor 111 starts counting the time since the speed increase process was permitted (step S162) and returns to the process of step S141 in Fig. 14. Because the processes of steps S141-S145, S161, and S162 are performed in a short time, it is assumed here that the "time since the speed increase process was permitted" and the "time since it was determined that the value of the charging current is equal to or less than the third threshold" are substantially the same.

[0151] After the processes of steps S141-S143, processor 111 determines whether or not the speed-up process is permitted (step S144). If the speed-up process is permitted, the process proceeds to the process of step S171 (FIG. 15).

[0152] In step S171, processor 111 determines whether the counted time has reached or exceeded a second predetermined time. If processor 111 determines that the counted time has reached or exceeded the second predetermined time, it further increases the upper speed limit by a third predetermined value (step S172). For example, if the upper speed limit is 5 km / h, processor 111 increases the upper speed limit to 6 km / h.

[0153] Processor 111 resets the counted time, starts counting the time since the upper speed limit value was further increased by the third predetermined value in step S172 (steps S173, S174), and returns to the process of step S141 in FIG.

[0154] When the deceleration mode is turned on while the electric wheelchair 1 is traveling, the user may feel a better riding sensation if the upper speed limit is returned to its original large value in a relatively short time. For example, the deceleration mode may be turned on when the electric wheelchair 1 enters a pothole while traveling. In such a case, the riding sensation can be improved by immediately increasing the upper speed limit by the third predetermined value after the speed increase process is permitted in step S145, without waiting for the second predetermined time to elapse.

[0155] The processing of the embodiment described using Figures 5 to 15 is preferably applied, for example, when the electric wheelchair 1 is traveling downhill. The processing of the embodiment described using Figures 5 to 15 is also preferably applied, for example, when the traveling speed of the electric wheelchair 1 is reduced based on the user's operation of the operation device 15. For example, the processing of this embodiment can also be applied when the user reduces the operation of the stick 16 of the operation device 15 while the electric wheelchair 1 is traveling, or returns the stick 16 to the neutral position, thereby reducing the traveling speed.

[0156] The processing of the above-described embodiment can also be applied to a power-assisted wheelchair as the electric wheelchair 1. For example, the processing of the above-described embodiment can be applied when detecting that the user has applied force to the hand rim to suppress the rotation of the wheel while the power-assisted wheelchair is traveling and slowing down the traveling speed.

[0157] The processing of the above-described embodiment can also be applied to a configuration in which the electric wheelchair 1 is provided with an operating device that allows an assistant to perform an operation to operate the electric motors 25L and 25R. For example, the processing of the above-described embodiment can be applied when an assistant slows down the operation of the lever of the operating device or returns the lever to the neutral position while the electric wheelchair 1 is traveling, thereby slowing down the traveling speed.

[0158] The processing of the above-described embodiment can also be applied to a configuration in which the operation for operating the electric motors 25L and 25R is performed using a mobile terminal device. For example, the processing of the above-described embodiment can be applied when the user operates the mobile terminal device to slow down the traveling speed of the electric wheelchair 1 while it is traveling.

[0159] In the above-described embodiment, the electric wheelchair 1 is equipped with two electric motors 25L and 25R, but the number of electric motors that the electric wheelchair 1 is equipped with is arbitrary, and may be one, or three or more.

[0160] The present invention has been described above with reference to exemplary embodiments. This specification discloses a drive system, an electric wheelchair, a control method, and a computer program as described in the following items.

[0161] [Item 1] A drive system 10 used in an electric wheelchair 1, At least one electric motor 25L and 25R that generates a driving force for propelling the electric wheelchair 1; a battery 7 for supplying power to at least one electric motor 25L and 25R; a control device 110 for controlling the operation of at least one electric motor 25L and 25R; speed sensors 26L and 26R that output signals related to the traveling speed of the electric wheelchair 1; a current sensor 115 that outputs a signal related to the current flowing through an electrical path between at least one of the electric motors 25L and 25R and the battery 7; Equipped with The control device 110 The current value of the charging current for charging the battery 7, which is generated by the regenerative braking, is acquired. The drive system 10 reduces the traveling speed of the electric wheelchair 1 based on the current value.

[0162] According to an embodiment of the present invention, the traveling speed of the electric wheelchair 1 is reduced based on the current value of the charging current generated by regenerative braking. This makes it possible to prevent the charging current generated by regenerative braking from becoming too large when traveling downhill, for example.

[0163] [Item 2] The control device 110 determining whether the current value is equal to or greater than a first threshold value; The drive system 10 according to item 1, wherein the driving speed of the electric wheelchair 1 is reduced when it is determined that the current value is equal to or greater than the first threshold value.

[0164] If the current value is equal to or greater than the first threshold, the traveling speed of the electric wheelchair 1 is reduced, thereby preventing the charging current from becoming too large.

[0165] [Item 3] The control device 110 Controlling the operation of the electric motors 25L and 25R so that the traveling speed of the electric wheelchair 1 is equal to or less than an upper speed limit, which is an upper limit of the traveling speed; 3. The drive system 10 according to item 1 or 2, wherein the upper speed limit is reduced based on the current value.

[0166] By reducing the upper speed limit, the traveling speed of the electric wheelchair 1 can be reduced.

[0167] [Item 4] The control device 110 determining whether the current value is equal to or greater than a first threshold value; Item 4. The drive system 10 according to item 3, wherein the upper speed limit is reduced when it is determined that the current value is equal to or greater than the first threshold value.

[0168] When the current value is equal to or greater than the first threshold, the upper speed limit is reduced to slow down the traveling speed of the electric wheelchair 1 and prevent the charging current from becoming too large.

[0169] [Item 5] 5. The drive system according to item 4, wherein the control device does not reduce the upper speed limit when it determines that the current value is not equal to or greater than the first threshold value.

[0170] If the current value is less than the first threshold value, the upper speed limit is not reduced, so that the electric wheelchair 1 can be driven at a speed that is in line with the user's intention.

[0171] [Item 6] 6. The drive system 10 according to item 4 or 5, wherein the control device 110 reduces the upper speed limit by a first predetermined value when it determines that the current value is equal to or greater than the first threshold value.

[0172] By reducing the upper speed limit by the first predetermined value, the traveling speed of the electric wheelchair 1 is reduced, and it is possible to prevent the charging current from becoming too large.

[0173] [Item 7] 6. The drive system 10 according to item 4 or 5, wherein the control device 110, when determining that the current value is equal to or greater than the first threshold, reduces the upper speed limit value by a first predetermined value every first predetermined time.

[0174] By decreasing the upper speed limit by the first predetermined value every first predetermined time, the traveling speed of the electric wheelchair 1 is reduced, and it is possible to prevent the charging current from becoming too large.

[0175] [Item 8] When the control device 110 determines that the current value is equal to or greater than the first threshold value, The upper speed limit value is reduced by a first predetermined value, Counting the time after the upper speed limit value is reduced by a first predetermined value, 6. The drive system 10 according to item 4 or 5, wherein when the counted time reaches a first predetermined time, the upper speed limit value is further reduced by the first predetermined value.

[0176] By decreasing the upper speed limit by the first predetermined value every first predetermined time, the traveling speed of the electric wheelchair 1 is reduced, and it is possible to prevent the charging current from becoming too large.

[0177] [Item 9] The drive system 10 described in any one of items 4 to 8, wherein the control device 110 determines that the current value is equal to or greater than a first threshold value and reduces the upper speed limit value, and then, when the current value is no longer equal to or greater than the first threshold value, stops the control of reducing the upper speed limit value based on the current value.

[0178] When the charging current becomes small, the control to reduce the upper speed limit is stopped, thereby preventing the traveling speed of the electric wheelchair 1 from becoming too slow.

[0179] [Item 10] The control device 110 determining whether the current value is equal to or greater than a second threshold value that is greater than the first threshold value; If it is determined that the current value is equal to or greater than the second threshold value, the upper speed limit value is reduced by a second predetermined value; Item 7. The drive system 10 according to item 6, wherein the second threshold value is greater than the first threshold value, and the second predetermined value is greater than the first predetermined value.

