JP2022074183A - Electric assist kick skater and torque control program - Google Patents

Abstract

To provide an electric assist type kick skater that is able to obtain an assist force corresponding to a kick force of a rider.SOLUTION: An electric assist kick skater 101 according to the present disclosure includes: an electric motor 3 that drives a wheel 7; a weight sensor that detects a load weight w of a vehicle body 1; and a torque control device 21 that controls torque of the electric motor 3. Based on torque τ of the electric motor 3, a rotation angle θ of the electric motor 3, and the detected load weight w, the torque control device 21 calculates a forward force F applied to the vehicle body kicked by a rider 90 and controls the torque τ of the electric motor 3 so as to apply a forward assist force corresponding to the calculated forward force F to the vehicle body 1.SELECTED DRAWING: Figure 2

Description

The present invention relates to an electrically assisted kick scooter and a control program thereof.

A kick scooter is a type of vehicle powered by the passenger's own human power, which moves forward by placing one foot on the tread and kicking the road surface with the other foot. Normally, a steering wheel is provided, and it is possible to arbitrarily change the direction of travel by grasping the steering wheel with both hands. Similarly, one of the differences from a bicycle powered by human power is that there is no pedal that receives the pedaling force that is the power source.

Regarding bicycles, electrically power assisted bicycles that assist human power with electric motors have been widely accepted in the market since their launch in 1993, as their comfort and safety have been recognized as a new means of transportation that combines human power and electric power. There is. In an electrically assisted bicycle, the pedaling force applied to the pedal is detected by the pedaling force sensor, and the assisting force corresponding to the pedaling force is generated by the electric motor (for example, Patent Document 1).

As a kick scooter, a type of electric kick scooter in which a propulsive force is obtained by an electric motor is known (for example, Patent Document 2). However, since the electric driving force is not added as an assisting force according to human power, there is a shortage in terms of comfort and safety, and for this reason, the electric kick scooter is not widely used at present. ..

Japanese Unexamined Patent Publication No. 2014-198505 Jitsuto 3081197

In view of this situation, the inventor of the present application considers that if an electrically assisted kick scooter that assists human power with an electric motor is realized as in the case of an electrically assisted bicycle, the safety of the user will be as high as that of the electrically assisted bicycle. I came to think that it would improve further. In order to realize an electrically assisted kick scooter, it is necessary to detect the pedaling force of the occupant's kick, which is the basis for calculating the assist force. The pedaling force of this kick gives a force in the forward direction to the vehicle body as a reaction. However, the pedaling force of the kick by the passenger acts directly on the road surface and is not applied to the pedal as in the case of a bicycle. Therefore, it is assumed that the kick scooter has a problem that it is not easy to detect the pedaling force, unlike the electrically assisted bicycle that detects the pedaling force applied to the pedal by the pedaling force sensor.

While conducting research on this problem, the inventor of the present application has found that the pedaling force of a occupant can be indirectly detected from the torque of an electric motor that assists electric power. The present invention has been made based on the discovery of the inventor of the present application, and an object of the present invention is to provide an electrically assisted kick scooter capable of obtaining an assist force according to a occupant's kicking force, and a control program thereof. And.

In order to achieve the above object, the first aspect of the present invention is an electric assist kick scooter, which is an electric motor for driving wheels, a weight sensor for detecting the load weight of the vehicle body, and the electric motor. It is equipped with a torque control device that controls the torque of the motor. The torque control device calculates and calculates a forward force applied to the vehicle body by a occupant's kick based on the torque of the electric motor, the rotation angle of the electric motor, and the detected load weight. The torque of the electric motor is controlled so as to apply the assist force in the forward direction corresponding to the applied force in the forward direction to the vehicle body.

According to this configuration, an electrically assisted kick scooter that can obtain an assist force according to the kicking force of the occupant is realized.

The second aspect of the present invention is the electric assist kick scooter according to the first aspect, and the torque control device includes a motor torque calculation unit, an acceleration calculation unit, a human-powered torque calculation unit, and a motor. It is equipped with a drive unit and a retreat force calculation unit. The motor torque calculation unit calculates the torque output by the electric motor from the energizing current of the electric motor. The acceleration calculation unit calculates the acceleration in the forward direction of the vehicle body from the rotation angle of the electric motor. When the electric motor does not output the torque, the human-powered torque calculation unit determines that the occupant has kicked if the acceleration satisfies the predetermined first criterion, and is applied to the vehicle body by the kick. The human-powered torque obtained by converting the force in the forward direction into the torque of the electric motor is calculated. After it is determined that the kick has occurred, the motor drive unit determines that the kick by the occupant has disappeared when the acceleration satisfies the predetermined second criterion, and responds to the calculated human power torque. The electric motor is driven so as to output the torque for a predetermined time. The retreat force calculation unit calculates the retreat force, which is the force in the retreat direction applied to the vehicle body, after it is determined that the kick by the passenger has disappeared and before it is determined that there has been a new kick. do. The human-power torque calculation unit calculates the force in the forward direction based on the detected load weight, the calculated acceleration, and the calculated retreat force. The retreat force calculation unit calculates the retreat force based on the detected load weight, the calculated acceleration, and the calculated motor torque.

