LMS9DS0 - Orientation, Position, and Velocity

Page last updated 14 Mar 2015, by Benjamin Smith. 0 replies

Project Description

Use the LMS9DS0 IMU to obtain the orientatin, position, and velocity from the IMU's accelerometer data. I have included details on how to interface with the uLCD-144-G2 128x128 pixel LCD breakout. This is not necessary, but will provide the user with a means to view the output data from the IMU

Components

mbed pinIMU pin
p9SDA
p10SCL
VoutVdd
GndGnd
mben pinuLCD Cable
p27Rx
p28Tx
p30RES
Vu5V
GndGnd

Library

Import programimu_lab4

Demo for finding orientation (pitch,roll) and velocity

Last commit 13 Mar 2015 by Benjamin Smith

Code

#include

#include "mbed.h"
#include "LSM9DS0.h"
#include "uLCD_4DGL.h"

LSM9DS0 imu(p9, p10, LSM9DS0_G_ADDR, LSM9DS0_XM_ADDR);
uLCD_4DGL lcd(p28, p27, p30);

Demo

int main()
{
    setup();  //Setup sensor and Serial
    lcd.printf("------ LSM0DS0 Demo -----------\n");

    while (true)
    {
    	 // lcd.cls();
    	
          imu.calcPitchRoll();  //calls member function to calculate pitch and roll
          lcd.printf("\nPitch: ");
    	  lcd.printf("%2f\n",imu.pitch);
    	  lcd.printf("Roll: ");
          lcd.printf("%2f\n\n",imu.roll);

          //print out accelerometer values from amu
          lcd.printf("X Accel: %2f\n",imu.ax);
          lcd.printf(", ");
          lcd.printf("Y Accel:%2f\n",imu.ay);
          lcd.printf(", ");
          lcd.printf("Z Accel: %2f\n\n",imu.az);           
	
	//use global variables to integrate over discrete values
        //Integrate acceleration once to obtain velocity and twice to obtain position
	      velx = oldVelx + REFRESH_TIME_MS * oldX/1000; 	
	      posx = oldPosx + REFRESH_TIME_MS * oldVelx/1000;
	    
	      vely = oldVely + REFRESH_TIME_MS * oldY/1000; 	
	      posy = oldPosy + REFRESH_TIME_MS * oldVely/1000;
	    
	      velz = oldVelz + REFRESH_TIME_MS * oldZ/1000; 	
	      posz = oldPosx + REFRESH_TIME_MS * oldVelz/1000;
	       	
    	
    	  lcd.printf("X Vel: %2f\n",velx);
          lcd.printf(", ");
          lcd.printf("Y Vel:%2f\n",vely);
          lcd.printf(", ");
          lcd.printf("Z Vel: %2f\n",velz);  
   
    	  oldVelx = velx;
    	  oldPosx = posx;
    	  oldVely = vely;
    	  oldPosy = posy;
    	  oldPosz = posz;
    	  oldVelz = velz;
    	  oldX = imu.ax;
          oldY = imu.ay;
          oldZ = imu.az;

		
		wait_ms(REFRESH_TIME_MS);
	}
}

Be aware that there will be an accumulating error in the velocity calculations due to there always being force read by the IMU even when at rest.

Video Demo

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