Small electric vehicle

Abstract

To provide a small electric vehicle capable of delivering turning performance according to a travel state through intuitive operation of a joystick type operator.SOLUTION: A small electric vehicle comprises: a vehicle body having an advancing / retracting direction and a width direction; right and left drive wheels installed separated from each other in the width direction of the vehicle body; swivel wheels installed separated from each other in the advancing / retracting direction with respect to the right and left drive wheels; right and left motors connected to the right and left drive wheels respectively so as to enable power thereof to be transmitted to the right and left drive wheels; right and left rotation speed sensors for detecting rotation speeds of the right and left motors; an operation section having a joystick type operator; and a control section for controlling the right and left motors according to an operation amount of the operator. The control section calculates target rotation speeds of the right and left motors on the basis of a target vehicle speed obtained through an operation position of the operator and a target vehicle angular speed obtained through the operation position of the operator and an actual vehicle speed, and controls the right and left motors so that actual rotation speeds thereof follow the target rotation speeds.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a small electric vehicle. [Background technology]

[0002] Small electric vehicles, such as pushcart-type electric walking aids and electric wheelchairs, for users who have difficulty walking, such as the elderly, are well known. For example, Patent Document 1 discloses a small electric vehicle (electric wheelchair) that is equipped with left and right motors that drive left and right drive wheels separately, determines the rotation speed of the left and right motors from the operating position of a joystick-type operation means, and moves forward when the operation lever is tilted forward, turns when tilted diagonally forward, rotates in a fixed position when tilted diagonally backward, and stops when tilted straight backward. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-64620 A DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0004] In small electric vehicles such as those described above, the speed (left and right speed difference) is determined by the position of the joystick-type controller, so when turning at low speeds, the controller must be held in an intermediate position, posing a challenge to driving at the speed and along the route intended by the user.

[0005] The present invention has been made in consideration of the above-mentioned shortcomings of the prior art, and its object is to provide a small electric vehicle that can obtain turning characteristics according to the driving conditions by intuitively operating a joystick-type controller. [Means for solving the problem]

[0006] In order to solve the above problems, the small electric 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; A swivel wheel is provided spaced apart from the left and right drive wheels in the forward and backward 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 left / right rotation speed sensor for detecting the rotation speeds of the left / right motors; an operation unit having a joystick type operator; Operation of the above-mentioned controls To Therefore, a control unit for controlling the left and right motors is provided, an angular velocity related to the turning of the vehicle is given in accordance with a rotational speed difference between the left and right drive wheels; The control unit determines a target vehicle speed given by the operation position of the operator, and The left and right components of and a target vehicle angular velocity given by the actual speed of the vehicle, and target rotational speeds of the left and right motors are calculated based on the target vehicle angular velocity given by the actual speed of the vehicle, and the left and right motors are controlled so that the actual rotational speeds of the left and right motors follow the target rotational speeds. Effect of the Invention

[0007] As described above, the small electric vehicle of the present invention is configured to calculate target rotational speeds for the left and right motors based on the target vehicle speed given by the operating position of the joystick-type operator and the target vehicle angular velocity given by that operating position and the actual speed of the vehicle, and to control the left and right motors so that the actual rotational speeds of the left and right motors follow the target rotational speeds.Therefore, the turning characteristics can be changed in accordance with the actual speed, and appropriate turning characteristics can be obtained in accordance with the driving conditions by simply intuitively operating the joystick-type operator, which is advantageous for simplifying operation and improving convenience and safety. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a side view showing a small electric vehicle. [Diagram 2] FIG. 2 is a block diagram showing a control system of the small electric vehicle. [Diagram 3] FIG. 4 is a block diagram showing left and right motor control. [Figure 4] This is a map of target vehicle speeds based on joystick operation. [Diagram 5] 13A shows a target angular velocity map for low speed and FIG. 13B shows a target angular velocity map for high speed, both of which are generated by joystick operation. [Figure 6] FIG. 2 is a schematic plan view showing a limiter plate of the joystick. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] 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 it (rear base 24), and can be used in a small electric vehicle mode (riding mode 1) indicated by a solid line in the figure, and an ambulatory support vehicle mode (1') indicated by a two-dot chain line in the figure.

