Electric wheelchair

Abstract

An electric wheelchair (1) comprises: a vehicle body (2a); drive wheels (14c) which cause the vehicle body (2a) to travel; motors (15) which drive the drive wheels (14c); grips (20) which can be held by an operator and which are displaceable in the front-back direction of the vehicle body (2a); a state sensor (21) which detects whether the operator is in an operating state or a holding state with respect to the grips (20); and a control device (18) which controls the motors (15). The control device (18) determines whether the operator is in the operating state or a non-operating state with respect to the grips (20), or whether the operator is in the holding state or a non-holding state with respect to the grips (20), and then controls the motors (15) depending on the operating state or the non-operating state, or on the holding state or the non-holding state.

Description

electric wheelchair

[0001] The present disclosure relates to power wheelchairs.

[0002] The following Patent Document 1 describes an electric wheelchair that is configured to provide a propulsive force in response to the operation of the operator. In this electric wheelchair, a grip that the operator holds is provided so as to be movable in the forward and backward directions, and a propulsive force is provided in response to the displacement of the grip.

[0003] Japanese Patent Application Publication No. 10-118125

[0004] In an electric wheelchair, the operator can operate the electric wheelchair when holding the grip, but cannot operate the electric wheelchair when not holding the grip. Therefore, there is a need to improve the safety of the electric wheelchair when the operator is not holding the grip.

[0005] Furthermore, in an electric wheelchair, if the drive wheels are controlled in the same way in both the forward and reverse states, the operator may find it difficult to operate. Furthermore, when going over a bump in the road surface, the operator lifts the front wheels off the road surface to move forward, and then places the front wheels on the ground. In this case, the drive wheels may go into a non-contact state with the road surface and then return to a contact state. If the drive wheels are controlled in the same way during this time, the operator may find it difficult to operate.

[0006] Therefore, it is important to know the state of the electric wheelchair from the viewpoint of safety and operability. However, Patent Document 1 does not mention how to know the state of the electric wheelchair.

[0007] The present disclosure has been made in consideration of such problems, and aims to provide an electric wheelchair that can improve safety or operability.

[0008] One aspect of the present disclosure is an electric wheelchair comprising: a vehicle body; drive wheels for propelling the vehicle body; a motor for driving the drive wheels; a grip that can be held by an operator and can be displaced in the fore-and-aft direction of the vehicle body by operation of the operator; a state sensor that detects the operating state or gripping state of the operator with respect to the grip; and a control device that controls the motor, wherein the control device determines whether the operator is in an operating state or a non-operating state with respect to the grip, or whether the operator is in a gripping state or a non-gripping state with respect to the grip, and controls the motor depending on the operating state or the non-operating state, or depending on the gripping state or the non-gripping state.

[0009] Another aspect of the present disclosure is an electric wheelchair comprising: a vehicle body; drive wheels for propelling the vehicle body; a motor for driving the drive wheels; a grip that can be held by an operator and can be displaced in the fore-and-aft direction of the vehicle body by operation of the operator; an operation detection unit that detects the position of the grip in the fore-and-aft direction; and a control device that controls the motor based on the position detected by the operation detection unit, wherein the control device determines whether the vehicle body is in a forward state or a backward state, and controls the motor depending on whether the vehicle body is in the forward state or the backward state.

[0010] Yet another aspect of the present disclosure is an electric wheelchair comprising: a vehicle body; drive wheels for propelling the vehicle body; a motor for driving the drive wheels; a grip that can be held by an operator and can be moved in the fore-and-aft direction of the vehicle body by operation of the operator; an operation detection unit that detects the position of the grip in the fore-and-aft direction; a rotation information detection unit that detects information related to the rotation of the drive wheels; and a control device that controls the motor based on the position detected by the operation detection unit, wherein the drive wheels are configured to be able to take a ground contact state and a non-ground contact spin state when driven, and when the control device determines that the drive wheels have transitioned from the non-ground contact spin state to the ground contact state based on the information detected by the rotation information detection unit, immediately after the determination, switches control of the motor from a normal running mode based on the position of the grip to a ground contact transition mode that is not based on the position of the grip.

[0011] According to one aspect of the present disclosure, the control device determines whether the operator is in an operating state or a non-operating state with respect to the grip, or whether the operator is in a gripping state or a non-gripping state with respect to the grip. The control device then controls the motor according to the operating state or the non-operating state, or the gripping state or the non-gripping state. Therefore, by understanding the state of the operator with respect to the electric wheelchair and controlling the motor according to that state, the safety of the electric wheelchair can be improved.

[0012] According to another aspect of the present disclosure, the control device determines whether the vehicle body is in a forward or reverse state, and controls the motor according to the forward or reverse state. The drive direction of the drive wheels in the forward state corresponds to the direction in which the electric wheelchair moves away from the operator. On the other hand, the drive direction of the drive wheels in the reverse state corresponds to the direction in which the electric wheelchair moves toward the operator. In this way, the drive direction of the drive wheels relative to the positional relationship between the operator and the electric wheelchair differs between the forward and reverse states. Therefore, by determining whether the vehicle body is in a forward or reverse state and controlling the motor according to that state, it is possible to improve operability for the operator.

