Servo drive auxiliary chair

Abstract

The invention relates to a servo drive control system of an auxiliary chair specially used for assisting exoskeleton and an electric wheelchair. The rated working voltage of the control system is 48V, the output rated power is 1500W, and the control system can be used for medical rehabilitation auxiliary chairs, household outdoor electric wheelchairs and the like. By adopting an independent research and development technology, the safety performance reaches the European Union fault detection standard. The design sequentially comprises design of an auxiliary chair structure, design of a control system, design of a driving scheme and design of a driving structure from bottom layer design to specific implementation. According to the servo control system, the computer programmable controller is adopted to control system operation, the position sensor, the central processing unit and the motion data acquisition card are used for controlling and analyzing the motion tendency, motion is stable and reliable, the auxiliary chair can recognize the motion intention of a passenger, and then the passenger is helped to drive the auxiliary chair more conveniently. Power control is reliable, the service life of the battery is long, and the specific heat conduction structure ensures good heat dissipation of the whole control system. And the unique braking system function forcibly closes the motor control under the condition that the main current exceeds the range (stalling and abnormal faults), so that the current is prevented from being further increased to damage the circuit, and the safety protection effect is achieved.

Description

Technical Field

[0001] This invention patent relates to a wearable servo drive technology specifically for medical assistive chairs, which can be used in medical rehabilitation assistive chairs and home and outdoor electric wheelchairs. Background Technology

[0002] Servo motor control technology. Servo motors can control speed and position with very high precision, converting voltage signals into torque and speed to drive the controlled object. The rotor speed of a servo motor is controlled by the input signal, converting the received electrical signal into angular displacement or angular velocity output on the motor shaft. Servo drive technology is a modern electrical control technology characterized by high precision and high efficiency. Today, servo drive technology, combined with computer control systems and digital control systems, has formed a more mature and precise drive technology in the field of medical assistive devices. The purpose of this invention is to provide a servo drive technology specifically designed for medical assistive chairs to assist exoskeleton systems. Summary of the Invention

[0003] The system determines the occupant's movement intentions by analyzing the external environment, and then controls the drive system to perform corresponding actions, thereby assisting the occupant in completing the next action. Since hydraulic drives are primarily used in intelligent assistive chairs, especially medical assistive chairs, the control system must be fast and accurate in its response and cycles, ensuring that the actual movement delay after recognizing the occupant's movement intention is less than 0.05 seconds.

[0004] The advantage of this design is that the assistive chair for paralyzed patients can be used freely without the slow response or difficulty in stopping the body's movements due to electromyographic signals. Furthermore, the load is not affected by the control mechanism; for example, if the assistive chair suddenly stops moving forward and switches to backward, the hydraulic cylinder can still bear the load on the chair without tipping over or getting stuck due to power issues. Attached Figure Description

[0005] like Figure 1 Servo drive control system

[0006] like Figure 2 Diagram of an assistive chair for paralyzed patients Detailed Implementation

[0007] 1. Composition of a servo drive system. For example... Figure 1The schematic diagram of the drive control system for the assistive chair shows that the power system consists of a DC motor, a hydraulic pump, and hydraulic valves. The control system comprises a computer, a central processing unit (CPU), a battery, a motion data acquisition card, a servo driver, and position sensors. The sensing system consists of an analog-to-digital converter (ADC) and an IMU sensor. When the hydraulic transmission is working, it drives the assistive chair forward or backward. The position sensor then sends position feedback to the servo driver. After receiving the position feedback, the servo driver transmits the drive signal to the motion data acquisition card. Simultaneously, the computer and CPU download programs and data. The CPU then exchanges control and motion signals with the motion data acquisition card. Meanwhile, the ADC receives and analyzes the motion signals through the IMU sensor, and transmits the motion signals back to the motion data acquisition card. Finally, the motion data acquisition card feeds back the position signal to the power system via signal analog, action command, and CAN bus connections. By changing the direction of valve core movement and the valve opening, the flow direction and velocity of the oil are controlled, thereby causing the controlled object to output parameters such as wheel rotation angle and handle tilt angle. These parameters are then compared with the given values ​​via feedback, and the difference is used as a control signal to gradually reduce system error and improve system control accuracy until the desired effect is achieved. This forms a closed-loop negative feedback control system. A closed-loop transfer function and output function for reducing error are established as follows:

[0008]

[0009]

[0010] According to the mean value theorem in modern control theory, the system input and output converge to a final value.

