Robots, smoke and lasers

As a part of a proposal for a project about improving accuracy of radiotherapy delivery system using a dexterous robot I got to perform an experiment with KUKA LWR 3 arm and a laser inside a smoke chamber. The aim of this experiment was to show we can use a dexterous robot to track a moving target while optimising the exposure to radiation by exploiting the working envelope of the robot. The robot is using Approximate Inference Control (AICO) to track the moving target while following a sample trajectory around the body. The motion of the target is a recording of respiratory motion of a real patient. During the experiment on the real hardware a respiratory motion simulator (phantom) has been used (courtesy of the Edinburgh Cancer Centre at Western General Hospital). The experiment was a success (see video below).

The biggest issue was to stop the smoke from triggering the fire alarm in the building. A smoke chamber was therefore built around the robot.

Unfortunately the respiratory motion simulator has a acrylic body which cased severe refraction and reflection of the laser beam (see image below). Fortunately the thick atmosphere inside the smoke chamber made the incident laser beam visible so the tracking behaviour can still be confirmed visually. This pilot study/experiment has been conducted under severe time constraints. The actual experiments validating our method will involve placing a light sensitive array on a moving tray (removing the acrylic body and thus the undesired optical phenomena).