Small electric vehicle

Abstract

To provide a small electric vehicle capable of providing travel characteristics according to the skill level of a user.SOLUTION: A small electric vehicle (1) includes: left and right motors (40L and 40R) connected to left and right driving wheels (4L and 4R) so that power can be transmitted thereto individually; left and right rotation speed sensors (43); a joystick-type operation element (83); and a control section (10). The control section calculates the target rotation speeds of the left and right motors on the basis of a target vehicle speed and a target vehicle angular speed that are provided according to the operation position of the operation element, and controls the left and right motors so that the actual rotation speeds of the left and right motors are allowed to follow the target rotation speeds. In addition, the control section updates at least one target value according to a cumulative frequency (β) obtained by dividing, by a prescribed control unit, the cumulative value of integrated power consumption obtained by a battery management section.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 electric wheelchairs and handcart-type electric walking aids, 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 is configured to move forward when the operation lever is tilted forward, turn when tilted diagonally forward, rotate in a fixed position when tilted diagonally backward, and stop when tilted straight backward. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-64620 A Summary of the Invention [Problem to be solved by the invention]

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

[0005] The present invention has been made in consideration of the above-mentioned shortcomings of the prior art, and has an object to provide a small electric vehicle that can provide operability and driving characteristics that correspond to the user's level of skill. [Means for solving the problem]

[0006] In order to solve the above problems, the inventors conducted intensive research and discovered that there is a certain degree of correlation between the usage time of a small electric vehicle and the level of proficiency, and that the usage time is correlated with the accumulated power consumption of the battery (number of times it has been fully charged). Therefore, by reflecting the accumulated power consumption in the control, it is possible to achieve operability and driving characteristics that correspond to the level of proficiency, and thus arrived at the present invention.

[0007] That is, the small electric vehicle according to the present invention is 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 battery for supplying power to the left and right motors; a battery management unit that manages charging and discharging of the battery; 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 amount of operation of the operator; the control unit is configured to calculate target rotation speeds of the left and right motors based on a target vehicle speed and a target vehicle angular velocity given by an operation position of the operator, and to control the left and right motors so that actual rotation speeds of the left and right motors follow the target rotation speeds; and The battery management unit is configured to update at least one target value among the target vehicle speed, the target vehicle angular velocity, the target vehicle acceleration given in accordance with the target vehicle speed and the actual vehicle speed, and the target vehicle angular acceleration given in accordance with the target vehicle angular velocity and the actual vehicle speed, depending on a cumulative frequency obtained by dividing the cumulative value of the integrated power consumption amount acquired by the battery management unit by a predetermined control unit. Effect of the Invention

[0008] As described above, the small electric vehicle according to the present invention is configured to gradually update target values ​​that determine the vehicle's driving and turning characteristics, such as the target vehicle speed, target vehicle angular velocity, target vehicle acceleration, and target vehicle angular acceleration, in accordance with the cumulative frequency obtained by dividing the cumulative value of the integrated power consumption by a predetermined control unit, thereby providing operability and driving characteristics that correspond to the user's level of proficiency. (i) At the beginning of use, by setting partial target values ​​relative to the rated values, mild driving characteristics can be obtained, and even users with low levels of proficiency can easily operate the vehicle. (ii) By updating the target value for each control unit (for example, the amount of power consumption equivalent to one or several full charges), it is possible to improve the driving characteristics without discomfort according to the user's level of proficiency. (iii) Ultimately, by reaching the target value equivalent to the rated value, the vehicle's performance will be fully utilized and the demands of sophisticated users will be satisfied. [Brief description of the drawings]

[0009] [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 according to the embodiment. [Figure 4] This is a map of initial / final target vehicle speeds according to cumulative frequency. [Diagram 5] 1A shows a target angular velocity map for initial / final low speeds according to the cumulative frequency, and FIG. 1B shows a target angular velocity map for initial / final high speeds according to the cumulative frequency. [Figure 6] This is a map of initial / final target vehicle acceleration according to cumulative frequency and actual speed. [Figure 7] 13 is a map of initial / final target vehicle angular acceleration according to cumulative frequency and actual speed. [Figure 8] This is a map of initial / final target vehicle deceleration according to cumulative frequency and actual speed. [Figure 9] This is a map of initial / final target vehicle angle deceleration according to cumulative degree and actual speed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] 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.

[0011] 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.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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 function, and is preferably a contactless joystick that uses a hall sensor. 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, that is, when the user's hand is removed from the joystick 83, the joystick automatically returns to the neutral position (operation origin). The control of the left and right motor units 40 (40L, 40R) by operating the joystick 83 will be described later.

[0017] 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).

