🚗Drive-By-Wire with Dithering

Introducing Control Loops to Improve Steering

Dithering in the context of autopilot and control systems is a technique that introduces a small, high-frequency, controlled perturbation (noise or signal) into a system's command signal to mitigate the effects of non-linearities in digital drive circuits (PWM), to mitigate the effects of friction and inertia that can lead to stray motion in autonomous drive systems.

Overview

In this guide you will learn how to manipulate and control the Rover based on the following basic concepts:

1. Please be sure to have implemented and ran base example(Man-In-The-Loop Obstacle first)

2. How to implement Dither in JavaScript example.

To access the program, simply follow this link https://mantiscode.azurewebsites.net/webble/mthjoystick.html.

Lines of Code to Modify

Since the desire is to drive straight long your course, the only two functions that require modification are the forward, and backward commands.

dither.js

                                    

function moveForward() {
    //both PWM's set to to the same negative direciton.
    let MTR1_PWM=-30;
    let MTR2_PWM=30;
    

    let  payload_data  = new Uint8Array(2);
    payload_data[0] = MTR1_PWM;
    payload_data[1] = MTR2_PWM;
    
    
    let  payload_cmd  = new Uint8Array(2);
    payload_cmd [0] = 0x05;//controls both motors
    payload_cmd [1] = 0x00;
    
    
    let MTR1_PWM=-30;
    let MTR2_PWM=-28;
    

    let  payload_data  = new Uint8Array(2);
    payload_data[0] = MTR1_PWM;
    payload_data[1] = MTR2_PWM;
    
    
    let  payload_cmd  = new Uint8Array(2);
    payload_cmd [0] = 0x05;//controls both motors
    payload_cmd [1] = 0x00;
    
    
    let MTR1_PWM=28;
    let MTR2_PWM=30;
    

    let  payload_data  = new Uint8Array(2);
    payload_data[0] = MTR1_PWM;
    payload_data[1] = MTR2_PWM;
    
    
    let  payload_cmd  = new Uint8Array(2);
    payload_cmd [0] = 0x05;//controls both motors
    payload_cmd [1] = 0x00;
    
    
    movecmd(payload_cmd,payload_data);

    console.log("Move Forward")

}