Electric wheelchair

Abstract

The invention relates to an electric wheelchair. An electrically powered wheelchair (1) is provided with: a vehicle body (2a); drive wheels (14c) that cause the vehicle body (2a) to travel; a motor (15) that drives the drive wheel (14c); a handle (20) that can be gripped by an operator and that can be displaced in the front-rear direction of the vehicle body (2a) by the operation of the operator; an operation detection unit (21) that detects the position of the handle (20) in the front-rear direction; and a control device (18) that controls the motor (15) on the basis of the position detected by the operation detection unit (21), the control device (18) changing a control parameter for controlling the motor (15) when a predetermined change in the operation state or a predetermined change in the ramp gradient by the operator occurs.

Description

Technical Field

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

[0002] Patent Documents 1 and 2 below describe electric wheelchairs configured to apply propulsion force in response to an operator's operation. In these electric wheelchairs, a handle gripped by the operator is movable in the front-rear direction, and propulsion force is applied in response to displacement of the handle.

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 10-118125

[0004] Patent Document 2: Japanese Patent Application Laid-Open No. 10-336803

[0005] In the design of such electric wheelchairs, for example, when starting or traveling on a slope, when the driving state changes, it is desirable to avoid sudden acceleration or excessive speed from the perspective of safety. Summary of the Invention

[0006] The present invention has been made in view of the above-mentioned problems, and aims to provide an electric wheelchair that is excellent in safety even when the operator's operating state changes or the slope gradient changes.

[0007] One embodiment of the present invention provides an electric wheelchair comprising: a vehicle body; drive wheels for moving the vehicle body; a motor for driving the drive wheels; a handle that can be gripped by an operator and can be displaced in the front-rear direction of the vehicle body by operation of the operator; an operation detection unit that detects the position of the handle in the front-rear direction; and a control device that controls the motor based on the position detected by the operation detection unit, the control device changing a control parameter used for controlling the motor when a specified change in the operation state performed by the operator or a specified change in the slope gradient occurs.

[0008] According to the electric wheelchair of the above embodiment, the control device is configured to change the control parameters used for controlling the motor when a predetermined change occurs in the operator's operating state or a predetermined change occurs in the slope gradient.

[0009] According to this structure, safe operation can be achieved by appropriately changing the control parameters of the motor in accordance with a prescribed change in the operator's operating state or a prescribed change in the slope gradient, for example, in a manner that suppresses the electric wheelchair from sudden acceleration or overspeeding.

[0010] As described above, according to the above embodiment, it is possible to provide an electric wheelchair that is excellent in safety when the operator's operating state changes or when the slope gradient changes.

[0011] In addition, the reference numerals in parentheses described in the claims indicate the correspondence with specific structures described in the embodiments described later, and do not limit the technical scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The above-mentioned object and other objects, features and advantages of the present invention will become more apparent from the following detailed description with reference to the accompanying drawings.

[0013] Figure 1 is a perspective view of an electric wheelchair according to an embodiment.

[0014] Figure 2 This is a diagram showing a drive unit disposed on the right side of the vehicle body as viewed from the center in the left-right direction of the vehicle body.

[0015] Figure 3 is a cross-sectional view of the first operating portion,

[0016] Figure 4 is a block diagram showing a configuration example for controlling the operation of a motor of an electric wheelchair.

[0017] Figure 5 is a diagram for explaining the control logic of the drive mechanism of the control device.

[0018] Figure 6 is a diagram schematically showing a situation when an operator operates an electric wheelchair.

[0019] Figure 7 is a flowchart showing the processing performed by the control device,

[0020] Figure 8 is a diagram for explaining the non-grip determination area of ​​the handle.

[0021] Figure 9 is a flowchart showing the non-control determination process.

[0022] Figure 10 Schematically illustrates a situation where the slope gradient changes from a first reference angle or more to a second reference angle that is smaller than the first reference angle.

[0023] Figure 11 is a graph showing the change pattern of the spring constant.

[0024] Figure 12 is a diagram schematically showing a situation where the slope gradient is between the first reference angle and the upper limit reference angle.

[0025] Figure 13 Schematically shows a situation in which the slope gradient shifts from between the first reference angle and the upper limit reference angle to a value greater than the upper limit reference angle. DETAILED DESCRIPTION

[0026] Hereinafter, an electric wheelchair according to one embodiment of the above-mentioned embodiment will be described with reference to the drawings.

[0027] (Implementation Method)

[0028] 1. Overall structure of electric wheelchair 1

[0029] like Figure 1 As shown in FIG, the electric wheelchair 1 of the embodiment is an electric vehicle that is driven by an operator. The driving of the electric wheelchair 1 is assisted by an electrically driven drive wheel 14c.

[0030] The electric wheelchair 1 includes a wheelchair unit 2, a drive mechanism 4, a control box 6, a first operating unit 10, and a second operating unit 12. The wheelchair unit 2 is a conventional wheelchair and includes a vehicle body 2a, which is primarily composed of a frame such as metal pipes, a pair of main wheels 2b, and a pair of casters 2c. The pair of casters 2c are located on the left and right sides of the vehicle body 2a. The pair of main wheels 2b are also located on the left and right sides of the vehicle body 2a. The pair of main wheels 2b are located behind the pair of casters 2c. Therefore, the pair of main wheels 2b are rear wheels. The pair of casters 2c are front wheels.

[0031] The vehicle body 2a has a seat 2a1 for passengers and a backrest 2a2. The vehicle body 2a has a pair of left and right support tubes 2a3. The pair of support tubes 2a3 supports the backrest 2a2. A pair of protrusions 2a4 are provided at the upper ends of the pair of support tubes 2a3. The pair of protrusions 2a4 protrude rearward from the backrest 2a2. The pair of protrusions 2a4 are tubes with openings at the rear ends. A pair of first operating parts 10 are provided on the pair of protrusions 2a4. Therefore, the pair of first operating parts 10 are arranged above and to the left and right of the backrest 2a2. The pair of first operating parts 10 each have a handle 20. The second operating part 12 is provided on the right protrusion 2a4. The second operating part 12 is provided with a plurality of operating switches 12a for receiving operator operation. The plurality of operating switches 12a include an operating switch for turning the power on and off, and an operating switch for switching the state of the drive mechanism 4 between a state in which assistance for the movement of the electric wheelchair 1 is initiated and a state in which such assistance is terminated.

