Electric bicycle self-balancing device and control system thereof

Abstract

The invention discloses an electric bicycle self-balancing device and a method thereof. A momentum wheel system is installed at the middle bottom of the electric bicycle and comprises a momentum wheel, a driving motor, a sensor assembly and a control unit. The sensor monitors real-time information such as the inclination angle and the angular speed of the bicycle in real time and transmits data to the control unit. The control unit accurately controls operation of the driving motor according to an algorithm preset in advance and received data, and therefore the rotating speed and the rotating direction of the momentum wheel are adjusted. When the bicycle tends to incline, the momentum wheel generates corresponding angular momentum change by utilizing the theorem of conservation of angular momentum, so that the tilting moment is counteracted, and the self-balance of the bicycle under static, low-speed running and even complex road conditions is effectively realized. According to the self-balancing electric bicycle, self-balancing of the two-wheeled electric bicycle is achieved, a foundation is laid for further achieving unmanned driving, and innovative breakthrough and development are brought to the technical field of bicycles.

Description

Technical Field

[0001] The present invention relates to balance technology and automatic control technology, and particularly to a balance control method for an electric bicycle. Background Art

[0002] To solve the balance problem of bicycles, there are many deficiencies in some existing technical solutions. For example, in a balance control system based on a gyroscope, although it can sense the change of the body posture and perform a certain degree of balance adjustment, the gyroscope has a drift error, which will cause the measurement accuracy to decrease after long-term use, affecting the balance control effect. Moreover, such systems usually have a complex structure and high cost, which is not conducive to large-scale popularization and application.

[0003] Due to the large self-weight of the electric bicycle, the mass or volume of the used momentum wheel is large, resulting in large power consumption, large noise, large battery occupancy space, large size, and large weight, which affect the endurance of the electric bicycle, as well as safety hazards caused by the large mass during rapid cornering. Lack of feasibility and safety has led to the failure of electric bicycles on the market to be popularized. The present invention implements different self-balancing controls for the difficulty of self-balancing at different vehicle speeds, increases the stability and safety of the electric bicycle balance, and at the same time has the characteristics of being light and small, increasing the endurance of the electric bicycle. Summary of the Invention

[0004] The present invention discloses a self-balancing control method for an electric bicycle, enabling the electric bicycle to achieve self-balancing both when stationary and at low speeds, and to stabilize the body and reduce power consumption at high speeds.

[0005] To achieve the above functions, the present invention adopts the following technical solutions:

[0006] The present invention provides a self-balancing device, including an attitude sensor assembly, a momentum wheel assembly, an encoder speed measurement assembly, a drive assembly, a brake assembly, and a steering assembly.

[0007] The wheel speed is obtained through the encoder to reflect the actual vehicle speed of the body.

[0008] When the vehicle is in a stationary or low-speed state, the angular momentum of the body tilt is calculated using the attitude sensor and fed back to the momentum wheel control system to control the rotation of the momentum wheel, so that the electric bicycle reaches balance.

[0009] When the vehicle is in a medium or high-speed driving state, the angular momentum of the body tilt is still calculated through the attitude sensor and reflected to the control unit. Due to the fast speed measurement, a front-wheel steering balance system is introduced. When the front wheel steers, a centrifugal force compensation is provided to the body. The control system drives the momentum wheel based on the rotational speed measured by the encoder and the angular momentum obtained by the attitude sensor to achieve self-balancing.

[0010] When the vehicle is stationary or traveling at a low speed, the system activates the first balance mode. In this mode, the vehicle relies solely on the momentum wheel to achieve self-balancing. When the vehicle enters the medium and high-speed driving stage, the system switches to the second balance mode. At this time, in addition to continuously utilizing the balancing effect of the momentum wheel, the vehicle also incorporates the operation of rotating the front wheel to provide a centrifugal compensation force, thereby achieving a more stable and reliable self-balancing state. Through these two balance modes and their intelligent switching system, the present invention successfully achieves a significant reduction in vehicle power consumption, greatly increases the cruising range, optimizes the battery configuration, reserves sufficient space for enriching other functions of the vehicle, and fundamentally improves the safety of the vehicle during medium and high-speed driving. Brief Description of the Drawings

[0011] The drawings are used to provide a further understanding of the present invention and form a part of the specification. They are used together with the embodiments of the present invention to explain the invention patent of the present invention and do not constitute a limitation to the present invention.

