Papers by Keyword: Parallel Mechanism

Abstract: In this paper a 6-DOF(Degree of Freedom) vibration isolation platform with structural configuration of 3CPS (3 Cylindrical-Prismatic-Spherical)-1UPS (1 Universal-Prismatic-Spherical) parallel mechanism is proposed. Firstly, the dynamic model is developed through virtual work principle. The transfer function and the complex frequency response function were obtained from the dynamical equation. Then, 36 amplitude frequency diagrams are obtained from the frequency response function. By analyzing the 36 amplitude frequency diagrams, 10 vibration coupling terms were chosen. The range of the spring stiffness coefficient and the range of the damping coefficient of the magneto-rheological damper are determined by analyzing the acceleration transmissibility of the 10 vibration coupling terms. At last, an integrated optimization combining structural and controller optimization is developed. The optimal parameters of the parallel mechanism are obtained through Genetic Algorithm (GA). This work is significant for the prototype design and verification of the vibration isolator.

Abstract: Based on a 3-DOF parallel mechanism, this paper establishes the dynamic model by Lagrange method, and gets 3 calculation curves of the input driving generalized forces by theoretical calculations (MATLAB) and simulation (ADAMS). After analyzing the results of calculation and simulation, it verifies the correctness of dynamic model and its good dynamic performance. At last, it shows that the input driving parameters have a great influence on the driving generalized force. This paper lays a foundation for driving force design and stiffness analysis of the 3-DOF working platform physical prototype.

Abstract: The Kane equations were applied in the dynamic analysis of a 3-DOF parallel mechanism, whose sub-chains consisted of three pairs of parallel legs. According to the characteristic of the parallel mechanism, it was simplified to 3PSS structure. Dynamics equations were derived based on the kinematical analysis. Computing simulation example was presented through MATLAB programming and verified by ADAMS simulation. The results showed that the approach was correct. It provides theoretical reference for the actual experiment and the choice of subsequent control method.

Abstract: It is important to calibrate the straightness and the squareness of the XY-stage for precision manufacturing and measurement. Normally it is calibrated using much higher precise and accurate measuring instruments and/or artifacts. The high precision and accurate instruments and artifacts are expensive. So, in this paper, Self-calibration method is applied to XY-stage. This method does not require any much high precision and accurate instruments and artifacts. The normal XY-stage moves to the location at the unique coordinates. In this case, it is difficult to apply self-calibration method. Therefore, XY-stage is expanded to XYθ-stage with parallel mechanism. As this stage moves to the location at a lot of coordinates, self-calibration method is applied. This method is confirmed in simulation and experiment. In simulation, the extension lengths of mechanism are estimated from known kinematic parameters and the target coordinates. After that, estimated kinematic parameters are calculated by least-squares method from the extension lengths and the target coordinates. Finally, the positioning coordinates are calculated from the estimated kinematic parameters and the extension lengths. It is proved that the calibration method is effective by comparing the target coordinates and the positioning coordinates. In experiment, the experimental process is similar to the simulation without the estimation of extension lengths. The results of simulation and experiment are shown in this paper.

Abstract: A 3-PUU parallel mechanism was studied, which can perform one-dimensional translation about z-axis and two-dimensional rotations about y-axis and x-axis. This paper shows the study about the precision analysis, the dimensional analysis and the synthesis problem of the parallel mechanism having less degree of freedom. First, the closed-loop vector model was built based on analyzing the branched-chains of 3-PUU, the pose error model was built through the differential geometry, and the error model of positive solutions was obtained which contains all the structural parameters errors. For the error of structural parameters given, the pose output error can be solved out by application of this model, the area of maximum error is found out. And the influence of pose output error was analyzed with postures changed. The dimensional analysis of 3-PUU was also done by this error model, and the reasonable selection of mechanism parameters was discussed. And then the rationality of structure dimensional design was discussed in this paper. Finally, this method also may be used in the dimensional analysis of other less freedom parallel mechanisms.

Abstract: A novel parallel mechanism which enlarges the workspace by singularity-free mode change is proposed. The proposed mechanism is inherited the design of Linear DELTA which has three degree-of-freedom translational moving plate driven by three linear actuators, in addition, extended it by redundantly actuation by four linear actuators and asymmetric design. New criterions about redundancy and singularity of redundantly actuated parallel mechanism using summation and product of determinants of minor matrices of the transposed Jacobian matrix are proposed. Redundantly actuation and asymmetric design enables singularity-free mode changes with loss redundancy but maintain non-singularity, that are evaluated by the proposed criterions. Numerical simulations demonstrate the singularity-free mode changes of the proposed mechanism.

Abstract: The structure parameters of the robot directly affects its workspace, in order to get the relationship between the structure parameters of the robot and the size of workspace, an evaluation standards of the size of workspace is presented based on the mechanism of the center height. This paper proposes an novel 2URS&UPS parallel robot, it has Six degree of freedom. By using the sphere coordinate searching method, through the MTLAB programming calculated the influence of structural parameters on the workspace. Analysis results show that the parallel robot has the maximum workspace, when the static platform radius is 140mm and the moving platform radius is 120 mm, the rod length is 160mm. The study showed the parallel robot has advantage of a large workspace and symmetry. The parallel robot can be used for walking leg, mechanism arm, etc. The paper provide a theoretical basis for design of the parallel robot.

Abstract: It introduces ways and means of designing this kind of vibration absorbers which are presented using parallel mechanisms as the main mechanisms ,it ,which takes the parallel mechanisms with 3-DOF translation as an example, validates the feasibility of the method, and enumerates some of the parallel mechanisms that are fit for multi-DIM vibration absorber. In a word, the multi-DIM vibration absorber system based on parallel mechanism is a new idea and breakthrough in multi-DIM vibration absorption field, which has the characteristic of simple structure, compact mechanism, high accuracy, partially or fully decoupled mechanism easy for control and so on, and provides a new method for the study of Multi-DIM vibration.

Abstract: This paper designs a modular parallel mechanism for single-driven multi-legged robots. The mechanism achieves the goal to coordinate the lifting and swinging of all the legs with only one actuator and has good motion characteristics. The mechanism is not only easy to control, but also capable to optimize the trajectory of the robot legs by changing the structure size of the mechanism. This paper implements the trajectory simulation and dynamic simulation of the key points of the mechanism on the basis of the kinematics model, and the results show that the mechanism has a good trajectory and motion characteristics. The modular parallel mechanism is also applicable to those multi-legged robots such as quadruped robots and eight-legged robots, indicating that it has a good scalability.

Abstract: The base of Parallel loading device withstand the pressure of hundreds of tons, Limited by the conditions of use, All components of the device must be manual handling, so Its weight becomes very sensitive. The initial design weight of base are about 170 kg, By handling environmental constraints, four men lift is also very convenient, Therefore it's urgent to reduce weight. In this paper, a powerful modeling capabilities of UG combined ANSYS topology optimization module on the base for a topology optimization, We refer to the shape of topology optimization design of the final design of the structure. Through finite element analysis, the structural stiffness and strength to meet the design requirements, And weight decreased from about 170 kg to 120 kg, reduced by nearly 30%.