According to this configuration, the backward force applied to the vehicle body when there is a kick is calculated by calculating the backward force when there is no kick by the passenger. This makes it possible to calculate two unknowns in the equation of motion: the retreating force such as the frictional force acting on the vehicle body and the force in the forward direction due to kicking. The "retracting force" includes a frictional force from the road surface applied to the vehicle body, an air frictional force applied to the vehicle body and passengers, and a backward force applied to the vehicle body due to the slope of the road surface.

The third aspect of the present invention is the electric assist kick scooter according to the second aspect, in which the motor drive unit sets a constant multiple of the calculated human-powered torque as the maximum torque, and the predetermined value. The electric motor is driven so as to output a torque having a magnitude within the maximum torque over time.

According to this configuration, the assist force can be set so as not to exceed an appropriate assist magnification in consideration of safety and the like.

The fourth aspect of the present invention is the electric assist kick skater according to the third aspect, and the torque control device calculates the speed in the forward direction of the vehicle body from the rotation angle of the electric motor. Further having a speed calculation unit, the motor drive unit sets a value depending on the speed as the constant.

According to this configuration, even when the vehicle body speed is high, the assist force can be set so as not to exceed an appropriate assist magnification in consideration of safety and the like.

The fifth aspect of the present invention is the electric assist kick scooter according to the third or fourth aspect, in which the motor drive unit outputs the maximum torque at the beginning of the predetermined time and thereafter. , The electric motor is driven so as to output a decaying torque.

According to this configuration, a natural assist force that does not give the passenger a sense of discomfort is added to the vehicle body.

The sixth aspect of the present invention is an electric assist kick scooter according to any one of the second to fifth aspects, and the electric motor is a brushless DC motor. Further, the motor torque calculation unit includes a q conversion unit that converts the energization current of the electric motor into a current of the q component, and a torque conversion unit that converts the converted current of the q component into the torque of the electric motor. Has.
According to this configuration, the torque of the electric motor can be easily calculated.

The seventh aspect of the present invention is the electric assist kick skater according to the sixth aspect, in which the motor drive unit calculates the current of the q component from the torque corresponding to the human power torque. The calculation unit and the energization current conversion unit that converts the converted current of the q component into the energization current of the electric motor, so that the converted energization current is energized to the electric motor. Drives an electric motor.
According to this configuration, the torque output by the electric motor can be easily controlled.

The eighth aspect of the present invention is an electrically assisted kick scooter according to any one of the second to seventh aspects, wherein the first reference is that the acceleration exceeds a positive reference value. be.
According to this configuration, it is easy to determine whether or not there was a kick by the passenger.

The ninth aspect of the present invention is an electrically assisted kick scooter according to any one of the second to eighth aspects, and the second criterion is that the acceleration changes from positive to negative. ..
According to this configuration, it is easy to determine whether or not the kick by the passenger has disappeared.

The tenth aspect of the present invention is a torque control program, which is a program that causes a computer to function as the torque control device included in the electrically assisted kick scooter according to any one of the first to ninth aspects.

According to this configuration, the computer can function as a torque control device provided in the electric assist kick scooter according to each aspect of the present invention.

As described above, according to the present invention, an electrically assisted kick scooter capable of obtaining an assist force according to the kicking force of a occupant and a control program thereof are realized.

It is a perspective view which illustrates the appearance of the electric assist kick scooter by one Embodiment of this invention. It is explanatory drawing which illustrates the force acting on the electric assist kick scooter of FIG. It is a block diagram which illustrates the structure of the electric assist kick scooter of FIG. It is a flowchart illustrating the operation procedure of the torque control device of FIG. It is a waveform diagram which illustrates the time change of the variable calculated in each part of the torque control device of FIG.

FIG. 1 is a perspective view illustrating the appearance of an electrically assisted kick scooter according to an embodiment of the present invention. Further, FIG. 2 is an explanatory diagram illustrating the force acting on the electric assist kick scooter of FIG. The electric assist kick skater 101 (hereinafter, abbreviated as "kicks skater 101" as appropriate) has an electric motor 3 that applies an assist force to the vehicle body 1, and the reaction of the pedaling force when the occupant 90 kicks the road surface 4. The force F in the forward direction applied to the vehicle body 1 is indirectly detected by using the torque τ of the electric motor 3, and the assist force corresponding to the detected force is obtained. In the illustrated example, the wheels are two wheels, a front wheel 5 and a rear wheel 7, and the shaft of the rotor of the electric motor 3 (not shown) is attached to the axle of the rear wheel 7 (not shown) without using a reduction gear or the like. It is directly connected. Therefore, the torque τ of the electric motor 3 corresponds to the torque of the rear wheels 7. The axle of the rear wheel 7 (not shown) is pivotally supported by the rear portion of the tread 9 which is a part of the vehicle body 1, and the axle is driven by the electric motor 3 also fixed to the tread 9. The vehicle body 1 is used as a term referring to the entire kick scooter 101 including the wheels 5, 7, and the like. Therefore, the weight of the vehicle body 1 means the total weight of the kick scooter 101.

