Design Control Architecture based on Environment Impedance Properties in Teleoperation Systems: a Bayesian Approach
Nowadays, regarding spread wide use of Teleoperation systems in medical applications like invasive surgeries, researchers are looking for a way to enhance two contradicting factor namely stability and transparency in the presence of uncertainty in models, medium and environment. Firstly, a decentralized $H_\infty$ robust controller is proposed with global stability criterion. On the other hand, based on nonlinearity and Non Gaussianity of environment, randomized algorithms are proposed for identification and control.
In this thesis, a generalization of Bayesian approaches to online estimation and identification of environment dynamic is proposed. Finally, this generalization will lead to a full probability distribution which wrap up whole information exist in the system. Then, a decision making paradigm is utilized to employ control signals which stabilized nominal system and perturbation in a probability robust approaches. The systematic way to utilized information in the decision making process is described in the proposed algorithm. Therefore, firstly particle filter is proposed as a robust suboptimal solution of Bayesian problem. In another approach, MCMC is used to identify whole parameter uncertainty online. Then by utilizing MMT structure to transfer model parameters rather than signals, adaptive probabilistic robust rule is proposed to derive control law.
|Pedram Agand, Ali Aalipour|
Minimally Invasion Eye Surgery Paralogram Robot Designed for Vitrectomy Surgery
Nowadays regarding to necessity of precision surgery in minimally invasive surgery (MIS), particularly eye surgery for intraocular operation such as vitrecotmy, widening demand for robotically assisted surgery has shade the world of industry. In MIS, the surgeon does not need to incise the skin totally to approach the organ; so the damages and complications after surgery are reduced grossly. One of new developing fields of robots in MIS is in ophthalmology i.e. vitrectomy. While performing vitreo-retinal surgery manually, the surgeon faces various challenges. Typically, delicate micrometer range thick tissue is operated, for which steady hand movements and high precision instrument manipulation (<10µm) are required. To achieve the minimum damage to the patient through vitroretinal surgery it is required that the incision point be fixed. In many other surgeries it is necessary to rotate tools about a fixed pivot point such as any kind of MIS surgeries. Therefore, remote center of motion (RCM) mechanism are recommended for most of medical robots. ARES is a spherical RCM mechanism with it’s unique parallel mechanism and three degrees of freedom (1 DOF for the needle). In spherical mechanisms each link may be considered as an arc of great circle on a sphere. All of the mechanism links are hinged together by revolute joints and the joints axis passes through the center of the sphere. Due to orientation of joints axis the mechanism has spherical workspace and all the links have pure rotational movement about the center that induces the RCM of the mechanism. In this robot we use two dynamixel MX64R motors for the parallel arms,and one DC motor for linear movment and design a board in order to communicate MX64R protocol (RS485) with matlab s-function in RTW mode and DC motor all in 1 msec.