[0032] The first operating unit 10 is provided with a brake lever 11 and a brake sensor 11a for detecting braking and releasing operations of the brake lever 11. The brake lever 11 is a brake operating unit operated by an operator to mechanically brake the vehicle body 2a. The operator's braking operation of the brake lever 11 mechanically applies braking force to the drive wheels 14c or the main wheels 2b. The brake sensor 11a is a brake detection unit that detects the operator's braking operation of the brake lever 11. When the operator applies the brake lever 11, the brake sensor 11a detects that the brake lever 11 is in the braking state. On the other hand, when the operator applies the brake lever 11, the brake sensor 11a detects that the brake lever 11 is in the released state.

[0033] In the following description, the direction in which a passenger faces forward when riding in the electric wheelchair 1 (the direction in which the backrest portion 2a2 faces forward) is referred to as the forward direction, and the direction opposite thereto is referred to as the backward direction. Therefore, the passenger rides the electric wheelchair 1 facing forward. Furthermore, the direction toward the left as viewed from the passenger is referred to as the left direction, and the direction toward the right as viewed from the passenger is referred to as the right direction.

[0034] The drive mechanism 4 includes a pair of drive units 14. These are fixed to the left and right sides of the vehicle body 2a. They are positioned inside the vehicle, relative to the pair of main wheels 2b. Each of the left and right drive units 14 includes a base plate 14a, an arm 14b, a drive wheel 14c, a motor 15, and a tilt lever 13.

[0035] 2. Structure of the drive unit 14

[0036] like Figure 1 as well as Figure 2 As shown, the base plate 14a is fixed to the frame of the vehicle body 2a. This allows the drive unit 14 to be mounted on the wheelchair unit 2. A tilt lever 13 is provided at the rear end of the base plate 14a. The tilt lever 13 is stepped on by the operator's foot when operating the electric wheelchair 1 from behind to negotiate a step. When the operator steps on the tilt lever 13, the caster 2c is lifted upward, with the main wheel 2b serving as a fulcrum.

[0037] Arm 14b is positioned on the vehicle interior side of base plate 14a. Arm 14b is fixed to base plate 14a so that it can swing vertically. Arm 14b can swing within a predetermined angular range. A motor 15 and a drive wheel 14c are provided at the front end of arm 14b. Arm 14b rotatably supports drive wheel 14c. Arm 14b elastically applies downward force to drive wheel 14c. This forces arm 14b to press drive wheel 14c against the road surface, grounding it.

[0038] The motor 15 is a hub motor and is arranged inside the drive wheel 14c. The rotor (not shown) of the motor 15 can rotate integrally with the drive wheel 14c. In addition, the stator (not shown) of the motor 15 is fixed to the arm 14b side. As a result, the motor 15 rotates and drives the drive wheel 14c. The motor 15 is connected to the battery, control device, etc. in the control box 6 via a cable (not shown). The above-mentioned cable is inserted into the arm 14b to connect the motor 15 and the control box 6. The control box 6 is fixed to the frame part on the lower right side of the seat 2a1. The control box 6 houses the battery, the control device for controlling each part, etc.

[0039] The drive wheel 14c is supported by the arm 14b so as to be able to rotate about a rotation axis C1 parallel to the left-right direction (see Figure 2 ) rotates. Drive wheels 14c are driven to rotate by motor 15 while in contact with the road surface. The left and right pair of motors 15 drive the left and right pair of drive wheels 14c, causing wheelchair unit 2 (vehicle body 2a) to travel.

[0040] like Figure 2 As shown, the drive wheel 14c is positioned between the caster 2c and the main wheel 2b. More specifically, the position of the rotation axis C1 in the fore-aft direction lies between the rotation axis C2 of the caster 2c and the rotation axis C3 of the main wheel 2b. Therefore, the contact point t1 of the drive wheel 14c on the road surface F lies between the contact point t2 of the caster 2c and the contact point t3 of the main wheel 2b. The contact point t1 of the drive wheel 14c only needs to be within the range from contact point t2 to contact point t3. In other words, the position of the rotation axis C1 in the fore-aft direction only needs to be within the range from the position of the rotation axis C2 to the position of the rotation axis C3.

[0041] 3. Structure of the First Operating Unit 10

[0042] like Figure 3 As shown in (a), the first operating portion 10 has an operation detection portion 21 in addition to the handle 20. The handle 20 is mounted on the front end portion of the protrusion 2a4 on the left side of the vehicle. The handle 20 has a cylinder 20a and a bottom 20b. The bottom 20b blocks the opening on the rear side of the cylinder 20a. The cylinder 20a is mounted on the outer peripheral side of the protrusion 2a4. The cylinder 20a can slide and move on the outer peripheral surface of the protrusion 2a4. Therefore, the handle 20 can move along the axial direction of the protrusion 2a4. The protrusion 2a4 extends in the front-to-back direction. Therefore, the handle 20 can be held by the operator and can be displaced in the front-to-back direction relative to the vehicle body 2a through the operator's operation.

[0043] The operation detection unit 21 has the function of detecting the position and displacement of the handle 20 in the front-to-back direction as information on the front-to-back displacement of the handle 20. Furthermore, the operation detection unit 21 has the function of detecting the operator's gripping of the handle 20 based on the information on the front-to-back displacement of the handle 20. Therefore, the operation detection unit 21 is configured as a state sensor that detects the operator's operating state or gripping state of the handle 20.