A weight sensor 11 is provided on the upper surface of the tread 9. The weight sensor 11 detects the load weight w applied to the tread 9. The load weight w may include the weight of the passenger 90 riding on the tread 9, the weight of the luggage carried by the passenger 90, and the like. As the weight sensor 11, for example, a load cell using a strain gauge can be used. On the lower surface of the tread plate 9, a power source 17 that supplies power to the electric motor 3 and the like, a torque control device 21 that controls the torque τ of the electric motor 3, and a current that energizes the electric motor 3 under the control of the torque control device 21 are applied. The PWM controller 19 to be adjusted is housed. The bearing 15 of the front wheel 5 is connected to the steering handle 13 pivotally supported by the front portion of the vehicle body 1. As a result, the vehicle body 1 can arbitrarily change the traveling direction by operating the handle 13 of the passenger 90.

FIG. 3 is a block diagram illustrating the configuration of the kick scooter 101. The kick scooter 101 has a power supply 17, a PWM controller 19, and a torque control device 21 in addition to the electric motor 3 and the weight sensor 11. The electric motor 3 is, for example, a three-phase brushless DC motor. The electric motor 3 has a hall sensor 23 that detects the position of the rotation angle of the rotor. The power source 17 is, for example, a rechargeable dry battery (secondary battery), and supplies electric power to each device such as the electric motor 3 and the torque control device 21. The PWM controller 19 adjusts the electric power supplied from the power supply 17 by pulse width modulation according to the control signal output from the torque control device 21, and makes the phase currents i _a , i _b , and i _c into the electric motor 3. It is an inverter circuit that conveys power.

The torque control device 21 is a forward direction given to the vehicle body 1 by the kick of the occupant 90 based on the torque τ of the electric motor 3, the rotation angle θ of the electric motor 3, and the load weight w detected by the weight sensor 11. The torque τ of the electric motor 3 is controlled by calculating the force F of the above and sending a control signal to the PWM controller 19 so as to apply the assist force in the forward direction corresponding to the calculated force F to the vehicle body 1. In the illustrated example, the control device 21 includes a motor rotation angle detection unit 22, a speed calculation unit 24, an acceleration calculation unit 25, a human power torque calculation unit 27, a total mass calculation unit 28, a motor torque calculation unit 29, and a retreat force calculation unit 31. And a motor drive unit 33. The torque control device 21 has a computer (not shown), and these device units 22 to 33 are realized by operating based on a program stored in a memory (not shown) built in the computer.

The motor rotation angle detection unit 22 calculates the rotation angle of the rotor of the electric motor 3, that is, the motor rotation angle θ, based on the signal of the hall sensor 23 provided in the electric motor 3. The speed calculation unit 24 calculates the speed v in the forward direction of the vehicle body 1 from the motor rotation angle θ calculated by the motor rotation angle detection unit 22. The acceleration calculation unit 25 calculates the acceleration dv / dt in the forward direction of the vehicle body 1 from the speed v calculated by the speed calculation unit 24. That is, in the illustrated example, the acceleration calculation unit 25 indirectly calculates the acceleration dv / dt from the rotation angle θ of the electric motor 3.

The motor torque calculation unit 29 calculates the torque τ output by the electric motor 3 from the phase currents i _a , i _b , and i _c of the electric motor 3. The motor torque calculation unit 29 has a phase current detection unit 34, a q conversion unit 35, and a torque conversion unit 36. The phase current detection unit 34 detects the voltage drop of a resistor (referred to as “shunt resistance”; not shown) provided in the path of the phase currents i _a , i _b , and i _c , thereby detecting the phase current i _a . , I _b , i _c are indirectly detected. The q conversion unit 35 converts the phase currents i _a , i _b , and i _c into the current i _q of the q component. The current _iq can be calculated for a three-phase brushless DC motor by performing a dq transformation represented by the mathematical formula (1). Equation (1) depends on the motor rotation angle θ. Therefore, the motor torque calculation unit 29 also refers to the motor rotation angle θ calculated by the motor rotation angle detection unit 22.

The current id of the _d component obtained by the conversion is an invalid current component that does not contribute to the torque τ, and the current i _q of the q component is an active current component that contributes to the torque τ. The q conversion unit 35 calculates the current id of the _d component at the same time as the current i _q of the q component by performing the dq conversion. As will be described later, the current i _q is used to calculate the torque τ, and the current _id is used to calculate the phase currents i _a , i _b , i _c using the equation (1) in reverse. A proportional relationship expressed by the mathematical formula (2) is established between the current i _q and the torque τ.