[0180] If the current value is equal to or greater than the second threshold, the pace at which the traveling speed of the electric wheelchair 1 is decelerated can be increased to quickly reach a state where the charging current is small.

[0181] [Item 11] The drive system 10 according to any one of items 2 and 4 to 10, wherein the first threshold value is smaller than a maximum charging current value set for the battery 7.

[0182] Because the first threshold value is smaller than the maximum charging current value, even if the charging current temporarily increases during the process of slowing down the traveling speed of the electric wheelchair 1, the current value of the charging current can be prevented from exceeding the maximum charging current value.

[0183] [Item 12] Item 11. The drive system 10 according to item 10, wherein the second threshold value is smaller than a maximum charging current value set for the battery 7.

[0184] Because the second threshold value is smaller than the maximum charging current value, even if the charging current temporarily increases during the process of slowing down the traveling speed of the electric wheelchair 1, the current value of the charging current can be prevented from exceeding the maximum charging current value.

[0185] [Item 13] further comprising a user interface for accepting user operations; The control device 110 start control to decelerate the traveling speed of the electric wheelchair (1) based on a user operation on the user interface; 13. The drive system 10 according to any one of items 1 to 12, wherein the pace at which the traveling speed of the electric wheelchair 1 is reduced is changed based on the current value.

[0186] This makes it possible to prevent the charging current generated by regenerative braking from becoming too large when the traveling speed is reduced in response to a user operation.

[0187] [Item 14] The drive system 10 described in any one of items 4 to 13, wherein the control device 110 determines that the current value is equal to or greater than a first threshold and reduces the upper speed limit value, and then increases the upper speed limit value if it determines that the current value has become equal to or less than a third threshold value that is smaller than the first threshold value.

[0188] When the charging current becomes sufficiently small, the upper speed limit can be increased to prevent the driving speed from being continuously limited to a low value, for example, even after moving from a downhill slope to a flat road.

[0189] [Item 15] When the control device 110 determines that the current value is equal to or less than the third threshold value, Counting the time since it is determined that the current value is equal to or less than the third threshold value, Item 15. The drive system 10 according to item 14, wherein when the counted time reaches a second predetermined time, the upper speed limit value is increased by a third predetermined value.

[0190] By increasing the upper speed limit after the second predetermined time has elapsed since it was determined that the current value is equal to or less than the third threshold, it is possible to prevent the running speed from increasing when the charging current temporarily decreases. Also, it is possible to smoothly transition from deceleration to acceleration.

[0191] [Item 16] The drive system 10 described in item 15, wherein the control device 110 increases the upper speed limit value by a third predetermined value when the counted time reaches a second predetermined time, and then increases the upper speed limit value by the third predetermined value every second predetermined time.

[0192] By increasing the upper speed limit by the third predetermined value every second predetermined time, the traveling speed can be increased gradually.

[0193] [Item 17] 17. The drive system 10 according to any one of items 14 to 16, wherein the control device 110 stops the control for increasing the upper speed limit value when the upper speed limit value reaches a predetermined maximum value, and maintains the upper speed limit value at the maximum value.

[0194] When the upper speed limit value reaches a predetermined maximum value, the control for increasing the upper speed limit value is stopped, thereby preventing the traveling speed of the electric wheelchair 1 from exceeding the maximum value.

[0195] [Item 18] The drive system 10 described in any one of items 14 to 16, wherein the control device 110 determines that the current value is equal to or less than a third threshold and increases the upper speed limit value, and then, if it determines that the current value is greater than the third threshold value, stops the control to increase the upper speed limit value and maintains the current upper speed limit value.

[0196] When the charging current becomes large, the control for increasing the upper speed limit value is stopped, thereby preventing the charging current from becoming too large.

[0197] [Item 19] 19. The drive system 10 according to any one of items 1 to 18, wherein the control device 110 reduces the traveling speed of the electric wheelchair 1 by at least regenerative braking.

[0198] By charging the battery 7 with the current generated by regenerative braking, the distance that the electric wheelchair 1 can travel can be increased.

[0199] [Item 20] Item 19. The drive system 10 according to item 19, wherein the control device 110 reduces the traveling speed of the electric wheelchair 1 by increasing the braking force generated by the regenerative brake based on the current value.