[0010] The movable base 21 comprises a rear base 24 (main body) on which left and right drive wheels 4 (rear wheels) and an upper frame 22 are provided, and a front base 25 on which left and right driven wheels 5 (front wheels) are provided. The front base 25 is connected to the front side of the rear base 24 so that it can slide in the front-to-rear direction, and the movable base 21 is configured so that the wheel base is extendable and contractible.

[0011] 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 portion, and as described later, the electric vehicle 1 can be steered and braked / driven simply by controlling the left and right motor units 40L, 40R.

[0012] The upper frame 22 has an inverted U-shape or a gate-shape, 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 being connected by an upper end frame extending 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.

[0013] The rear handle 3 is in the shape of a T-bar with a pair of gripping parts extending to the left and right from a connection part 32 with the upper end of the stem 31. The left and right gripping parts of the rear handle 3 are provided with gripping sensors 30 that detect a state in which the user (or caregiver) is gripping them (hands-on). A touch sensor such as a capacitance sensor or a pressure sensor can be used as the gripping sensor 30. The left and right gripping parts of the rear handle 3 serve as operation parts when the user uses the rear handle 3 in the walking aid mode (1') and when a caregiver or the like operates the electric vehicle with the user seated on the seat 7. Although omitted in FIG. 1, an electromagnetic brake release switch 34 and a speaker 35 are provided at the connection part 32 in the center of the rear handle 3.

[0014] A base of a support frame 81 of an armrest 82 is fixed to a bent portion in the middle in the height direction of the upper frame 22 (side frame). A joystick 83 constituting the riding mode operation unit 8 is provided at the front end of the right armrest 82, which is the back side in Fig. 1, and a display unit 80 and a travel permission switch 84 are provided on the upper surface of a grip of the same shape at the front end of the left armrest 82, which is the front side in Fig. 1.

[0015] The joystick 83 may be a two-axis joystick that can be tilted forward, backward, left, and right and that can obtain an output according to the tilt angle, or a multi-axis joystick that includes the above functions, and a non-contact joystick that uses a hall sensor is preferable. The joystick 83 is configured such that a biasing force (restoring force, operation reaction force) toward a neutral position according to the tilt angle is applied by a biasing member (such as a spring) not shown, and when no operating force is applied, i.e., when the user's hand is removed from the joystick 83, the joystick automatically returns to the neutral position. The control of the left and right motor units 40 (40L, 40R) by operating the joystick 83 will be described later.

[0016] A support frame 71 of the seat 7 (seat cushion) is pivotally supported by an axis 7a in the vehicle width direction on the pivot part 27 protruding 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).

[0017] With the above configuration, when the seat 7, which is in the seating position, is rotated forward and downward as shown by the two-dot chain line in the figure from the riding mode (1) shown by the solid line in the figure to the folding position (7'), the front base 25 slides rearward in conjunction with this and the movable base 21 shortens, resulting in a walking aid mode (1') in which the user can operate the vehicle while gripping the rear handle 3 and walking upright.

[0018] Conversely, when the seat (7') in the folded position is rotated rearward and upward from the handicapped vehicle mode (1') to the seating position 7, the front base 25 slides forward, and the movable base 21 is extended to enter the riding mode (1). In this state, the upper surface 25b of the front base 25, which has moved forward of the tray 24b, can be used as a footrest for the passenger.

[0019] A locking mechanism (such as a lock pin biased by a biasing member such as a spring) that locks the front base 25 at each of the extended and retracted positions is provided inside the moving base 21, and a vehicle state detection sensor 28 (such as a mechanical switch) that detects the locked state at each position is also provided. Furthermore, a biasing member (such as a spring) that biases the front base 25 toward the intermediate position (release direction) is provided at each of the extended and retracted positions, and a release tag 26 that is connected to the locking mechanism via a Bowden cable is provided at the upper end of the support frame 71.

[0020] As a result, when the release tag 26 is pulled to release the locking mechanism in each of the extended and retracted positions, the body 2 moves to the intermediate position due to the force of the biasing member, and from this state, when the seat 7 (support frame 71) is rotated forward or backward from the intermediate position against the force of the biasing member, the locking mechanism is locked at the extended and retracted positions of the front base 25.

[0021] FIG. 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 has an interlock function that performs control corresponding to the riding mode (1) and the ambulatory support vehicle mode (1') when in the locked state at each position detected by the vehicle state detection sensor 28.

