Code repository and issue tracker for the Fall 2015 of "Advanced Robotics" (Independent Study group)

http://correll.cs.colorado.edu/?page_id=3748

This repo contains the files necessary to build and control a Stewart platform.

1. Getting Started
2. Setting up the main Stewart Platform Workspace
3. Setting up the IMU workspace
4. Running the Stewart Platform
5. Windows Dynamixel Manager

This code uses:

• Ubuntu 14.04

• ROS Indigo

Install ROS indigo if you haven't already: http://wiki.ros.org/indigo/Installation/Ubuntu

Setup environment variables:

source /opt/ros/indigo/setup.bash

Additional dependencies to install:

sudo apt-get install ros-indigo-rosserial-arduino ros-indigo-rosserial ros-indigo-rosserial-server python-catkin-tools

Install Dynamixel Dependencies:

sudo apt-get install ros-indigo-dynamixel-motor

The inverse kinematics calculations for the stewart platform are here.

Setup the workspace:

mkdir -p ~/stewart_ws/src
cd ~/stewart_ws/src
catkin_init_workspace

cd ~/stewart_ws/src
git clone <https://address>
mv advancedrobotics/ stewart_platform/

cd ~/stewart_ws
mkdir src/stewart_platform/include
catkin build
source ~/stewart_ws/devel/setup.bash
sudo cp ~/stewart_ws/src/stewart_platform/dev_rules/*.rules /etc/udev/rules.d/
sudo udevadm trigger
roscd stewart_platform/

Make sure to unplug and replug the usb devices after running udevadm trigger.

A Razor tutorial. Use this tutorial to calibrate the Sparkfun Razor 9DOF IMU.

NOTE Yaw will not be correct if the magnetometer is not set up properly.

Create a separate workspace for the IMU using similar instuctions. Substitute the command "catkin_make" for "catkin build". Use this source or another similar one. A few more things will need to be done so that the IMU is calibrated and communicating with the other ros nodes.

Modify my_razor.yaml (calibration may vary on your IMU):

## USB port
port: /dev/razor

##### Calibration ####
### accelerometer
accel_x_min: -289.0
accel_x_max: 292.0
accel_y_min: -263.0
accel_y_max: 316.0
accel_z_min: -279.0
accel_z_max: 232.0

### magnetometer — should be calibrated when IMU is mounted to stewart platform
# standard calibration
magn_x_min: -600.0
magn_x_max: 600.0
magn_y_min: -600.0
magn_y_max: 600.0
magn_z_min: -600.0
magn_z_max: 600.0

# AHRS to robot calibration
imu_yaw_calibration: 0.0

### gyroscope
gyro_average_offset_x: -40.71
gyro_average_offset_y: 17.44
gyro_average_offset_z: -2.55

Modify the publishers in imu_node.py:

pub = rospy.Publisher('/stewart_platform/imu', Imu, queue_size=1)
...
diag_pub = rospy.Publisher('/stewart_platform/imu/diagnostics', DiagnosticArray, queue_size=1)

Modify the subscriber in display_3D_visualization.py:

sub = rospy.Subscriber('/stewart_platform/imu', Imu, processIMU_message)

With roscore running, launch the IMU node:

roslaunch razor_imu_9dof razor-pub-and-display.launch

gedit ~/.bashrc

Add these 3 lines at the bottom. Make sure the workspace names are correct.

source /opt/ros/indigo/setup.bash
source ~/stewart_ws/devel/setup.bash
source ~/razor_ws/devel/setup.bash

Make sure roscore is running. If not, run this command in a separate terminal:

roscore

In a new terminal, bring up the dynamixel servos:

roslaunch stewart_platform controller_manager.launch

Then, you can start the main node:

rosrun stewart_platform stewart.py

That script accepts different options, and you may first want to test that the servos are working well by passing the test argument:

rosrun stewart_platform stewart.py test

You should see the motors move to the min range, max range, and then a neutral position when running this test. If they don't move, but you don't have any errors, try restarting everything. If you have errors, good luck!

If you want to manually control the pose from the keyboard, launch the following node:

rosrun stewart_platform controller.py

download the RoboPlus software from dynamixel

see this page for driver installation problems

Use the Dynamixel wizard to set up the servos. 2, 4, 6 need to be in the reverse direction mode. The files in this package assume the communication baud rate is (0x34) 57600.