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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 operating (amount of operation, direction of operation) the joystick 83 that constitutes the riding mode operation unit 8, so that driving operations including moving the electric vehicle 1 forward, backward, turning, and braking and stopping can be performed.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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 low remaining battery capacity, 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 portion of the rear handle 3, but can be operated regardless of grip detection by the grip sensor 30.

[0031] The inclination sensor 20 is mounted on a circuit board of the control unit 10 mounted inside the moving base 21 (rear base 24) of the vehicle body 2, and may be a two-axis inclination sensor or acceleration sensor that detects the longitudinal inclination (pitch angle P) and lateral inclination (roll angle R) of the vehicle body 2, or a multi-axis inertial sensor that integrates the above with an angular acceleration sensor (gyro sensor). When the inclination sensor 20 detects an inclination equal to or greater than a predetermined threshold, the control unit 10 is preferably configured to correct the target vehicle speed and target vehicle angular velocity so as to at least partially offset the gravity (load) acting in accordance with the inclination.

[0032] The battery 9 is a secondary battery such as a lithium ion battery mounted inside the mobile base 21, and may be configured as a detachable battery pack so that it can be easily charged from a commercial power source, etc. The battery 9 is equipped with a BMS 90 (battery management unit) for monitoring the input / output current, total voltage, remaining capacity, etc., and for managing the battery status.

[0033] The BMS90 has a function of acquiring the remaining capacity (SOC) based on the integrated value of the input / output current (integrated power consumption), and the remaining capacity acquired by the BMS90 is stored in the control unit 10 and displayed on the display unit 80. The control unit 10 is configured to prompt the user to charge the battery on the display unit 80 when the remaining capacity acquired from the BMS90 falls below a predetermined threshold.

[0034] (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 control target values ​​(target rotational speeds, etc.) of the left and right motors 41 (40L, 40R) are not immediately determined from the operation position of the joystick 83. Rather, the control target values ​​are updated according to the accumulated driving time (accumulated frequency β) in the riding mode by the user, thereby changing the driving characteristics and cornering characteristics.

[0035] The control unit 10 has an update management unit 19 that calculates a cumulative value Ps of the integrated power consumption amount acquired from the BMS 90 during driving in the riding mode, and divides this cumulative value Ps by a predetermined control unit Pu to obtain an accumulated frequency β. In the BMS 90, the remaining capacity and the integrated power consumption amount of the battery 9 are reset when charging is completed, but the calculation of the cumulative value Ps in the update management unit 19 continues, and the cumulative value Ps and the cumulative frequency β are held in memory.

[0036] The control unit Pu is a unit for specifying the timing (interval) for executing update control of the control map described later. For example, if the integrated power consumption amount equivalent to one full charge of the battery (charging equivalent to the rated capacity) is taken as the control unit, the cumulative frequency β corresponds to the number of full charges since the start of use in the riding mode. This cumulative frequency β roughly corresponds to the cumulative travel distance of the electric vehicle 1 in the riding mode, and corresponds to the cumulative travel time of the electric vehicle 1 in the riding mode by the user. Therefore, although there are differences depending on individual differences and usage conditions, it roughly corresponds to the user's proficiency in traveling the electric vehicle 1 in the riding mode.

[0037] The control unit 10 has a control map for specifying the control target values ​​(e.g., target rotation speeds) of the left and right motors 41 (40L, 40R) based on the operation position of the joystick 83 by the user in the riding mode (1). In order to execute update control of the control target values, i) An initial target map (x0) corresponding to the control target value at the start of use (β=0); ii) A final target map (xm) corresponding to the control target value at the end of the update control (β=βm) It is equipped with:

[0038] Based on the initial value (X0) and final value (Xm) specified in the above map, the control target value at the cumulative frequency β is calculated by proportionally allocating the cumulative frequency β to the final frequency βm using a conversion formula such as the following Equation 1. (Formula 1) X=X0+β*(Xm-X0) / βm

[0039] The above-described update control based on the cumulative frequency β continues from the start of use (β=0) until the cumulative frequency β reaches the final frequency βm, and after the final frequency βm is reached, a control target value is immediately specified according to the final target map (xm).

[0040] This final target map (xm) is a rated target map (xm) that specifies target values ​​equivalent to the ratings of the electric vehicle 1, and is assumed to be set to obtain driving characteristics and turning characteristics that enable the electric vehicle 1 to fully exhibit its performance when operated by an experienced user. In contrast, the initial target map (x0) specifies target values ​​that are suppressed compared to the rated equivalent so that even users with low skill levels can easily operate the vehicle, and is set to obtain mild driving characteristics (acceleration / deceleration characteristics) and turning characteristics.

