The paper presents a general procedure to determine the instantaneous rotation center for planar mechanisms, or its kinematical equivalent in the case of spherical or spatial cases, from the velocity analysis of the mechanism. The procedure is based on the theoretical results of the Lie algebra, se(3), of the Euclidean group, together with the Killing and Klein forms. The paper shows that a previous contribution contains fundamental errors and it was done in order to unify the theory.

With the requirement of heavy load for pick-and-place operation, a new 3-DoF asymmetric translational parallel manipulator is invented in this paper. This manipulator is assembled by a kinematic limb with the parallel linear motion elements(PLMEs), and a single loop 2-UPR. Owning to the linear actuators directly connecting the moving and the fixed platforms, this parallel manipulator has high force transmission efficiency, and adapts to pick-and-place operation under heavy load.

The present work describes the design and build of a new completely mechanical propulsion system for manual wheelchairs for use in ascending or descending long ramps. The design is characterized by a self-locking mechanism that activates automatically to brake the chair when the user stops pushing. The main component of the propulsion system is a planetary gear train that can self-lock, this means that the user does not need to activate external brakes.

• With a large load on the vibrating table, the oscillation of the motor shaft angular velocity and the effect of friction on it are more significant. • Simulink model of the mechanism was developed for numerical calculations. • Friction increases the difference between the maximum and minimum values of the angular velocity and the coefficient of non-uniformity of rotation. • Sliding friction influences the frequency, the maximum and minimum values of the work-table kinematic parameters.

Force sensing plays an important role in minimally invasive surgery. In this study, a new asymmetric cable-driven type of micromanipulator for a surgical robot was designed, and a joint angle estimator(JAE) was designed based on the dynamical model system. Closed-loop control of the joint angle was carried out by regarding the JAE output as the feedback signal. An external force estimator was designed using a disturbance observer. The experimental results shown the correctness and validity.

This paper presents the complete dynamic model of a new six degrees of freedom (DOF) spatial 3-RPRS parallel manipulator. Further, a robust task-space trajectory tracking control is also designed for the manipulator along with a nonlinear disturbance observer. To demonstrate the efficacy and show the complete performance of the proposed controller, virtual prototype experiments are executed using one of multibody dynamics software namely MSC Adams.

A flexure-based monolithic micro manipulation stage with large workspace is designed and analyzed. The piezoelectric actuators are adopted to drive the manipulation stage. The optimized lever amplifier is integrated into the mechanism in order to compensate the stroke of the piezoelectric actuators. The working range of the manipulation stage along each axis is ± 42.31 μm, ± 48.56 μm, 0–10.28 m rad, respectively.

This paper presents a gravity unloading facility to simulate micro-gravity environment of space. The facility unloads the gravity of artificial antenna of satellite and its pointing mechanism to test the performance of the pointing mechanism on the ground. The facility consists of two layers to unload gravity hierarchically and simultaneously while the antenna pointing mechanism consists of two joints. The calculation, simulation and experiments all show the effectiveness of the method applied.

We propose two Interval Analysis based methods to characterize novel robots. Interval analysis theory allows us to consider intervals instead of values, making it possible to use computer algorithms, without the drawback of rounding errors. The first proposed method can isolate chosen interest points and is applied to the characteristic cusp and node points of 3R orthogonal manipulators. The second method encloses the robot available postures, giving complementary information on the novel robot.

The problem of dimensional synthesis of mechanisms to trace a given closed curve is solved by (a) representation of curve shape using normalized Fourier descriptors and (b) learning the relation between Fourier descriptors and mechanism dimensions by an artificial neural network (ANN). The ANN developed suggests dimensions of a four-bar mechanism with coupler curve of shape similar to the one desired. The dimensions are further refined by optimization.

This paper deals with an elasto-static analysis of a 2-DOF spherical parallel wrist where the links and the joints are considered flexible. An FEM approach is used to analyze the problem in a series of configurations of the wrist. The results are elaborated in order to obtain continuous maps of the positioning and orientation errors over the workspace of the machine.