An off-line robot motion planning approach for the reduction of the energy consumption

Abstract

The paper proposes an off-line robot motion planning approach, aimed at the reduction of the energy consumption, for any trajectory defined on a set of target points including some "fly" ones, i.e., points that must not be exactly reached by the robot. The proposed solution is based on the search for alternative paths close to the fly target points originally defined by the operator, and on the computation of the mechanical and total energy associated to each single possible motion defined for the generated alternative paths. A branch and bound algorithm is employed to scan all the possible motions and find the complete trajectory that corresponds to the minimum energy consumption. The approach has been implemented in a software architecture that exploits some COMAU software modules, but it could be easily adapted to generic, similar modules. The results that have been experimentally obtained for two typical industrial cycles, performed by a COMAU Racer robot, can be considered as very satisfying.

A Review on Energy-Saving Optimization Methods for Robotic and Automatic Systems

“…In MP trajectory optimization, the energy consumption of a mechatronic system is achieved by both optimizing the path and the timing [68][69][70][79][80][81]. In literature, the studied systems are usually multi-degrees-of-freedom systems.…”

“…The system dynamics are usually modeled by means of a classical formulation, Equations (1) and (2). Generally, parameters are retrieved by datasheet, by CAD, or are estimated on the basis of some assumptions [68,70,[79][80][81]. Rarely are the dynamic parameters obtained through an identification procedure such as that in [69], for which the robot performs a specific excitation trajectory and data about torque, speed and acceleration are collected directly or indirectly before the dynamic parameters are extrapolated.…”

“…In literature, the studied systems are usually multi-degrees-of-freedom systems. If planar motion is to be achieved, both planar (e.g., two-degrees-of-freedom [70] and three-degrees-of-freedom [68] redundant manipulators) and spatial kinematics (e.g., six-degrees-of-freedom anthropomorphic industrial manipulators [69,[79][80][81]) are exploited. The system dynamics are usually modeled by means of a classical formulation, Equations (1) and (2).…”

“…In [79], a path of at least three points (either "no-fly" or "fly" points), connected through straight lines and circular arcs in the proximity of a fly point is planned. The method searches among alternative paths, close to the fly points, so as to reduce the energy consumption during the execution of the trajectory, without worsening the cycle time.…”

“…In literature, different approaches are used to build the model; it can be defined through a mathematical formulation and by considering only the main important factors (i.e., basic mathematical model) , or it is possible to also take into account secondary terms that increase the results' precision but on the other hand need more computational efforts (i.e., extended mathematical model) [71][72][73][74][75][76][77]. The availability of software simulation tools allows thus the simple implementation of complex extended models [78][79][80][81] that can describe several physical domains [37,[82][83][84][85]. These allow for the integration of several simulation approaches that are evaluated separately: control, kinematic, dynamic, physical behavior, and discrete event simulations [83].…”