Research On Motion Control Of DELTA Robot Based On Dynamic Model

Industrial robots are the basis of manufacturing industry. The wide use of industrialrobots can not only promote the production but also improve the products. DELTA robotis one kind of parallel robots that gain intense interest. One of the most advantages ofDELTA robot is that it can put the actuators on the base, which make high stiffness, highvelocity and high precision possible. DELTA robots are widely used in food packagingand electric industry. However, as a result of closed-loop chains, the kinematical anddynamic models are hard to compute and use in real time. In order to consider thedynamics of robot and make real-time calculation of dynamic model possible and easy,it is necessary to simplify the dynamic model and apply it into industrial application.Firstly, based on the simplified geometric model, eight possible inverse kinematicsolutions are studied and a new way to choose the right inverse kinematical angleamong eight choices is presented. A full kinematic model is set up and testified throughsimulation.Secondly, a full dynamic model is givern based on vitrual work principle. A plan tosimplify the full dynamic model is carried out after analysis to generalized mass matrix.Further more, the distribution of the generalized mass matrix in space is given.Thirdly, based on the calculated Jacobian matrix using marix method, the sigularityof the robot and methods to avoid the sigularity is analysed. According to the simplifieddynamic model, take the limit of actutors into consideration to get the maximumallowed velocity and acceleration of end-effector.Last, simulation platform and experiment platform are set up to study the followingerror of different control alghorithms. To make the simplified dynamic calculation inreal time, the gravity term is neglected and use a constant as the coefficient of velocityterm. The generalized mass matrix is fitted offline and is calculated through PLC in realtime. Through the modification of the parameters of PMAC, the inertia term is addedinto the control alghorithm as forwardfeed. Following errors of angle joint andend-effector are compared to test the control alghorithms.