[0012] Figure 1 It is the operation process of the control system for the electric bicycle of the present invention to perform balance regulation using a momentum wheel during driving.

[0013] Figure 2 It is the selection and judgment of the speed regulation system for the electric bicycle of the present invention during driving.

[0014] Figure 3 It is a schematic structural diagram of the self-balancing device and its control system of the electric bicycle of the present invention. Figure 4 It is the cooperation relationship of each component of a self-balancing device and its control system of an electric bicycle of the present invention. Specific Embodiment Method

[0015] The following further details the specific embodiments of the present invention in conjunction with the drawings. In the description, the terms "first" and "second" are only used for descriptive purposes and do not indicate or imply relative importance. Among them, the term "connection" is interpreted in a broad sense, including physical connection, mechanical connection, circuit connection, and communication connection.

[0016] In the actual use of the electric bicycle, we divide it into two driving states according to the vehicle speed: stationary or low-speed driving and medium and high-speed driving. Figure 2 It is the general schematic diagram of the control system of the invention. The self-balancing device and its control system of the electric bicycle of the present invention include a main control system, a drive system, a speed measurement system, a steering system, a momentum wheel system, and a power supply system. The functions of each system and the connection between the systems will be described below.

[0017] The power battery 5 of the electric bicycle supplies power to the whole vehicle. The drive system drives the mid-mounted motor 4 to work. When the mid-mounted motor 4 rotates, let the torque of the motor be Tm , the total transmission ratio i of the transmission system is, and the transmission efficiency is η. A driving force is generated, During the forward movement of the electric bicycle, it is subject to the rolling friction force of the road surface and the air resistance, and the resultant force is F = F d -F τ -F a . Thus, the dynamic equation is established:

[0018] In the formula, F τ is the rolling friction force, F τ = μmgcosθ, where μ is the rolling friction coefficient, F a is the air resistance, where ρ is the air density, C d is the air resistance coefficient, A is the frontal area of the electric bicycle, and through the rack and pinion transmission, the rear wheel 6 rotates to drive the vehicle forward.

[0018] When the inclination angle and the angular velocity of the inclination angle of the electric bicycle are zero, it is in a stable state. At this time, sin(x) = x and cos(x) = 1. The specific state space equation is:

[0019] During the driving process of the vehicle, the speed measurement system works. By installing an encoder on the rear wheel shaft and using the frequency measurement method, within a fixed timing time (usually in seconds), a fixed time interval T is set 0 ., within the time T 0 , the number of pulses M emitted by the encoder is counted 0 . Knowing that the total number of pulses per revolution of the encoder is C, the rotational speed can be calculated through the formula The rotational speed n is input to the main control system. According to the current driving speed of the vehicle and the vehicle speed set by the potentiometer, a magnitude comparison is made to determine the self-balancing control method.

[0020] If the vehicle is driving at a low speed, the encoder feeds back the slower rotational speed of the rear wheel to the main control system. Through the judgment of the main control system, when the vehicle is stationary or driving at a low speed, the momentum wheel system is started, and the motor drives the momentum wheel 3 to rotate, enabling the vehicle to achieve self-balancing. At the same time, the attitude sensor module in the main control system continuously obtains the attitude simulation data of the electric bicycle. The obtained attitude simulation data is converted into digital data through the calculation of the single-chip microcomputer and fed back to the momentum wheel control system to further rotate the momentum wheel, accelerating or decelerating the rotational speed of the momentum wheel 3, realizing closed-loop control, and thus achieving the purpose of self-balancing of the vehicle when it is stationary or driving at a low speed.

[0021] If the vehicle is traveling at a relatively high speed, the encoder feeds back a relatively high rotational speed to the main control system. When it is determined by the main control system that the vehicle is in a medium-high speed driving state, the momentum wheel system and the steering system are activated, and the motor still drives the momentum wheel 3 to rotate to balance the vehicle body.

[0022] According to the principle of moment balance: f*h = F n tan(θ), and F n = G. Combining the above formula, we can get: f = Gtan(θ), where γ represents the turning angle of the electric bicycle, w is the distance between the front and rear wheels of the bicycle, P is the center of the turning circle of the bicycle, and R is the radius of the turning circle.