[0022] In the riding mode (1), the grip sensor 30 is disabled, and when the travel permission switch 84 is turned on, the control unit 10 controls the speed of the left and right motor units 40 (40L, 40R) based on a control map described later by the operation (amount of operation, direction of operation) of the joystick 83 constituting the riding mode operation unit 8, and is capable of performing driving operations including moving forward, backward, turning, and braking / stopping the electric vehicle 1. Note that when the tilt sensor 20 detects a tilt of a predetermined threshold value or more, the target speed is corrected taking into account the gravity (load) acting according to the tilt.

[0023] On the other hand, in the handicapped vehicle mode (1'), the riding mode operation unit 8 is disabled, and the control unit 10 executes torque control of 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 predetermined control map. When the tilt sensor 20 detects a tilt equal to or greater than a predetermined threshold, a compensation torque that offsets the gravity (load) acting in accordance with the tilt is superimposed on the torque command value. The grip sensor 30 detects only the grip of the rear handle 3 by the user (hands on / off), and is not involved in the torque control of the motor units 40.

[0024] The control unit 10 is composed of a computer (microcomputer) consisting 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 CPU that performs the 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.

[0025] 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, and the drive shaft of the motor 41 is connected to the drive wheels 4 (4L, 4R) via a reduction gear not shown in the figure so that power can be transmitted.

[0026] The left and right motors 41 are brushless DC motors in which a drive circuit switches the current of each phase coil in accordance with the rotor phase detected by a rotational position sensor (43). In the riding mode (1), the rotational position sensor (Hall sensor) is used as a vehicle speed sensor (43) that detects the actual speed of the electric vehicle 1, and in the handicapped vehicle mode (1'), the rotational position sensor is used as the rotational speed sensor 43.

[0027] In addition, the drive circuits of the left and right motors 41 are 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 by PWM control (pulse width modulation control) or the like, thereby controlling the torques of the left and right motors 41.

[0028] The electromagnetic brake 42 is preferably a negative actuation type electromagnetic brake that locks the drive shaft of the motor 41 in a non-excited state and unlocks it in an excited state. By using a negative actuation type electromagnetic brake, the electric vehicle 1 can be stopped reliably without consuming power when the key is turned off or while the vehicle is stopped.

[0029] On the other hand, in the event of an emergency or special situation, for example when it is desired to move the electric vehicle 1 without using the power of the motor 41 or when driving is impossible due to a low battery level, an electromagnetic brake release switch 34 is provided as a means for forcibly releasing the electromagnetic brake 42 so that the electromagnetic brake 42 can be unlocked and the electric vehicle 1 can be moved. The electromagnetic brake release switch 34 is provided adjacent to the grip part of the rear handle 3, but can be operated regardless of grip detection by the grip sensor 30.

[0030] The inclination sensor 20 is implemented on a circuit board of the control unit 10 mounted inside the movable base 21 (rear base 24) of the vehicle body 2, and can use a two-axis inclination sensor or acceleration sensor that detects the longitudinal and lateral inclination of the vehicle body 2, or a multi-axis inertial sensor that integrates an acceleration sensor and an angular acceleration sensor (gyro sensor).

[0031] (Driving control in riding mode) In the electric vehicle 1 configured as described above, in the riding mode (1), the rotational speeds of the left and right motors 41 (40L, 40R) are controlled based on the operation (amount of operation, direction of operation) of the joystick 83 by the user. However, the target rotational speeds of the left and right motors 41 (40L, 40R) are not immediately determined from the operating position of the joystick 83. Instead, a target vehicle speed (straight-line speed) based on the operating position of the joystick 83 and a target vehicle angular velocity based on the left and right component of the operating position of the joystick 83 are calculated separately, and the target rotational speeds of the left and right motors 41 (40L, 40R) corresponding to the rotational speeds of the left and right drive wheels 4 (4L, 4R) are calculated based on these.

[0032] That is, as shown in the block diagram of Fig. 3, the target vehicle speed calculation block 110 utilizes not only forward / rearward inputs of the joystick 83 but also left / right inputs, which allows speed control different from that during straight driving when turning, for example, decelerating driving, to be performed without special consideration. Also, the target vehicle angular speed calculation block 120 reflects not only the left / right inputs of the joystick 83 but also the actual vehicle speed at the time of operation, which allows the turning characteristics to be changed according to the driving speed of the electric vehicle 1.