[0044] In this embodiment, the operation detection unit 21 is a potentiometer. The operation detection unit 21 is arranged inside the protrusion 2a4. The operation detection unit 21 includes a main body 21a and a rod 21b. The main body 21a is fixed to the protrusion 2a4. The rod 21b extends backward from the main body 21a. The rod 21b passes through the inside of the cylindrical portion 20a and the protrusion 2a4. The rod 21b is capable of axial relative movement relative to the main body 21a. The operation detection unit 21 detects and outputs the axial displacement of the rod 21b. The front end 21b1 of the rod 21b is fixed to the bottom 20b. Therefore, the rod 21b moves integrally with the handle 20 in the front-to-back direction. Thus, the operation detection unit 21 can detect the displacement of the handle 20 in the front-to-back direction relative to the vehicle body 2a. The operation detection unit 21 is connected to a control device described later in the control box 6. The output of the operation detection unit 21 is provided to the control device.

[0045] Inside the protrusion 2a4, in addition to the aforementioned operation detector 21, there is also a sleeve 22, a front bushing 23, a rear bushing 24, and a spring 25. The sleeve 22 is a cylindrical member that is inserted into and fixed to the inner circumference of the protrusion 2a4. The front bushing 23, the rear bushing 24, and the spring 25 are arranged on the inner circumference of the sleeve 22.

[0046] The front bushing 23 has a cylindrical portion 23a and a bottom portion 23b. The cylindrical portion 23a is inserted into and fixed to the inner circumferential surface 22a of the sleeve 22. The bottom portion 23b is provided at the opening on the front side of the cylindrical portion 23a. The bottom portion 23b has a center hole 23b1. The rod 21b is inserted through the center hole 23b1. The rear bushing 24 has a cylindrical portion 24a and a bottom portion 24b. The cylindrical portion 24a is inserted into and fixed to the inner circumferential surface 22a of the sleeve 22. The bottom portion 24b is provided at the opening on the rear side of the cylindrical portion 24a. The bottom portion 24b has a center hole 24b1. The rod 21b is inserted through the center hole 24b1.

[0047] The spring 25 is positioned between the front bushing 23 and the rear bushing 24. Therefore, the rod 21b passes through the front bushing 23, the rear bushing 24, and the spring 25. The rod 21b is provided with a front retainer 26a, a front retainer 27a, a rear retainer 26b, and a rear retainer 27b. The front retainer 27a is positioned in front of the spring 25. It is fixed to the rod 21b. It fits into a circumferential groove provided in the rod 21b. Therefore, the front retainer 27a can move axially together with the rod 21b. The rear retainer 27b is positioned in the rear of the spring 25. The rear retainer 27b is also fixed to the rod 21b. It fits into a circumferential groove provided in the rod 21b. Therefore, the rear retainer 27b can move axially together with the rod 21b. That is, the front retainer 27a and the rear retainer 27b are fixed to the rod 21b with a constant interval in the axial direction.

[0048] The front retainer 26a, rear retainer 26b, and spring 25 are positioned between the front retainer 27a and rear retainer 27b. The front retainer 26a and rear retainer 26b are annular components penetrated by the rod 21b. They retain the front and rear surfaces of the spring 25. The front retainer 26a is sandwiched between the front bushing 23 and the front end of the spring 25. The rear retainer 26b is sandwiched between the rear bushing 24 and the rear end of the spring 25.

[0049] 4. Neutral position of handle 20

[0050] Figure 3 (a) in the figure shows the handle 20 in the neutral position. The handle 20 is in the neutral position when it is not being gripped by the operator and when no operating force is being input by the operator. When the handle 20 is in the neutral position, the spring 25 biases the front retainer 26a toward the front bushing 23. Furthermore, the spring 25 biases the rear retainer 26b toward the rear bushing 24. At this point, the front retainer 26a abuts the cylindrical portion 23a of the front bushing 23. Furthermore, the rear retainer 26b abuts the cylindrical portion 24a of the rear bushing 24.

[0051] That is, when the handle 20 is in the neutral position, the distance between the front retainer 26 a and the rear retainer 26 b is shorter than the free length of the spring 25 .

[0052] 5. Front position of handle 20

[0053] Figure 3(b) in the figure shows the situation where the handle 20 moves to the front position forward of the neutral position. If the handle 20 moves forward from the neutral position, the rod 21b also moves forward. As a result, the output of the operation detection unit 21 changes. If the handle 20 and the rod 21b move forward of the neutral position, the spring 25 is pressed forward by the rear retainer 26b and the rear retainer ring 27b. Therefore, the rear retainer 26b is separated from the rear bushing 24. If the handle 20 moves further forward, Figure 3 As shown in (b) of FIG. 1 , the front stopper 27a contacts the bottom portion 23b of the front bush 23. Thus, the front stopper 27a and the front bush 23 restrict the forward movement of the rod 21b.

[0054] 6. Rear position of handle 20

[0055] Figure 3 (c) in the figure shows the situation where the handle 20 moves to a rear position behind the neutral position. If the handle 20 moves rearward from the neutral position, the rod 21b also moves rearward. As a result, the output of the operation detection unit 21 changes. If the handle 20 and the rod 21b move rearward compared to the neutral position, the spring 25 is pressed rearward by the front retainer 26a and the front retainer ring 27a. Therefore, the front retainer 26a is separated from the front bushing 23. If the handle 20 moves further rearward, as shown in FIG. Figure 3 As shown in (c) in FIG. 1 , the rear stopper 27b contacts the bottom portion 24b of the rear bushing 24. As a result, the rear stopper 27b and the rear bushing 24 restrict the rearward movement of the rod 21b.

[0056] According to the above structure, the handle 20 can be elastically moved in the front-back direction around the neutral position by the spring 25. In addition, the front-back movement range of the handle 20 and the rod 21b is limited by the front bushing 23, the rear bushing 24, the front stopper 27a and the rear stopper 27b.