[0041] The control target values ​​for implementing the update control based on the cumulative frequency β as described above are assumed to be the target vehicle speed v, the target vehicle angular speed ω, the target vehicle acceleration a and the target vehicle deceleration d given in accordance with the target vehicle speed and the actual vehicle speed, and the target vehicle angular acceleration α and the target vehicle angular deceleration δ given in accordance with the target vehicle angular speed and the actual vehicle speed. First, the update control of the basic target vehicle speed v and the target vehicle angular speed ω will be described.

[0042] (Update control of target vehicle speed and target vehicle angular speed) FIG. 3 is a block diagram showing left and right motor control including update control based on the cumulative frequency β. As shown in the figure, the target vehicle speed calculation block 110 reflects not only the forward / backward input of the joystick 83 but also the left and right input and the cumulative frequency β, and the target vehicle angular velocity calculation block 120 reflects not only the left and right input of the joystick 83 and the cumulative frequency β, but also the actual vehicle speed at the time of operation. As a result, as described below, a speed control different from that during straight driving can be executed when turning, and the turning characteristics can be changed by update control based on the cumulative frequency β.

[0043] 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.

[0044] 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.

[0045] In addition, when the inclination sensor 20 detects a vehicle body inclination 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.

[0046] (Target vehicle speed map) FIG. 4 shows a target vehicle speed map for calculating the target vehicle speed by joystick operation (110). The solid lines in the longitudinal operation amount and the lateral operation amount in the figure show the initial target vehicle speed map v(x0) at the start of use (β=0), and the dashed lines show the final target vehicle speed map v(xm) at the end of the update control (β=final frequency βm).

[0047] These target vehicle speed maps are stored as look-up tables in the ROM area of ​​the control unit 10, and the target vehicle speed according to the cumulative frequency β is calculated using the above-mentioned equation 1. After the cumulative frequency β reaches the final frequency βm, the final target vehicle speed map v(xm) is applied.

[0048] 4, in the initial target vehicle speed map v(x0), 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 / right region F2 including the left / right ends, a target forward speed vc is specified, and when it is in a central region n including the center (neutral position), a stop (target speed zero) is specified.

[0049] 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, in the initial target vehicle speed map v(x0), the target forward speed va can be set to 3 to 5 km / h, the target forward speed vc to 1 to 2 km / h, and the target reverse speed vb to 1 km / h.

[0050] 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.

[0051] 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.

[0052] This means that when a user first begins using the device and has a low level of proficiency, operating the joystick 83 to the left or right will transition to forward turning, providing a steering feel similar to that of a car or bicycle steered with a handlebar, and by not immediately transitioning to the on-the-spot turning (spin turn) that is unique to wheelchairs, stable maneuverability that prioritizes forward travel is achieved.

[0053] In addition, in the omni-wheel 5, lateral movement is achieved by the rotation of the rollers 50, and since starting performance and step running performance are reduced compared to straight-ahead driving, there is an advantage in that the load on the system can be reduced by not immediately transitioning to turning on the spot. However, when the joystick 83 is operated diagonally backward FB, the target speed becomes zero halfway between the left and right side areas F2 and the rear area B1, and turning on the spot (spin turn) is also possible in narrow places such as indoors or elevator halls.

[0054] 4, the target forward speed vam when the operation position of the joystick 83 is in the forward region F1 is set to a larger value than when the cumulative frequency β = 0. In other words, the target forward speed va when the cumulative frequency β = 0 is set to a smaller value than the final target forward speed vam.

[0055] For example, when the joystick 83 is operated in the forward region F1, the final target forward speed vam = 5 to 6 km / h, whereas the initial target forward speed va = 4 to 5 km / h; and when the joystick 83 is operated in the backward region B1, the final target reverse speed vbm = 2 km / h, whereas the initial target forward speed vb = 1 km / h.

[0056] On the other hand, in the final target vehicle speed map v(xm), the target forward speed is zero when in the left or right region F2. That is, for an experienced user, stable steering can be maintained even when shifting from forward driving by operating the joystick 83 forward to forward turning by slight operation to the side, so that the advantage of the electric vehicle 1 can be maximized by allowing the vehicle to immediately shift to turning on the spot (spin turn) when the joystick 83 is operated to the left or right side.

[0057] (Target vehicle angular velocity map) Next, FIG. 5 shows a target vehicle angular velocity map for calculating the target vehicle angular velocity (120) by joystick operation. The target vehicle angular velocity map includes a low speed target vehicle angular velocity map (a) that specifies the target vehicle angular velocity when the actual speed is in the low speed range or zero speed, and a high speed target vehicle 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.

[0058] These target vehicle angular velocity maps (a) and (b) also respectively include an initial target vehicle angular velocity map ω(x0) at the start of use (β=0) indicated by a solid line, and a final target vehicle angular velocity map ω(xm) at the end of update control (β=final frequency βm) indicated by a dashed line, and both are stored as look-up tables in the ROM area of ​​control unit 10, and the target vehicle angular velocity ω corresponding to the accumulated frequency β is calculated by the above-mentioned equation 1, and after the accumulated frequency β reaches the final frequency βm, the final target vehicle angular velocity map ω(xm) is applied.