[0033] In the block diagram of FIG. 3, a left and right motor target rotational speed calculation block 130 calculates the target rotational speeds of the left and right motors 41 (40L, 40R) based on the target rotational speeds of the left and right motors 41 (40L, 40R) corresponding to the target vehicle speed v calculated in the target vehicle speed calculation block 110 and the target rotational speed difference of the left and right motors 41 (40L, 40R) corresponding to the target vehicle angular speed ω calculated in the target vehicle angular speed calculation block 120.

[0034] Furthermore, in the left and right motor required torque calculation block 150, the left and right motor required torque is calculated by feedback control (e.g., PID control) that causes the actual rotational speeds of the left and right motors 41 (40L, 40R) to track the target rotational speeds based on the actual rotational speeds of the left and right motors 41 (40L, 40R) detected by the left and right rotational speed sensors 43 and the target rotational speeds of the left and right motors 41 (40L, 40R), and current control of the left and right motors 41 (40L, 40R) is executed based on the calculated left and right motor required torque.

[0035] In addition, when the inclination sensor 20 detects a vehicle body inclination (pitch angle P, roll angle R) equal to or greater than a predetermined threshold, the compensation torque calculation block 140 calculates a compensation torque in a direction that compensates for the uphill / downhill load acting according to the pitch angle P and / or the lateral load acting according to the roll angle R, and superimposes this compensation torque on the left and right motor required torque calculated in the left and right motor required torque calculation block 150.

[0036] (Target vehicle speed map) 4 shows a target vehicle speed map for calculating the target vehicle speed by joystick operation (110). The target vehicle speed map is stored in the ROM area of ​​the control unit 10 as a look-up table.

[0037] 4, when the operation position of the joystick 83 is in a forward region F1 including the front end of the operation range, a target forward speed va is specified, and when it is in a rear region B1 including the rear end, a target backward speed vb is specified. Also, when the operation position of the joystick 83 is in a left or right region F2 including the left or right ends, a target forward speed vc is specified, and when it is in a central region n including the center (neutral position), stop (target speed zero) is specified.

[0038] 4, the target forward speed va in the forward region F1 is greater than the target forward speed vc in the left and right regions F2, and the target forward speed vc in the left and right regions F2 has an absolute value greater than (or equal to) the target reverse speed vb in the rear region B1. For example, the target forward speed va may be 3-5 km / h, the target forward speed vc may be 1-2 km / h, and the target reverse speed vb may be 1 km / h.

[0039] Furthermore, in FIG. 4, between the central region n and the forward region F1, and between the central region n and the left and right regions F2, transition regions F3 and F4 are provided, in which the target forward speed increases from the central region n toward the forward region F1 and the left and right regions F2, and between the central region n and the rear region B1, a transition region B2 is provided, in which the target reverse speed increases from the central region n toward the rear region B1. When the operation position of the joystick 83 is in the transition region F3 or transition region B2, an intermediate target forward speed and an intermediate target reverse speed are specified.

[0040] Therefore, the target forward speed vc is specified not only when the joystick 83 is operated into the forward area F1 (and its transition area F3) but also when it is operated into the left or right area F2 (and its transition area F4), and forward rotation is output even if the target vehicle angular speed ±ω is input from the target vehicle angular speed calculation 120 block described below.

[0041] This is because in the omni-wheel swivel wheels 5, lateral movement is achieved by the rotation of the rollers 50, which results in lower starting performance and step-crossing performance compared to straight-ahead driving, and so the load on the system is reduced by preventing on-the-spot turning (spin turn) with intuitive turning operations. However, when the joystick 83 is operated diagonally rearward FB, the target speed becomes zero halfway between the left and right side areas F2 and the rear area B1, and on-the-spot turning (spin turn) is possible in narrow places such as indoors or elevator halls.

[0042] (Target vehicle angular velocity map) 5 shows a target angular velocity map for calculating the target vehicle angular velocity (120) by joystick operation, and the target angular velocity map includes a low-speed target angular velocity map (a) that specifies the target vehicle angular velocity when the actual speed is in the low-speed range or zero, and a high-speed target angular velocity map (b) that specifies the target vehicle angular velocity when the actual speed is in the maximum speed within the set speed range of the vehicle or in a predetermined high-speed range. These target angular velocity maps are also stored as look-up tables in the ROM area of ​​the control unit 10.

