JP7567489B2 - Electric walking aid - Google Patents

Description

The present invention relates to an electric walking aid vehicle.

Pushcart-type electric walking aids have been developed for users who have difficulty walking, such as the elderly. For example, Patent Document 1 discloses a pushcart in which a force sensor detects the force with which the user pushes the handlebars, and the drive torque of the electric motor is controlled so that an assist force is applied according to the magnitude and direction of the force.

Patent No. 6620326

This device detects the pressure (handle force) applied by the user to the handlebars with a force sensor (pressure sensor) attached to the joint between the handlebars and the support pole, and determines the assist force, which creates problems with the control and structure. Also, since humans are generally not as good at walking backwards as they are at walking forwards, there is also the problem that excessive assistance in the backward direction occurs when assistance is provided symmetrically (equally) in the forward and backward directions, as shown in Figure 4 of Patent Document 1.

The present invention was made in consideration of the above-mentioned shortcomings of the conventional technology, and its purpose is to provide an electric walking aid that can provide stable assistance according to the situation with a simple configuration.

In order to solve the above problems, the electric walking assist vehicle according to the present invention comprises:
A vehicle body having a forward/backward direction and a width direction;
Left and right drive wheels spaced apart in a width direction of the vehicle body;
Left and right motors connected to the left and right drive wheels so as to be capable of transmitting power thereto, respectively;
A swivel wheel is provided spaced apart from the left and right drive wheels in the forward and backward direction of the vehicle body;
A gripping portion provided on an upper portion of the vehicle body so that a user can grip the gripping portion in a standing walking position;
A grip sensor that detects a grip of the grip portion by a user;
a left and right rotation speed sensor that detects the rotation speeds of the left and right drive wheels individually;
An inclination sensor that detects an inclination of the vehicle body in a forward and backward direction;
A control unit for controlling the left and right motors,
The control unit is configured to generate torque in the left and right motors according to a basic torque map that specifies the relationship between the rotational speeds of the left and right drive wheels detected by the left and right rotational speed sensors and the torque command values of the left and right motors when the grip sensor detects a grip, and an additional torque map that adds a tilt compensation torque to the left and right motors to offset the rotational force generated in the left and right drive wheels due to gravity acting on the vehicle body, depending on the tilt detected by the tilt sensor.

As described above, the electric walking assist vehicle according to the present invention is configured to generate torque in the left and right motors according to a basic torque map that specifies torque command values for the left and right motors according to the rotational speeds of the left and right drive wheels detected when the user grips the gripping parts and pushes/pulls the vehicle body, and an additional torque map that adds tilt compensation torque to the left and right motors. This eliminates the need for a force sensor (pressure sensor) that detects the force with which the user pushes/pulls the gripping parts, simplifying the vehicle structure and control. In particular, there is an advantage that there is no need to consider the traction force detected by the force sensor when the left and right motors are driven, and stable assistance including tilt compensation can be performed with simple operations.

In addition, in a preferred embodiment of the present invention, the additional torque map is configured so that when the tilt sensor detects a negative tilt in which the vehicle body tilts forward relative to the forward/backward direction of the vehicle body, the tilt compensation torque in the backward direction of the vehicle body is smaller than the tilt compensation torque in the forward direction of the vehicle body. This has the advantage of being able to provide assistance that takes into account the characteristics of humans who are less adept at walking backwards than forwards, while avoiding complicating control.

1 is a side view showing an electric walking assist vehicle according to an embodiment of the present invention. FIG. 2 is a block diagram showing a control system of the electric walking assist vehicle according to the embodiment of the present invention. 4 is a basic torque map for control of the electric walking assist vehicle according to the embodiment of the present invention. 5 is a flowchart showing control of the electrically powered walking assist vehicle according to the embodiment of the present invention. 1A is a schematic plan view showing turning assist, FIG. 1B is a schematic plan view showing on-the-spot turning assist (spin turn), and FIG. 1C is an additional torque map during turning. 1A and 1B are schematic side views showing the tilt compensation assist when the vehicle body is tilted backward, that is, when the vehicle is moving forward uphill and backward downhill, respectively. 1A and 1B are schematic side views showing the tilt compensation assist when the vehicle body is tilted forward, that is, when going downhill in a forward direction, and when the vehicle body is tilted backward in a reverse direction. 13 is an additional torque map for lean compensation assist. FIG. 13 is a schematic perspective view showing a lateral tilt compensation assist.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
In FIG. 1, an electric vehicle 1 according to an embodiment of the present invention has a vehicle body 2 consisting of a mobile base 21 (lower running body) and an upper frame 22 erected at the rear of the mobile base 21 (rear base 24), and can be used in an ambulatory vehicle mode (1) indicated by a solid line in the figure, and a small electric vehicle mode (riding mode 1') indicated by a two-dot chain line in the figure.