[0057] 7. Structure of electric wheelchair 1

[0058] like Figure 4 As shown, the electric wheelchair 1 further includes left and right driving speed sensors 17, an inertial sensor 8, a battery 16, and a control device 18. The inertial sensor 8, the battery 16, and the control device 18 are all housed in the control box 6 (see FIG. Figure 1 ).

[0059] The drive speed sensor 17 is a component for detecting the drive speed of the drive wheel 14c. The drive speed sensor 17 is attached to the drive wheel 14c. The drive speed sensor 17 is electrically connected to the control device 18. Therefore, the output of the drive speed sensor 17 is provided to the control device 18. The driving speed of the drive wheel 14c can be used to calculate the travel speed of the vehicle body 2a of the electric wheelchair 1. Therefore, the drive speed sensor 17 can be referred to as a travel speed detection unit that detects the travel speed of the vehicle body 2a of the electric wheelchair 1.

[0060] The inertial sensor 8 is a component for detecting information related to the inertia acting on the vehicle body 2a. In this embodiment, the inertial sensor 8 is, for example, an IMU (Inertial Measurement Unit), which includes at least a three-axis acceleration sensor. The inertial sensor 8 is electrically connected to the control device 18. Therefore, the output of the inertial sensor 8 is provided to the control device 18. The control device 18 calculates the tilt angle of the vehicle body 2a in the front-to-back direction based on the output of the inertial sensor 8. That is, the inertial sensor 8 functions as a sensor for detecting the tilt angle of the vehicle body 2a in the front-to-back direction. According to the inertial sensor 8, when the road surface is a slope, the tilt angle of the vehicle body 2a can be detected as the slope gradient.

[0061] The battery 16 supplies power to the pair of motors 15 and various components requiring operating power. The control device 18 controls the drive mechanism 4 (the pair of motors 15) by providing a command value to the drive mechanism 4, thereby controlling the speed of the vehicle body 2a.

[0062] The drive mechanism 4, which includes a pair of motors 15, has a pair of drive circuits 34. Furthermore, each of the motors 15 includes a motor body 15a and a rotation detector 15b. The motor body 15a includes a rotor, a stator, and other major components of the motor. The rotation detector 15b is, for example, a Hall effect sensor mounted on the motor body 15a. The rotation detector 15b detects the rotation angle of the rotor of the motor body 15a. The rotation detector 15b is connected to the drive circuit 34 and the control device 18. Therefore, the output of the rotation detector 15b is provided to the drive circuit 34 and the control device 18. At this time, the rotation speed of the motor 15 is derived from the rotation angle of the rotor of the motor body 15a. Therefore, the rotation detector 15b functions as a motor information detection unit that detects motor information related to the rotation speed of the motor 15. Furthermore, the motor information detected by the rotation detector 15b also relates to the rotation of the drive wheel 14c. Therefore, the rotation detector 15b can also be referred to as a rotation information detection unit that detects information related to the rotation of the drive wheel 14c.

[0063] The pair of drive circuits 34 are, for example, inverters. They may be housed within the control box 6 or provided on the base plate 14a or arm 14b. The pair of drive circuits 34 are connected to the control device 18, the battery 16, and the pair of motors 15. The pair of drive circuits 34 supply power from the battery 16 to the pair of motors 15. Based on the speed command value provided by the control device 18 and the output of the rotation detector 15b, the pair of drive circuits 34 applies drive power to the pair of motors 15, controlling the motors 15 to achieve the rotational speed indicated by the speed command value.

[0064] The pair of drive circuits 34 and the pair of motors 15 (motor bodies 15a) are connected by a pair of power lines 34a. A pair of current detection units 36 are provided on the pair of power lines 34a. The pair of current detection units 36 are current sensors that detect the current flowing through the pair of power lines 34a. In other words, the pair of current detection units 36 detect the motor current flowing through the pair of motors 15. The pair of current detection units 36 are connected to the control device 18. Therefore, the output of the pair of current detection units 36 is provided to the control device 18.

[0065] The pair of first operating units 10 and second operating units 12 are also connected to the control device 18. As described above, the output of the first operating unit 10 (i.e., the output of the operation detection unit 21) and the output of the second operating unit 12 are provided to the control device 18. In this embodiment, the output of the pair of operation detection units 21 is defined as the operation input of the pair of handles 20 to the control device 18.

[0066] The control device 18 is configured by a computer or the like, including a processing unit 38 comprised of a processor or the like, and a storage unit 40 comprised of a memory, a hard disk, or the like. The storage unit 40 stores computer programs and necessary information for execution by the processing unit 38. The processing unit 38 implements the various processing functions of the control device 18 by executing computer programs stored on a non-transitory computer-readable recording medium such as the storage unit 40.

[0067] 8. Structure of Control Device 18

[0068] The control device 18 is based on Figure 5 The control logic shown is used to control the drive mechanism 4.

[0069] Based on the operation input (displacement) of the pair of handles 20, impedance control and cornering speed command value generation are performed. In the impedance control, the spring / shock absorber model described later is used. According to the impedance control, the basic propulsion force is calculated based on the sum of the operation input of the pair of handles 20 (the sum of the displacement). In contrast, the cornering speed command value is generated based on the difference in the operation input of the pair of handles 20 (the difference in the displacement). The total propulsion force is calculated by reducing the external force and the braking force from the basic propulsion force. The external force is a force that the vehicle body 2a receives from the outside, and is based on the current detection unit 36 ​​(refer to Figure 4 ) is calculated using the motor current detected by the drive speed sensor 17 (see Figure 4 ) is used to calculate the driving speed detected.

