Closed Loop Motor Control

The following program sets the the motor speed and runs the motor in closed loop. The speed units are counts per second divided by ten (count/sec/10). If the motor is slowed down the system will try to compensate for it by increasing the motor power (PWM duty cycle)

/*
* Robot Navigation Program
* www.robotnav.com
*
* (C) Copyright 2013 Lauro Ojeda
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include
#include "lms2012.h"

// Motor speed 0..100
const int MOTOR_SPEED = 10; //[count/s]/10
// The motor operations use a single bit (or a combination of them)
// to determine which motor(s) will be used
// A = 0x01, B = 0x02, C = 0x04, D = 0x08
// AC = 0x05
const char MOTOR_PORT = 0x1;

int main()
{
//DEFINE VARIABLES
char motor_command[3];
int motor_file;

//INITIALIZE DEVICE
//Open the device file asscoiated to the motor controlers
if((motor_file = open(PWM_DEVICE_NAME, O_WRONLY)) == -1)
return -1; //Failed to open device

//ACTUATE MOTORS
// All motor operations use the first command byte to indicate the type of operation
// and the second one to indicate the motor(s) port(s)
motor_command[1] = MOTOR_PORT;
// Set the motor desired power 0 to 100
motor_command[0] = opOUTPUT_SPEED;
motor_command[2] = MOTOR_SPEED;
write(motor_file,motor_command,3);
// Start the motor
motor_command[0] = opOUTPUT_START;
write(motor_file,motor_command,2);
// Run the motor for a couple of seconds
sleep(2);
// Stop the motor
motor_command[0] = opOUTPUT_STOP;
write(motor_file,motor_command,2);

//CLOSE DEVICE
close(motor_file);
return 0;
}