The mobile base 21 comprises a rear base 24 (main body) on which the left and right drive wheels 4 (rear wheels) and upper frame 22 are mounted, and a front base 25 on which the left and right driven wheels 5 (front wheels) are mounted. The front base 25 is connected to the front side of the rear base 24 so that it can slide in the front-rear direction, and the mobile base 21 is configured so that the wheel base can be extended and retracted.

The left and right drive wheels 4 are independently driven by left and right motor units 40 (40L, 40R) mounted on the rear base 24. The left and right driven wheels 5 are configured as free wheels (omni-wheels, omnidirectional wheels) equipped with a number of rollers 50 that can rotate around a circumferential axis on the contact part, and as described below, the electric vehicle 1 can be steered and driven by controlling only the left and right motor units 40L, 40R.

The upper frame 22 is shaped like an inverted U or gate, with the upper ends of a pair of left and right side frames standing upward from both the left and right sides of the rear base 24, connected by an upper end frame that extends in the vehicle width direction. The lower end of the stem 31 of the rear handle 3 is rigidly connected to a joint 23 in the center of the upper end frame in the vehicle width direction, and the seat back 6 is supported by the joint 23.

The rear handle 3 is shaped like a T-bar with a pair of grips extending to the left and right from a connection 32 with the upper end of the stem 31. The left and right grips of the rear handle 3 are provided with grip sensors 30 that detect when the user (or caregiver) is gripping them (hands-on). The grip sensors 30 can be touch sensors such as capacitance sensors or pressure sensors. The left and right grips of the rear handle 3 serve as operating parts when the user uses the vehicle in the walking aid mode (1) and when a caregiver or the like operates the electric vehicle with the user seated in the seat 7.

The base of the support frame 81 of the armrest 8 is fixed to the bent part in the middle of the height direction of the upper frame 22 (side frame). A ride mode operation unit 83 is provided at the front end of the right armrest 8, which is the rear side in Fig. 1, and a display unit 80 is provided on the top surface of a grip part (83) of the same shape at the front end of the left armrest 8, which is the front side in Fig. 1. The ride mode operation unit 83 is composed of a two-axis joystick that can be tilted forward, backward, left and right.

The support frame 71 of the seat 7 (seat cushion) is pivoted by an axis 7a in the vehicle width direction to the pivot part 27 that protrudes forward from the bent part of the upper frame 22 (side frame), while the lower end of the support frame 71 is rotatably and slidably connected to the front base 25 (pin) via a connecting part 7b (slot).

With the above configuration, when the seat 7, which is in the folded position, is rotated upward and rearward as shown by the two-dot chain line in the figure from the walking aid mode (1) shown by the solid line in the figure to the seating position 7', the front base 25 slides forward in conjunction with this, and the movable base 21 is extended to enter the riding mode (1'). In this state, the top surface 25b of the front base 25, which has moved forward of the tray 24b, can be used as a footrest for the passenger.

Conversely, when the seat 7 is rotated forward and downward from the riding mode (1') to the folded position, the front base 25 slides backward and the movable base 21 shortens, resulting in a walking aid mode (1) in which the user can grip the rear handle 3 and operate the device while standing and walking.

Figure 2 is a block diagram showing the control system of the electric vehicle 1. The electric vehicle 1 is equipped with a battery 9 that supplies power to the left and right motor units 40 (40L, 40R), and a control unit 10 that controls the left and right motor units 40 (40L, 40R). The control unit 10 is equipped with an interlock mechanism that performs corresponding control in each of the handicapped vehicle mode (1) and the riding mode (1').