[0043] In the low-speed target angular velocity map (a), a target vehicle angular velocity ω1 is specified when the operation position of the joystick 83 is in a left or right region T1 including the left or right ends within the operation range, and a target vehicle angular velocity of zero is specified when the operation position is in a central region n1 including the center (neutral position). Between the central region n1 and the left or right region T1, there is provided a transition region T3 where the target angular velocity ω gradually increases from the central region n to the left or right region T1.

[0044] Similarly, in the high-speed target angular velocity map (b), when the operation position of the joystick 83 is in a left or right region T2 including the left or right ends within the operation range, a target vehicle angular velocity ω2 is specified, and when it is in a central region n2 including the center (neutral position), a target vehicle angular velocity of zero is specified. Between the central region n2 and the left or right region T2, a transition region T4 is provided in which the target angular velocity ω gradually increases from the central region n2 to the left or right region T2.

[0045] Here, the maximum target angular velocity ω2 in the left and right regions T2 of the high speed target angular velocity map (b) is greater than the maximum target angular velocity ω1 in the left and right regions T1 of the low speed target angular velocity map (a), and the central region n2 of the high speed target angular velocity map (b) is narrower than the central region n1 of the low speed target angular velocity map (a), and the transition region T4 of the high speed target angular velocity map (b) is wider than the transition region T3 of the low speed target angular velocity map (a).

[0046] In a preferred embodiment, the low speed target angular velocity map (a) corresponds to a case where the actual vehicle speed is 0.5 km / h or less, which can be regarded as substantially zero, and the high speed target angular velocity map (b) corresponds to a case where the actual vehicle speed is 4.5 km / h, and the maximum target angular velocity ω1 in the left and right regions T1 of the low speed target angular velocity map (a) is 30 degrees per second (0.52 rad / s), and the maximum target angular velocity ω2 in the left and right regions T2 of the high speed target angular velocity map (b) is 60 degrees per second (1.05 rad / s) to 120 degrees per second (2.09 rad / s).

[0047] Instead of setting a transition region T4 between the left and right regions T2 and the central region n2, in which the target angular velocity changes continuously depending on the operating position of the joystick 83, a region of an intermediate target angular velocity, for example, 90 degrees per second (1.57 rad / s), may be set.

[0048] The control unit 10 calculates the actual speed of the electric vehicle 1 based on the actual rotational speeds of the left and right motor units 40 (40L, 40R) detected by the rotational speed sensor 43, and selectively applies the target angular velocity map for low speed (a) or the target angular velocity map for high speed (b) depending on the actual vehicle speed, or, if the actual speed is in a speed range intermediate between the low speed range and the high speed range, calculates the target angular velocity corresponding to the actual speed from the target angular velocity map for low speed (a) and the target angular velocity map for high speed (b).

[0049] For example, by setting two speed thresholds, a first and a second, and switching to the high speed target angular velocity map (b) when the actual speed rises from the low speed range to equal to or greater than the second speed threshold (e.g., 2.5 km / h) while the low speed target angular velocity map (a) is being applied, and switching to the low speed target angular velocity map (a) when the actual speed falls below the first speed threshold (e.g., 1.5 km / h) that is smaller than the second speed threshold while the high speed target angular velocity map (b) is being applied, the frequency of map switching can be reduced, enabling stable control.

[0050] In addition, when calculating a target angular velocity corresponding to an actual velocity from the target angular velocity map for low speed (a) and the target angular velocity map for high speed (b), a target angular velocity may be specified such that the target angular velocity designated values ​​of the target angular velocity map for low speed (a) and the target angular velocity map for high speed (b) are proportionally distributed in accordance with the ratio of the current actual velocity to the actual velocity corresponding to the target angular velocity map for high speed (b).

[0051] By applying the above-mentioned low speed target angular velocity map (a) and high speed target angular velocity map (b) in accordance with the actual speed, the following turning characteristics are obtained.