[0013] According to yet another aspect of the present disclosure, the control device determines that the drive wheels have transitioned from a non-contact spin state to a contact state, and immediately after the transition, the control of the motor is switched from a normal driving mode based on the grip position to a contact transition mode not based on the grip position. For example, when going over a bump, the drive wheels transition from a non-contact spin state to a contact state. In such a case, the control device grasps the state and controls the motor according to that state, thereby improving operability immediately after the drive wheels transition to a contact state.

[0014] As described above, according to the above-described aspects, it is possible to provide an electric wheelchair that can improve safety or operability.

[0015] Note that the symbols in parentheses in the claims indicate the correspondence with the specific means described in the embodiments described below, and do not limit the technical scope of the present disclosure.

[0016] The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. 1 is a perspective view of an electric wheelchair according to an embodiment, FIG. 2 is a view of the drive unit arranged on the right side of the vehicle body as viewed from the center of the vehicle body in the left-right direction, FIG. 3 is a cross-sectional view of the first operating unit, FIG. 4 is a block diagram showing an example of a configuration for controlling the operation of the motor in an electric wheelchair, FIG. 5 is a diagram for explaining the control logic of the drive mechanism by the control device, FIG. 6 is a diagram showing typically the state when an operator operates the electric wheelchair, FIG. 7 is a flowchart showing the processing executed by the control device, FIG. 8 is a diagram for explaining the non-grasp determination area of ​​the grip, FIG. 9 is a flowchart showing the non-grasp determination processing in FIG. 7, FIG. 10 is a diagram showing typically the state when an operator moves the electric wheelchair backward, FIG. 11 is a flowchart showing the backward determination processing in FIG. 7, FIG. 12 is a diagram showing typically the state when the operator operates the electric wheelchair to overcome a step, and FIG. 13 is a flowchart showing the step-over determination processing in FIG. 7.

[0017] Hereinafter, an electric wheelchair as one embodiment of the above aspect will be described with reference to the drawings.

[0018] 1, 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 electrically driven drive wheels 14c.

[0019] The electric wheelchair 1 comprises a wheelchair section 2, a drive mechanism 4, a control box 6, a first operating section 10, and a second operating section 12. The wheelchair section 2 is a typical wheelchair, and comprises a vehicle body 2a mainly composed of a frame such as a metal pipe, a pair of main wheels 2b, and a pair of casters 2c. The pair of casters 2c are provided on both the left and right sides of the vehicle body 2a. The pair of main wheels 2b are also provided on both the left and right sides of the vehicle body 2a. The pair of main wheels 2b are provided behind the pair of casters 2c. Therefore, the pair of main wheels 2b are rear wheels. The pair of casters 2c are front wheels.

[0020] The vehicle body 2a has a seat 2a1 on which a passenger sits and a backrest 2a2. The vehicle body 2a has a pair of left and right support pipes 2a3. The pair of support pipes 2a3 support the backrest 2a2. A pair of protrusions 2a4 is provided at the upper ends of the pair of support pipes 2a3. The pair of protrusions 2a4 protrude rearward from the backrest 2a2. The pair of protrusions 2a4 are pipes with openings at their rear ends. A pair of first operating units 10 is provided on the pair of protrusions 2a4. Therefore, the pair of first operating units 10 is disposed above the left and right sides of the backrest 2a2. Each of the pair of first operating units 10 has a grip 20. A second operating unit 12 is provided on the right protrusion 2a4. The second operating unit 12 has a plurality of operating switches 12a for receiving operations by the operator. The multiple operation switches 12a include an operation switch for turning the power on and off, and an operation switch for switching the state of the drive mechanism 4 between a state in which assistance for the operation of the electric wheelchair 1 has begun and a state in which the assistance has ended.

[0021] In the following description, the direction in which the rider faces when riding in the electric wheelchair 1 (the direction in which the backrest 2a2 faces forward) is referred to as the forward direction, and the opposite direction is referred to as the rearward direction. Therefore, the rider rides facing the front of the electric wheelchair 1. Also, the direction facing left from the rider's perspective is referred to as the leftward direction, and the direction facing right from the rider's perspective is referred to as the rightward direction.

[0022] The drive mechanism 4 includes a pair of drive units 14. The pair of drive units 14 are fixed to the left and right sides of the vehicle body 2a. The pair of drive units 14 are arranged on the vehicle inward side of the pair of main wheels 2b. Each of the pair of left and right drive units 14 has a base plate 14a, an arm 14b, a drive wheel 14c, a motor 15, and a tipping bar 13.

[0023] 2. Structure of the drive unit 14 As shown in Figures 1 and 2, the base plate 14a is fixed to the frame of the vehicle body 2a. This allows the drive unit 14 to be attached to the wheelchair section 2. The tipping bar 13 is provided at the rear end of the base plate 14a. The tipping bar 13 is a member that is stepped on by the foot of an operator operating the electric wheelchair 1 from behind to climb over a step. When the operator steps on the tipping bar 13, the caster 2c is lifted upward with the main wheel 2b as a fulcrum.