In the handicap assist vehicle mode (1), the riding mode operation unit 83 is disabled, and the control unit 10 controls the left and right motor units 40 (40L, 40R) based on detection information from the tilt sensor 20, the left and right rotation speed sensors 43, etc., and a preset control map. The grip sensor 30 only detects the grip of the rear handle 3 by the user (hands on/off), and is not involved in the torque control of the motor unit 40.

On the other hand, in the riding mode (1'), the grip sensor 30 is disabled, and the control unit 10 controls the left and right motor units 40 (40L, 40R) based on the operation of the riding mode operation unit 83 and the detection information of the tilt sensor 20.

The control unit 10 is composed of a ROM that stores programs and data for executing control in each of the above modes, a RAM that temporarily stores the results of calculation processing, a computer (microcomputer) consisting of a CPU that performs calculation processing, drive circuits (motor drivers) for the left and right motors 41, and a power supply circuit including a relay that turns the power of the battery 9 on and off.

The left and right motor units 40 (40L, 40R) each include a motor 41, an electromagnetic brake 42 that locks the rotor of the motor 41, and a rotational position sensor (43) that detects the rotational position of the motor 41. The drive shaft of the motor 41 is connected to the drive wheels 4 (4L, 4R) via reduction gears (not shown) so that power can be transmitted.

In this embodiment, the left and right motors 41 are brushless DC motors that use a drive circuit to switch the current of each phase coil in accordance with the rotor phase detected by a rotational position sensor (43), and as described below, in the walking aid mode (1), the rotational position sensor (Hall sensor) is used as the rotational speed sensor 43.

The drive circuits of the left and right motors 41 are also equipped with current sensors that detect coil currents. These coil currents correspond to the torques of the left and right motors 41, and the control unit 10 controls the coil currents to control the torques of the left and right motors 41.

The electromagnetic brake 42 is preferably a negatively actuated electromagnetic brake that locks the drive shaft of the motor 41 in a non-excited state and unlocks it in an excited state. In addition, an electromagnetic brake release switch 34 is provided so that the electromagnetic brake 42 can be unlocked in an emergency, such as when the battery level is low, to allow the electric vehicle 1 to move.

The tilt sensor 20 is implemented on the circuit board of the control unit 10 mounted inside the moving base 21 (rear base 24) of the vehicle body 2, and can be a two-axis tilt sensor or acceleration sensor that detects the longitudinal and lateral tilt of the vehicle body 2, or a multi-axis inertial sensor that integrates an acceleration sensor and an angular acceleration sensor (gyro sensor).

(Basic control in ambulatory mode)
In the electric vehicle 1 configured as described above, in the ambulatory support vehicle mode (1), torque is generated in the left and right motor units 40 (40L, 40R) in accordance with the rotational speeds of the left and right drive wheels 4L, 4R detected by the left and right rotational speed sensor 43 as the user pushes/pulls the vehicle body 2 while gripping the rear handle 3, thereby enabling torque assist to be performed in all operations of moving forward, backward, and turning.

First, the basic control in the manually propelled vehicle mode (1) will be described assuming forward/reverse movement on a flat road.
3 shows a basic torque map that defines the relationship between the rotation speed V detected by the left and right rotation speed sensor 43 and the torque T command value of the left and right motor 41. As already described, in this embodiment, the rotation position sensor of the left and right motor 41 is used as the left and right rotation speed sensor 43, and the rotation speeds of the left and right drive wheels 4L, 4R are detected as the rotation speed V of the left and right motor 41 (rotors) that is increased by the gear ratio of the reduction gear.

For example, if the left and right motors 41 are three-phase brushless DC motors, three rotational position sensors (43) arranged at 120 degree intervals can detect up to 60 degrees, or 1/6 rotation. If the gear ratio of the reduction gear is 10:1, the left and right motors 41 (rotors) will rotate once when the left and right drive wheels 4L, 4R rotate 36 degrees, so that a practically sufficient resolution can be obtained as the rotational speed or number of rotations per unit time [rpm] of the left and right motors 41 (rotors).