[0059] 5, the target vehicle angular velocity map (a) for initial low speed at the start of use (β=0) is designated as a target vehicle angular velocity ω1 when the operation position of the joystick 83 is in a left or right region T1 including the left or right ends of the operation range, and is designated as a target vehicle angular velocity of zero 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 vehicle angular velocity ω gradually increases from the central region n to the left or right region T1.

[0060] Similarly, in the initial high speed target vehicle angular velocity map (b) at the start of use (β=0), when the operation position of the joystick 83 is in the left and right side regions T2 including the left and right ends within the operation range, the target vehicle angular velocity ω2 is specified, and when it is in the central region n2 including the center (neutral position), the target vehicle angular velocity zero is specified. Between the central region n2 and the left and right side regions T2, there is provided a transition region T4 where the target vehicle angular velocity ω gradually increases from the central region n2 to the left and right side regions T2.

[0061] Here, the maximum target vehicle angular velocity ω2 in the left and right regions T2 of the high speed target vehicle angular velocity map (b) is greater than the maximum target vehicle angular velocity ω1 in the left and right regions T1 of the low speed target vehicle angular velocity map (a), and the central region n2 of the high speed target vehicle angular velocity map (b) is narrower than the central region n1 of the low speed target vehicle angular velocity map (a), and the transition region T4 of the high speed target vehicle angular velocity map (b) is wider than the transition region T3 of the low speed target vehicle angular velocity map (a).

[0062] In a preferred embodiment, the low speed target vehicle 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 vehicle angular velocity map (b) corresponds to a case where the actual vehicle speed is 4.5 km / h or more, and the initial maximum target vehicle angular velocity ω1 in the left and right regions T1 of the low speed target vehicle angular velocity map (a) at the start of use (β=0) is 60 degrees per second (1.05 rad / s), and the initial maximum target vehicle angular velocity ω2 in the left and right regions T2 of the high speed target vehicle angular velocity map (b) at the start of use (β=0) is 90 degrees per second (1.57 rad / s) to 120 degrees per second (2.09 rad / s).

[0063] 5, when the operation position of the joystick 83 is in the left or right region T1, the final target vehicle angular velocity ω1m of the low speed target vehicle angular velocity map (a) and the final target vehicle angular velocity ω2m of the high speed target vehicle angular velocity map (b) are both specified to be greater than the values ​​at the start of use (β=0). For example, the target vehicle angular velocity ω1m at the end of the update control (β=final degree βm) is specified to be 90 degrees per second (1.57 rad / s), and the target vehicle angular velocity ω2m is specified to be 150 degrees per second (2.62 rad / s), and in addition, the central regions n1, n2 where the target vehicle angular velocity is specified to be zero are reduced.

[0064] 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 vehicle angular velocity map for low speed (a) or the target vehicle angular velocity map for high speed (b) depending on the actual vehicle speed and the cumulative frequency β, or, if the actual speed is in a speed range between the low speed range and the high speed range, calculates the target vehicle angular velocity corresponding to the actual speed and the cumulative frequency β from the target vehicle angular velocity map for low speed (a) and the target vehicle angular velocity map for high speed (b).

[0065] For example, by setting two speed thresholds, a first and a second, and switching to the high-speed target vehicle angular velocity map (b) when the actual speed rises from the low-speed range to equal or exceed the second speed threshold (e.g., 2.5 km / h) while the low-speed target vehicle angular velocity map (a) is being applied, and switching to the low-speed target vehicle 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 vehicle angular velocity map (b) is being applied, the frequency of map switching can be reduced, enabling stable control.

[0066] In addition, when calculating a target vehicle angular velocity corresponding to the actual speed from the target vehicle angular velocity map for low speed (a) and the target vehicle angular velocity map for high speed (b), a target vehicle angular velocity may be specified such that the target vehicle angular velocity specified values ​​of the target vehicle angular velocity map for low speed (a) and the target vehicle angular velocity map for high speed (b) are proportionally distributed according to the ratio of the current actual speed to the actual speed corresponding to the target vehicle angular velocity map for high speed (b).

[0067] The above-mentioned target vehicle angular velocity map for low speed (a) and target vehicle angular velocity map for high speed (b) are applied in accordance with the actual speed, and the target vehicle angular velocity map ω(x0) at the start of use (β=0) is gradually updated to the target vehicle angular velocity map ω(xm) at the end of the update control (β=final frequency βm) in accordance with the cumulative frequency β, thereby obtaining the following turning characteristics.

