Design of McLennan chassis motion control system based on RT-Thread+RA6M4

This project designs a trolley chassis motion system with a McIlrod structure. After kinematic analysis of the chassis, the motion information of each McIlrod is calculated.

Then, the 8-way PWM controls the 4-way bridge circuit to drive the 4-wheel motor. Its chassis can achieve omnidirectional movement, that is, longitudinal and lateral movement of the plane and rotation movement in place.

Application Background

In the current development of mobile robots, in addition to robots with bionic structures, mobile robots with McDonnell Douglas structures and mobile robots with universal wheel structures are also used very frequently.

Especially for robots in the consumer field, such as sweeping robots, building disinfection robots and subway inspection robots, the chassis structures in these fields basically adopt the McLennan structure, which is more flexible, more reliable and easier to implement than bionic robots.

Implementing functions

8-way PWM output
Omnidirectional chassis movement

Overall framework

Hardware Framework

The RA development board generates 8 PWM signals, which are provided to the DRV8833 bridge circuit module, which drives each wheat wheel motor.

Software Framework

There are not many threads involved in the software. In addition to the main thread and the serial port interrupt thread used for debugging, there is also the motion mode switching thread.

Use of RT-Thread

In my project, I used RTT as the thread implementation of RTOS

RTT has a HAL layer that is adapted to the board level. In this project, PWM and serial port peripherals are used, both of which use the functions of the HAL layer provided by RTT, which enhances portability.

This project also uses the RTT automatic initialization mechanism, which means that the initialization function does not need to be called in reality, but only needs to be declared in the function definition through macro definition, and it will be executed during the system startup process. INIT_PREV_EXPORT() searches and initializes the pwm device.

INIT_APP_EXPORT() initializes the motion mode thread.