[0024] The arm 14b is provided on the vehicle interior side of the base plate 14a. The arm 14b is fixed to the base plate 14a so as to be swingable up and down. The arm 14b can swing within a predetermined angular range. A motor 15 and a drive wheel 14c are provided at the tip of the arm 14b. The arm 14b supports the drive wheel 14c so as to be able to rotate freely. The arm 14b elastically biases the drive wheel 14c downward. As a result, the arm 14b presses the drive wheel 14c against the road surface to bring it into contact with the road surface.

[0025] The motor 15 is an in-wheel motor and is provided inside the drive wheel 14c. A rotor (not shown) of the motor 15 can rotate integrally with the drive wheel 14c. A stator (not shown) of the motor 15 is fixed to the arm 14b side. This allows the motor 15 to rotate and drive the drive wheel 14c. The motor 15 is connected to a battery, a control device, etc. in the control box 6 via a cable (not shown). The cable is inserted into the arm 14b and connects the motor 15 and the control box 6. The control box 6 is fixed to a frame portion on the lower right side of the seat portion 2a1. The control box 6 houses a battery, a control device that controls each part, etc.

[0026] The drive wheels 14c are supported by the arms 14b so as to be rotatable about a rotation axis C1 (see FIG. 2) parallel to the left-right direction. The drive wheels 14c are driven to rotate by the motors 15 while in contact with the road surface. The pair of left and right motors 15 drive the pair of left and right drive wheels 14c, causing the wheelchair section 2 (vehicle body 2a) to move.

[0027] As shown in Figure 2, the drive wheel 14c is disposed between the caster 2c and the main wheel 2b. More specifically, the position of the rotation axis C1 in the front-to-rear direction is between the rotation axis C2 of the caster 2c and the rotation axis C3 of the main wheel 2b. Therefore, the ground contact position t1 of the drive wheel 14c on the road surface F is located between the ground contact position t2 of the caster 2c and the ground contact position t3 of the main wheel 2b. The ground contact position t1 of the drive wheel 14c may be located in the range from the ground contact position t2 to the ground contact position t3. In other words, the position of the rotation axis C1 in the front-to-rear direction may be located in the range from the position of the rotation axis C2 to the position of the rotation axis C3.

[0028] 3. Structure of the First Operating Unit 10 As shown in FIG. 3(a), the first operating unit 10 has an operation detection unit 21 in addition to the grip 20. The grip 20 is attached to the tip of the protrusion 2a4 on the left side of the vehicle. The grip 20 has a tubular portion 20a and a bottom portion 20b. The bottom portion 20b closes the rear opening of the tubular portion 20a. The tubular portion 20a is attached to the outer periphery of the protrusion 2a4. The tubular portion 20a can move while sliding on the outer periphery of the protrusion 2a4. Therefore, the grip 20 can move along the axial direction of the protrusion 2a4. The protrusion 2a4 extends in the front-rear direction. Therefore, the grip 20 can be held by an operator and can be displaced in the front-rear direction relative to the vehicle body 2a by operation by the operator.

[0029] The operation detection unit 21 has a function of detecting the position and displacement amount of the grip 20 in the front-rear direction as displacement information of the grip 20 in the front-rear direction. The operation detection unit 21 also has a function of detecting grip information of the grip 20 by the operator from the displacement information of the grip 20 in the front-rear direction. Therefore, the operation detection unit 21 corresponds to a state sensor that detects the operation state or grip state of the grip 20 by the operator.

[0030] In this embodiment, the operation detection unit 21 is a potentiometer. The operation detection unit 21 is provided 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 rearward from the main body 21a. The rod 21b passes through the inside of the tubular portion 20a and the protrusion 2a4. The rod 21b is movable axially relative to the main body 21a. The operation detection unit 21 detects and outputs the amount of axial displacement of the rod 21b. A tip 21b1 of the rod 21b is fixed to the bottom 20b. Therefore, the rod 21b moves in the front-rear direction together with the grip 20. This allows the operation detection unit 21 to detect the amount of front-rear displacement of the grip 20 relative to the vehicle main 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 detector 21 is given to the control device.

[0031] In addition to the operation detector 21, the protruding portion 2a4 is provided therein with 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 circumferential surface of the protruding portion 2a4. The front bushing 23, the rear bushing 24, and the spring 25 are disposed on the inner circumferential side of the sleeve 22.

[0032] 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 front opening of the cylindrical portion 23a. The bottom portion 23b has a central hole 23b1. The rod 21b is inserted through the central 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 rear opening of the cylindrical portion 24a. The bottom portion 24b has a central hole 24b1. The rod 21b is inserted through the central hole 24b1.

[0033] The spring 25 is disposed between the front bushing 23 and the rear bushing 24. Thus, the rod 21b passes through the front bushing 23, the rear bushing 24, and the spring 25. A front retainer 26a, a front retaining ring 27a, a rear retainer 26b, and a rear retaining ring 27b are provided on the rod 21b. The front retaining ring 27a is provided on the front side of the spring 25. The front retaining ring 27a is fixed to the rod 21b. The front retaining ring 27a is fitted into a circumferential groove provided in the rod 21b. Thus, the front retaining ring 27a can move integrally with the rod 21b in the axial direction. The rear retaining ring 27b is provided on the rear side of the spring 25. The rear retaining ring 27b is also fixed to the rod 21b. The rear retaining ring 27b is fitted into a circumferential groove provided in the rod 21b. Thus, the rear retaining ring 27b can move integrally with the rod 21b in the axial direction. That is, the front retaining ring 27a and the rear retaining ring 27b are fixed to the rod 21b at a fixed distance in the axial direction.