[0070] Based on the above-mentioned total propulsion force and the turning speed torque, a speed command value for the motor 15 is generated. Based on the turning speed torque, a speed command value for each of the pair of motors 15 for turning the vehicle body 2a is generated. The turning torque is calculated based on the value obtained by subtracting the yaw rate from the turning speed command value. The yaw rate is the turning speed and is calculated based on the driving speed of the drive wheel 14c and the wheel spacing of the pair of drive wheels 14c. That is, the yaw rate is derived by dividing the difference in the driving speed of the pair of drive wheels 14c by the wheel spacing. In addition, in the calculation process of the turning torque, it is preferable to use proportional control (P control) in which an adjustment is made in proportion to the deviation between the current output value and the target value. This simplifies the calculation process of the turning torque. In addition, in this embodiment, the external force used in the calculation of the total propulsion force is not used when calculating the turning torque. As long as no external force is used in the calculation of the turning torque, the turning control is not easily affected by external factors.

[0071] The speed of the motor 15 is then controlled based on the generated speed command value and the drive speed of the drive wheels 14c. Specifically, a speed command value is generated for each of the pair of drive wheels 14c, and each of the two generated speed command values ​​is adapted to each of the pair of motors 15. To improve responsiveness in this speed control, for example, known PID control can be utilized. PID control is a combination of integral feedback control (I control) and differential feedback control (D control) in addition to the aforementioned P control.

[0072] like Figure 6As shown, when operator A wishes to move the electric wheelchair 1 along a road surface F, operator A grasps and operates the handles 20 of the pair of first operating components 10 with their left and right hands. At this point, the pair of handles 20 moves relative to the vehicle body 2a in the front-rear direction. The pair of first operating components 10 provide outputs corresponding to the movement of the pair of handles 20 to the control device 18. Based on the outputs from the pair of first operating components 10, the control device 18 generates speed command values ​​for the motor 15 and provides these values ​​to the pair of drive circuits 34. In this manner, the control device 18 controls the motor 15.

[0073] When operator A grips handle 20 and presses forward, motor 15 is controlled so that drive wheel 14c assists the forward movement of electric wheelchair 1. Furthermore, when operator A grips handle 20 and pulls it backward, motor 15 is controlled so that drive wheel 14c assists the backward movement of electric wheelchair 1. In contrast, when operator A is not gripping handle 20, or when operator A is not manipulating handle 20 forward or backward from a neutral position, motor 15 is controlled to drive drive wheel 14c. Thus, control device 18 determines whether operator A is in an operated or inoperable state with respect to handle 20, or whether operator A is in a gripping or inoperable state with respect to handle 20, and controls motor 15 based on either the operated or inoperable state or the gripping or inoperable state.

[0074] The output from the pair of first operating parts 10 represents the displacement of the pair of handles 20 in the front-to-back direction relative to the vehicle body 2a. The control device 18 calculates the displacement of each of the pair of handles 20 in the front-to-back direction based on the output from the pair of first operating parts 10. In addition, the displacement is the distance between a reference position (e.g., a neutral position) that is pre-set within the movable range of the handle 20 and the current position of the handle 20. When the reference position and the current position are consistent in the front-to-back direction, the displacement becomes 0 (zero). The control device 18 obtains the displacement of the handle 20 discretely over time and stores it in the storage unit 40.

[0075] When the operator A holds and operates the first operating unit 10 and the second operating unit 12, the control device 18 controls the drive mechanism 4 so that the movement of the vehicle body 2a relative to the displacement becomes a movement that simulates the mechanical impedance characteristic. Figure 6 As shown, the control device 18 controls the driving mechanism 4 so as to reproduce the action of connecting the handle 20 and the vehicle body 2a by the imaginary spring 42 and the imaginary shock absorber 44 and to keep the distance H between the handle 20 and the vehicle body 2a constant. Figure 5) uses a spring / shock absorber model consisting of an imaginary spring 42 and a shock absorber 44.

[0076] Controlling the drive mechanism 4 so that the distance H between the handle 20 and the vehicle body 2a remains constant includes controlling the displacement to be maintained at 0 (zero) or a predetermined set value. Thus, the control device 18 controls the drive mechanism 4 so that the vehicle body 2a moves forward according to the displacement of the handle 20. For example, if the operator A moves forward and presses the handle 20 forward, the control device 18 controls the drive mechanism 4 so that the vehicle body 2a moves forward. Conversely, if the operator A moves backward and pulls the handle 20 rearward, the control device 18 controls the drive mechanism 4 so that the vehicle body 2a moves backward. Furthermore, when the handle 20 is in the reference position (neutral position), the control device 18 controls the drive mechanism 4 so that the vehicle body 2a stops.

[0077] The spring / shock absorber model is represented by the following equation (1). The processing unit 38 of the control device 18 calculates the target propulsion force F of the motor 15 based on the following equation (1). th (Hereinafter, referred to as "propulsion force.").

[0078] [Mathematical formula 1]

[0079]

[0080] Formula (1) represents the propulsion force F after Laplace transformation th In formula (2), K is the imaginary spring coefficient, D is the imaginary shock absorber coefficient, μ is the friction coefficient, M is the imaginary mass of the electric wheelchair 1, v is the speed of the electric wheelchair 1, α is the coefficient, s is the Laplace operator, ω1 and ω2 are the specified cutoff frequencies, and the displacement x is UI_R , displacement x UI_L is the displacement of the handle 20, μ is the friction coefficient, F op It is an external force in the front-to-back direction.

[0081] The first term shown below in the formula (1) shows a model for realizing the mechanical impedance characteristics.

[0082] [Mathematical formula 2]

[0083] Item 1:

[0084] Multiply the spring coefficient K in the first term by the displacement x of the right handle 20 UI_R and the left handle 20 displacement x UI_L The product of the spring coefficient K and the total displacement represents an elastic term based on the displacement. The elastic term is based on the displacement x of the handle 20. UI_R 、xUI_L The spring coefficient K is the value of the imaginary spring 42 ( Figure 4 ) is a spring constant and is a preset constant. The shock absorber coefficient D in the first term is multiplied by the Laplace operator and the total displacement. The product of the total displacement and the Laplace operator represents the differential value of the displacement. Therefore, the product of the shock absorber coefficient D, the Laplace operator, and the total displacement represents a viscosity term based on the differential value of the displacement. This viscosity term is based on the displacement speed of the handle 20. The shock absorber coefficient D represents the virtual shock absorber 44 (refer to Figure 6 ) is a coefficient of viscosity and is a preset constant. Thus, the first term includes an elastic term based on the displacement and a viscous term based on the differential value of the displacement.

