Study On Design And Control Of 3-TPS Hybrid Robot Based On Digital Prototype

With the rapid advancement of industrial automation,the robots technology with high precision,high efficiency,intelligence and industrialization are the directions in developing modern robot technology.Moreover,the hybrid robot with many advances is considered as the direction in developing modern industrial machining equipments.Although the structure of hybrid robot is very simple,in the view of its complicated control method,various mechanisms and geometrical parameters resulting in the different inverse kinematics models.Because the hybrid robot is needed to be controlled by multi-axis linkage,the requirements in terms of accuracy,openness,flexibility and the character of real-time of its numerical control system are quite high.A hybrid robot is researched and developed by repeatedly comparable multi-scheme experiments with a lot of technical investments and a quite long development cycle.The key technologies of hybrid robots,in terms of rapid design,precision analysis,identification of structural parameters,improving the motion control technique and optimization of performance with the available technology,were considered and solved based on relevant researches.A theoretical modeling and comprehensive analysts with simulations and experiments was conducted by using numerical prototype according to the 3-TPS hybrid robot's structure characteristics and task space with five-degree freedom developed by Northeastern University independently.Therefore,the digital prototype can provide significant references to hybrid robot's structural design,precision analysis,control system implementation and feasibility for application.The main contents were shown as follows:(1)The hybrid robot's mathematical kinematics model was built and the range of its task space was determined according to the 3-TPS hybrid robot's structure characteristics and the requirement of five-degree freedom task space.The hybrid robot's position inverse solution and analysis of the relationship between structural parameters and task space were also deduced in this paper.Moreover,the concept of effective task space was proposed and the effect of relevant parameters on its sensitivity was also investigated.(2)The curves of robot's velocity,acceleration and force of the driving poles were obtained by hybrid robot's kinematic and dynamic characteristics analysis based on the problems of its motor parameter selection and part design.The statics and modal analysis of the key assembly units using CAE technique was conducted.The analysis of hybrid robot's overall and key components was deduced,which provides references for optimization design of the mechanism.(3)Multi axis motion controller was selected as the core component of 3-TPS hybrid robot's control system,according to its characteristics and motion functions.Two different position control methods such as kinematic buffer and rotary motion buffer were discussed.Furthermore,the robot's velocity control method has also been discussed.All the methods mentioned would provide the foundation of the design for control systems.(4)An open numerical control system hardware platform of 3-TPS hybrid robot was designed and built.And the software platform of control system and relevant applications was developed as well.Additionally,the theory applied to Clipper controller's multi axis motion controller interfaces and servo-circuit was analyzed.The open numerical system hardware platform was designed.The structure of hybrid robot's numerical system software platform was laid out.The theory and progress of its motion control was determined.The development of G-code program and man-machine interaction interface was conducted,which realizes the motion and auxiliary function of hybrid robot's numerical system.(5)The calibration on errors in 3-TPS hybrid robot's main structures was conducted.Moreover,the effect of errors existing in the length of bars and the positions of hinges on terminal platform poses was analyzed,according to which the mathematical model of errors in structural calibration was built.With the calibration experiment on hybrid robot,the experimental data were obtained.Furthermore,the actual length of bars in hybrid robot and its hinges'*coordinates can be acquired by means of parameter identification.Finally,by replacing theoretical structural parameters with actual ones in the kinematic equations,the comparison of robot's motion precision with and without calibration can be conducted.(6)The motion control and machining experiments were conducted.Moreover,the 3-TPS hybrid robot's control system was proven to be feasible based on Clipper controller and the validity of its kinematics inverse model and motion program was verified as well based on 4 degrees of freedom planar motion and 5 degrees of freedom space motion experiments.