[0023] Then the centrifugal force required for the electric bicycle to turn at this time is: where v q is the running speed of the front wheel of the bicycle.

[0024] At this time, the centripetal force when the electric bicycle turns is equal to the maximum static friction force of the ground on the electric bicycle. The relationship between the inclination angle θ of the electric bicycle and the turning radius R is:

[0025] The relationship between the inclination angle θ of the electric bicycle, the forward speed v q and the turning angle γ is as follows:

[0026] In summary, the centrifugal force compensation formula can be obtained as:

[0027] At the same time, the rotation system works, causing the stepper motor 1 located on the front side of the vehicle body to rotate. Through the rack connection, the rotation lever of the front wheel 2 is controlled, so that the front wheel makes a slight rotation, providing a centrifugal compensation force to assist in balancing the vehicle body. At the same time, the attitude sensor module in the main control system real-time obtains the attitude simulation data of the electric bicycle. The obtained attitude simulation data is calculated and converted into digital data by the single-chip microcomputer, and fed back to the momentum wheel system and the steering system to increase or decrease the rotational speed of the momentum wheel 3 and increase or decrease the turning amplitude of the front wheel 2, realizing closed-loop control, so as to achieve the purpose of self-balancing of the vehicle when driving at medium-high speed.

Claims

1. A balance control method for an electric bicycle, the electric bicycle comprising a handlebar steering control motor for controlling the steering of the bicycle, a device for realizing self-balancing of the electric bicycle, an inclination sensor for measuring the inclination angle of the electric bicycle, a precession angle sensor for measuring the precession angle of a gyroscope, a gyro speed sensor, a steering angle sensor, a momentum wheel and an encoder for measuring the speed of the electric bicycle; It is characterized in that The balance control of electric bicycle is as follows: Construct the dynamic model and state space equations of electric bicycles; The speed of the electric bicycle obtained by the encoder, if the speed is static or low speed, only self-balancing is achieved; if the speed is medium or high speed, the handlebar steering adjustment is added to achieve self-balancing; Calculate centrifugal force compensation when the bicycle is turning; After calculating the centrifugal force compensation, the momentum wheel and the bicycle inclination angle are controlled simultaneously to achieve self-balancing control.

2. The self-balancing device according to claim 1, characterized in that: The steering motor is connected to the bicycle head through a reducer to control the speed and angle of rotation of the bicycle head. The main controller and the encoder of the steering motor detect the speed and position of the steering motor.

3. The self-balancing device according to claim 1, characterized in that: The balancing plan can be adjusted according to the motion state of the electric bicycle. Dividing the motion state into static, low speed and medium and high speed can better cover the driving state in daily life. By optimizing the momentum wheel balance under static or low speed conditions, unnecessary energy consumption can be reduced. In the medium and high speed state, adding handlebar balance can make the self-balancing of the electric bicycle more perfect.

4. The self-balancing device according to claim 1, characterized in that: The steering motor is connected to the front of the bicycle through a reducer to control the speed and angle of rotation of the front of the bicycle. The main controller and the encoder of the steering motor detect the speed and position of the steering motor. When the bicycle is running, the main controller first obtains the bicycle's speed through the encoder, and then the internal sensor module detects the bicycle's tilt angle and tilt angular velocity. If it is stationary or low speed, only the momentum wheel is used to achieve balance. If it is medium or high speed, the rotation of the bicycle head is controlled according to this tilt angle. At the same time, the momentum wheel also plays an auxiliary role, allowing the bicycle body to continuously return to a balanced state and maintain it. The tilt angle on the bicycle is restored to the angle value of the bicycle's balanced state through closed-loop control, but the bicycle head cannot move left and right or rotate infinitely. Therefore, during the rotation of the bicycle head, the rotation angle must be controlled and limited; when the bicycle needs to stop, the controller gradually reduces the bicycle speed. When the bicycle speed decreases to the set speed lower limit, the main controller controls the electric screw through the relay to start powering on. The main controller sends a brake signal to the brake line of the motor controller, and the bicycle stops: closed-loop control is divided into position closed-loop and angle closed-loop. Position closed-loop control is performed according to the measured position and target position of the bicycle head, and the target angle is output. According to the target angle and. The main controller detects the measured angle and performs angle closed-loop control to control the steering motor to rotate the front of the vehicle for balance control.

Images