[0200] Increasing the braking force generated by the regenerative brake can temporarily increase the charging current, but as the traveling speed decreases, the regenerative current decreases, allowing the charging current to be reduced.

[0201] [Item 21] An electric wheelchair 1 equipped with a drive system 10 according to any one of items 1 to 20.

[0202] It is possible to realize an electric wheelchair 1 that can prevent the charging current generated by regenerative braking from becoming too large.

[0203] [Item 22] A control method executed by a computer for controlling a charging current for charging a battery 7 of an electric wheelchair 1, comprising: The battery 7 supplies power to at least one of the electric motors 25L and 25R, which generate a driving force for propelling the electric wheelchair 1. The control method is Obtaining a current value of a charging current for charging the battery 7, which is generated by regenerative braking; Decreasing the traveling speed of the electric wheelchair 1 based on the current value; A control method comprising:

[0204] According to an embodiment of the present invention, the traveling speed of the electric wheelchair 1 is reduced based on the current value of the charging current generated by regenerative braking. This makes it possible to prevent the charging current generated by regenerative braking from becoming too large when traveling downhill, for example.

[0205] [Item 23] A computer program that causes a computer to execute a process for controlling a charging current for charging a battery 7 of an electric wheelchair 1, The battery 7 supplies power to at least one of the electric motors 25L and 25R, which generate a driving force for propelling the electric wheelchair 1. The computer program is Obtaining a current value of a charging current for charging the battery 7, which is generated by regenerative braking; Decreasing the traveling speed of the electric wheelchair 1 based on the current value; A computer program that causes a computer to execute the following.

[0206] According to an embodiment of the present invention, the traveling speed of the electric wheelchair 1 is reduced based on the current value of the charging current generated by regenerative braking. This makes it possible to prevent the charging current generated by regenerative braking from becoming too large when traveling downhill, for example. [Industrial Applicability]

[0207] The present invention is particularly useful in the field of power wheelchairs. [Explanation of symbols]

[0208] 1: electric wheelchair, 2L, 2R: wheel, 3L, 3R: hand rim, 4: body frame, 5L, 5R: caster, 6: seat, 7: battery, 8: armrest, 9: backrest, 10: drive unit (drive system), 15: operation device, 16: stick, 21: wheel hub, 22: spoke, 23: outer periphery, 24: connecting member, 25L, 25R: electric motor, 26L, 26R: speed sensor, 41: seat frame, 42: armrest frame, 43: base frame, 44: underframe, 45: back frame, 45a: handlebar, 46: hand grip, 47: footrest, 110: control device, 111: processor, 112: ROM, 113: RAM, 114L, 114R: drive circuit, 115: Current sensor

Claims

1. A drive system for use in an electric wheelchair, comprising: at least one electric motor that generates a driving force for propelling the electric wheelchair; a battery for powering the at least one electric motor; a control device for controlling the operation of the at least one electric motor; a speed sensor that outputs a signal related to the traveling speed of the electric wheelchair; a current sensor that outputs a signal related to a current flowing through an electrical path between the at least one electric motor and the battery; Equipped with The control device A current value of a charging current for charging the battery, which is generated by regenerative braking, is acquired; A drive system that reduces the traveling speed of the electric wheelchair based on the current value.

2. The control device determining whether the current value is equal to or greater than a first threshold; The drive system according to claim 1 , wherein the driving speed of the electric wheelchair is reduced when it is determined that the current value is equal to or greater than the first threshold value.

3. The control device controlling the operation of the electric motor so that the traveling speed of the electric wheelchair is equal to or less than an upper speed limit value that is an upper limit value of the traveling speed; The drive system according to claim 1 , wherein the upper speed limit is reduced based on the current value.

4. The control device determining whether the current value is equal to or greater than a first threshold; The drive system according to claim 3 , wherein the upper speed limit is reduced when it is determined that the current value is equal to or greater than the first threshold value.

5. The drive system according to claim 4 , wherein the control device does not reduce the upper speed limit when it determines that the current value is not equal to or greater than the first threshold value.