[0034] The front retainer 26a, the rear retainer 26b, and the spring 25 are disposed between the front snap ring 27a and the rear snap ring 27b. The front retainer 26a and the rear retainer 26b are annular members that are passed through by the rod 21b. The front retainer 26a and the rear retainer 26b hold the front and rear end faces of the spring 25. The front retainer 26a is interposed between the front bushing 23 and the front end face of the spring 25. The rear retainer 26b is interposed between the rear bushing 24 and the rear end face of the spring 25.

[0035] 4. Neutral Position of Grip 20 (a) in Figure 3 shows the case where the grip 20 is in the neutral position. The grip 20 is in the neutral position when it is not being held by the operator or when the operator is not inputting an operating force. When the grip 20 is in the neutral position, the spring 25 biases the front retainer 26a toward the front bushing 23. The spring 25 also biases the rear retainer 26b toward the rear bushing 24. At this time, the front retainer 26a abuts against the cylindrical portion 23a of the front bushing 23. The rear retainer 26b abuts against the cylindrical portion 24a of the rear bushing 24. In other words, when the grip 20 is in the neutral position, the distance between the front retainer 26a and the rear retainer 26b is shorter than the free length of the spring 25.

[0036] 5. Front Position of Grip 20 (b) in FIG. 3 shows the case where the grip 20 has moved to a front position forward of the neutral position. When the grip 20 moves forward from the neutral position, the rod 21b also moves forward. This changes the output of the operation detection unit 21. When the grip 20 and rod 21b move forward of the neutral position, the spring 25 is pressed forward by the rear retainer 26b and rear snap ring 27b. Therefore, the rear retainer 26b moves away from the rear bush 24. When the grip 20 moves further forward, the front snap ring 27a abuts against the bottom 23b of the front bush 23, as shown in (b) in FIG. 3. As a result, the front snap ring 27a and the front bush 23 restrict the forward movement of the rod 21b.

[0037] 6. Rear Position of Grip 20 (c) in FIG. 3 shows the case where the grip 20 has moved to a rearward position rearward from the neutral position. When the grip 20 moves rearward from the neutral position, the rod 21b also moves rearward. This changes the output of the operation detection unit 21. When the grip 20 and rod 21b move rearward from the neutral position, the spring 25 is pressed rearward by the front retainer 26a and the front snap ring 27a. As a result, the front retainer 26a moves away from the front bush 23. When the grip 20 moves further rearward, the rear snap ring 27b abuts against the bottom 24b of the rear bush 24, as shown in (c) in FIG. 3. As a result, the rear snap ring 27b and the rear bush 24 restrict the rearward movement of the rod 21b.

[0038] With the above-described configuration, the grip 20 can be elastically moved in the front-to-rear direction around the neutral position by the spring 25. Furthermore, the range of movement of the grip 20 and the rod 21b in the front-to-rear direction is limited by the front bushing 23, the rear bushing 24, the front retaining ring 27a, and the rear retaining ring 27b.

[0039] 7. Configuration of the Electric Wheelchair 1 As shown in Fig. 4, the electric wheelchair 1 further includes left and right drive 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. 1).

[0040] The drive speed sensor 17 is used to detect 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 running speed of the vehicle body 2a of the electric wheelchair 1 can be calculated from the drive speed of the drive wheel 14c. Therefore, the drive speed sensor 17 can be said to be a running speed detection unit that detects the running speed of the vehicle body 2a of the electric wheelchair 1.

[0041] The inertial sensor 8 is 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) and 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 determines the tilt angle of the vehicle body 2a in the longitudinal direction based on the output of the inertial sensor 8. In other words, the inertial sensor 8 functions as a sensor for detecting the tilt angle of the vehicle body 2a in the longitudinal direction.

[0042] The battery 16 supplies power to the pair of motors 15 and each component that requires operating power. The control device 18 controls the drive mechanism 4 (the pair of motors 15) by providing command values ​​to the drive mechanism 4, thereby controlling the speed of the vehicle body 2 a.

[0043] The drive mechanism 4, which includes a pair of motors 15, has a pair of drive circuits 34. Each of the pair of motors 15 includes a motor body 15a and a rotation detector 15b. The motor body 15a includes the main components of a motor, such as a rotor and a stator. The rotation detector 15b is, for example, a Hall sensor provided 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. The output of the rotation detector 15b is therefore provided to the drive circuit 34 and the control device 18. The rotation speed of the motor 15 is then derived from the rotation angle of the rotor of the motor body 15a. Therefore, the rotation detector 15b functions as a motor information detector that detects motor information related to the rotation speed of the motor 15. The motor information detected by the rotation detector 15b also includes information related to the rotation of the drive wheels 14c. Therefore, the rotation detector 15b can also be referred to as a rotation information detector that detects information related to the rotation of the drive wheels 14c.