The handicapped vehicle mode (1) is based on the user gripping the rear handle 3 and moving forward, and the basic torque map shown in Figure 3 has the operation origin Vn (neutral point) set slightly on the negative side of the rotation speed V so that the electric vehicle 1 does not move backward due to the initial rotation to the negative side (toward the user) that accompanies the user gripping the rear handle 3.

With this configuration, even if an initial rotation in the negative direction is detected when the user grips the rear handle 3, a forward assist torque is generated within the rotation speed Vn of the left and right drive wheels 4L, 4R, and a backward assist torque is generated only when the user pulls the rear handle 3 with a clear intention (when the rotation speed in the negative direction becomes greater than Vn).

The basic torque map shown in FIG. 3 also has a peak region A1 (-Vn to +Va1) of the torque command value that generates a starting torque in the forward direction on the positive side of the operating origin Vn, and a peak region B1 (-Vn to -Vb1) of the torque command value that generates a starting torque in the reverse direction on the negative side of the operating origin Vn.

With this configuration, when the electric vehicle 1 is stopped, torque assist is performed in immediate response to the user's gripping and pushing of the rear handle 3, and the electric vehicle 1 can be quickly started and transitioned to steady forward travel (A2). Also, in response to the user's pulling of the rear handle 3, the electric vehicle 1 can be quickly transitioned to steady reverse travel (B2).

Furthermore, the basic torque map shown in FIG. 3 has a forward steady-state torque region A2 (+Va1 to +Va2) on the further positive side of the forward peak region A1, and a reverse steady-state torque region B2 (-Vb1 to -Vb2) on the further negative side of the reverse peak region B1.

The steady torque region A2 (+Va1 to +Va2) in the forward direction increases according to the rotation speed V in order to compensate for the frictional resistance that increases according to the speed of the electric vehicle 1, but it is intended that torque assist be performed according to the expected standard walking speed of the user using torque command values roughly close to the rated values of the left and right motors 41.

The same is true for the steady torque region B2 (-Vb1 to -Vb2) in the backward direction, but because the walking speed when moving backward is slower than when moving forward, it is preferable that the torque command value itself is smaller than in the steady torque region A2 in the forward direction and that the rate of increase in the torque command value according to the rotational speed is also smaller; in the illustrated example, the torque command value in the steady torque region B2 is constant.

The basic torque map shown in FIG. 3 further includes a forward braking torque region A3 (+V2 to +V3) on the positive side of the forward steady torque region A2, and a reverse braking torque region B3 (-Vb2 to -Vb3) on the negative side of the reverse steady torque region B2.

In the forward braking torque region A3, the torque command value is reduced as the traveling speed of the electric vehicle 1 approaches the upper limit of the expected standard walking speed range for the user (e.g., 6 km/h), and a braking torque is generated in the electric vehicle 1 by executing torque assist in the direction opposite to the traveling direction near the upper limit of the expected walking speed range, thereby controlling the traveling speed of the electric vehicle 1 to fall within the expected walking speed range.

The braking torque area B3 in the reverse direction is similar, but because the walking speed when reversing is slower than when moving forward, the braking torque is generated at a lower rotational speed than when moving forward. The basic torque map is stored as a lookup table in the ROM area of the control unit 10.

As described above, the basic torque map shown in FIG. 3 provides torque command values corresponding to the peak region A1 (starting torque region), steady torque region A2, and braking torque region A3 in the forward direction. When the user grips and pushes the rear handle 3, the vehicle starts quickly and transitions to the steady torque region A2. If the vehicle speed increases beyond the steady torque region A2, torque assist in the braking direction is performed in the braking torque region A3. If the vehicle speed decreases below the steady torque region A2, torque assist in the acceleration direction is performed in the peak region A1. This has the advantage that the user can maintain the steady torque region A2, which corresponds to the standard walking speed range (+Va1 to +Va2), without the user even being aware of it, by simply gripping the rear handle 3 and pushing/pulling it, and stable assistance can be performed.