[0068] In other words, when a user has a low level of proficiency immediately after starting use, and the electric vehicle 1 is substantially stopped (actual speed is in the low speed range or zero speed), 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 even if the user operates the joystick 83 left or right within this range, the electric vehicle 1 will not start moving, and an immediate transition from a stopped state to a turning operation is avoided, and forward turning will only begin when the user operates the joystick 83 to the left or right region T1 with a clear intention.

[0069] In addition, 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 travel forward, a transition region T4 is set near both the left and right sides of the neutral position, and the user can travel in the desired direction while fine-tuning the course by operating the joystick 83 left or right from the forward tilted position. Furthermore, as described above, the target forward speed vc (FIG. 4) is specified even when the joystick 83 is operated to the left or right, so that even users with low proficiency can obtain steering performance appropriate to the straight-line speed of the electric vehicle 1.

[0070] On the other hand, as the cumulative frequency β increases, the central regions n1 and n2 where the target vehicle angular velocity is set to zero are reduced, which allows fine adjustment of the course with a small operation of the joystick 83, and also allows a quick transition from a stopped state or from forward or reverse to turning on the spot (spin turn), improving the turning by operating the joystick 83 to the left or right and the operational sensitivity of the turning on the spot, and allowing a transition to characteristic turning characteristics of a wheelchair. Moreover, there is an advantage in that such a change in turning characteristics is made gradually according to the cumulative frequency β, without giving a sense of discomfort to the user.

[0071] (Update control of target vehicle acceleration / deceleration and target vehicle angular acceleration / angular deceleration) Next, the update control of the target vehicle acceleration a, the target vehicle deceleration d, the target vehicle angular acceleration α, and the target vehicle angular deceleration δ based on the cumulative frequency β will be described.

[0072] 3, the target vehicle speed v, the actual vehicle speed, and the cumulative frequency β calculated in the target vehicle speed calculation block 110 according to the cumulative frequency β are input to both a target vehicle acceleration calculation block 111 and a target vehicle deceleration calculation block 112. At this time, if the deviation between the actual vehicle speed and the target vehicle speed v is positive, the target vehicle acceleration a is calculated in the target vehicle acceleration calculation block 111 according to the cumulative frequency β, and if the deviation between the actual vehicle speed and the target vehicle speed v is negative, the target vehicle deceleration d is calculated in the target vehicle deceleration calculation block 112 according to the cumulative frequency β.

[0073] The target vehicle acceleration a and the target vehicle deceleration d are the speed change rates in the control for making the actual vehicle speed follow the target vehicle speed v given by the front / rear / right / left inputs of the joystick 83 and the cumulative frequency β, and correspond to the sensitivity of the speed control.

[0074] On the other hand, the target vehicle angular velocity ω and the accumulated frequency β calculated in the target vehicle angular velocity calculation block 120 according to the accumulated frequency β are input to both a target vehicle angular acceleration calculation block 121 and a target vehicle angular deceleration calculation block 122. At this time, if the deviation between the target rotational speed difference of the left and right motors 41 (40L, 40R) corresponding to the target vehicle angular velocity ω and the actual rotational speed difference of the left and right motors 41 (40L, 40R) detected by the rotational speed sensor 43 is positive, the target vehicle angular acceleration calculation block 121 calculates the target vehicle angular acceleration α according to the accumulated frequency β, and if the deviation between the target rotational speed difference of the left and right motors 41 (40L, 40R) corresponding to the target vehicle angular velocity ω and the actual rotational speed difference of the left and right motors 41 (40L, 40R) detected by the rotational speed sensor 43 is negative, the target vehicle angular deceleration calculation block 122 calculates the target vehicle angular deceleration δ according to the accumulated frequency β.

[0075] These target vehicle angular acceleration α and target vehicle angular deceleration δ are angular velocity change rates in control for making the actual rotational speed difference follow the target rotational speed difference of the left and right motors 41 (40L, 40R) corresponding to the target vehicle angular velocity ω given by the left and right inputs of the joystick 83, the actual vehicle speed, and the cumulative frequency β, and correspond to the sensitivity of the turning control.

[0076] Therefore, in addition to the target vehicle speed v calculated in the target vehicle speed calculation block 110 and the target vehicle angular velocity ω calculated in the target vehicle angular velocity calculation block 120, the left and right motor target rotational speed calculation block 130 receives the target vehicle acceleration a or target vehicle deceleration d corresponding to the cumulative frequency β, and the target vehicle angular acceleration α or target vehicle angular deceleration δ corresponding to the cumulative frequency β, and calculates the target rotational speeds of the left and right motors 41 (40L, 40R) based on the target rotational speed of the left and right motors 41 (40L, 40R) corresponding to the target vehicle speed v, and the target rotational speed difference of the left and right motors 41 (40L, 40R) corresponding to the target vehicle angular velocity ω, the target vehicle acceleration a or target vehicle deceleration d, and the target vehicle angular acceleration α or target vehicle angular deceleration δ.