[0044] The pair of drive circuits 34 are, for example, inverters. The pair of drive circuits 34 may be housed in the control box 6, or may be provided on the base plate 14a or the 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 provide power from the battery 16 to the pair of motors 15. The pair of drive circuits 34 have the function of providing drive power to the pair of motors 15 based on a speed command value provided by the control device 18 and the output of the rotation detector 15b, and controlling the motors 15 to rotate at the speed indicated by the speed command value.

[0045] 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 detectors 36 are provided on the pair of power lines 34a. The pair of current detectors 36 are current sensors that detect the current flowing through the pair of power lines 34a. In other words, the pair of current detectors 36 detect the motor current flowing through the pair of motors 15. The pair of current detectors 36 are connected to the control device 18. Therefore, the outputs of the pair of current detectors 36 are provided to the control device 18.

[0046] The pair of first operating unit 10 and second operating unit 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 outputs of the pair of operation detection units 21 are defined as operation inputs of the pair of grips 20 to the control device 18.

[0047] The control device 18 is configured by a computer or the like that includes a processing unit 38 consisting of a processor or the like, and a storage unit 40 consisting of a memory, a hard disk, etc. The storage unit 40 stores computer programs and necessary information to be executed by the processing unit 38. The processing unit 38 realizes the various processing functions of the control device 18 by executing computer programs stored in a computer-readable, non-transitory recording medium such as the storage unit 40.

[0048] 8. Configuration of the Control Device 18 The control device 18 controls the drive mechanism 4 in accordance with the control logic shown in FIG.

[0049] Impedance control and generation of a swing speed command value are performed based on the operation input of the pair of grips 20. In impedance control, a spring-damper model, which will be described later, is used. According to impedance control, a basic thrust force is calculated based on the sum of the operation inputs of the pair of grips 20. In contrast, a swing speed command value is generated based on the difference between the operation inputs of the pair of grips 20. A total thrust force is calculated by subtracting the external force and the braking force from the basic thrust force. The external force is calculated based on the motor current detected by the current detection unit 36 ​​(see FIG. 4). The braking force is calculated using the traveling speed. The traveling speed is calculated from the driving speed detected by the driving speed sensor 17 (see FIG. 4).

[0050] A speed command value for the motor 15 is generated based on the total propulsive force and the turning speed torque. The turning torque is calculated based on the turning speed command value and the yaw rate. The yaw rate is calculated based on the drive speed of the drive wheels 14c and the wheel spacing between the pair of drive wheels 14c. Then, speed control of the motor 15 is performed based on the generated speed command value and the drive speed of the drive wheels 14c. In this speed control, for example, known PID control can be used to improve responsiveness. PID control adds integral action feedback control (I control) and differential action feedback control (D control) to control (P control) that performs adjustment proportional to the deviation between the current output value and the target value.

[0051] As shown in Figure 6, when operator A wants to move the electric wheelchair 1 along a road surface F, operator A of the electric wheelchair 1 grasps and operates the grips 20 of the pair of first operating units 10 with each hand. At this time, the pair of grips 20 move relatively in the front-to-rear direction with respect to the vehicle body 2a. The pair of first operating units 10 provide outputs corresponding to the movement of the pair of grips 20 to the control device 18. Based on the outputs provided by the pair of first operating units 10, the control device 18 generates speed command values ​​for the motor 15 and provides them to the pair of drive circuits 34. In this way, the control device 18 controls the motor 15.

[0052] When the operator A grips the grip 20 and operates it to push forward, the motor 15 is controlled so that the drive wheels 14 c assist the forward movement of the electric wheelchair 1. When the operator A grips the grip 20 and operates it to pull backward, the motor 15 is controlled so that the drive wheels 14 c assist the backward movement of the electric wheelchair 1. On the other hand, when the operator A is in a non-gripping state where the operator A is not gripping the grip 20, or when the operator A does not operate the grip 20 in the forward or backward direction from the neutral position, the motor 15 is controlled so as not to drive the drive wheels 14 c. In this way, the control device 18 determines whether the operator A is in an operating state or a non-operating state with respect to the grip 20, or whether the operator A is in a gripping state or a non-gripping state with respect to the grip 20, and controls the motor 15 according to the operating state or the non-operating state, or according to the gripping state or the non-gripping state.

[0053] The output from the pair of first operating units 10 indicates the amount of longitudinal displacement of the pair of grips 20 relative to the vehicle body 2a. The control device 18 calculates the amount of longitudinal displacement of each of the pair of grips 20 based on the output from the pair of first operating units 10. This amount of displacement is the distance between a reference position (e.g., a neutral position) that is preset within the movable range of the grips 20 and the current position of the grips 20. When the reference position and the current position coincide in the longitudinal direction, the amount of displacement is 0 (zero). The control device 18 discretely acquires the amount of displacement of the grips 20 over time and stores it in the memory unit 40.

[0054] When the operator A grips 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 in response to the amount of displacement simulates mechanical impedance characteristics. That is, as shown in Fig. 6, the control device 18 controls the drive mechanism 4 so that the distance H between the grip 20 and the vehicle body 2a is constant while reproducing a movement in which the grip 20 and the vehicle body 2a are connected by a virtual spring 42 and a virtual damper 44. In this embodiment, a spring-damper model using the virtual spring 42 and damper 44 is used for impedance control (see Fig. 5).

