During April-May 2013, initial integration of the US system and Robotic system was performed. We received the latest version of the KUKA LWR, and are arranging to send the previous one back for replacement/repairs. After setting up the new robot, tests were performed on an artificial bone as seen in the photo. The 2D US probe was manipulated freehand, and the drill was co-manipulated with the robot arm. Testing was performed to assess the best free-hand motion for the probe, and the achievable error in the position of the drilling point and orientation.

Preliminary results showed errors below 10mm, highly dependent of the free-hand motion of the probe. Without the US system, and attaching the optical markers directly to the bone, the achievable error is in average 1mm in position and .01rad in orientation. Further testing in continuing, in order to lower the error with the US system, as well as the registration time cycle. 

2D ultrasound in freehand and manipulated by a robotic arm has been tested.

Rigid registration algorithms have been tested, and are now being optimized for usage in real time.

Variable Impedance Control Design

A virtual compliant environment around the femoral head has been implemented. Tests with the native impedance controllers of the LWR have been finished, and an external tip force sensor is now being tested.