Here, Pn is the number of poles of the electric motor 3, and φ _a is a constant. The torque conversion unit 36 converts the current i _q converted by the q conversion unit 35 into torque τ.

The retreat force calculation unit 31 calculates a retreat force Rb, which is a force in the retreat direction applied to the vehicle body 1. The kick scooter 101 and the passenger 90 are subjected to a drag force R _res due to air resistance, road surface friction, and the like. Further, when the road surface 4 on which the kick scooter 101 travels is inclined, a backward force having a magnitude of mg · sin (γ) is applied to the vehicle body 1 according to the forward inclination angle γ of the road surface 4. The forward tilt angle γ is defined to be positive on an uphill and negative on a downhill. Therefore, the retreat force Rb is given by the mathematical formula 3.

Here, m is the total mass of the mass of the vehicle body 1 and the mass of the load including the passenger 90, that is, the total mass, and g is the gravitational acceleration. The mass of the vehicle body 1 is known to the manufacturer of the vehicle body. The mass of the load can be obtained by converting the load weight w into mass (that is, as w / g). The total mass m is calculated by the total mass calculation unit 28 based on the load weight w detected by the weight sensor 11.
The equation of motion that describes the motion of the vehicle body 1 is expressed by the mathematical formula (4). In formula (4), r is the radius of the wheel 7.

In the equation of motion expressed by the equation (4), the total mass m, the acceleration dv / dt, and the torque τ are calculated by the above-mentioned means. Further, the wheel radius r is known to the manufacturer of the kick scooter 101.
In the equation (4), the unknown number is two variables, a retreat force Rb such as a frictional force R _res acting on the vehicle body 1, and a force F in the forward direction due to kicking. Therefore, the torque control device 21 calculates the retreat force Rb when there is no kick by the occupant 90, that is, when the force F in the forward direction applied to the vehicle body 1 by the kick is zero, and there is a kick. The force F in the forward direction sometimes applied to the vehicle body 1 is calculated by using the backward force Rb calculated immediately before. This makes it possible to calculate two unknowns in the equation of motion of equation (4). Therefore, the retreat force calculation unit 31 calculates the retreat force Rb by the mathematical formula (5).

Whether or not there was a kick is determined based on the acceleration dv / dt. As an example, when the acceleration dv / dt exceeds a predetermined positive reference value α ₀ , it is determined that there was a kick, and when the acceleration dv / dt becomes negative thereafter, the kick disappears. It is judged. Therefore, the retreat force calculation unit 31 calculates the retreat force Rb by the total mass m calculated by the total mass calculation unit 28, the acceleration dv / dt calculated by the acceleration calculation unit 25, and the motor torque calculation unit 29. Calculated based on the torque τ.

The human-powered torque calculation unit 27 calculates the human-powered torque τ _person , which is obtained by converting the forward force F applied to the vehicle body 1 by the kick of the passenger 90 into the torque of the electric motor 3. The human power torque τ _person is given by the mathematical formula (6).

Therefore, the human power torque τ _person is calculated by the mathematical formula (7) using the retreat force Rb most recently calculated by the retreat force calculation unit 31. Formula (7) is derived from formulas (4) and (6).

The human power torque τ _person is a reference for setting the torque τ of the electric motor 3 that applies the assist force to the vehicle body 1, that is, the magnitude of the assist torque τ. That is, the assist force by the assist torque τ corresponding to the magnitude of the human power torque τ _person is applied to the vehicle body 1. The assist force is applied only for a finite predetermined time, and if the human power torque τ _person based on the new kick is calculated on the assumption that the application of the assist force is completed, the human power torque τ _person is a formula ( Instead of 7), it is calculated according to the formula (8). In this case, the human-powered torque calculation unit 27 uses the human-powered torque τ _person as the total mass m calculated by the total mass calculation unit 28, the acceleration dv / dt calculated by the acceleration calculation unit 25, and the retreat force calculation unit 31. It will be calculated based on the retreat force Rb calculated by.