[0055] Controlling the drive mechanism 4 so that the distance H between the grip 20 and the vehicle body 2a remains constant includes controlling the amount of displacement to 0 (zero) or a predetermined set value. As a result, the control device 18 controls the drive mechanism 4 to move the vehicle body 2a forward according to the amount of displacement of the grip 20. For example, when the operator A moves forward and presses the grip 20 forward, the control device 18 controls the drive mechanism 4 to move the vehicle body 2a forward. Conversely, when the operator A moves backward and pulls the grip 20 rearward, the control device 18 controls the drive mechanism 4 to move the vehicle body 2a backward. Furthermore, when the position of the grip 20 is in the reference position (neutral position), the control device 18 controls the drive mechanism 4 to stop the vehicle body 2a.

[0056] 9. Processing of the Control Device 18 As shown in FIG. 7, the processing unit 38 of the control device 18 sequentially executes processing from step S1 to step S15 for controlling the drive mechanism 4.

[0057] Note that the grip 20 being in a gripped state or a non-grip state is essentially the same as the grip 20 being in an operated state or a non-operated state. That is, the operator operates the grip 20 while gripping the grip 20, whereas the operator releases the grip of the grip 20 when releasing the operation of the grip 20. For this reason, in this specification, the "non-grip determination" and the "grip determination" are also referred to as the "non-operation determination" and the "operation determination", respectively, and the "non-grip state" and the "grip state" are also referred to as the "non-operation state" and the "operation state", respectively.

[0058] 10. Non-Grip Determination Process Step S1 in FIG. 1 is a step for performing non-grip determination processing for the grip 20. This non-grip determination processing is non-operation determination processing. For this non-grip determination processing, in this embodiment, as shown in FIG. 8, a non-grip determination region is set for the grip 20. The non-grip determination region includes the neutral position (see (a) in FIG. 3), which is the initial position of the grip 20. This non-grip determination region is a non-operation determination region.

[0059] As shown in FIG. 9, the non-grasping determination process in step S1 in FIG. 7 includes steps S1a and S1b.

[0060] Step S1a is a step for determining whether or not the grip 20 is within the non-grip determination area. If the grip 20 is within the non-grip determination area ("Yes" in step S1a), the process proceeds to step S1b. On the other hand, if the grip 20 is not within the non-grip determination area ("No" in step S1a), a "grip determination" is made that the grip 20 is in a gripped state. This grip determination is also an "operation determination" that the grip 20 is in an operation state.

[0061] Step S1b is a step for determining whether the displacement speed of the grip 20 is equal to or less than a threshold value. If the displacement speed of the grip 20 is equal to or less than the threshold value (if "Yes" in step S1b), a "non-grip determination" is made that the grip 20 is in an ungrip state. This non-grip determination is also a "non-operation determination" that the grip 20 is in an unoperated state. On the other hand, if the displacement speed of the grip 20 exceeds the threshold value (if "No" in step S1b), a "grip determination" is made that the grip 20 is in a grip state. The threshold value used in step S1b is stored in advance in the storage unit 40.

[0062] Returning to FIG. 7 , step S2 is a step for detecting whether the grip 20 is in a non-gripping state based on the result of the non-gripping determination process in step S1. If the grip 20 is in a non-gripping state ("Yes" in step S2), the process proceeds to step S3. On the other hand, if the grip 20 is not in a non-gripping state ("No" in step S2), the process proceeds to step S4. This step S2 is the starting point for switching the control parameters for the drive mechanism 4.

[0063] Step S3 is a step for setting the grip 20 to the neutral position. According to this step S3, the amount of displacement of the grip 20 from the neutral position becomes 0 (zero). After executing step S3, the process proceeds to step S7.

[0064] 11. Reverse Determination Process Step S4 is a step for performing the reverse determination process. That is, the reverse determination process of step S4 is executed in a state where the grip 20 is being held by the operator A. In this embodiment, the reverse determination process refers to a state where the grip 20 is being held by the operator A and the electric wheelchair 1 is reversing along the road surface F together with the operator A, as shown in FIG. 10 .

[0065] As shown in FIG. 11, the reverse determination process in step S4 in FIG. 7 includes steps S4a and S4b.

[0066] Step S4a is a step for determining whether the grip 20 has been displaced backward. If the grip 20 has been displaced backward ("Yes" in step S4a), the process proceeds to step S4b. On the other hand, if the grip 20 has not been displaced backward ("No" in step S4a), a "forward movement determination" is made to determine whether the electric wheelchair 1 is in a forward movement state.

[0067] Step S4b is a step for determining whether the traveling speed of the vehicle body 2a of the electric wheelchair 1 is equal to or greater than a threshold value. The traveling speed of the vehicle body 2a is calculated from the drive speed detected by the drive speed sensor 17 (see FIG. 4). In this embodiment, the traveling speed is always a positive value, regardless of whether the electric wheelchair 1 is moving forward or backward. That is, when the electric wheelchair 1 is moving forward, the traveling speed is calculated with the forward direction as a positive value, and when the electric wheelchair 1 is moving backward, the traveling speed is calculated with the backward direction as a positive value. If the traveling speed is equal to or greater than the threshold value ("Yes" in step S4b), a "reverse determination" is made that the vehicle body 2a of the electric wheelchair 1 is in a reverse direction. On the other hand, if the traveling speed is below the threshold value ("No" in step S4b), a "forward determination" is made that the vehicle body 2a of the electric wheelchair 1 is in a forward direction. The threshold value used in step S4b is pre-stored in the memory unit 40.