Furthermore, in the torque assist control described above, there is no distinction (and no need to distinguish) between an increase or decrease in the rotational speed V caused by the user gripping and pushing/pulling the rear handle 3 and an increase or decrease in the rotational speed V caused by the drive of the left and right motors 41 (torque assist). Instead, torque assist is performed according to the rotational speed V resulting from the cooperation between the user gripping and pushing the rear handle 3 and the drive forces of the left and right motors 41. This not only eliminates the need for a force sensor (such as a pressure sensor) that detects the direction and magnitude of the force with which the user pushes/pulls the rear handle 3, but also simplifies the vehicle structure and control, with the advantage that the control is not affected by fluctuations in the direction and magnitude of the detected force.

Furthermore, in the torque assist control described above, torque assist is performed based on a basic torque map that is asymmetric between the forward and backward directions, taking into account the human characteristic of being less adept at walking backwards than walking forwards. This prevents the user from feeling excessive torque assist in the backward direction when gripping and pulling the rear handle 3, and has the advantage of realizing a walking assist that is intuitively balanced between forward and backward walking.

(Turning assist in walking aid mode)
Next, turning assistance in the manually propelled vehicle mode (1) will be described with reference to FIGS.
As already mentioned, the electric vehicle 1 is equipped with a rotation speed sensor 43 in each of the motor units 40 (40L, 40R) of the left and right drive wheels 4L, 4R. When a user holds the rear handle 3 with the left and right hands (or with either one of the hands) and pushes/pulls the vehicle body 2 with different forces on the left and right, a difference occurs in the rotation speeds of the left and right drive wheels 4L, 4R.

For example, as shown in FIG. 5(a), by pushing the right side of the rear handle 3 relatively strongly, a rotational speed VR of the right drive wheel 4R that is greater than the rotational speed VL of the left drive wheel 4L is detected, and a rotational speed difference ΔV=VR-VL occurs between the rotational speeds VR and VL detected by the left and right rotational speed sensor 43. Here, if the basic torque map shown in FIG. 3 is directly applied to the control of the motor units 40 (40L, 40R) of the left and right drive wheels 4L, 4R, even if a slight rotational speed difference occurs, the rotational speed difference is magnified by the individual torque assist for the left and right, causing the electric vehicle 1 to turn and making it impossible to move forward/backward stably.

As shown in FIG. 5(c), an additional torque map that defines the relationship between the rotational speed difference ΔV between the left and right drive wheels 4L, 4R and the additional torques TL, TR is used to perform torque assist according to the rotational speed difference ΔV as follows, thereby making it possible to perform stable forward/reverse assist and cornering assist appropriately according to the situation. Note that this additional torque map is also stored in the ROM area of the control unit 10 as a lookup table, just like the basic torque map.

(i) If the rotational speed difference ΔV between the left and right drive wheels 4L, 4R is less than a predetermined threshold value ±VT0, the rotational speed difference ΔV between the left and right drive wheels 4L, 4R is ignored, and the left and right motor units 40 (40L, 40R) generate essentially equal torques selected from either the left and right rotational speeds VR, VL or their intermediate value (average value) according to the basic torque map in Figure 3, thereby executing forward/reverse assist.

(ii) When the rotational speed difference ΔV between the left and right drive wheels 4L and 4R is equal to or greater than a predetermined threshold value ±VT0, turning assist control is executed to increase the torque command value of the motor with the higher rotational speed and decrease the torque command value of the motor with the lower rotational speed according to the rotational speed difference ΔV.

(iii) However, if the rotational speed difference ΔV between the left and right drive wheels 4L, 4R is equal to or greater than the second threshold ±VT1, the torque command value is not increased or decreased according to the rotational speed, and turning assist control is performed with the torque command values TL, TR corresponding to the second threshold ±VT1.

The above-described turning assist control compensates for the steering resistance generated in the driven wheels 5, and light and reliable turning assistance can be performed by pushing one side of the rear handle 3. Also, as shown in FIG. 5(b), light and reliable on-the-spot turning (spin turn) assistance can be performed by pushing one side of the rear handle 3 and pulling the other side.

