Fuzzy force control and state detection in vertebral lamina milling

Laminectomy is a typical high-risk surgical operation on the spine, during which milling is the key procedure to remove part of vertebral lamina and release the pressure on the spinal nerve. Because many important vessels and nerves surround the vertebral lamina, any incorrect maneuver can cause irreparable damage to patients. In this paper, a fuzzy force control is designed specifically for vertebral lamina milling. The force control is implemented to adjust the milling parameters to copy the complex anatomical structure of the vertebral lamina, and fuzzy combiner is integrated into the force controller to tune its control parameters on-line. For safety purposes, the state detection method based on energy consumption is proposed in the process of vertebral lamina milling. Three different milling states can be detected and the safety control point, which is the stop point of the milling, is found, effectively improving the quality of the vertebral lamina milling. The results of contrast experiments showed that the milling process under fuzzy force control has shorter time and more stable longitudinal contact force. The state detection method based on energy consumption can detect the three milling states, resulting in an acceptable thickness of the remaining vertebral lamina. (C) 2016 Elsevier Ltd. All rights reserved.