The wireless rail car model operates under weak current mode
01 radio track
1. Problem/goal
In the wireless track group, there is a competition subject that the charging efficiency of the car is relatively low when the power supply of the track is insufficient. The upper line voltage is insufficient, so the car is easy to get stuck at the corner of the track. This raises a question, that is, how to make the car model automatically stop running at low voltage on the weak current track, only complete charging on the track, and when the voltage reaches a certain level, go all out to complete the curve. run. Aiming at this idea, I would like to introduce to you the implementation method of Yu Jiajun from class 24, as well as the test results.
2. Basic principles
In a wireless rail car model, the wireless power is stored in farad capacitors on the car model. After the voltage on the capacitor is divided by the resistor, it can be measured by the microcontroller ADC0. According to the measured value of ADC0, the voltage on the car model energy storage farad capacitor can be judged. If the value is higher than a certain number, such as 600, corresponding to a voltage of 9V, when the voltage on the capacitor is detected to exceed this value, start the motor. At this time, the car model can run at a higher speed. Since the electric energy consumed by the motor is faster than the wireless energy, the voltage on the farad energy storage capacitor will gradually drop. When it is lower than a certain value, such as 300, corresponding to a voltage of 5V, the motor will stop running. The power consumption of the whole vehicle will be greatly reduced. The wireless energy obtained from the coil is greater than the consumed electric energy, and the capacitor voltage will gradually increase, and the motor will be started again after exceeding 600. The process then iterates. It should be noted that the above-mentioned 600, 300 is an estimated value, and the specific value needs to be determined according to actual measurement. One of the simplest methods is to display the ADC0 value when the car model is running, and determine the reasonable value for starting the motor and closing the motor by observing the running situation of the car model later.
3. Application example
In the previous ESP32 main control board ADC experiment, we know the application method of ADC0, which is to declare an ADC that reads the voltage value from Pin36, and set its attenuation parameters so that the input range can reach 3.3V. In the main program, you can use the read function of adc0 to read the voltage on the external capacitor, and the read value is proportional to the voltage on the capacitor. In the main loop, judge according to the read value of adc0, that is, the value stored in the val0 variable here, and if it is lower than a certain set value, set the corresponding PWM duty cycle value duty of the motor to 0, Stop the motor from running. After reading the value of adc0 is greater than a certain value, set the motor PWM duty value. According to the debugging, you can choose the appropriate size to make the car model run farther. Through such control logic, it can be realized that when the voltage of the car model is too low, it will automatically stop charging. When fully charged, it can run at full speed.
Let's take a look at the test effect of this method. The car model runs very fast at the beginning, but after a curve, the power consumption is very fast, the voltage is lower than the predetermined value, and the motor stops running. When the voltage is restored, the car model continues to run. Running to a curve, the car model deviates from the track, the charging voltage drops, and the car model stops again. Move the car model to the center of the track, after charging, the car model starts running again. After the power consumption of the straight line is completed and the power is replenished, the car model will run again. When it reaches a corner and deviates from the track, the voltage drops and stops running. This process goes back and forth, so that it can travel intermittently under weak current conditions or when the car model is off-track.
4. Practice/Experiment
This article introduces that the car model can complete the movement goal when the track voltage is low through the intermittent operation mode. Of course, behind this method, it is necessary to set appropriate parameters through experiments, so as to ensure the normal operation of the car model. This mode can further improve the reliability of the car model operation.
02 Lecture information
1. Lecture video
The wireless rail car model operates under weak current mode
2. Lecture information
- Tsinghua cloud disk data download : https://cloud.tsinghua.edu.cn/d/7471180bdb0f4d1ebbc7/
- Wireless track smart car school competition | How to learn wireless track car models?
- Basic Python learning website Learn Python : https://www.learnpython.org/
■ Links to related literature: