Self balancing car

Projects Programming
1

Hey I am trying to make a self balancing car (two wheels on either sides ). I have got it to balance itself but it still struggles and adjusts a lot to balance. Here is the code I used

#include <Wire.h>
const int MPU_addr=0x68; 
int16_t AcX,AcY,AcZ,Tmp,GyX,GyY,GyZ;
int minVal=265; int maxVal=402;
double x;         //A4 (SDA), A5 (SCL)
double y; 
double z;
int lmt1=6;
int lmt2=5;
int rmt1=10;
int rmt2=9;
int value;

void setup(){
  pinMode(lmt1,OUTPUT);
  pinMode(lmt2,OUTPUT);
  pinMode(rmt1,OUTPUT);
  pinMode(rmt2,OUTPUT);
  Wire.begin();
  Wire.beginTransmission(MPU_addr);
  Wire.write(0x6B); Wire.write(0);
Wire.endTransmission(true);
Serial.begin(9600); } 

void loop(){ 
  Wire.beginTransmission(MPU_addr);
  Wire.write(0x3B);
Wire.endTransmission(false); 
Wire.requestFrom(MPU_addr,14,true);
AcX=Wire.read()<<8|Wire.read(); 
AcY=Wire.read()<<8|Wire.read();
AcZ=Wire.read()<<8|Wire.read(); 
int xAng = map(AcX,minVal,maxVal,-90,90);
int yAng = map(AcY,minVal,maxVal,-90,90);
int zAng = map(AcZ,minVal,maxVal,-90,90);

x= RAD_TO_DEG * (atan2(-yAng, -zAng)+PI);
y= RAD_TO_DEG * (atan2(-xAng, -zAng)+PI);
z= RAD_TO_DEG * (atan2(-yAng, -xAng)+PI);

y=y-78;
if(y<(-1) || y>1){
if(y<0){//backward tilt
  y=y*(-1);
  value=map(y,0,20,0,255);
  analogWrite(lmt1,0);
  analogWrite(lmt2,value);
  analogWrite(rmt1,0);
  analogWrite(rmt2,value);
}
else if(y>0){// forward tilt
  value=map(y,0,20,0,255);
  analogWrite(lmt1,value);
  analogWrite(lmt2,0);
  analogWrite(rmt1,value);
  analogWrite(rmt2,0);
}}

}

The code is actually is done using very basic algorithms. Is there any way to like make this code little better (I tried using code from online, youtube etc. None of them are like suitable with the hardwares I use or too complicated to modify). I also want to make this remote controlled but I don't know how to tackle the problem where I have to maintain balance at the same time move the robot.

Thanks for helping.

2

Cars usually sit on 4 wheels so don't have any problem balancing. Perhaps you're talking about something else?

Steve

3

Sorry I didn't think it would be interpreted that way.

I meant a self balancing car with two wheels (one on each side).
like this one Arduino Project-Self Balancing Robot - YouTube

but with a simple dc motor.

4

Is there any way to like make this code little better

Better than what?

Why are you asking for 14 bytes when you only care about 6 bytes?

Properly laying out the code would help. Using functions to get the accelerometer data and to consume the accelerometer data would help.

Typically, JUST using accelerometer data is NOT sufficient to balance.

5

You could use a multi core uController, splitting the tasks to each core. You could use a SPI MPU for faster readings. You could use a STM32 blue pill as a balancing controller.

6

atan2()

Trig functions are very slow on 8-bit Arduinos. If you can adjust your algorithm to remove or reduce the 3 atan2() calls it will run a lot faster.

For a start, it appears you aren't using the values of x and z. So don't waste time calculating them.

Don't do this:
}}

Don't ever put two } on one line.

Balancing would be so much better with a gyro, such as available in a typical 6-axis or 9-axis chip.

7

Two-wheeled gyro-stabilised car