The motor drive unit 33 drives the electric motor 3 so as to output the assist torque τ according to the human power torque τ _person calculated by the human power torque calculation unit 27 for a predetermined time as an example. As a result, an assist force is added to the vehicle body 1. In the illustrated example, the motor drive unit 33 has an assist torque calculation unit 40, a q component calculation unit 37, and an energization current conversion unit 39. The assist torque calculation unit 40 calculates the assist torque τ based on the human power torque τ _person calculated by the human power torque calculation unit 27. As will be described later, the assist torque calculation unit 40 may also refer to the speed v calculated by the speed calculation unit 24 in order to calculate the torque τ corresponding to the human power torque τ _person . The q component calculation unit 37 calculates the current i _q of the q component from the assist torque τ calculated by the assist torque calculation unit 40. This calculation can be performed according to the formula (2). The energization current conversion unit 39 converts the current i _q into the energization current of the electric motor 3, that is, the phase currents i _a , i _b , and i _c . A mathematical formula (1) can be used for this conversion. Therefore, the energization current conversion unit 39 performs the calculation by also referring to the motor rotation angle θ detected by the motor rotation angle detection unit 22. As the current id of the _d component required for conversion, the current _id most recently calculated by the q conversion unit 35 is used. Unlike the phase currents i _a , i _b , and i _c , the current I _q and the current I _d do not depend on the motor rotation angle θ and are relatively stable. Therefore, the current I _q and the current I _d Even if the calculated time points are slightly different between the two, there is no problem in the calculation accuracy of the phase currents _ia , _ib , and _ic . The motor drive unit 33 drives the electric motor 3 through the PWM controller 19 so that the converted phase currents i _a , i _b , and i _c are energized to the electric motor 3.

FIG. 4 is a flowchart illustrating the operation procedure of the torque control device 21. Hereinafter, the operation flow of the torque control device 21 will be described with reference to FIG. When the passenger 90 operates a start key (not shown) provided on the vehicle body 1, the power supply 17 starts supplying electric power to each device including the torque control device 21, so that the torque control device 21 operates. Once started, initialization is first performed in step S1. In this step S1, all the variables used by the torque control device 21 are initialized. When the initialization is completed, the processes of steps S3 to S17, which are the processes of the main loop, are repeatedly executed. At the same time, interrupts are repeatedly performed, and each time, the processes of steps S21 to S29 are executed as interrupt processes. Interrupts are performed, for example, at regular intervals. The processing of the main loop and the interrupt processing are continued until the passenger 90 operates the start key to cut off the power supply from the power source 17 to the torque control device 21.

In the interrupt process, first, in step S21, the phase current detection unit 34 of the motor torque calculation unit 29 detects the phase currents _ia , _ib , and _ic of the electric motor 3, and the motor rotation angle detection unit 22 electrically detects them. The rotation angle θ of the motor 3 is detected, and the total mass m is calculated by the total mass calculation unit 28. Next, in step S23, the detected phase currents i _a , i _b , and i _c are dq converted by the q conversion unit 35, whereby the current i _q of the q component and the current id of the _d component are obtained. Next, in step S25, the torque conversion unit 36 converts the current i _q into the torque τ. Next, in step S27, the speed v is calculated by the speed calculation unit 24 from the detected rotation angle θ. The velocity v is calculated, for example, based on the difference between the rotation angle θ detected in the previous interrupt processing and the rotation angle θ detected in the current interrupt processing. Next, in step S29, the acceleration dv / dt is calculated by the acceleration calculation unit 25 from the calculated velocity v. The acceleration dv / dt is calculated based on, for example, the difference between the velocity v calculated in the previous interrupt process and the velocity v detected in the current interrupt process.

In order to improve the accuracy of the calculated value, for example, the average value of the values obtained by the interrupt processing a predetermined number of times up to now may be calculated as the velocity v and the acceleration dv / dt. The average value may be a weighted average in which the weight is increased as it is closer to the present. In addition, the order of each step executed in the interrupt processing is arbitrary as long as the processing is possible. For example, steps S23 and 25 may be executed after steps S27 and 29.

In the main loop, first, in step S3, it is determined whether or not the kick by the occupant 90 has occurred depending on whether or not the acceleration dv / dt exceeds a predetermined positive reference value α ₀ . This process is performed by the human-powered torque calculation unit 27. The human-powered torque calculation unit 27 repeats the process of step S3 until the acceleration dv / dt exceeds the reference value α ₀ . When the human power torque calculation unit 27 determines that the acceleration dv / dt exceeds the reference value α ₀ , the human power torque calculation unit 27 calculates the human power torque τ _person in step S5. At this time, since the assist torque τ is not added, the human power torque τ _person is calculated by the mathematical formula (8). In the first step S5 after the main loop is started, the retreat force Rb has not been calculated yet, so the initial value given in step S1, for example, the value of "0" is used as the retreat force Rb. .. Next, the human-powered torque calculation unit 27 determines in step S7 whether or not the kick by the occupant 90 has been completed by determining whether or not the acceleration dv / dt has turned to a negative value. The human-powered torque calculation unit 27 repeats the loops of steps S5 and S7 until it is determined that the acceleration dv / dt has turned negative.

The human power torque calculation unit 27 repeats the loops of steps S5 and S7, and in order to improve the accuracy of the human power torque τ _person , the human power torque τ calculated in the loops of a predetermined number of times (for example, 4 times) up to now. The average value of humans _or the average value of all _human power torques τ calculated by repeating the loop may be calculated. The average value may be a weighted average in which the weight is increased as it is closer to the present. Further, the maximum value of the human power torque τ _person repeatedly calculated in the loops of steps S5 and S7 may be calculated as the human power torque τ _person .

When the human power torque calculation unit 27 determines in step S7 that the acceleration dv / dt has turned negative, the motor drive unit 33 outputs the assist torque τ according to the human power torque τ _person calculated by the human power torque calculation unit 27. As described above, the electric motor 3 is driven. In the illustrated example, first, in step S9, the initial assist torque τ ₀ is set from the human power torque τ _person . This process is executed by the assist torque calculation unit 40 of the motor drive unit 33. The initial assist torque τ ₀ is an initial value of the assist torque τ of the electric motor 3. As will be described later with respect to step S15, the assist torque τ is set so as not to exceed the initial assist torque τ ₀ . Therefore, the initial assist torque τ ₀ is also the maximum value of the assist torque τ. The initial assist torque τ ₀ is set to, for example, a coefficient multiple of the human power torque τ _person . The coefficient may be a constant such as double. Alternatively, the assist torque calculation unit 40 may set a value depending on the speed v as a coefficient by referring to the speed v calculated by the speed calculation unit 24. For example, when the speed v is high, the coefficient may be set to be low. As a result, safety is further enhanced.

Next, the motor drive unit 33 starts assist in step S11. That is, the assist torque calculation unit 40 sets the initial assist torque τ ₀ as the assist torque τ, and the q component current i _q corresponding to the set assist torque τ is calculated and calculated by the q component calculation unit 37. The generated current _iq is converted into phase currents i _a , i _b , and i _c by the energization current conversion unit 39. For this conversion, the current id of the _d component calculated in step S23 of the latest interrupt processing is used together with the current I _q calculated by the q component calculation unit 37. Since the interrupt processing is performed constantly and repeatedly, the calculated time difference between the current I _q and the current I _d is small. Therefore, there is no problem in the calculation accuracy of the phase currents i _a , i _b , and i _c . The motor drive unit 33 sends a control signal to the PWM controller 19 so that the converted phase currents i _a , i _b , and i _c are energized in the electric motor 3. As a result, the electric motor 3 outputs the set assist torque τ.

Next, in step S12, the retreat force Rb is calculated by the retreat force calculation unit 31, and the calculated retreat force Rb is stored in a memory (not shown) in the torque control device 21. Since the kick by the occupant 90 has been completed, in step S12, the force F in the forward direction applied to the vehicle body 1 by the kick is zero. The retreat force Rb is calculated by (5).

Next, in step S13, it is determined whether or not a predetermined time has elapsed since the assist was started. This process is performed by the assist torque calculation unit 40 of the motor drive unit 33 as an example. When the assist torque calculation unit 40 determines that the predetermined time has not elapsed, in step S15, the assist torque τ is set by reducing or maintaining the assist torque τ. The q component calculation unit 37 and the energization current conversion unit 39 calculate the phase currents i _a , i _b , and i _c corresponding to the newly set assist torque τ. The motor drive unit 33 sends a control signal to the PWM controller 19 so that the converted phase currents i _a , i _b , and i _c are energized in the electric motor 3. As a result, the electric motor 3 outputs the newly set assist torque τ.

After that, the process returns to step S12, and the retreat force Rb is calculated again by the retreat force calculation unit 31. In this way, the retreat force Rb is calculated and the assist torque τ output by the electric motor 3 is updated until a predetermined time elapses. For example, the assist torque τ may be set to continue to decrease from the initial assist torque τ ₀ until a certain time before the predetermined time elapses, and then to maintain a constant value until the predetermined time elapses. Alternatively, the assist torque τ may be set so as to decrease from the initial assist torque τ ₀ , for example, according to an exponential function of time until a predetermined time elapses. Further, in step S9, instead of the initial assist torque τ ₀ , the maximum assist torque is generally set according to the human power torque τ _person , and in steps S11 and S15, the set maximum assist torque is not exceeded. The assist torque τ may be set to. Similar to the initial assist torque τ ₀ , the maximum assist torque can be set to, for example, a coefficient multiple of the human power torque τ _person , and the coefficient can be further dependent on the speed v. For example, when the speed v is high, the coefficient may be set to be low. As a result, safety is further enhanced.

The retreat force calculation unit 31 repeats the loops of steps S12, S13, and S15, and in order to improve the accuracy of the retreat force Rb, the retreat force calculated in a predetermined number of loops (for example, 4 times) up to now. The average value of Rb or the average value of all the retreating forces Rb calculated by repeating the loop may be calculated. The average value may be a weighted average in which the weight is increased as it is closer to the present.