[0011]

[0012] Therefore, the steady-state error E SC =EY(∞). Given the worst-case utilization G... amax And worst missed ratio G mmax ,At once

[0013] The control parameter K can be directly derived. p This ensures the system's stability and steady-state error meet predetermined requirements, so that the actual movement delay after the assistive chair recognizes the human's movement intention is less than 0.05 seconds.

[0014] 2. Schematic diagram of the assistive chair. (e.g.) Figure 2As shown, the chair components include a base 10, a backrest 11, and a footrest 7. The base 10 is horizontally positioned, the backrest 11 is located above the base 11, and the footrest 7 is located below the other end of the base 11. The corresponding end of the base 10 is fixedly connected to the lower end of the backrest 11. To provide better comfort for the occupant, the backrest 11 can be adjusted from 10 to 30 degrees. Furthermore, two sponge pads are provided above the base 11 to provide better comfort for the occupant. In front of the sponge pads, on the left side above the seat cushion, there is a rocker arm for controlling the movement of the chair, and on the right side, there is a handle.

[0015] 3. Servo Drive System and Assistive Chair Integration. The lower power system of the assistive chair consists of a base bracket 1, a lead screw nut 2, a motor base plate 3, a DC motor 4, a lower frame 5, and a sliding column 8. When the user presses the button on the rocker arm 9 and shakes it, the computer of the drive system receives the drive signal and downloads the program to the central processing unit (CPU). The CPU then transmits control commands to the motion data acquisition card, which in turn transmits position signals to the servo driver. Finally, the servo driver issues motion commands to the drive system, at which point the DC motor, hydraulic pump, hydraulic valves, and other components in the drive system begin to operate. When the assistive chair begins to move forward, the position sensor transmits position feedback to the servo driver in real time. The servo driver then transmits drive signals to the data acquisition card. Simultaneously, the IMU sensor and analog-to-digital converter in the sensing system transmit motion signals to the motion data acquisition card. After the motion data acquisition card receives and processes the drive and motion signals, it integrates the motion signals and transmits them to the CPU. Finally, the CPU downloads the data to the computer for control, forming a closed-loop negative feedback servo control system.

Claims

1. A medical auxiliary chair all-in-one machine control method, characterized in that The control method includes: acquiring a pressure signal and a handbrake on / off signal applied to the handle device of the integrated wheelchair and walker; determining the working mode of the integrated medical assistive chair based on the acquired pressure signal, wherein the working mode includes a walker mode and a wheelchair mode; When the working mode is the walking aid mode, the position sensor can detect the acceleration and angle changes between the wheels and obtain the riding status between the assistive seat and the rider. Based on the obtained acceleration, angle and pressure changes, the operating status of the assistive seat is controlled. The motion status includes running assistance status, driving stability status, downhill resistance status and parking status. When the mode is wheelchair mode, the position and angle change information of the assistive chair joystick are acquired to control the speed of the motor drive and the rotation angle of the front wheels of the assistive chair.

