Research On A Six-Pyramid Parallel Robot Driven By Linear Actuator

Parallel robot has strong bearing capacity, small accumulated error, fast dynamic response and other advantages, so it gradually becomes one of the research focus. This dissertation presents a novel parallel robot driven by linear actuator which rail was tilted as a six pyramid. Combined the method of simulation analysis and experimental verification, mechanism、kinematics and dynamics theory of parallel robot has conducted in-depth research to deepen the parallel robot theory and expand engineering application. This dissertation mainly includes the following several aspects of the theory and experiment research:(1) The general structure scheme of the six pyramid parallel robot driven by linear actuator is presented. The structural characteristics of typical Stewart and Hexaglide are analyzed from drive source, hinge and rail structure. Set the maximum angle and maximum frequency as basic performance index, determined the overall program consist of linear actuator and six pyramid rail, through the analysis it has the advantages of high speed and precision, small moment of inertia and large rotation angle.(2) The kinematics and dynamics model of six pyramid parallel robot are established. According to the geometric constraints that the length of the connecting rod is invariant, the displacement, velocity and acceleration mapping relationship between load platform and linear actuator are established using geometric method and derivation method, and obtained the Jacobian matrix of the robot. Particle system combined with Lagrange method to establish force relationship between load platform and linear actuator is proposed. The kinetic energy is calculated regarding the connecting rod as a particle system, which can guaranteeing the computing speed and improves the precision of the model. The mathematical model is the base of follow-up to more in-depth theoretical study and engineering application of the robot theory.(3) Main structure parameters are determined. With compact structure, no singular and mechanical interference principle, the effects of parameter such as connecting rod length, load platform radius and angle of tilt rail change on translation and rotation performance are discussed, the relationship between frequency and force, angle of tilt rail and consumption are analyzed. Completion the engineering design of the robot and selection and configuration of hardware/software based on dSPACE are done successfully developed a prototype and control system, then the kinematics and dynamics of example verification experiment are done to show that the model is correct, feasible. (4) Singularity and workspace of the six pyramid parallel robot has conducted in-depth research. Based on Jacobian matrix, singular condition of the six pyramid parallel robot is discussed, and introduce the operational characterization to show the degree of path away from the singularity; workspace constraints are analyzed, and three axis motion range and rotate range are obtained using the cylindrical coordinate search method, provide a theoretical basis for track planning. Experiment for the performance of prototype show that the performance of prototype and simulation results and can meet the design requirements of performance index.(5) Optimization of driving forces under redundancy task of the six pyramid parallel robot has conducted in-depth research. Set instantaneous kinetic energy as the optimization target, optimization and validation experiment of single degree of freedom and3DOF redundant driving force distribution are done respectively using the extreme value method and genetic algorithm. The results show that, contrast with zero trajectory case on the redundant degree of freedom, optimized mechanism energy consumption is greatly reduced; the optimization method is correct and feasible.(6) Applications of six pyramid parallel robot in the field of vehicle engineering were studied. Based on the prototype characteristics and the requirements of different application occasions, the application scheme of vehicle parts of the vibration test is presented. National A-class road spectrum is obtained using harmonic superposition method by programming with Matlab, and the vibration of vehicle parts on six degree of freedom are obtained by a simplified model. Vibration experiments done to show that the six pyramid type parallel robot can reproduce the vibration of vehicle parts.