6. The drive system according to claim 4 or 5, wherein the control device reduces the upper speed limit by a first predetermined value when it determines that the current value is equal to or greater than the first threshold value.

7. 6. The drive system according to claim 4, wherein the control device reduces the upper speed limit by a first predetermined value every first predetermined time when the control device determines that the current value is equal to or greater than the first threshold value.

8. When the control device determines that the current value is equal to or greater than the first threshold value, The upper speed limit value is reduced by a first predetermined value, Counting the time since the upper speed limit value is reduced by the first predetermined value, 6. The drive system according to claim 4, wherein when the counted time reaches a first predetermined time, the upper speed limit value is further reduced by the first predetermined value.

9. 6. The drive system according to claim 4, wherein the control device determines that the current value is equal to or greater than the first threshold value and reduces the upper speed limit value, and then, when the current value is no longer equal to or greater than the first threshold value, stops the control of reducing the upper speed limit value based on the current value.

10. The control device determining whether the current value is equal to or greater than a second threshold value that is greater than the first threshold value; When it is determined that the current value is equal to or greater than the second threshold value, the speed upper limit value is reduced by a second predetermined value; 7. The drive system according to claim 6, wherein the second threshold value is greater than the first threshold value, and the second predetermined value is greater than the first predetermined value.

11. The drive system according to claim 4 or 5, wherein the first threshold value is smaller than a maximum charging current value set for the battery.

12. The drive system according to claim 10 , wherein the second threshold value is smaller than a maximum charging current value set for the battery.

13. further comprising a user interface for accepting user operations; The control device starting control to reduce the traveling speed of the electric wheelchair based on an operation of the user on the user interface; The drive system according to claim 1 or 2, wherein the pace at which the traveling speed of the electric wheelchair is decelerated is changed based on the current value.

14. 6. The drive system according to claim 4, wherein the control device determines that the current value is equal to or greater than the first threshold value and reduces the upper speed limit value, and then increases the upper speed limit value when the control device determines that the current value has become equal to or less than a third threshold value that is smaller than the first threshold value.

15. When the control device determines that the current value is equal to or less than the third threshold value, Counting the time since it is determined that the current value is equal to or less than the third threshold value; The drive system according to claim 14 , wherein when the counted time reaches a second predetermined time, the upper speed limit value is increased by a third predetermined value.

16. 16. The drive system according to claim 15, wherein, after the counted time reaches a second predetermined time and the control device increases the upper speed limit value by the third predetermined value, the control device increases the upper speed limit value by the third predetermined value every second predetermined time.

17. 15. The drive system according to claim 14, wherein when the upper speed limit value reaches a predetermined maximum value, the control device stops the control for increasing the upper speed limit value and maintains the upper speed limit value at the maximum value.

18. 15. The drive system according to claim 14, wherein the control device determines that the current value is equal to or less than the third threshold value and increases the upper speed limit value, and then, if the control device determines that the current value has become greater than the third threshold value, stops the control to increase the upper speed limit value and maintains the current upper speed limit value.

19. The drive system according to claim 1 or 2, wherein the control device reduces the traveling speed of the electric wheelchair by at least the regenerative braking.

20. 20. The drive system according to claim 19, wherein the control device reduces the traveling speed of the electric wheelchair by increasing the braking force generated by the regenerative brake based on the current value.

21. An electric wheelchair comprising the drive system according to claim 1 or 2.

22. A computer-implemented control method for controlling a charging current for charging a battery of an electric wheelchair, comprising: the battery supplies power to at least one electric motor that generates a driving force for propelling the electric wheelchair; The control method includes: Obtaining a current value of a charging current generated by regenerative braking for charging the battery; reducing the traveling speed of the electric wheelchair based on the current value; A control method comprising:

23. A computer program that causes a computer to execute a process for controlling a charging current for charging a battery of an electric wheelchair, the battery supplies power to at least one electric motor that generates a driving force for propelling the electric wheelchair; The computer program comprises: Obtaining a current value of a charging current generated by regenerative braking for charging the battery; reducing the traveling speed of the electric wheelchair based on the current value; A computer program that causes the computer to execute the above.

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