When it is determined in step S13 that the predetermined time has elapsed, the motor drive unit 33 ends the assist in step S17. That is, the assist torque calculation unit 40 sets the assist torque τ to zero, and the phase currents i _a , i _b , corresponding to the assist torque τ set to zero by the q component calculation unit 37 and the energization current conversion unit 39. _ic is calculated. The motor drive unit 33 sends a control signal to the PWM controller 19 so that the converted phase currents i _a , i _b , and i _c are energized in the electric motor 3. As a result, the electric motor 3 stops the output of the assist torque τ.

When step S17 is completed, the process returns to step S3, and the process of the main loop is repeated. In the second and subsequent main loops, the calculation of the human power torque τ _person in step S5 is performed according to the mathematical formula (8) using the retreat force Rb calculated in step S12 of the immediately preceding main loop. Even in the second and subsequent main loops, the assist torque τ is not applied in step S5, so the retreat force Rb can be calculated according to the equation (8). By the above processing exemplified in FIG. 4, an electrically assisted kick scooter 101 capable of obtaining an assist force corresponding to the kicking force of the occupant 90 is realized.

FIG. 5 is a waveform diagram illustrating the time change of variables calculated in each part of the torque control device 21 that operates according to the procedure of FIG. The vertical axis represents acceleration dv / dt, assist torque τ, human power torque τ _person , and velocity v. In the illustrated example, the kick by the passenger 90 occurs at time t1, and the kick ends at time t4. During the period from time t1 to t4 when the kick is performed, the acceleration dv / dt changes as shown in the figure as an example due to the force F in the forward direction applied to the vehicle body 1 by the kick. In the illustrated example, the acceleration dv / dt has the highest value at time t3. At time t4, the acceleration dv / dt turns negative as the kick disappears. As can be understood from the equation (4), if there is no kick, the acceleration dv / dt becomes a negative value due to the retreat force Rb. During the period from time t1 to t4 when the acceleration dv / dt is positive, the velocity v increases according to the rate of increase represented by the acceleration dv / dt, as shown in the figure.

At time t2, when the acceleration dv / dt exceeds a predetermined positive reference value α ₀ , the calculation of the human power torque τ _person is started. The calculation of the human power torque τ _person is repeated until the time t4 when the acceleration dv / dt turns negative. Since the human power torque τ _person is calculated by the mathematical formula (8), it increases or decreases in the same manner as the acceleration dv / dt. That is, the waveform of the human power torque τ _person is a waveform obtained by shifting the waveform of the acceleration dv / dt in the positive direction in the vertical axis direction, as drawn by the dotted line curve in FIG.

In the illustrated example, the assist is started at the time t5 slightly later than the time t4. In the illustrated example, the initial assist torque τ ₀ is set to twice the human power torque τ _person . Further, in the illustrated example, the maximum value of the repeatedly calculated human power torque τ _person is adopted as the human power torque τ _person used as the reference for setting the initial assist torque τ ₀ . The assist torque τ is repeatedly set from the time t5 to the time t7 when a predetermined time elapses, and the electric motor 3 operates so as to generate the set assist torque τ. In the illustrated example, the assist torque τ is set to decrease linearly from the time t5 to the time t6 before the predetermined time elapses, and is a constant low value in the subsequent time period t6 to t7. Is maintained at. As can be understood from the equation (4), the acceleration dv / dt can take a positive value by the assist torque τ even without the force F in the forward direction due to the kick, and increases or decreases in the same manner as the assist torque τ. do. Therefore, during the period from time t5 to t7 when the assist is performed, the waveform of the acceleration dv / dt is a waveform obtained by shifting the waveform of the assist torque τ in the negative direction in the vertical axis direction as represented by the curve shown in the figure. ..

The acceleration dv / dt is negative in a short period of time t4 to t5 from when the force F in the forward direction disappears due to the end of the kick to when the assist is started. Therefore, in this period, the velocity v decreases. When the assist is started at the time t5, the acceleration dv / dt turns positive, and the acceleration dv / dt is positive until the time t7 when the assist ends. Therefore, the speed is the acceleration dv during the period from the time t5 to t7. It increases according to the rate of increase proportional to / dt. After the time t7 when the assist ends, the acceleration dv / dt is negative, so the velocity v decreases.

When a new kick by the passenger 90 occurs after the time t7 when the assist ends, the acceleration dv / dt, the human power torque τ _person , and the assist torque τ will redraw the same waveforms as in the illustrated example. The velocity v is shifted in the vertical axis direction so that the velocity v when a new kick is newly generated is set as the initial value, and the same waveform as in the illustrated example is drawn again.