[0068] Returning to Fig. 7, step S5 is a step for detecting whether the electric wheelchair 1 is in a backward movement state based on the result of the backward movement determination process in step S4. If the electric wheelchair 1 is in a forward movement state ("No" in step S5), the process proceeds to step S7. Step S6 is a step for setting control parameters for backward movement if the electric wheelchair 1 is in a backward movement state ("Yes" in step S5). After step S6 is executed, the process proceeds to step S7.

[0069] Step S7 is a step for calculating the input torque that the motor 15 inputs to the drive wheels 14c. In step S7, if the electric wheelchair 1 is in a forward movement state, the input torque is calculated based on the forward movement control parameters, and if the electric wheelchair 1 is in a backward movement state, the input torque is calculated based on the backward movement control parameters. Step S8 is a step for generating a speed command value for the motor 15 using the input torque calculated in step S7.

[0070] Step S9 is a step for determining whether the traveling speed of the vehicle body 2a of the electric wheelchair 1 is within the assist range. If the traveling speed is within the assist range ("Yes" in step S9), the process proceeds to step S10. On the other hand, if the traveling speed is not within the assist range ("No" in step S9), i.e., if the traveling speed exceeds the assist range, the process proceeds to step S14.

[0071] Step S14 is a step for setting the motor 15 to a servo-off state. When the motor 15 is set to a servo-off state, the assistance of the drive wheels 14c in the movement of the electric wheelchair 1 is canceled. After step S14 is executed, the process proceeds to step S15. Step S15 is a step for replacing the speed command value for the motor 15 with the current speed of the motor 15. After step S15 is executed, the process proceeds to step S13.

[0072] 12. Step-Climbing Determination Process Step S10 is a step for performing step-climbing determination process. In this embodiment, the operation of the electric wheelchair 1 by the operator A so that the electric wheelchair 1 climbs over a step is referred to as a "step-climbing operation." This step-climbing operation is shown in stages, for example, by (a) to (c) in FIG. 12.

[0073] As shown in (a) in Figure 12, operator A pushes his / her foot against the tipping bar 13 of the electric wheelchair 1, which is stopped on a horizontal road surface F, and pulls the grip 20 toward him / her. Then, operator A uses the main wheel 2b as a fulcrum to lift the caster 2c and drive wheel 14c upward. At this time, the drive wheel 14c is configured to be able to take a ground contact state and a non-ground contact spin state when driven. Therefore, the state of the drive wheel 14c transitions from a ground contact state in which it is in contact with the road surface F to a non-ground contact spin state in which it is not in contact with the road surface F. In the non-ground contact spin state, the drive wheel 14c no longer contacts the road surface F, and the load acting on the motor 15 drops sharply.

[0074] Thereafter, as shown in (b) of Figure 12, operator A moves the lifted caster 2c onto the step surface Fs. Then, as shown in (c) of Figure 12, operator A lifts the grip 20 upward, lifts the main wheel 2b and drive wheel 14c upward, and further moves the drive wheel 14c onto the step surface Fs. At this time, the state of the drive wheel 14c transitions from a non-grounded, idling state to a grounded state in which the drive wheel 14c is in contact with the step surface Fs. When the drive wheel 14c touches the step surface Fs, a load acts on the motor 15.

[0075] As shown in FIG. 13 , the step-over-step determination process of step S10 in FIG. 7 includes step S10a. Step S10a is a step in which a speed command value for the motor 15 and the current speed of the motor 15 are used to determine whether the difference between the speed command value and the current speed is equal to or greater than a threshold value. The current speed of the motor 15 is derived from the rotation angle of the rotor of the motor main body 15a, detected by the rotation detector 15b. If the difference between the speed command value and the current speed is equal to or greater than the threshold value (if "Yes" in step S10a), the drive wheels 14c have transitioned from a ground-contact spin state to a ground-contact state (see (c) in FIG. 12 ), and a "step-over-step determination" is made to determine that the electric wheelchair 1 is in a step-over-step state. On the other hand, if the difference between the speed command value and the current speed is below the threshold value (if "No" in step S10a), a "normal running determination" is made to determine that the electric wheelchair 1 is in a normal running state. The threshold value used in step S10a is stored in advance in the storage unit 40.

[0076] In addition, instead of using the speed information of the motor 15 to determine whether the drive wheel 14c is in a ground contact spin state or a ground contact state, a drive speed sensor 17 may be used in addition to detecting the drive speed of the drive wheel 14c.

[0077] Returning to Fig. 7, step S11 is a step for detecting whether the electric wheelchair 1 is in a step-climbing state based on the result of the step-climbing determination process in step S10. If the electric wheelchair 1 is in a step-climbing state ("Yes" in step S11), the process proceeds to step S12. On the other hand, if the electric wheelchair 1 is not in a step-climbing state ("No" in step S11), the process proceeds to step S13.