[0077] In this way, the target rotational speeds of the left and right motors 41 (40L, 40R) are calculated not only from the target vehicle speed v and target vehicle angular speed ω corresponding to the cumulative frequency β, but also reflecting the target vehicle acceleration a or target vehicle deceleration d, target vehicle angular acceleration α or target vehicle angular deceleration δ given according to the cumulative frequency β, and in the left and right motor required torque calculation block 150, the left and right motor required torques are calculated based on the deviation between the actual rotational speeds 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 performed.

[0078] As a result, in the update control of the target vehicle speed v and the target vehicle angular speed ω according to the cumulative frequency β, the sensitivity, i.e., the response speed, of the speed control and the turning control is further adjusted.

[0079] (Target vehicle acceleration map) FIG. 6 shows a target vehicle acceleration map that specifies the relationship between the actual vehicle speed v and the target vehicle acceleration a for the target vehicle acceleration calculation (111). In the figure, the solid line shows the initial target vehicle acceleration map a(x0) at the start of use (β=0), and the dashed line shows the final target vehicle acceleration map a(xm) at the end of the update control (β=final frequency βm).

[0080] These target vehicle acceleration maps are also stored as look-up tables in the ROM area of ​​the control unit 10, and the target vehicle acceleration a corresponding to the cumulative frequency β is calculated using the above-mentioned formula 1. After the cumulative frequency β reaches the final frequency βm, the final target vehicle acceleration map a(xm) is applied.

[0081] In the target vehicle acceleration map shown in FIG. 6, the maximum target vehicle acceleration a2, am is basically specified when the actual vehicle speed v is zero. However, the initial target vehicle acceleration a2 (for example, 2 km / h / s=0.56 m / s) at the start of use (β=0) is also specified. 2 ), the final target vehicle acceleration am (for example, 4 km / h / s = 1.11 m / s) at the end of the update control (β = final frequency βm) 2 ) is specified as a large value, and in either case, as the actual vehicle speed v increases, the target vehicle acceleration decreases. In the high speed range in the forward and reverse directions, the lower limit a1 (for example, 1 km / h / s = 0.28 m / s 2 ) becomes.

[0082] In other words, when the speed is zero or in the low speed range, the target vehicle speed v can be quickly reached, while when the vehicle is already traveling at a high speed range, sudden changes in speed are suppressed to ensure traveling stability.The basic characteristics are the same, but in the initial target vehicle acceleration map a(x0) at the start of use (β=0), the target vehicle acceleration is suppressed to approximately 50-60% compared to the final target vehicle acceleration map a(xm).

[0083] With this configuration, the sensitivity of the speed control is suppressed for users with low proficiency, enabling stable operation, while the sensitivity of the speed control is increased according to the update frequency β, allowing experienced users to fully utilize the acceleration performance of the electric vehicle 1.

[0084] (Target vehicle angular acceleration map) FIG. 7 shows a target vehicle angular acceleration map that defines the relationship between the angular velocity ω and the target vehicle angular acceleration α for the target vehicle angular acceleration calculation (121). In the figure, the solid line shows the initial target vehicle angular acceleration map α(x0) at the start of use (β=0), and the dashed line shows the final target vehicle angular acceleration map α(xm) at the end of the update control (β=final frequency βm).

[0085] In the target vehicle angular acceleration map shown in FIG. 7, the initial target vehicle angular acceleration α1 (for example, 120 degrees / s 2 =2.09rad / s 2 ) is the final target vehicle angular acceleration αm (for example, 150 degrees / s) at the end of the update control (β = final degree βm). 2 =2.62rad / s 2 ) is suppressed to a value (80%) smaller than the

[0086] With this configuration, the sensitivity of the turning control is suppressed for less skilled users, thereby preventing sharp turns and enabling stable turning, while the sensitivity of the turning control is increased according to the update frequency β, allowing more skilled users to fully utilize the turning performance of the electric vehicle 1.

[0087] (Target vehicle deceleration map) FIG. 8 shows a target vehicle deceleration map that defines the relationship between the actual vehicle speed v and the target vehicle deceleration d for the target vehicle deceleration calculation (112). In the figure, the solid line shows the initial target vehicle deceleration map d(x0) at the start of use (β=0), and the dashed line shows the final target vehicle deceleration map d(xm) at the end of the update control (β=final frequency βm).

[0088] These target vehicle deceleration maps are also stored as look-up tables in the ROM area of ​​the control unit 10, and the target vehicle deceleration d corresponding to the cumulative frequency β is calculated using the above-mentioned equation 1. After the cumulative frequency β reaches the final frequency βm, the final target vehicle deceleration map d(xm) is applied.

