With the increasing trend toward Minimally Invasive Surgery (MIS) procedures, the need to develop new robotic systems to facilitate such surgeries is more and more recognized. This paper describes the design and development of a 4 DOF force-reflective master robot (RoboMaster1) for haptic telesurgery applications. A two-double parallelogram robot is introduced including a novel mechanism at the base for producing and control of the end effector's linear motion. This eliminates the deficiencies caused due to suspending massive actuators at the end effector or cabling from the base. The kinematics and work space of the system were analyzed and a prototype was developed for primary practical evaluations. The results showed that the system can effectively simulate the surgeon's hand maneuvers inside the abdominal cavity with a Remote Center of Motion (RCM) located at the backside. With this important feature, the system is expected to facilitate the key hole surgeries by eliminating the need for inverse and/or scaled maneuvers during minimally invasive surgeries.

In this paper, nonlinear oscillation of the automobile gear system is studied. The backlash dynamic parameter is included in the nonlinear mathematical modeling of the problem. Using multiple scale method, forced vibration responses of the gear system including Primary, Sub-harmonic and Super-harmonic resonances are investigated. In each case, the jump phenomenon and stability analysis are studied. In addition, the effect of dynamic and manufacturing parameters of the gear system on the time responses are analyzed. Simulation and nonlinear analysis of the problem are developed in MAPLE and MATLAB environments.

Abstract. Estimation of physical parameters of a parametrically excited gyroscope is studied in this paper. This estimation is possible by reading the input and output data of the gyroscope. Because of di erent faults in the manufacturing process and tolerances, physical parameters of a gyroscope are not exactly same as the expected values of the manufacturer. Moreover, changing of temperature, humidity, external acceleration, etc. can change the physical parameters of the gyro. Thus, the physical parameters of gyroscope are not xed values and may deviate from the desired designed values. The physical parameters of gyroscope determine the optimal region for working of gyroscope. Thus, if the parameters deviate from the original ones but the excitation frequency is xed at its initial value, the sensitivity of the gyroscope will be reduced. The new parameters of the gyroscope can determine the new point of excitation frequency and, because of this, estimation of these parameters should be done to prevent sensitivity reduction. Estimation of these new parameters using the input and output values is studied here.

In this paper design and evaluation of an adaptive critic-based neurofuzzy controller for the stabilizing periodic orbits of chaotic systems has been presented in detail. The main superiority of the proposed controller over previous analogous fuzzy logic controller design approaches, e.g., genetic fuzzy logic controller, is its online tuning characteristic and remarkable reduced amount of computations used for parameter adaptation, which makes it desirable for real time applications. Considering the simplicity of this controller and its independence from the system model, this control method has the advantage of online learning and control, and can be applied to a large variety of systems. The proposed adaptive scheme is used for stabilizing the 2-π and 4-π periodic orbits of a Duffing system to investigate numerically the effectiveness of the method. Also the robustness of the proposed controller was examined using input noise and parameter uncertainty in the system model. Simulation results show that the proposed algorithm can be successfully used for chaos suppression when there is not any crisp mathematical model of the dynamical system.

In this paper, the problem of boundary control of vibration in a clamped-free strain gradient Timoshenko microcantilever is studied. For getting systems closer to reality, the force/moment exertion conditions should be modeled. To this end, a piezoelectric layer is laminated on one side of the beam and the controlling actuation is applied through the piezoelectric voltage. The beam and piezoelectric layer are coupled and modeled at the same time and the dynamic equations and boundary conditions of the system are achieved using the Hamilton principle. To achieve the purpose of eliminating vibration of the system, the control law is obtained from a Lyapunov function using LaSalle's invariant set theorem. The control law has a form of feedback from the spatial derivatives of boundary states of the beam. The finite element method using the strain gradient Timoshenko beam element has been used and then the simulation is performed to illustrate the impact of the proposed controller on the microbeam.