2. The medical auxiliary chair all-in-one machine control method according to claim 1, characterized in that, The operation of the integrated assistive chair is controlled based on the acquired acceleration, angle, and pressure signals, as well as the occupant's state, including: Determine the on / off status of the handbrake on the auxiliary seat. When the handbrake is on, the auxiliary seat should be in braking mode. The system determines whether the pressure applied to the control button on the assistive chair exceeds a threshold. If the pressure exceeds the threshold, the assistive chair operates in motion assistance mode; otherwise, it operates in braking mode. The system determines whether the vehicle's acceleration and angle change rapidly when the assistive chair is in motion. If the acceleration and angle change rapidly, it indicates an uphill climb or an obstacle encounter, and the assistive chair operates in motion assistance mode. When the acceleration is 0, the speed tends to be stable, and the assistive chair operates in smooth driving mode. When the acceleration decreases rapidly, it indicates a downhill climb, and the assistive chair operates in downhill resistance mode.

3. The control method for the integrated auxiliary chair according to claim 2, characterized in that, Controlling the operation of the integrated assistive chair to a motion-assisted state includes: Increase the positive torque of the motor used to drive the assistive chair; Controlling the operation of the integrated auxiliary chair to a downhill resistance state includes: Increase the reverse torque of the motor used to drive the assistive chair, or decrease the forward torque of the motor used to drive the assistive chair, or increase the braking resistance.

4. The medical auxiliary chair all-in-one machine control method according to claim 1, characterized in that By changing the direction of movement of the valve core and the opening of the valve, the flow direction and velocity of the oil are controlled, thereby enabling the controlled object to output parameters such as wheel rotation angle and handle tilt angle. The output is then compared with the given value through feedback, and the difference is used as a control signal to gradually reduce the system error, forming a closed-loop negative feedback control system.

5. The medical auxiliary chair all-in-one machine control method according to claim 4, characterized in that The closed-loop transfer function and output function of the auxiliary chair for reducing system error are as follows: where G amax is the worst utilization ratio, G mmax is the worst miss ratio, K p is the control parameter, M e is the expected miss ratio.

6. The medical auxiliary chair all-in-one machine control method according to claim 4, characterized in that According to the mean value theorem in modern control theory, the control system of the auxiliary chair converges to a final value: So the steady state error E SC = E - Y(∞). If the worst utilization rate G amax and the worst miss rate G mmax are given, the control parameter K p can be directly derived to ensure the stability of the system and the steady state error to meet the predetermined requirements. The actual movement delay of the auxiliary chair after recognizing the human body movement intention is less than 0.05 seconds.

7. The medical auxiliary chair all-in-one machine control method according to claim 1, characterized in that The wheelchair control joystick is a medium-sized handheld joystick, and the integrated medical assistive chair includes a left-wheel drive component and a right-wheel drive component; the rotational speed of the drive wheels of the integrated wheelchair assistive device is controlled based on the position change information of the assistive chair control joystick, including: The position change data of the control lever of the auxiliary chair is obtained in a first direction, which is perpendicular to the travel direction of the wheel-assisted chair; When the position change data in the first direction is zero, the driving speed and acceleration of the wheelchair-assisted walking device are calculated based on the projected straight line of the medium-sized hand joystick. Based on the calculated driving speed and acceleration, the rotation speed and rotation angle of the left wheel drive component and the right wheel drive component are determined.

8. The medical auxiliary chair all-in-one machine control method according to claim 4, characterized in that When the position change data in the first direction is not zero, the turning angular velocity, angular acceleration and turning radius of the auxiliary chair are calculated based on the position coordinates of the end of the projection line of the medium-sized hand joystick. The speed of the motor and the speed of the drive wheel are determined based on the turning angular velocity, angular acceleration and turning radius.

9. A control system for an integrated wheelchair and walking aid, characterized in that... The control system includes: A pressure detection component is installed on the handle of the integrated wheelchair walker to acquire pressure signals applied to the handle of the integrated wheelchair walker. A DC motor, located under the seat, is used to drive the auxiliary chair. The hydraulic pump and hydraulic valves are located inside the drive wheel and are used to detect the drive and drive assistance of the system. The braking component is located on the handlebar device of the auxiliary seat and is used for the on / off signal of the handbrake; A position sensor, installed under the seat, is used to acquire the position information of the auxiliary chair; A motion data acquisition card is installed under the seat to acquire motion data of the assistive chair.

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