[0085] The second term shown below in the formula (1) represents the deceleration force in the front-rear direction of the vehicle body 2a.

[0086] [Mathematical formula 3]

[0087] Item 2:

[0088] In the second term, the friction force corresponding to the travel speed v and the deceleration force corresponding to the acceleration are calculated. The sum of these becomes the deceleration force in the front-rear direction of the vehicle body 2a. The deceleration force in the front-rear direction of the vehicle body 2a calculated from the second term is added to the calculation result of the first term.

[0089] The third term shown below in the formula (1) is a term for correcting the movement in the front-rear direction.

[0090] The third item: -αF op

[0091] The coefficient α in the third term is a variable that changes according to the total displacement and is used to calculate the external force F. op Hereinafter, this coefficient α will be referred to as “feedback coefficient α”. op It is derived by integrating the motor current value and the torque coefficient (motor torque per unit current) of the motor 15. OP It is a value that changes according to the external force in the front-back direction and the total displacement, and is appropriately adjusted according to the external force in the front-back direction and the total displacement. OP An upper limit and a lower limit are set, thereby preventing excessive deceleration or acceleration.

[0092] 9. Processing of the control device 18

[0093] like Figure 7 As shown, the processing unit 38 of the control device 18 sequentially executes the processes from step S1 to step S9 regarding the control of the drive mechanism 4 .

[0094] Furthermore, whether the handle 20 is in a gripped state or a non-gripped state is actually the same as whether the handle 20 is in an operated state or a non-operated state. That is, the operator operates the handle 20 while gripping it, while the operator releases the grip of the handle 20 when releasing the grip. Therefore, in this specification, "non-grip determination" and "grip determination" may be referred to as "non-operation determination" and "operation determination," respectively, and "non-grip state" and "grip state" may be referred to as "non-operation state" and "operation state," respectively.

[0095] Figure 7 Step S1 is based on the driving speed sensor 17 (refer to Figure 4 ) to detect information about whether the electric wheelchair 1 is in the driving state and to determine whether it is in the driving state. If the electric wheelchair 1 is in the driving state ("YES" in step S1), the handle 20 is in the gripping or operating state by the operator, and the brake lever 11 is in the brake release state by the operator, and the process proceeds to step S2.

[0096] 10. Non-control judgment processing

[0097] The non-grip determination process of the handle 20 is a non-operation determination process of the handle 20. In this embodiment, the non-grip determination process is as follows: Figure 8 As shown, a non-grip determination area is set relative to the handle 20. The non-grip determination area includes the initial position of the handle 20, that is, the neutral position (see Figure 3 (a) in FIG. 1 ). The non-holding determination area is a non-operation determination area.

[0098] like Figure 9 As shown, the non-grip determination process includes step S1a and step S1b.

[0099] Step S1a is a step for determining whether the handle 20 is within the non-grip determination area. If the handle 20 is within the non-grip determination area ("Yes" in step S1a), the process proceeds to step S1b. On the other hand, if the handle 20 is not within the non-grip determination area ("No" in step S1a), a "grip determination" is performed to determine whether the handle 20 is in a gripping state. This grip determination is also known as an "operation determination" to determine whether the handle 20 is in an operating state.

[0100] Step S1b is a step for determining whether the displacement speed of the handle 20 is below a threshold value. If the displacement speed of the handle 20 is below the threshold value ("Yes" in step S1b), a "non-grip determination" is performed, indicating that the handle 20 is in a non-grip state. This non-grip determination is also a "non-operation determination," indicating that the handle 20 is in a non-operation state. On the other hand, if the displacement speed of the handle 20 exceeds the threshold value ("No" in step S1b), a "grip determination" is performed, indicating that the handle 20 is in a grip state. The threshold value used in step S1b is pre-stored in the storage unit 40.

[0101] Figure 7 Step S2 determines whether any of the following four conditions are met. If any of the four conditions are met ("Yes" in step S2), the process proceeds to step S3; if not ("No" in step S2), the process proceeds to step S4. These four conditions relate to the switching points of the control parameters used to control motor 15.

[0102] The first condition in step S2 is a condition that the determination of the handle 20 is shifted from the grip determination to the grip determination. The control device 18 determines that the first condition is met when it is determined based on the non-grip determination process that the operator's operating state of the handle 20 has switched from the non-grip state or the non-operation state to the grip state or the operation state.

[0103] The second condition of step S2 is that the vehicle body 2a (electric wheelchair 1) is no longer overspeeding. The control device 18 is based on the driving speed sensor 17 (refer to Figure 4 ) information that the speed of the vehicle body 2a has changed from exceeding the speed limit to below the speed limit, or that the state of the motor 15 has switched from the servo-off state to the servo-on state, the second condition is determined to be met. Furthermore, when the motor 15 is in the servo-on state, the drive wheels 14c assist the movement of the electric wheelchair 1. When the motor 15 is in the servo-off state, the drive wheels 14c are no longer assisting the movement of the electric wheelchair 1.

[0104] The third condition of step S2 is that the operator releases the operation of the brake lever 11. The control device 18 is based on the brake sensor 11a (refer to Figure 4 ) information, and when it is detected that the operation state of the brake lever 11 is switched from the brake operation state to the brake operation release state, it is determined that it corresponds to the third condition.

[0105] The fourth condition of step S2 is that the slope gradient θ of the road surface changes from a first reference angle θa to a second reference angle θb smaller than the first reference angle θa (see Figure 10 ). The control device 18 is based on the inertial sensor 8 (refer to Figure 4 ) information, and when it is detected that the slope gradient θ switches from greater than the first reference angle θa to less than the second reference angle θb, it is determined that it corresponds to the fourth condition.

