This car was a birthday present for my son, a sleek styling and powerful ride on car, which can be manually or wirelessly operated. Although running on a single 6V lead-acid battery, the motor is quite strong and enough to carry an one-year-old baby at 3 km/h for over one hour. The wireless controller is a nice feature, which allows parents to directly control the car have fun with the baby, however the controller only has a limited function: forward/backward and left/right at full speed. Since the motor is switched on and off by a mechanical relay rather than MOSFET transistors, the speed of the car is fixed at a maximum level and that is uncomfortable for the baby when starting up.
Lamborghini Aventador ride on car
The idea is to modify the wireless controller and the car’s internal circuitry to control the speed of the car via PWM. A simple solution is to use a Playstation 2 wireless controller, which has two analog joysticks and various buttons to play with. The controller comes with a wireless receiver, originally should be plugged into the PS2/PS3 box or PC, but now it will be connected to an Arduino board.
Wireless PS2 controller
The Arduino, which is a Pro Micro version with the Atmega32u4 microcontroller, is programmed to receive joystick’s data from the controller, then to calculate and output the corresponding speed values to the motors via PWM channels. The motors should be driven by the motor driver boards to handle the high current, which at first I used a L298N motor driver board. This is a popular choice for many robot builder and hobbyists, which can deliver up to 2A current, maximum 35V input and very cheap ($5 ebay). However, the rear motor is quite power-hungry and above 1A would make the board extremely hot, and in addition to that, the voltage drops about 3 – 4V as the current rises, which is very inefficient and unreliable.
After searching the internet, the BTS7960B board is another board which can be deliver much higher current (43A) to the rear motor and has a reasonable price ($12 ebay). The rear motor is controlled by 3 lines from the Arduino (1 PWM and 2 directions), and similarly another 3 lines are used for the steering motor via the L298N board.
The circuit diagram
Then the circuit is fitted nicely in a enclosure, next to the original control box of the car. To provide more strength to the motor, a 7.4V 5000mAh Lipo battery is also installed.
Car control circuit
The action is shown below:
Comments ( 0 )