(Hill climbing/descent assist in walking aid mode)
Next, the hill climbing/descent assistance in the manually propelled vehicle mode (1) will be described with reference to FIGS.
In the above explanation, for convenience, control on flat roads has been described. However, on an uphill road 91 shown in Figures 6(a) and 6(b) or a downhill road 92 shown in Figures 7(a) and 7(b), gravity acting on the vehicle body 2 generates a load (mg sin θp) in the same direction or opposite to the traveling direction depending on the vehicle weight m and the inclination θp.

Therefore, on an uphill road 91 or a downhill road 92, an additional torque map as shown in FIG. 8 is used in combination, and compensation torques Tca, Tcb, Tda, and Tdb that offset the load generated according to the inclination (angle) θp detected by the inclination sensor 20 are added to the torque command value. In other words, the compensation torque command value of the additional torque map is superimposed on the torque command value of the basic torque map. This additional torque map is also stored in the ROM area of the control unit 10 as a look-up table, just like the basic torque map.

Note that a threshold value (less than ±θp1, dead band) is set for the inclination θp, and torque compensation is generally not performed if the inclination θp is less than the threshold value, which does not affect basic control or turning control.

(i) As shown in FIG. 6(a), when moving forward up an uphill road 91 with a gradient of θp1 or more (when moving forward uphill), in order to offset the load in the direction opposite to the forward direction that is applied in accordance with the positive gradient +θp of the uphill road 91, a compensating torque Tca in the same direction that increases in proportion to the positive gradient +θp of the uphill road 91 is added, as shown by the solid line on the right side of the additional torque map in FIG. 8, and climbing assistance is performed.

(ii) As shown in FIG. 6(b), when reversing down an uphill road 91 with a gradient of θp1 or more (when reversing downhill), a load is applied in the same direction as the reverse direction, which is increased according to the positive gradient +θp of the uphill road 91. As a result, braking assistance is performed by adding a compensation torque Tcb in the opposite direction, which increases in proportion to the positive gradient +θp of the uphill road 91, as shown by the solid line on the right side of the additional torque map in FIG. 8, as described above.

(iii) As shown in Figure 7(a), when traveling forward down a downhill road 92 with a gradient of θp1 or more (traveling forward downhill), a load is applied in the same direction as the traveling direction that is weighted according to the negative gradient -θp of the downhill road 92, so braking assistance is performed by adding a compensation torque Tda in the opposite direction (regenerative direction) that increases in proportion to the negative gradient -θp of the downhill road 92, as shown by the solid line on the left side of the additional torque map in Figure 8. Also, when the negative gradient -θp reaches a predetermined threshold, a predetermined braking torque with an absolute value greater than the gradient-based compensation torque is generated, and braking control is performed.

(iv) As shown in FIG. 7(b), when reversing up a downhill road 92 with a gradient of θp1 or more (when reversing uphill), a load is applied in the direction opposite to the reverse direction according to the negative gradient -θp of the downhill road 92. Therefore, as shown by the dashed line on the left side of the torque map in FIG. 8, a compensation torque Tdb in the opposite direction is added which increases in proportion to the negative gradient -θp of the downhill road 92 to perform climbing assistance.

However, the compensation torque Tdb when going backwards uphill is set to a smaller value than when going backwards downhill (Tda) taking into consideration the human characteristic of walking backwards less well than walking forward, as well as the human characteristic of walking backwards uphill, where the heel lands earlier and it becomes more difficult to take a step than when going backwards downhill.

In addition, in the case of reverse climbing, as shown in FIG. 8, if the negative slope -θp is less than a predetermined threshold (-θp1), a predetermined torque Tdb" in the braking direction that is smaller than the calculated slope compensation torque in this negative slope range is added, and in addition to the control using the basic torque map described above, it is also possible to suppress excessive torque assist in the reverse climbing direction caused by the user pulling the rear handle 3.

(Lateral tilt compensation assist in ambulatory mode)
FIG. 9 shows lateral tilt compensation assist when moving forward on a road surface 93 that has a slope (lateral tilt θr) in a direction intersecting the traveling direction of the electric vehicle 1 in the manually propelled vehicle mode (1) (or when moving forward in a direction intersecting the slope θr of the slope 93).

In other words, in FIG. 9, when the center of gravity is located at a distance L forward of the axles of the drive wheels 4L and 4R, the gravity mg acting on the center of gravity and the lateral inclination θr generate a deflection moment (mg sin θr L) in the downward direction of the lateral inclination θr in the electric vehicle 1.

Therefore, in order to offset this deflection moment with the assist torque of the motor units 40 (40L, 40R) of the left and right drive wheels 4L, 4R, compensation torques TaL, TaR in opposite directions are added to the left and right motor units 40 (40L, 40R) so as to generate a couple equivalent to the compensation moment centered at the center (D/2) of the tread width D. Assuming that the coefficient δ takes into account the radius r of the drive wheels 4L, 4R, the running resistance of the road surface, etc., the compensation torques TaL, TaR for the lateral inclination θr are given by the following equation.
TaL=TaR=δ・mg・sinθr・Lr/D

A threshold value (dead band) is also set for lateral tilt θr, and lateral tilt compensation assistance is not performed if the tilt is below a threshold value that does not affect basic control or turning control.

(Basic control flow in ambulatory mode)
When the electric vehicle 1 configured as described above is powered on by operating the key 11 to start up the system, it is set to either the manually propelled vehicle mode (1) or the riding mode (1') depending on the frame configuration at the time of startup. As already mentioned, when the electric vehicle 1 is stopped, the electromagnetic brake 42 is in a locked state.

The following describes the control when the handicapped vehicle mode (1) is set at startup, or when the handicapped vehicle mode (1) is set by the user while the vehicle is stopped after startup, with reference to the flowchart in Figure 4.

First, when the handicapped vehicle mode (1) is set (step 100), the grip sensor 30 is activated. In this state, when the user grips the rear handle 3 and the grip sensor 30 detects the gripping state (hands-on) (step 101), the tilt sensor 20 detects the forward/backward tilt θp and the lateral tilt θr of the vehicle body 2 (step 102).

If the forward/backward tilt θp and/or the lateral tilt θr are equal to or greater than a threshold value, torque assist is performed to generate compensation torques Tca, Tcb, Td and/or compensation torques TaL, TaR in the left and right motor units 40 (40L, 40R), and the vehicle waits in a neutral state with an initial forward torque applied to the left and right drive wheels 4L, 4R (step 103).

Next, it is checked whether the left and right electromagnetic brakes 42 are locked (step 104), and if they are locked (such as at the time of initial startup), the left and right electromagnetic brakes 42 are unlocked (step 105).

At this time, the electric vehicle 1 is stationary, but the external force associated with the tilt is offset by the compensation torque, and the vehicle is ready to move immediately regardless of whether it is tilted or not. When the user pushes/pulls the rear handlebar 3 in this state, the left and right drive wheels 4L, 4R rotate, and when the rotation speed sensor 43 detects the rotation speed V (VL, VR), torque is generated in the left and right motor units 40 (40L, 40R) according to the rotation speed V (VL, VR) and the torque map, and torque assist such as forward/reverse/turning is performed (step 106).

The grip sensor 30 continues to detect the grip state (hands on) even while the electric vehicle 1 is traveling (step 107). When the grip sensor 30 no longer detects the grip state and the control unit 10 determines that the hands are off, the torque command value to the left and right motor units 40 (40L, 40R) is gradually reduced, and torque assist is executed to decelerate and stop the electric vehicle 1 (step 108). At the same time, the left and right electromagnetic brakes 42 are locked after a predetermined time (e.g., 2 seconds) has elapsed since the hands were off (step 109).

When the left and right electromagnetic brakes 42 are in the locked state and the key 11 is detected as being turned off (step 110), the power supply to the left and right motor units 40 (40L, 40R) is stopped, and then the system is shut down (step 111).

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications and variations are possible based on the technical concept of the present invention.

For example, in the above embodiment, the electric walking aid vehicle 1 is described as having a small electric vehicle mode (riding mode), but the present invention can also be implemented as an electric walking aid vehicle that does not have a riding mode.

In addition, in the above embodiment, an omniwheel is used as the driven wheel 5, but a caster-type swivel wheel can also be used.