[0106] Step S3 is a step of gradually increasing (increasing) the spring coefficient K (refer to formula (1)) of the elastic term constituting the spring / shock absorber model. Figure 11 As shown in the spring coefficient change pattern, the spring coefficient K is gradually increased from the first value Ka to the second value Kb in accordance with the switching point condition of the control parameter. The spring coefficient K is one of the control parameters used to control the motor 15. Following step S3, the propulsion force of the motor 15 is calculated in step S9. Based on steps S3 and S9, the motor 15 is controlled so that the propulsion force of the motor 15 gradually increases. As a result, the generated acceleration changes in a gradually increasing manner. As a result, emergency acceleration, in which the acceleration acting on the vehicle body 2a suddenly increases, can be suppressed, so that safe operation can be achieved.

[0107] Step S4 is a step for determining whether the road surface slope gradient θ is less than a first reference angle θa based on information from the inertial sensor 8. If the slope gradient θ is less than the first reference angle θa ("YES" in step S4), the process proceeds to step S5. If the slope gradient θ is greater than the first reference angle θa ("NO" in step S4), the process proceeds to step S6.

[0108] For example, if the slope gradient θ changes from the second reference angle θb to a position between the second reference angle θb and the first reference angle θa, or if the slope gradient θ changes from the first reference angle θa to a position between the second reference angle θb and the first reference angle θa, the process proceeds from step S4 to step S5. On the other hand, if the slope gradient θ changes from the second reference angle θb to a position greater than the first reference angle θa, the process proceeds from step S4 to step S6.

[0109] Step S5 is a step of setting the current control parameters used for controlling the motor 15 to continue to be used. After step S5 is executed, the process proceeds to step S9. Based on steps S5 and S9, the motor 15 is controlled without changing the control logic.

[0110] Step S6 is a step in which the feedback coefficient α, which constitutes the third term of the spring / damper model, and the upper limit of the speed command value for motor 15 are changed while maintaining the spring coefficient K constant. Both the feedback coefficient α and the upper limit of the speed command value are control parameters used to control motor 15. In step S6 of this embodiment, compared to the case where the slope gradient θ is less than the first reference angle θa, the feedback coefficient α is increased and the upper limit of the speed command value for motor 15 is decreased. After step S6 is executed, the process proceeds to step S7.

[0111] In step S6, motor 15 is controlled by increasing the feedback coefficient α, thereby reducing the propulsion force generated by motor 15. Furthermore, by decreasing the upper limit of the speed command value for motor 15, motor 15 is controlled to prevent the rotational speed of motor 15 from exceeding the changed upper limit. Therefore, when the slope gradient θ is greater than the first reference angle θa, the rotational speed of motor 15 can be limited, and the propulsion force of motor 15 can be reduced. This prevents the electric wheelchair 1 from accelerating suddenly or exceeding the speed limit, thereby achieving safe operation.

[0112] Step S7 is a step for determining whether the road surface slope gradient θ is less than the upper limit reference angle θc based on information from the inertial sensor 8. If the slope gradient θ is less than the upper limit reference angle θc ("YES" in step S7), the process proceeds to step S9. If the slope gradient θ is greater than the upper limit reference angle θc ("NO" in step S7), the process proceeds to step S8.

[0113] For example, when the slope gradient θ is between the first reference angle θa and the upper limit reference angle θc (see Figure 12 ), the process proceeds from step S7 to step S9. On the other hand, for example, when the slope gradient θ changes from between the first reference angle θa and the upper limit reference angle θc to a value greater than the upper limit reference angle θc (see Figure 13 ), go from step S7 to step S8.

[0114] Step S8 is a step in which the feedback coefficient α and the upper limit of the speed command value for motor 15 are changed simultaneously after the operation input of handle 20 is set to 0 (zero). In step S8 of this embodiment, compared to the case where the slope gradient θ is less than the upper limit reference angle θc, the feedback coefficient α is increased and the upper limit of the speed command value for motor 15 is decreased. The value of the feedback coefficient α in this case is greater than the value set in step S6. Furthermore, the upper limit of the speed command value in this case is less than the value set in step S6. After executing step S8, the process proceeds to step S9.

[0115] In step S8, the propulsion force of motor 15, calculated based on the information detected by operation detection unit 21, becomes zero, and the assist provided by operation of handle 20 is disabled. Furthermore, motor 15 is allowed to freely operate with its speed limited by the upper limit of the speed command value. Therefore, as the slope gradient θ increases to a value greater than the upper limit reference angle θc, safe operation is achieved.

[0116] In step S6 and step S8 , the case where both the feedback coefficient α and the upper limit of the speed command value of the motor 15 are changed is described. However, only at least one of the two control parameters may be changed as needed.

[0117] 11. Specific example of the reference angle of the slope gradient

[0118] In this embodiment, three reference angles for the slope gradient are determined (a first reference angle θa, a second reference angle θb, and an upper limit reference angle θc). The values ​​of the reference angles are not particularly limited, but as an example, the first reference angle θa is set to 15 degrees, the second reference angle θb is set to 13 degrees, and the upper limit reference angle θc is set to 25 degrees. These values ​​can be used to set the feedback coefficient α and the upper limit of the speed command value, respectively.

[0119] 12. Upper limit of speed command value

[0120] When the slope gradient is below the second reference angle θb, the upper limit of the speed command value is set to 6 [km / h]. When the slope gradient is above the first reference angle θa and below the upper limit reference angle θc, the upper limit of the speed command value is set to 3 [km / h]. When the slope gradient is above the upper limit reference angle θc, the upper limit of the speed command value is set to 0.5 [km / h].

[0121] 13. Feedback coefficient α

[0122] When the slope gradient is greater than or equal to the first reference angle θa and less than the upper limit reference angle θc, the feedback coefficient α can be set to 0.5, and when the slope gradient is greater than or equal to the upper limit reference angle θc, the feedback coefficient α can be set to 5. When a grip-or-non-grip determination is made or when the brake lever 11 is being braked, the feedback coefficient α can be set to 0 (zero), and when a grip determination is made, the feedback coefficient α can be set to 0.5.

