Control Structure Design and Implementation for Eye Surgery Training Dual Master Haptic System
Surgery training have always been one of the most important challenges for the surgeons. Owing to the higher accuracy required in eye surgery than in other surgeries, any mistake made by the trainee might lead to undesired complications for the patient. Recently, dual-user haptic systems consisting of two haptic consoles, one for the trainer and one for the trainee, has been developed as an assistive tool to facilitate surgery training. In these systems, the trainer and the trainee collaboratively perform surgical tasks through their haptic consoles. In the proposed surgery training haptic system, the environment is directly manipulated by one surgeon and the other surgeon is indirectly involved in the procedure through the haptic system. This makes a special training framework which is applicable to not only virtual environment but also real environments such as physical phantoms, cadavers and patients with special focus on the vitrectomy surgery. Initially, the surgery is directly performed by the trainer and the position of the trainer is transformed to the trainee’s hands through the haptic system. Utilizing this step, the trainee can increase his/her expertise in different tasks by learning the true movements. After obtaining the required level of surgical skills, the trainee can perform the surgery directly on the environment with trainer’s supervision. To avoid undesired complications, the trainer is able to interfere into the procedure in the case of sudden mistakes happens by the trainee. Due to the interaction between the users in the dual user haptic systems, the decision of each user is affected by the other user. Hence, new application-based control structures are required to be further investigated. The majority of the previously proposed control methodologies for this system have not simultaneously considered special requirements of surgery training and stability analysis of the nonlinear closed-loop system which is the objective of this thesis. In order to describe the objectives and facilitate controller design for dual user haptic systems, this thesis introduces two training approaches including Expert Continual Action (ECA) and Expert Supervision & Intervention (ES&I). The ECA training approach is based on the trainer to perform all details of surgical operation, while the trainee freely experiences the task and receives the haptic guidance signals from the trainer. The control schemes based on ECA are appropriate for the most primary level of training in which the trainee does not have sufficient experience to perform the operation. On the other hand, the ES&I training approach is based on giving the trainee the chance to conduct the surgical operations and be supervised and corrected as needed, while the trainer is provided with the facilities to interfere in the operation and correct probable mistakes made by the trainee. In this approach, the trainer is not required to be involved at every stage of surgical procedures. Thus, the trainer is just given a supervisory role to interfere with the procedure only when a mistake is performed by the trainee. Notably, a unique feature of the proposed training structure is its application to remote training with real environment. In this case, one surgeon holds the surgical instrument and directly performs the surgical procedure, whereas the other surgeon is indirectly involved in the surgical operation through the haptic system. This requires a specially designed haptic system for each surgical task to provides the necessary movements required for that surgery. This issue is specially studied for the vitrectomy surgery and the designed haptic system is presented. In brief, the main contribution of this thesis is to introduce the above training approaches and develop some control schemes based on each training approach. Each control scheme is developed based on its respective training approach by utilizing the necessary mathematical tools of control theory. The stability of the closed-loop system for each control scheme is studied using input-to-state stability (ISS) analysis. Besides, some simulation and experimental results are presented to support the proposed methodologies. Finally, the specially designed haptic system for facilitating vitrectomy surgery training is presented.