Abstract
In this article, the concurrent optimal design of a planar five-bar parallel robot for a high-speed pick and place task is considered. A trade-off between trajectory tracking, energy consumption and deformation of the flexible links is sought. Due to the high-speed operation, the minimization of the vibratory effect is considered since the design stage. Thus, the design is stated as a non-linear multi-objective dynamic optimization problem that is solved through the Differential Evolution (DE) algorithm, as well as, feasibility rules for constraints handling. Mechanical structural variables that modify the inertial parameters of the rigid and flexible links, as well as, control variables related to gains of a PID controller are considered as independent variables. This problem is subject to maximum torque that each motor could provide; inherent constraints for link manufacture; dimensional synthesis; Grashof’s criterion and initial and boundary conditions. Results show that it is possible, despite the vibrational phenomenon, to reduce the energy consumption without loss of precision through an appropriate mass balance of the actuated links.
Highlights
Parallel robots have shown to have better repeatability properties than serial robots, [1]
The finite difference method FDM by [36] is a suitable procedure for the solution of a bi-dimensional equation such as the one faced; this is because a uniform cross-section geometry is considered, otherwise Finite Element Method (FEM) is more advisable
In this work, the structure-control design of a five-bar parallel robot is solved through the use of the Differential Evolution (DE) algorithm as a search engine and the use of finite differences as a tool to solve the dynamics of the flexible links
Summary
Parallel robots have shown to have better repeatability properties than serial robots, [1]. Parallel robots present lower inertia to movement since actuators are fixed, and as a consequence they are faster. Their structures are stiffer because the load is distributed among more links, [2]. The disadvantages of parallel robots consist of a smaller workspace and requiring a more complicated analysis of singularities than serial robots, [3], they appeared to be the preferred candidates for high-speed and high-precision tasks. Efficient robots must be more accurate and faster, and lighter. This fact leads to no longer considering a rigid model but a flexible one, which accounts for the elastic deformation on links, [4]. The distributed nature of the flexible links entails a non-minimum phase system with infinite degrees of freedom and for these reasons complicated controllers, [5], [6], or extra piezoelectric
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
