CN-121994267-A - Electric wheelchair theoretical travel distance measuring device and method based on fluxgate

CN121994267ACN 121994267 ACN121994267 ACN 121994267ACN-121994267-A

Abstract

The invention discloses a device and a method for measuring the theoretical driving distance of an electric wheelchair based on a fluxgate, wherein the measuring device comprises a power supply module, a sensing measuring module, a signal conversion module and a main control module, the power supply module, the sensing measurement module, the signal conversion module and the main control module are connected through standardized wires to realize signal transmission and power supply isolation. The invention realizes accurate measurement of energy consumption of 24V voltage and maximum 50A current through cooperative work of a sensing measurement module, an isolated power supply design and an MCU main control, suppresses inherent fluctuation of working conditions, low-frequency temperature drift noise, electromagnetic interference high-frequency noise and sampling quantization noise by using dynamic window moving average filtering, calculates theoretical driving distance of the electric wheelchair according to energy consumption data and battery capacity of the electric wheelchair, and provides guarantee for users to select the electric wheelchair and ensure travel safety of the users.

Inventors

ZHANG WEIKANG
GU HUIRU
WU SAINAN
LUAN HUIQIN
LI JIAHAO

Assignees

国家康复辅具研究中心

Dates

Publication Date: 20260508
Application Date: 20260203

Claims (7)

1. The electric wheelchair theoretical driving distance measuring device based on the fluxgate is characterized by comprising a power supply module, a sensing measuring module, a signal conversion module and a main control module, wherein signal transmission and power supply isolation are realized among the power supply module, the sensing measuring module, the signal conversion module and the main control module through wiring; The power supply module comprises a MCU special power supply and a multi-output isolation power supply, and is used for respectively providing independent power supply for the main control module and the sensing measurement module and guaranteeing electrical isolation; The sensing measurement module comprises a fluxgate current sensor and an isolation voltage transmitter, and current and voltage parameters of a wheelchair power supply are respectively acquired; the signal conversion module adopts an ADC module to convert the analog signal output by the sensing module into a digital signal for the main control module to read; The main control module adopts MCU as a core control unit, receives digital signals through I2C bus, and realizes parameter calculation, data storage and output.
2. The electric wheelchair theoretical travel distance measuring device based on a fluxgate according to claim 1, characterized in that: The power supply anode (+5V) of the MCU special power supply is connected with the Pin2 Pin of the MCU, and the power supply cathode (GND) is connected with the Pin6 Pin of the MCU to provide stable power supply for the MCU and the ADC module; The multi-output isolation power supply is an isolation power supply module supporting + -12V and +24V multi-output, the output end of the multi-output isolation power supply is connected with +12V output end and-12V output end, which is connected with a VCC pin of the fluxgate sensor, of the fluxgate sensor VEE pin, and provides dual power supply for the closed loop fluxgate sensor; The +24V output end is connected with the VCC pin of the isolation voltage transducer, and the power supply GND is connected with the GND pin of the isolation voltage transducer to provide working power supply for the voltage transducer.
3. The electric wheelchair theoretical travel distance measuring device based on a fluxgate according to claim 1, characterized in that: The fluxgate current sensor is a closed-loop fluxgate sensor, and a signal output end (Vout) is connected with a current limiting resistor in series and then connected to an AIN0 channel of the ADC module, and is used for outputting 0-5V analog signals in direct proportion to current; the Signal Ground (SGND) is connected to the GND pin of the ADC module, so that the signal ground is commonly grounded; The isolated voltage transmitter is an isolated voltage transmitter with an input range of 0-50V DC and an output range of 0-5V DC, and the positive electrode (IN+), the negative electrode (IN-) of the voltage input end of the isolated voltage transmitter are respectively connected to the positive electrode and the negative electrode of a 24V power supply of the wheelchair IN parallel to realize voltage parallel measurement; the signal output end (OUT) is connected in series with a current limiting resistor and then connected to an AIN1 channel of the ADC module, and the Signal Ground (SGND) is connected to a GND pin of the ADC module and shares a signal reference ground with the fluxgate current sensor.
4. The electric wheelchair theoretical travel distance measuring device based on a fluxgate according to claim 1, characterized in that: The power supply Pin of the ADC module is specifically connected with Pin2 (+ 5V) of the MCU, and GND is connected with Pin6 (GND) of the MCU, and the power supply Pin and the main control module are grounded together; The communication pins of the ADC module are specifically connected with SDA (data Pin) and SCL (clock Pin) which are respectively connected to I2C pins (Pin 3 and Pin 5) corresponding to the MCU, so that digital signal transmission is realized; an address selection pin (ADDR) of the ADC module is connected with GND, an I2C communication address is fixed, and communication stability is ensured.
5. The device for measuring the theoretical driving distance of the electric wheelchair based on the fluxgate according to claim 1, wherein the MCU reads the digital signal of the ADC module through the I2C bus, and the MCU embeds a data processing algorithm, performs parameter conversion based on a calibration coefficient, and calculates the energy consumption of the electric wheelchair, specifically: current conversion, namely calculating an actual current value according to a linear relation of the output corresponding current of the fluxgate sensor; And (3) converting the voltage, and calculating an actual voltage value according to the linear relation of the output of the isolated voltage transmitter and the corresponding voltage input.
6. A method for measuring the theoretical travel distance of an electric wheelchair based on a fluxgate according to any one of claims 1 to 5, comprising the steps of: S1, recording the voltage U (t i ) and the current I (t i ) of the electric wheelchair measured at the current moment t i by using an MCU; s2, filtering through dynamic window moving average filtering to obtain final stable voltage And current ; S3, calculating the instantaneous power after filtering ; S4, calculating accumulated energy consumption Accumulated energy consumption of electric wheelchair Converting the unit into Wh; s5, calculating the unit mileage power consumption value of the electric wheelchair E c is expressed in Wh/km, where D c is 20 times the length of the test distance, and m; s6, calculating the theoretical running distance of the electric wheelchair The unit is km; Wherein E BAT is the 5h discharge rate capacity of the electric wheelchair battery, and the unit is Wh.
7. The method for measuring the theoretical travel distance of the electric wheelchair based on the fluxgate according to claim 6, wherein the specific contents of the dynamic window moving average filtering are as follows: Voltage filtering Current filtering Wherein And The voltage and current original data of N sampling periods are obtained, wherein one sampling period is 10ms; n is the window size; Calculating a rate of change of current using an MCU , When (when) When n=3; When (when) When n=5; When (when) When n=8.