[0052] That is, when the electric vehicle 1 is substantially at a standstill (the actual speed is in the low speed range or zero), a relatively wide central region n1 (dead zone) is set on both the left and right sides of the neutral position of the joystick 83, and the electric vehicle 1 will not start moving even if the user operates the joystick 83 left or right within this range. This avoids an immediate transition from a substantially stopped state to a turning operation as described above, and forward turning is started only when the user operates the joystick 83 to the left or right region T1 with a clear intention.

[0053] On the other hand, when the actual speed of the electric vehicle 1 is in the high-speed region, such as when the user operates the joystick 83 forward to drive the vehicle forward, a transition region T4 is set near both the left and right sides of the neutral position, and the user can operate the joystick 83 left or right from the forward tilted position to fine-tune the course while driving in the desired direction, and steering performance appropriate for the straight-line speed of the electric vehicle 1 can be obtained.

[0054] (Joystick embodiment) Next, Fig. 6 shows an embodiment of a joystick and limiter plate 304 in a riding mode operation unit 308 suitable for operating the above-mentioned electric vehicle 1. The limiter plate 304 has a function of mechanically restricting the operation area (movable range) of the joystick shaft portion 383, and as shown in Fig. 6, the limiter plate 304 has an opening (304) having a basic regular octagonal shape, with eight moderation portions 341 to 348 formed on the edge of the opening.

[0055] Of these, the moderation portions 341, 342 located at the front and rear with respect to the direction of travel are formed in an arc-like or curved shape having a larger radius of curvature than the shaft portion 383, over a predetermined angular range 341a, 342a, and are continuous with the adjacent side portions.

[0056] With this configuration, as shown by the two-dot chain line in the figure, when the joystick (383′) is tilted forward to travel forward, the joystick (383″) can be moved left and right along the moderation portion 341 to easily perform operations for traveling forward while finely adjusting the course. Similarly, when the joystick (383) is operated backward, i.e., toward the user, to travel in reverse, the joystick can be moved left and right along the moderation portion 342, which has the advantage of easily fine-tuning the course.

[0057] On the other hand, the other detent portions 343-348 are corners with a smaller radius of curvature than the shaft portion 383, which has the advantage that a definite detent feeling can be obtained at each of the detent portions 343-348 and the joystick (383) can be moved definite to the adjacent detent portion.

[0058] For example, by operating the joystick (383) from the front moderation portion 341 to the left and right diagonally forward moderation portions 345, 346, the vehicle can transition to forward turning, by operating the joystick (383) from the neutral position in a stopped state to the left and right moderation portions 343, 344, the vehicle can transition to forward turning, and by operating the joystick (383) to the diagonally rear moderation portions 347, 348, the vehicle can perform a turn on the spot (spin turn).

[0059] In an electric vehicle 1 whose maximum speed is limited to walking speed range (for example, 6 km / h) or less, users tend to perform simple and definite operations such as tilting the joystick all the way to the front when driving forward, and all the way to the rear when driving backward. This has the advantage that while allowing fine adjustment of the course using the front and rear control parts 341, 342, the turning range can be limited (over-turning can be prevented) using the diagonally forward control parts 345, 346 that smoothly connect to the front control part 341.

[0060] Moreover, when moving from forward driving (341; forward region F1 in FIG. 4) to forward turning (345, 346; transition region F3 in FIG. 4), the vehicle decelerates according to the target vehicle speed map, so that speed control according to steering operation can be performed without special awareness, and turning characteristics according to the driving speed can be obtained.

[0061] As described above in detail, the electric vehicle 1 according to the present invention is configured to calculate the target rotational speeds of the left and right drive wheels 4 (4L, 4R) based on the target vehicle speed v given by the operating position of the joystick 83 and the target vehicle angular speed ω given by the operating position of the joystick 83 and the actual speed of the vehicle, and to control the left and right motors 41 (40L, 40R) to make the actual rotational speeds of the left and right drive wheels 4 (4L, 4R) follow the target rotational speeds. Therefore, the turning characteristics can be changed according to the actual speed, and appropriate turning characteristics can be obtained according to the driving conditions by simply intuitively operating the joystick 83, which is advantageous for simplifying the operation and improving convenience and safety.

