Enhanced approach for energy-efficient trajectory generation of industrial robots

Abstract

This paper proposes a novel cost function formu lation for minimization of the energy consumption of industrial robots by trajectory optimization. Besides the dynamics of the robot including friction losses, the model especially takes into account the losses of servo drives and inverters. Furthermore, the ability of energy exchange between the robot axes via the coupled DC-bus is included, since the servo drives support generator mode during deceleration. The utilized energy-based robot model is applicable to different manipulator types. For the energy-efficient motion planning, point-to-point trajectories are defined by B-spline functions. The given nonlinear optimization problem is solved using gradient-based methods, considering kinematic and dynamic constraints. Several simulation results are presented, demonstrating the intense effect of energy ex change in the robot controller's power electronics. Furthermore, a comparative study is given showing that the proposed method is able to outperform existing torque-based approaches.

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

“…Operation scheduling: Re-scheduling of subsequent movements and operations is considered. [72] 2014 Conference paper Trajectroy optimization PTP-direct Generic mechatronic system (1 DoF) [37] 2010 Conference paper Trajectroy optimization PTP-direct Serial robot (6 DoFs) [84] 2010 Journal paper Trajectroy optimization PTP-direct Serial robot (6 DoFs) [85] 2014 Journal paper Trajectroy optimization PTP-direct Serial robot (6 DoFs) [73] 2016 Journal paper Trajectroy optimization PTP-direct Mechatronic system (1 DoF)-constant inertia [74] 2012 Journal paper Trajectroy optimization PTP-direct Storage and retrieval vehicle (2 DoFs) [75] 2013 Journal paper Trajectroy optimization PTP-direct Storage and retrieval vehicle (2 DoFs) [38] 2013 Conference paper Trajectroy optimization PTP-inverse Serial robot (1 DoF) mounted on a flexible base [39] 2016 Journal paper Trajectroy optimization PTP-inverse Serial robot (1 DoF) mounted on a flexible base [40] 2016 Journal paper Trajectroy optimization PTP-inverse Redundant serial robot (3 DoFs) [41] 2010 Conference paper Trajectroy optimization PTP-inverse Serial robot (6 DoFs) [57] 2015 Conference paper Trajectroy optimization PTP-inverse Mechatronic system (1 DoF)-linear axis [42] 1996 Conference paper Trajectroy optimization PTP-inverse Serial robot (6 DoFs) [43] 2011 Journal paper Trajectroy optimization PTP-inverse Underactuated serial kinematics [44] 2011 Conference paper Trajectroy optimization PTP-inverse Underactuated serial kinematics [46] 2014 Journal paper Trajectroy optimization PTP-inverse Underactuated serial kinematics [49] 2013 Conference paper Trajectroy optimization PTP-inverse Generic mechatronic system (2 DoFs) [48] 2012 Conference paper Trajectroy optimization PTP-inverse Serial robot (6 DoFs) [50] 2012 Conference paper Trajectroy optimization PTP-inverse Generic mechatronic system (1 DoF) [51] 2011 Conference paper Trajectroy optimization PTP-inverse Mechatronic system (1 DoF)-positoning table [45] 2012 Conference paper Trajectroy optimization PTP-inverse Mechatronic system (1 DoF)-toggle mechanism [47] 2014 Journal paper Trajectroy optimization PTP-inverse Mechatronic system (1 DoF)-toggle mechanism [52] 2011 Conference paper Trajectroy optimization PTP-inverse Mechatronic system (1 DoF)-positioning table [53] 2012 Journal paper Trajectroy opt...…”

“…However, an exception is given by the [37,84,85] works, for which an extended model of a six-degrees-of-freedom anthropomorphic industrial manipulator is created, exploiting a model-based simulation tool. Indeed, the inverse approach has been adopted on a broad variety of systems with one degree of freedom-such as a liquid-crystal display glass-handling robot [43,44,46]; a toggle mechanism [45,47]; a precision positioning table [51][52][53]; a linear axis [57]; generic, one-degree-of-freedom systems [55,56,58]; and one-degree-of-freedom manipulators mounted on a flexible base [38,39]-with two degrees of freedom with rigid [49] and flexible links [59]; with three degrees of freedom, such as a redundant planar manipulator [40,54]; and with six degrees of freedom, such as an anthropomorphic industrial manipulator [41,42,48].…”

“…Often, for serial robots, the trajectory is formulated in the joint space exploiting either a high-degree polynomial [41,[43][44][45][46][47][51][52][53] or a B-spline formulation [40,48,49]. In [42], the phase-space representation (i.e., joint velocity versus joint angle interpolation with B-splines for each joint) of the trajectory between two points is considered, while in [38,39,57] and in [55,56,58], a cycloidal trajectory and a modified parabolic velocity profile are adopted, respectively.…”

“…where N j,d (t, k i ) are the basis functions and c i,j are the m + 1 control points [48]. The next step of the approach is to define a function to be minimized, referred to as the cost or objective function.…”

“…An exception to this common way to operate is presented in [48], where the losses of servo drives and inverters are taken into account as the bus-DC sharing is considered.…”