[0123] Alternatively, the feedback coefficient α can be changed so that the greater the slope gradient, the greater the feedback coefficient α, and the greater the speed of the vehicle body 2a. In this case, when the slope gradient is greater than the first reference angle θa and less than the upper limit reference angle θc, the feedback coefficient α can be set to 0.5, provided that the speed of the vehicle body 2a is below the upper limit of the speed command value (e.g., 3 km / h), and can be set to 1, provided that the speed of the vehicle body 2a exceeds the upper limit of the speed command value. When the slope gradient is greater than the upper limit reference angle θc, the feedback coefficient α can be set to 5, provided that the speed of the vehicle body 2a is below the upper limit of the speed command value (e.g., 0.5 km / h), and can be set to 10, provided that the speed of the vehicle body 2a exceeds the upper limit of the speed command value. This allows the feedback coefficient α to be finely adjusted according to changes in the slope gradient and the speed of the vehicle body 2a.

[0124] 14. Effects

[0125] Next, the effects of the above-described embodiment will be described.

[0126] According to the electric wheelchair 1 of the embodiment, the control device 18 is configured to change the control parameters for controlling the motor 15 when a predetermined change occurs in the operating state of the operator A or a predetermined change occurs in the slope gradient.

[0127] According to this configuration, the control parameters of the motor 15 are appropriately changed in accordance with a predetermined change in the operator A's operating state or a predetermined change in the slope gradient to suppress sudden acceleration or overspeeding of the electric wheelchair 1, thereby achieving safe operation.

[0128] Therefore, according to the above embodiment, it is possible to provide an electric wheelchair 1 that is excellent in safety when the operator's operating state changes or when the slope gradient changes.

[0129] While the present invention has been described based on the above embodiments, it should be understood that the present invention is not limited to these embodiments or configurations. The present invention also encompasses various modifications and variations within the scope of equivalents. Furthermore, various combinations and configurations, including only one component, or combinations and configurations that are greater than or less than these components, are also encompassed within the scope and spirit of the present invention.

[0130] In the above embodiment, the feedback coefficient α and the upper limit of the speed command value are changed among the control parameters of the motor 15 . However, other control parameters may be changed instead of or in addition to these control parameters.

[0131] In the above embodiment, although another operation detection unit 21 is used to perform the non-grip determination, other mechanisms may be used for the operation detection unit 21. Examples of other mechanisms include a pressure sensor provided on the handle 20. For example, when the pressure detected by the pressure sensor is below a threshold, it can be determined that the state is non-grip, and when the pressure is above the threshold, it can be determined that the state is gripped.

Claims

1. An electric wheelchair (1), wherein: have: Vehicle body (2a); driving wheels (14c) for driving the vehicle body; a motor (15) for driving the driving wheel; a handle (20) capable of being gripped by an operator (A) and capable of being displaced in the front-rear direction of the vehicle body by the operator; an operation detection unit (21) for detecting the position of the handle in the front-rear direction; as well as a control device (18) for controlling the motor based on the position detected by the operation detection unit, The control device changes a control parameter used for controlling the motor when a predetermined change occurs in an operation state performed by the operator or a predetermined change occurs in a slope gradient.

2. The electric wheelchair according to claim 1, wherein: The control device calculates the propulsion force of the motor using a spring / shock absorber model that includes an elastic term based on the displacement of the handle and a viscous term based on the displacement speed of the handle, and changes the control parameter, i.e., the spring coefficient of the elastic term, by gradually increasing when a prescribed change in the operating state performed by the operator or a prescribed change in the ramp gradient occurs.

3. The electric wheelchair according to claim 2, wherein: The predetermined change in the operation state performed by the operator is an operation in which the operator switches the operation state of the handle from a non-operated state to an operated state, or an operation in which the operator switches the operation state of the handle from a non-gripped state to a gripped state.

4. The electric wheelchair according to claim 2, wherein: A brake operating unit (11) is provided, which is operated by the operator to mechanically brake the vehicle body. The predetermined change in the operation state performed by the operator is an operation by the operator to switch the operation state of the brake operating portion from a brake operation state to a brake operation release state.

5. The electric wheelchair according to claim 2, wherein: The predetermined change in the operation state performed by the operator is an operation in which the operator switches the operation state of the handle so that the speed of the vehicle body changes from a state exceeding the speed limit to a state below the speed limit.

6. The electric wheelchair according to claim 2, wherein: The predetermined change in the ramp gradient is a change in which the ramp gradient is switched from a first reference angle (θa) or greater to a second reference angle (θb) smaller than the first reference angle.

7. The electric wheelchair according to claim 1, wherein: The control device calculates the propulsion force of the motor using a spring / shock absorber model including an elastic term based on the displacement of the handle and a viscous term based on the displacement speed of the handle, and generates a speed command value for the motor based on a value obtained by subtracting the external force in the front-rear direction from the propulsion force. When a specified change in the ramp gradient occurs, the feedback coefficient used to calculate the control parameter, i.e., the external force, is changed, or the upper limit value of the control parameter, i.e., the speed command value, is changed.

8. The electric wheelchair according to claim 7, wherein: The control device changes the feedback coefficient to a larger value or changes the upper limit of the speed command value to a smaller value when the ramp gradient changes to a larger value than the reference angle (θa, θc) as a prescribed change of the ramp gradient, compared to a case where the ramp gradient is smaller than the reference angle.

9. The electric wheelchair according to claim 8, wherein: The control device sets the propulsion force of the motor calculated based on the position detected by the operation detection unit to zero when the slope gradient changes to be equal to or greater than an upper limit reference angle (θc).

10. The electric wheelchair according to claim 7, wherein: The control device changes the value of the feedback coefficient so as to increase as the slope gradient increases, and changes the value of the feedback coefficient so as to increase as the traveling speed of the vehicle body increases.

Images