1 Electric vehicle 2 Vehicle body 3 Rear handle (grip)
4 Drive wheels (rear wheels)
5. Driven wheels (swivel wheels, front wheels)
6 Seat back 7 Seat 8 Armrest 9 Battery 10 Control unit 20 Tilt sensor 21 Movement base 22 Upper frame 24 Rear base 25 Front base 30 Grasping sensor (touch sensor)
34 Electromagnetic brake release switch 40 (40L, 40R) Motor unit 41 Left and right motors 42 Left and right electromagnetic brakes 43 Left and right rotation speed sensors 80 Display unit 83 Ride mode operation unit

Claims (3)

A vehicle body having a forward/backward direction and a width direction;
Left and right drive wheels spaced apart in a width direction of the vehicle body;
Left and right motors connected to the left and right drive wheels so as to be capable of transmitting power thereto, respectively;
A swivel wheel is provided spaced apart from the left and right drive wheels in the forward and backward direction of the vehicle body;
A gripping portion provided on an upper portion of the vehicle body so that a user can grip the gripping portion in a standing walking position;
A grip sensor that detects a grip of the grip portion by a user;
a left and right rotation speed sensor that detects the rotation speeds of the left and right drive wheels individually;
An inclination sensor that detects an inclination of the vehicle body in a forward and backward direction;
A control unit for controlling the left and right motors,
the control unit is configured to generate torques in the left and right motors in accordance with a basic torque map that defines a relationship between the rotational speeds of the left and right drive wheels detected by the left and right rotational speed sensors and torque command values of the left and right motors when the grip sensor detects a grip, and an additional torque map that adds to the left and right motors tilt compensation torques that offset rotational forces generated in the left and right drive wheels due to gravity acting on the vehicle body in accordance with the tilt detected by the tilt sensor ,
The additional torque map is configured so that when the tilt sensor detects a negative tilt in which the vehicle body tilts forward relative to the forward/backward direction of the vehicle body, the tilt compensation torque in the backward direction of the vehicle body is smaller than the tilt compensation torque in the forward direction of the vehicle body, and when the tilt of the vehicle body detected by the tilt sensor is less than a predetermined threshold, the tilt compensation torque is not added, but when the negative tilt is detected relative to the forward/backward direction of the vehicle body and the left/right rotation speed sensor detects the rotation speed of the vehicle body in the backward direction, a predetermined torque in the braking direction that is smaller than the tilt compensation torque in the negative tilt range is added . A vehicle body having a forward/backward direction and a width direction;
Left and right drive wheels spaced apart in a width direction of the vehicle body;
Left and right motors connected to the left and right drive wheels so as to be capable of transmitting power thereto, respectively;
A swivel wheel is provided spaced apart from the left and right drive wheels in the forward and backward direction of the vehicle body;
A gripping portion provided on an upper portion of the vehicle body so that a user can grip the gripping portion in a standing walking position;
A grip sensor that detects a grip of the grip portion by a user;
a left and right rotation speed sensor that detects the rotation speeds of the left and right drive wheels individually;
An inclination sensor that detects an inclination of the vehicle body in a forward and backward direction;
A control unit for controlling the left and right motors,
the control unit is configured to generate torques in the left and right motors in accordance with a basic torque map that defines a relationship between the rotational speeds of the left and right drive wheels detected by the left and right rotational speed sensors and torque command values of the left and right motors when the grip sensor detects a grip, and an additional torque map that adds to the left and right motors tilt compensation torques that offset rotational forces generated in the left and right drive wheels due to gravity acting on the vehicle body in accordance with the tilt detected by the tilt sensor ,
the basic torque map has an operation origin set on the negative side of the rotational direction of the left and right drive wheels detected by the left and right rotational speed sensors, has a peak region for generating a starting torque in a forward direction on the positive side of the operation origin, and has a peak region for generating a starting torque in a reverse direction on the negative side of the operation origin . 3. The electric walking assist vehicle according to claim 2, wherein the basic torque map has a forward direction steady-state torque region on the further positive side of the positive side peak region and a reverse direction steady-state torque region on the further negative side of the negative side peak region, and the torque command value and/or an increase rate of the torque command value according to the rotational speed is smaller in the negative side steady-state torque region than in the positive side steady-state torque region.