[0078] Step S12 is a step in which the speed command value for the motor 15 is replaced with the current speed of the motor 15. According to this step S12, immediately after it is determined that the drive wheel 14c has transitioned from a non-ground contact spin state to a ground contact state, the control of the motor 15 is switched from a normal running mode based on the position of the grip 20 to a ground contact transition mode not based on the position of the grip 20. After execution of step S12, the process proceeds to step S13. Step S13 is a step in which the currently set speed command value is output.

[0079] 13. Effects and Advantages Next, the effects and advantages of the above-described embodiment will be described.

[0080] According to the electric wheelchair 1 of the embodiment, the control device 18 determines whether the operator A is in an operating state or a non-operating state with respect to the grip 20, or whether the operator A is in a gripping state or a non-gripping state with respect to the grip 20. The control device 18 then controls the motor 15 according to the operating state or the non-operating state, or the gripping state or the non-gripping state. Therefore, by understanding the state of the operator A with respect to the electric wheelchair 1 and controlling the motor 15 according to that state, the safety of the electric wheelchair 1 can be improved.

[0081] Furthermore, according to the electric wheelchair 1 of this embodiment, the control device 18 determines whether the vehicle body 2a is in a forward or reverse state, and controls the motor 15 according to whether it is in a forward or reverse state. The drive direction of the drive wheels 14c in the forward state corresponds to the direction in which the electric wheelchair 1 moves away from the operator A. On the other hand, the drive direction of the drive wheels 14c in the reverse state corresponds to the direction in which the electric wheelchair 1 moves toward the operator A. In this way, the drive direction of the drive wheels 14c relative to the positional relationship between the operator A and the electric wheelchair 1 differs between the forward and reverse states. Therefore, by determining whether the vehicle body 2a is in a forward or reverse state and controlling the motor 15 according to that state, it is possible to improve operability for the operator A.

[0082] Furthermore, with the electric wheelchair 1 of this embodiment, when going over a step, the control device 18 determines that the drive wheels 14c have transitioned from a non-ground contact spin state to a ground contact state, and immediately after the drive wheels have transitioned from a non-ground contact spin state to a ground contact state, the control of the motor 15 is switched from a normal driving mode based on the position of the grip 20 to a ground contact transition mode not based on the position of the grip 20. This makes it possible to improve operability immediately after the drive wheels 14c have transitioned to a ground contact state when going over a step.

[0083] Therefore, according to the above-described embodiment, it is possible to provide an electric wheelchair 1 that can improve safety or operability.

[0084] Although the present disclosure has been described based on the above-described embodiments, it is understood that the present disclosure is not limited to such forms or structures. The present disclosure also encompasses various modifications and modifications within the scope of equivalents. In addition, various combinations and forms, as well as other combinations and forms including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

[0085] In the above-described embodiment, the case where the non-grasping determination is performed using the operation detection unit 21 has been exemplified, but it is also possible to use a means other than the operation detection unit 21. An example of such a means is a pressure sensor provided in the grip 20. For example, it is possible to determine that the non-grasping state exists when the pressure detected by the pressure sensor is below a threshold, and that the gripping state exists when the pressure is equal to or greater than the threshold.

[0086] In the above embodiment, the case where the operation detection unit 21 is used to perform the retreat determination is exemplified, but a means other than the operation detection unit 21 may be used. For example, a distance measurement sensor capable of measuring distance, such as an ultrasonic sensor, may be used as the alternative means. If the distance measurement sensor is used to detect the amount of rearward displacement of the grip 20, this displacement amount can be used in the retreat determination.

[0087] In the above embodiment, the rotation detector 15b is used to determine whether a step has been passed over, but a means other than the rotation detector 15b may be used. For example, a load cell capable of detecting a load may be used as the other means. If the load applied to the drive wheel 14c is detected using the load cell, this load can be used to determine whether a step has been passed over.

Claims

1. A vehicle body (2a), A driving wheel (14c) for driving the vehicle body; a motor (15) for driving the drive wheels; a grip (20) that can be held by an operator (A) and can be displaced in the front-rear direction of the vehicle body by operation of the operator; a state sensor (21) for detecting an operation state or a grip state of the operator with respect to the grip; a control device (18) for controlling the motor; Equipped with the control device determines whether the operator is in an operating state or a non-operating state with respect to the grip, or whether the operator is in a gripping state or a non-gripping state with respect to the grip, and controls the motor according to the operating state or the non-operating state, or according to the gripping state or the non-gripping state; The state sensor is an operation detection unit (21) that detects the position of the grip in the front-rear direction, The control device determines that the operator is not gripping the grip when the forward / backward position of the grip is within a non-grasping area and the forward / backward displacement speed of the grip is equal to or less than a threshold, based on the position detected by the operation detection unit.

2. 2. The electric wheelchair of claim 1, wherein the control device determines, based on the position detected by the operation detection unit, that the operator is in a gripping state with respect to the grip when the forward / backward position of the grip is within a non-grasping area and the forward / backward displacement speed of the grip exceeds a threshold value.