[0089] In the target vehicle deceleration map shown in FIG. 8, when the actual vehicle speed v in the forward direction is in the high speed range (e.g., 4 km / h or more), the maximum target vehicle deceleration da, dm in the forward direction is specified. However, the initial target vehicle deceleration da (e.g., 5 km / h / s=1.39 m / s) at the start of use (β=0) is 2 ) is the final target vehicle deceleration dm (for example, 6km / h / s = 1.67m / s) at the end of the update control (β = final frequency βm). 2 ) is smaller than that.

[0090] With this configuration, the sensitivity of the deceleration control is suppressed for users with low proficiency, enabling stable operation, while the sensitivity of the deceleration control is increased according to the update frequency β, allowing experienced users to fully utilize the deceleration performance of the electric vehicle 1.

[0091] On the other hand, when the actual vehicle speed v in the reverse direction is in the high speed range (e.g., -1 km / h), the maximum target vehicle deceleration db (e.g., 7 km / h / s = 1.94 m / s) during reverse travel is set at the start of use (β = 0). 2 ) is specified. This is because the absolute value of the traveling speed is kept low in the reverse direction, so even if a large value is specified as the target vehicle deceleration, the vehicle does not suddenly decelerate, and priority is given to a reliable stop.

[0092] In addition, when moving forward or backward, as the actual vehicle speed v decreases, the target vehicle deceleration d decreases. In the zero speed or low speed range, the lower limit value d1 (for example, 1 km / h / s = 0.28 m / s 2 ) becomes.

[0093] (Target vehicle angle deceleration map) FIG. 9 shows a target vehicle angular deceleration map that defines the relationship between the angular velocity ω and the target vehicle angular deceleration δ for the target vehicle angular deceleration calculation (122). In the figure, the solid line shows the initial target vehicle angular deceleration map δ(x0) at the start of use (β=0), and the dashed line shows the final target vehicle angular deceleration map δ(xm) at the end of the update control (β=final frequency βm).

[0094] In the target vehicle angular deceleration map shown in FIG. 9, the initial target vehicle angular deceleration δ1 (for example, 480 degrees / s 2 =8.38rad / s 2 ) is the final target vehicle angular deceleration δm (for example, 360 degrees / s) at the end of the update control (β = final degree βm). 2 =6.28rad / s 2 )Yo A value larger than the specified value is specified.

[0095] As a result, for users with low skill levels, priority is given to reliable stopping of turns, while for experienced users, priority is given to ride comfort, reducing the reaction when stopping a turn by lowering the angular deceleration according to the update frequency β, enabling smooth stopping of turns. In addition, such a setting, in the target speed control described above, the target forward speed vc is specified even when the operation position of the joystick 83 is in the left or right side area F2 at the start of use (β=0), and coupled with the feature of not immediately transitioning to turning on the spot, this is also related to the fact that a sudden stop of turns does not occur even if a large value is specified for the target vehicle angular deceleration.

[0096] As described above in detail, the electric vehicle 1 of the present invention is configured to gradually update control target values ​​that determine the driving and turning characteristics of the electric vehicle 1, such as the target vehicle speed v, the target vehicle angular velocity ω, the target vehicle acceleration a, the target vehicle angular acceleration α, the target vehicle deceleration d, and the target vehicle angular deceleration δ, in accordance with the cumulative frequency β (=Ps / Pu) obtained by dividing the cumulative value Ps of the integrated power consumption by a predetermined control unit Pu, thereby providing operability and driving characteristics that correspond to the user's level of proficiency.

[0097] In the above embodiment, update control of the target vehicle speed v, the target vehicle angular speed ω, the target vehicle acceleration a, the target vehicle angular acceleration α, the target vehicle deceleration d, and the target vehicle angular deceleration δ according to the update frequency β has been described. However, instead of performing update control of all of these, it is also possible to execute update control of only one of the control target values.

[0098] For example, by only performing update control of the target vehicle speed v and the target vehicle angular velocity ω, whose control target values ​​are determined based on the operating position of the joystick 83, the operation sensitivity of the joystick 83, the driving characteristics, and the turning characteristics can be gradually changed; conversely, by only performing update control of the target vehicle acceleration a, the target vehicle angular acceleration α, the target vehicle deceleration d, or the target vehicle angular deceleration δ, the sensitivity of the acceleration / deceleration and turning control can be gradually changed (increased / relaxed), thereby responding to the user's level of proficiency.

[0099] In addition, in the above embodiment, a case is described in which a common update control period (tutorial period, final frequency βm) is applied to all control target values, but by applying a different final frequency βm depending on the control target value, it is also possible to vary the end time of the update control depending on the control target value.