Description

Electric wheelchair theoretical travel distance measuring device and method based on fluxgate Technical Field The invention relates to the technical field of medical instrument detection, in particular to a device and a method for measuring the theoretical driving distance of an electric wheelchair based on a fluxgate. Background The electric wheelchair is used as an important mobility aid for people with mobility impairment, and the accuracy of the nominal endurance mileage of the electric wheelchair relates to the trip safety of a user. The endurance mileage is measured, and the energy consumption of the electric wheelchair and the battery capacity of the electric wheelchair need to be comprehensively considered. Measuring an electric wheelchair is time-consuming, and the energy consumption meter needs to move along with the electric wheelchair, so that high portability is required. Meanwhile, higher measurement accuracy is required to ensure the measurement accuracy. The voltage of the batteries of the wheelchair at home and abroad is mostly 24V, the current during walking is about 20A, and the starting current is up to 50A. Currently, most of the existing energy consumption measuring methods of electric wheelchair are based on the current divider principle. Since it is difficult for a conventional ammeter to measure the direct current 50A, a shunt is used to indirectly measure the current. The current divider is connected in series in the main loop, and the voltage difference before and after the current divider is measured respectively, so that the current flowing through the current divider is calculated. And calculating the energy consumption of the electric wheelchair according to the current and the voltage. However, this measurement method has the following disadvantages: 1. There is a safety risk. The shunt needs to be connected in series in the main loop, no electrical isolation exists, and if the wiring is wrong, short circuit is easily caused; 2. The measurement accuracy is poor. The shunt is greatly affected by temperature, and the measurement accuracy is about +/-1% under the dynamic current working condition that the wheelchair is frequently started and stopped; 3. when measuring electric wheelchair current and voltage, a large amount of noise can be mixed in measurement data due to electromagnetic environment interference, and measurement accuracy is affected. Disclosure of Invention The invention aims to provide a device and a method for measuring the theoretical running distance of an electric wheelchair based on a fluxgate, which are used for supplying power to an adaptive electric wheelchair 24v and have the working condition of 50A of instantaneous maximum current. The invention has the advantages of high safety, high precision and high adaptability. The technical scheme of the invention is as follows: the electric wheelchair theoretical driving distance measuring device based on the fluxgate comprises a power supply module, a sensing measuring module, a signal conversion module and a main control module, wherein signal transmission and power supply isolation are realized among the power supply module, the sensing measuring module, the signal conversion module and the main control module through wiring; The power supply module comprises a MCU special power supply and a multi-output isolation power supply, and is used for respectively providing independent power supply for the main control module and the sensing measurement module and guaranteeing electrical isolation; The sensing measurement module comprises a fluxgate current sensor and an isolation voltage transmitter, and current and voltage parameters of a wheelchair power supply are respectively acquired; the signal conversion module adopts a high-precision ADC module ADS1115 to convert the analog signals output by the sensing module into digital signals for the main control module to read; The main control module adopts MCU as a core control unit, receives digital signals through I2C bus, and realizes parameter calculation, data storage and output. In the electric wheelchair theoretical driving distance measuring device based on the fluxgate, the special power supply of the MCU is a 5V direct current power supply, and the output end of the special power supply is correspondingly connected with a power supply Pin of the MCU, wherein the positive electrode (+ 5V) of the special power supply of the MCU is connected with a Pin2 Pin of the MCU, and the negative electrode (GND) of the special power supply of the MCU is connected with a Pin6 Pin of the MCU to provide stable power supply for the MCU and the ADC module; The multi-output isolation power supply is an isolation power supply module supporting + -12V and +24V multi-output, the output end of the multi-output isolation power supply is connected with +12V output end and-12V output end, which is connected with a VCC pin of the fluxgate sensor, of the fluxgate sensor VEE pin, and