(Other embodiments)
As the kick scooter 101, an example is shown in which the shaft of the rotor of the electric motor 3 is directly connected to the axle of the rear wheel 7 without using a reduction gear or the like. As a result, the torque τ of the electric motor 3 matched the torque of the rear wheels 7. On the other hand, the shaft of the rotor of the electric motor 3 may be connected to the axle of the rear wheel 7 via a reduction gear, a belt, or the like. Even in this case, if the reduction ratio of the reduction gear or the like is N, the equations (4) to (8) are established as they are by simply replacing the radius r of the rear wheel 7 with r / N. That is, the kick scooter 101 using a reduction gear or the like having a reduction ratio N is equivalent to the kick scooter 101 in which the radius r of the rear wheel 7 is reduced by N times with respect to the operation of the control device 21. Therefore, there is no change in the operation illustrated in FIG.

1 car body, 3 electric motor, 4 road surface, 5 front wheel, 7 rear wheel, 9 tread plate, 11 weight sensor, 13 handle, 15 bearing, 17 power supply, 19 PWM controller, 21 torque control device, 22 motor rotation angle detector, 23 Hall sensor, 24 speed calculation unit, 25 acceleration calculation unit, 27 manpower torque calculation unit, 28 total mass calculation unit, 29 motor torque calculation unit, 31 retreat force calculation unit, 33 motor drive unit, 34 phase current detection unit, 35 q Conversion unit, 36 Torque conversion unit, 37 q component calculation unit, 39 Current current conversion unit, 40 Assist torque calculation unit, 90 Passenger, 101 Electric assist kick skater, F Forward force, g Gravity acceleration, _ia , i _b , i _c phase current, id _d component current, i _q q component current, m total mass, r wheel radius, Rb retreat force, Rres resistance force, v speed, dv / dt acceleration, w load weight, α ₀ Reference value, γ forward tilt angle, θ motor rotation angle, τ torque (assist torque), τ _human- powered torque, τ ₀ initial assist torque.

Claims (10)

An electric motor that drives the wheels and
A weight sensor that detects the load weight of the vehicle body and
A torque control device for controlling the torque of the electric motor is provided.
The torque control device calculates and calculates the forward force applied to the vehicle body by the kick of the occupant based on the torque of the electric motor, the rotation angle of the electric motor, and the detected load weight. An electric assist kick skater that controls the torque of the electric motor so as to apply an assist force in the forward direction corresponding to the applied force in the forward direction to the vehicle body. The torque control device is
A motor torque calculation unit that calculates the torque output by the electric motor from the energizing current of the electric motor, and
An acceleration calculation unit that calculates the acceleration of the vehicle body in the forward direction from the rotation angle of the electric motor,
If the acceleration satisfies the predetermined first criterion when the electric motor does not output the torque, it is determined that the occupant has kicked, and the forward force applied to the vehicle body by the kick. With a human-powered torque calculation unit that calculates the human-powered torque converted into the torque of the electric motor.
When it is determined that the kick has occurred and the acceleration satisfies the predetermined second criterion, it is determined that the kick by the occupant has disappeared, and the torque corresponding to the calculated human power torque is determined. A motor drive unit that drives the electric motor so that it outputs over time,
A retreat force calculation unit that calculates a retreat force, which is a retreat force applied to the vehicle body, after it is determined that the kick by the passenger has disappeared and before it is determined that there has been a new kick. And, with
The human-power torque calculation unit calculates the force in the forward direction based on the detected load weight, the calculated acceleration, and the calculated retreat force.
The electric assist kick scooter according to claim 1, wherein the retreat force calculation unit calculates the retreat force based on the detected load weight, the calculated acceleration, and the calculated motor torque. The motor drive unit sets a constant multiple of the calculated human-powered torque as the maximum torque, and drives the electric motor so as to output a torque having a magnitude within the maximum torque over the predetermined time. The electric assist kick skater according to Item 2. The torque control device further includes a speed calculation unit that calculates the speed of the vehicle body in the forward direction from the rotation angle of the electric motor.
The electric assist kick scooter according to claim 3, wherein the motor drive unit sets a value depending on the speed as the constant. The electric assist kick according to claim 3 or 4, wherein the motor driving unit drives the electric motor so as to output the maximum torque at the beginning of the predetermined time and then output the decaying torque. skater. The electric motor is a brushless DC motor.
The motor torque calculation unit is
The q conversion unit that converts the energizing current of the electric motor into the current of the q component,
The electric assist kick scooter according to any one of claims 2 to 5, further comprising a torque conversion unit that converts the converted current of the q component into the torque of the electric motor. The motor drive unit is
A q component calculation unit that calculates the current of the q component from the torque corresponding to the human power torque,
It has an energization current conversion unit that converts the converted current of the q component into the energization current of the electric motor.
The electric assist kick scooter according to claim 6, which drives the electric motor so that the converted energizing current is applied to the electric motor. The electric assist kick scooter according to any one of claims 2 to 7, wherein the first criterion is that the acceleration exceeds a positive reference value. The electric assist kick scooter according to any one of claims 2 to 8, wherein the second criterion is that the acceleration changes from positive to negative. A torque control program that causes a computer to function as the torque control device included in the electric assist kick scooter according to any one of claims 1 to 9.

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