[0100] In addition, the display unit 80 may be configured to display the consumption rate (β / βm) of the cumulative number of points β relative to the final number of points βm as the progress (%) of the tutorial period, and a selective setting change means (such as a switch) may be provided that allows the user to speed up / slow down / end the progress of the tutorial period.

[0101] Furthermore, the update control as described above may be executed as a tutorial period for the user to become familiar with the operation, or may be executed as a break-in period for the electric vehicle 1 itself.

[0102] 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.

[0103] 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.

[0104] 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]

[0105] 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 19 Update Management Department 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 90 BMS (Battery Management Unit)

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 battery for supplying power to the left and right motors; a battery management unit that manages charging and discharging of the battery; 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 amount of operation of the operator; the control unit is configured to calculate target rotation speeds of the left and right motors based on a target vehicle speed and a target vehicle angular velocity given by an operation position of the operator, and to control the left and right motors so that actual rotation speeds of the left and right motors follow the target rotation speeds; and A small electric vehicle configured to update at least one target value among the target vehicle speed, the target vehicle angular velocity, the target vehicle acceleration given in response to the target vehicle speed and an actual vehicle speed, and the target vehicle angular acceleration given in response to the target vehicle angular velocity and the actual vehicle speed, in accordance with a cumulative frequency obtained by dividing a cumulative value of the integrated power consumption acquired by the battery management unit by a predetermined control unit.

2. 2. The small electric vehicle according to claim 1, wherein the update of the at least one target value according to the cumulative frequency includes an increase in at least one of a target maximum vehicle speed given by a maximum forward operation position of the operator, or a target maximum vehicle angular velocity given by a maximum lateral operation position of the operator.

3. the control unit includes a target vehicle speed map that defines a relationship between an operation position of the operator and the target vehicle speed, or a target vehicle angular velocity map that defines a relationship between an operation position of the operator and the target vehicle angular velocity, the target vehicle speed map or the target vehicle angular velocity map is configured to specify zero as a target value in a central region including an operation origin of the operation element, 2. The small electric vehicle according to claim 1, wherein the update of the at least one target value according to the cumulative frequency is provided by updating the target vehicle speed map or the target vehicle angular speed map, and includes a reduction of the central region.

4. The control unit includes a target vehicle speed map that defines a relationship between an operation position of the operation member and the target vehicle speed, and the target vehicle speed map includes: a target angular velocity of zero is specified in a central region including the operation origin of the operation element, a first target forward speed is specified in a forward region including the front end of the operation position, a target backward speed is specified in a rear region including the rear end of the operation position, and a second target forward speed is specified in left and right side regions including the left and right side ends of the operation position, 2. The small electric vehicle according to claim 1, wherein the updating of the at least one target value according to the accumulated frequency is provided by updating the target vehicle speed map, and is configured such that the first target forward speed and the target reverse speed increase and the second target forward speed decrease, and that the second target forward speed becomes zero when the accumulated frequency has a predetermined final value.

5. 2. The small electric vehicle according to claim 1, wherein the control unit includes a target vehicle acceleration map that defines a relationship between an actual vehicle speed and the target vehicle acceleration, the target vehicle acceleration map is configured to specify a maximum target acceleration when the actual vehicle speed is zero and to asymptotically approach a minimum target acceleration as the actual vehicle speed increases, and the update of the at least one target value according to the cumulative frequency includes an increase in the maximum target acceleration.

6. 6. The small electric vehicle according to claim 5, wherein the control unit is provided with a target vehicle deceleration map that defines the relationship between the actual speed of the vehicle and the target vehicle deceleration, separate from the target vehicle acceleration map, the target vehicle deceleration map is configured to specify a maximum target vehicle deceleration when the actual speed of the vehicle is at a maximum, and to asymptotically approach a minimum target vehicle deceleration as the actual speed of the vehicle decreases, and the update of the at least one target value according to the cumulative frequency includes an increase in a maximum target vehicle deceleration when moving forward and a decrease in a maximum target vehicle deceleration when moving backward.

7. The small electric vehicle according to claim 1 , wherein the updating of the at least one target value according to the cumulative frequency includes an increase in the target vehicle angular acceleration or a decrease in the target vehicle angular deceleration.

8. A small electric vehicle as claimed in any one of claims 1 to 7, wherein the updating of the at least one target value according to the cumulative frequency is continued until the cumulative frequency reaches a preset final frequency, and after the final frequency is reached, the at least one target value is maintained at a final target value at the final frequency.

9. 9. The small electric vehicle according to claim 8, wherein the update of the at least one target value according to the cumulative frequency is configured to be calculated by proportionally allocating the initial value and the final value, which are specified based on a map that specifies an initial value of the target value and a map that specifies a final value of the target value, in a ratio of the cumulative frequency to the final frequency.

10. The small electric vehicle according to any one of claims 1 to 9, further comprising a means for setting or changing the control unit.

Images