[0062] In particular, the control unit 10 is provided with a target speed map that defines the relationship between the operating position of the joystick 83 and the target vehicle speed, and a target angular velocity map that defines the relationship between the operating position of the joystick 83 and the target vehicle angular velocity depending on the actual speed, and is configured to calculate the target rotational speeds of the left and right drive wheels 4 (4L, 4R), thereby making it possible to configure a stable small electric vehicle while avoiding complex control.

[0063] Furthermore, the target speed map has a forward region F1 including the front end within the operating range of the joystick 83, a rear region B1 including the rear end, left and right regions F2 including the left and right ends, and a central region n including the center, and the forward region F1 indicates a first target forward speed (va), the rear region B1 indicates a target reverse speed (vb), the left and right regions F2 indicate a second target forward speed (vc), and the central region n indicates a stop, and the first target forward speed (va) is greater than the second target forward speed (vc), and the second target forward speed (vc) has an absolute value greater than or equal to the target reverse speed (vb). Therefore, a forward speed can be obtained even when turning by operating the joystick 83 to the left or right region F2, and the load on the system of the small electric vehicle 1 equipped with the left and right drive wheels 4 (4L, 4R) and the swivel wheel (omni wheel) 5 is reduced, and a practical and lightweight system can be configured with a relatively small-output motor.

[0064] In addition, the target speed map has transition regions F3, F4, B2 between the central region n and the front region F1, rear region B1, and left and right side regions F2, where the target speed increases from the central region n toward each of the regions F1, F2, B1, so that the target speed can be input according to the amount of operation of the joystick 83, and continuous and smooth control can be performed while reducing the burden on the motor.

[0065] On the other hand, the target angular velocity map includes a high-speed target angular velocity map (b) that specifies the target vehicle angular velocity when the actual speed is in the maximum speed or a predetermined high-speed range within the set speed range of the electric vehicle 1, and a low-speed target angular velocity map (a) that specifies the target vehicle angular velocity when the actual speed is in the low-speed range or zero speed. Each map has left and right side regions (T1, T2) including the left and right ends within the operation range of the joystick 83, and a central region (n1, n2) including the center, and the left and right side regions are each set to a maximum target angular velocity. (ω1, ω2), the central region indicates a target angular velocity of zero, and the maximum target angular velocity ω2 of the high speed target angular velocity map (b) is greater than the maximum target angular velocity ω1 of the low speed target angular velocity map (a). The control unit 10 selectively applies the high speed target angular velocity map (b) or the low speed target angular velocity map (a) in accordance with the actual speed of the electric vehicle 1. Therefore, by simple control that applies a control map in accordance with the actual speed, it is possible to obtain turning characteristics and steering performance that match the user's operating intention and the traveling speed of the electric vehicle 1.

[0066] In addition, the high speed target angular velocity map (b) and the low speed target angular velocity map (a) have transition regions T3, T4 between the central region n1, n2 and the left and right regions T1, T2, respectively, in which the target angular velocity increases from the central region to the left and right regions. This suppresses sudden turning operations, reduces the burden on the motor, and enables continuous and smooth control, allowing a smooth transition from straight driving to forward turning and turning on the spot.

[0067] In particular, by configuring the central region n2 of the high-speed target angular velocity map to be narrower than the central region n1 of the low-speed target angular velocity map, the sensitivity of steering operation using the joystick 83 is increased when driving forward at high speeds, allowing the vehicle to travel in the desired direction while fine-tuning the course with the joystick 83. Meanwhile, in the low-speed range and when stopped, a sufficient dead zone for operation of the joystick 83 is ensured, which is advantageous in preventing the vehicle from starting to move or erroneous operation due to the user placing their hand on the joystick 83, etc.

[0068] 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 changes can be made based on the technical concept of the present invention.

[0069] For example, in the above embodiment, the electric vehicle 1 is described as having an ambulatory assistance vehicle mode, but the present invention can also be implemented as a small electric vehicle or electric wheelchair that does not have an ambulatory assistance vehicle mode.

