"Controls for an Autonomous Robot that Measures the amount of Uranium present in Pipes"
Field Robotics Center (Jan'18 - May'18)
Carnegie Mellon University, USA
Advisor - Prof. Red Whittaker
Background
The amount of Uranium secreted in pipes of nuclear facilities is to be measured. Hence, an Autonomous robot has been designed and built, called 'Radpiper', which travels back and forth in a cylindrical pipe for measuring the same.
Dynamics of the robot in a pipe
1. Robot Position in a pipe while its traversing is
d = R*theta (for small angles of theta)
R - Radius of the pipe (inches)
Theta - Roll angle of the robot (degrees)
d - Robot position (inches)
Image along axis of the cylindrical pipe
2. Path is the trace of the Robot location while driving through the pipe. Roll angle is directly read from IMU senor (The quaternions are converted to Euler angles). Robot offset 'd' from the centerline shown below is Radius times the Roll angle.
3. The Yaw angle for the Radpiper is the slope of the path. Yaw is computed as the first derivative of the path with respect to the distance travelled by Radpiper along the pipe. The points A and B are locations of the IMU in the Radpiper. The green marker represents the location of the detector that measures the amount of Uranium, the straight lines are vectors from IMU to detector viewed from a top view.
4. A test was conducted to analyse the steering control algorithm implemented by obtaining the roll, pitch, yaw and skew angles of the robot. Plots are represented below.
5. A Proportional controller was implemented on the robot to make sure that the sensor remains at the center of the piper at all times to reduce the error in measurement of Uranium. The code was written in C++ and integrated through ROS architecture finally and was deployed in Ohio Nuclear Facility.
Long Range Distance Sensor - DT1000 testing
The long range sensor DT1000 has been tested and the spot size projected by the same is checked for its presence in the end of the pipe. The plots are attached below. X axis - Distance in meters.
1 - The full spot size reaches the launch rig in the beginning of the pipe
0 - Full spot size doesn't reach the launch rig due to steering parameters and the increase in spot size projected with distance which makes the spot size less probable to reach the launch rig through the opening of the 30 inch pipe.
