IMU to PC Python Interface:


The video to the right demonstrates the JB Robotics IMU in action. As the IMU is moved through a series of motions, the data is transmitted to a PC and shown graphically on the PC screen.

In this example, the IMU is being used in its ASCII serial data transmission mode.

Roll, pitch, and yaw data are transmitted to the PC over an FTDI/USB connection.

The Python program listed below graphically shows the orientation of the IMU.
Python Program:

# Code is a modified version of 'Jose Julio @2009 "IMU_Razor9DOF.py"'
# This script needs VPhyton, pyserial and pywin modules

# First Install Python 2.6.4
# Install pywin from http://sourceforge.net/projects/pywin32/
# Install pyserial from http://sourceforge.net/projects/pyserial/files/
# Install Vphyton from http://vpython.org/contents/download_windows.html

from visual import *
import serial
import string
import math

from time import time

deg2rad = 3.141592/180.0
ser = serial.Serial(port='COM9',baudrate=115200,timeout=1)
# Main scene
scene=display(title="JB Robotics IMU")
scene.range=(1.2,1.2,1.2)
scene.forward = (1,0,-0.25)
scene.up=(0,0,1)

# Second scene (Roll, Pitch, Yaw)
scene2 = display(title='JB Robotics IMU',x=0, y=0, width=500, height=200,center=(0,0,0), background=(0,0,0))
scene2.range=(1,1,1)
scene.width=500
scene.y=200

scene2.select()
#Roll, Pitch, Yaw
cil_roll = cylinder(pos=(-0.4,0,0),axis=(0.2,0,0),radius=0.01,color=color.red)
cil_roll2 = cylinder(pos=(-0.4,0,0),axis=(-0.2,0,0),radius=0.01,color=color.red)
cil_pitch = cylinder(pos=(0.1,0,0),axis=(0.2,0,0),radius=0.01,color=color.green)
cil_pitch2 = cylinder(pos=(0.1,0,0),axis=(-0.2,0,0),radius=0.01,color=color.green)
arrow_course = arrow(pos=(0.6,0,0),color=color.cyan,axis=(-0.2,0,0), shaftwidth=0.02, fixedwidth=1)

#Roll,Pitch,Yaw labels
label(pos=(-0.4,0.3,0),text="Roll",box=0,opacity=0)
label(pos=(0.1,0.3,0),text="Pitch",box=0,opacity=0)
label(pos=(0.55,0.3,0),text="Yaw",box=0,opacity=0)
label(pos=(0.6,0.22,0),text="N",box=0,opacity=0,color=color.yellow)
label(pos=(0.6,-0.22,0),text="S",box=0,opacity=0,color=color.yellow)
label(pos=(0.38,0,0),text="W",box=0,opacity=0,color=color.yellow)
label(pos=(0.82,0,0),text="E",box=0,opacity=0,color=color.yellow)
label(pos=(0.75,0.15,0),height=7,text="NE",box=0,color=color.yellow)
label(pos=(0.45,0.15,0),height=7,text="NW",box=0,color=color.yellow)
label(pos=(0.75,-0.15,0),height=7,text="SE",box=0,color=color.yellow)
label(pos=(0.45,-0.15,0),height=7,text="SW",box=0,color=color.yellow)

L1 = label(pos=(-0.4,0.22,0),text="-",box=0,opacity=0)
L2 = label(pos=(0.1,0.22,0),text="-",box=0,opacity=0)
L3 = label(pos=(0.7,0.3,0),text="-",box=0,opacity=0)

# Main scene objects
scene.select()
# Reference axis (x,y,z)
arrow(color=color.green,axis=(1,0,0), shaftwidth=0.02, fixedwidth=1)
arrow(color=color.green,axis=(0,-1,0), shaftwidth=0.02 , fixedwidth=1)
arrow(color=color.green,axis=(0,0,-1), shaftwidth=0.02, fixedwidth=1)
# labels
label(pos=(0,0,0.8),text="JB Robotics IMU",box=0,opacity=0)
label(pos=(1,0,0),text="X",box=0,opacity=0)
label(pos=(0,-1,0),text="Y",box=0,opacity=0)
label(pos=(0,0,-1),text="Z",box=0,opacity=0)
# IMU object
platform = box(length=1, height=0.05, width=1, color=color.red)
p_line = box(length=1,height=0.08,width=0.1,color=color.yellow)
plat_arrow = arrow(color=color.green,axis=(1,0,0), shaftwidth=0.06, fixedwidth=1)

roll=0
pitch=0
yaw=0
while 1:
line = ser.readline()
line = line.replace("RPY: ","")
words = string.split(line," ") # Fields split
if len(words) > 2:
try:
roll = float(words[0])*deg2rad
pitch = float(words[1])*deg2rad
yaw = float(words[2])*deg2rad
except:
print("Invalid line")
axis=(cos(pitch)*cos(yaw),-cos(pitch)*sin(yaw),sin(pitch))
up=(sin(roll)*sin(yaw)+cos(roll)*sin(pitch)*cos(yaw),sin(roll)*cos(yaw)-cos(roll)*sin(pitch)*sin(yaw),-cos(roll)*cos(pitch))
platform.axis=axis
platform.up=up
platform.length=1.0
platform.width=0.65
plat_arrow.axis=axis
plat_arrow.up=up
plat_arrow.length=0.8
p_line.axis=axis
p_line.up=up
cil_roll.axis=(0.2*cos(roll),0.2*sin(roll),0)
cil_roll2.axis=(-0.2*cos(roll),-0.2*sin(roll),0)
cil_pitch.axis=(0.2*cos(pitch),0.2*sin(pitch),0)
cil_pitch2.axis=(-0.2*cos(pitch),-0.2*sin(pitch),0)
arrow_course.axis=(0.2*sin(yaw),0.2*cos(yaw),0)
L1.text = str(float(words[0]))
L2.text = str(float(words[1]))
L3.text = str(float(words[2]))
ser.close
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