[0070] Furthermore, in the above embodiment, an omniwheel is used as the driven wheel 5, but a caster-type free wheel may also be used. [Explanation of symbols]

[0071] 1 Electric vehicles 2. Body 3 Rear handle (operating part for walking aid mode) 4 Drive wheels (rear wheels) 5 Driven wheels (swivel wheels, front wheels) 6 Seat back 7 Sheets 8. Ride mode operation section 9 Battery 10 Control section 20 Tilt Sensor 21 Mobile Base 22 Upper Frame 24 Rear base 25 Front Base 26 Release Tag 28 Vehicle condition detection sensor 30 Grasping 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 sensor 80 Display section 82 Armrest 83 Ride mode operation section 84 Travel permission switch

Claims

1. 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; A swivel wheel is provided spaced apart from the left and right drive wheels in the forward and backward 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 left / right rotation speed sensor for detecting the rotation speeds of the left / right motors; an operation unit having a joystick type operator; a control unit that controls the left and right motors in accordance with an operation of the operator, an angular velocity related to the turning of the vehicle is given in accordance with a rotational speed difference between the left and right drive wheels; the control unit is configured to calculate target rotation speeds of the left and right motors based on a target vehicle speed given by an operation position of the operator and a target vehicle angular velocity given by a left-right component of the operation position of the operator and an actual vehicle speed, and to control the left and right motors so that the actual rotation speeds of the left and right motors follow the target rotation speeds. Small electric vehicle.

2. 2. The small electric vehicle according to claim 1, wherein the control unit includes a memory means for storing a target speed map that defines the relationship between the operation position of the operator and a target vehicle speed, and a target angular velocity map that defines the relationship between the operation position of the operator and a target vehicle angular velocity depending on an actual speed, and is configured to calculate the target rotational speeds of the left and right drive wheels using the target speed map and the target angular velocity map depending on the actual speed.

3. the target speed map has a front region including a front end within an operation range of the operator, a rear region including a rear end, left and right regions including left and right ends, and a central region including a center, 3. The small electric vehicle according to claim 2, wherein the front region instructs a first target forward speed, the rear region instructs a target reverse speed, the left and right side regions instruct a second target forward speed, and the central region instructs a stop, and the first target forward speed is greater than the second target forward speed, and the second target forward speed has an absolute value greater than or equal to the target reverse speed.

4. 4. The small electric vehicle according to claim 3, wherein the target speed map has transition regions between the central region and the front region, between the central region and the rear region, and between the central region and the left and right side regions, in which the target speed increases from the central region toward each of the regions.

5. the target angular velocity map includes a high-speed target angular velocity map that specifies a target vehicle angular velocity when the actual speed is in a maximum speed or a predetermined high-speed range within a set speed range of the vehicle, and a low-speed target angular velocity map that specifies a target vehicle angular velocity when the actual speed is in a low-speed range or is zero; the high-speed target angular velocity map and the low-speed target angular velocity map each have left and right regions including left and right ends within an operation range of the operator and a central region including a center, the left and right regions indicate a maximum target angular velocity, and the central region indicates a target angular velocity of zero, respectively, and the maximum target angular velocity of the high-speed target angular velocity map is greater than the maximum target angular velocity of the low-speed target angular velocity map; The small electric vehicle according to any one of claims 2 to 4, wherein the control unit is configured to selectively apply the high speed target angular velocity map or the low speed target angular velocity map depending on an actual speed of the vehicle.

6. 6. The small electric vehicle according to claim 5, wherein the control unit is configured to, when the actual speed is in a speed range intermediate between the high speed range and the low speed range or zero speed, apply a target angular velocity map for intermediate speed, or calculate a target angular velocity corresponding to the actual speed from the target angular velocity map for high speed and the target angular velocity map for low speed.

7. 7. The small electric vehicle according to claim 5, wherein the high speed target angular velocity map and the low speed target angular velocity map each have a transition region between the central region and the left and right regions, in which the target angular velocity increases from the central region toward the left and right regions.

8. 8. The small electric vehicle according to claim 5, wherein the central region of the high speed target angular velocity map is narrower than the central region of the low speed target angular velocity map.

9. 4. The small electric vehicle according to claim 3, wherein the operating unit is provided with a limiter plate that defines a movable range of the operator, the limiter plate including a front moderation portion corresponding to the front region of the target speed map, a rear moderation portion corresponding to the rear region, left and right side moderation portions corresponding to the left and right side regions, and left and right oblique front moderation portions and left and right oblique rear moderation portions therebetween, the front moderation portion and the rear moderation portion having an arc-like or curved shape having a radius of curvature larger than the radius of curvature of the peripheral surface of the operator.

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