In this paper, a concept of totally decoupling is proposed for the design of a flexure parallel micromanipulator with both input and output decoupling. Based on flexure hinges, the design procedure for an XY totally decoupled parallel stage (TDPS) is presented, which is featured with decoupled actuation and decoupled output motion as well. By employing (double) compound parallelogram flexures and a compact displacement amplifier, a class of novel XY TDPS with simple and symmetric structures are enumerated, and one example is chosen for further analysis. The kinematic and dynamic modeling of the manipulator are conducted by resorting to compliance and stiffness analysis based on the matrix method, which are validated by finite-element analysis (FEA). In view of predefined performance constraints, the dimension optimization is carried out by means of particle swarm optimization, and a prototype of the optimized stage is fabricated for performance tests. Both FEA and experimental studies well validate the decoupling property of the XY stage that is expected to be adopted into micro-/nanoscale manipulations.

This paper proposes an improved sliding mode control with perturbation estimation (SMCPE) featuring a PID-type sliding surface and adaptive gains for the motion tracking control of a micromanipulator system with piezoelectric actuation. One advantage of the proposed controller lies in that its implementation only requires the online estimation of perturbation and control gains without acquiring the knowledge of bounds on system uncertainties. The dynamic model of the system with Bouc-Wen hysteresis is established and identified through particle swarm optimization (PSO) approach, and the controller is designed based on Lyapunov stability analysis. A high-gain observer is adopted to estimate the full state from the only measurable position information. Experimental results demonstrate that the performance of proposed controller is superior to that of conventional SMCPE in both set-point regulation and motion tracking control. Moreover, a submicron accuracy tracking and contouring is achieved by the micromanipulator with dominant hysteresis compensated for a low magnitude level, which validates the feasibility of the proposed controller in the field of micro/nano scale manipulation as well.

A cable-driven hyper-redundant manipulator (CDHM) has superior dexterity for confined space applications. However, the modeling and control considering the cables are very complex. In this paper, we established the kinematics and dynamics models and proposed a dynamics control strategy. The multi-level mapping between the motors, cables, joints and end-effector was first analyzed. The corresponding kinematics equations were derived and solved by combining analytical and numerical methods. Especially, the cable coupling relationship was established and a decoupling method was addressed to compensate the coupled motion between cables. Furthermore, we derived the dynamics equations including the cable forces and the joint variables. Considering practical control requirements, the cables' forces were distributed by simplifying the dynamics equations and obtaining the minimal solutions. Then, we presented a dynamics control strategy, which uses the forward and inverse kinematics of multi-level mapping for motion resolution and compensation, and computes the feedforward torques for the motors using recursive dynamics and "cable force - motor torque" relationship. Finally, a prototype and a truss inspection experiment system were developed to verify the corresponding models and methods. Experiment results show that the derived kinematic and the dynamic equations, and the proposed dynamic control strategy are effective.

This paper reports the design and development processes of a totally decoupled flexure-based XYZ parallel-kinematics micropositioning stage with piezoelectric actuation. The uniqueness of the proposed XYZ stage lies in that it possesses both input and output decoupling properties with integrated displacement amplifiers. The input decoupling is realized by actuation isolation using double compound parallelogram flexures with large transverse stiffness, and the output decoupling is implemented by employing two-dimensional (2-D) compound parallelogram flexures. By simplifying each flexure hinge as a two-degree-of-freedom (2-DOF) compliant joint, analytical models of kinematics, statics, and dynamics of the XYZ stage are established and then validated with finite-element analysis (FEA). The derived models are further adopted for optimal design of the stage through particle swarm optimization (PSO), and a prototype of XYZ stage is fabricated for performance tests. The nonsymmetric hysteresis behavior of the piezo-stage is identified with the modified Prandtl-Ishlinskii (MPI) model, and a control scheme combining the inverse model-based feedforward with feedback control is constructed to compensate the plant nonlinearity and uncertainty. Experimental results reveal that a submicron accuracy 1-D and 3-D positioning can be achieved by the system, which confirms the effectiveness of the proposed mechanism and controller design as well.