gms | German Medical Science

Objectives: In orthopaedic surgery robotic milling systems are used to enhance the implantation accuracy by optimizing implant size and orientation in accordance to a preoperative plan. The BioROB^® is based on a bionic concept of the human arm. The construction principle of the BioROB^® is inspired by the elastic characteristics of the muscle tendon system of the human arm, which makes the makes the robotic system particularly adequate for human machine interactions. The aim of the study was to determine the accuracy of a bionic inspired robotic arm during specific milling tasks in comparison to human subjects in an experimental study.

Methods: A burr was connected to the robotic arm with a clamp. The robot had to mill 4 different tasks (straight vertical and horizontal line, circles and squares) and the results were compared to 4 human subjects. The resulting burr tracks were digitized using a 3D digitizer. Planar and depth deviation as well as processing time were recorded for each measurement.

Results and Conclusion: The performance of the robotic device is similar to a human arm, when carrying out simple milling tasks. The robot resulted to be faster and more precisely in performing the different milling tasks only in a few cases compared to the four test persons. More complex maneuvers resulted in a higher deviation from the original plan.

Surprisingly the human subjects were faster and more precise than the BioROB^® in almost all tasks. We believe that by optimizing the control algorithm for the rotational joints better results may be achieved. The device has the advantages of using elastic couplings, which makes it particularly attractive for human interaction.