Page - 59 - in Joint Austrian Computer Vision and Robotics Workshop 2020

SeveralApproaches for theOptimizationofArmMotionsofHumanoids DanielLichtenecker,GabrielKro¨g,HubertGattringerandAndreasMu¨ller InstituteofRobotics, JohannesKeplerUniversityLinz, Altenbergerstraße69,4040Linz,Austria www.robotik.jku.at {daniel.lichtenecker,gabriel.kroeg,hubert.gattringer,a.mueller}@jku.at Abstract.Thispaperpresents several point-to-point optimization tasksofhumanoidarmmotions. Thefo- cus lies on optimization of elementary armmotions. Several cost functions for optimization tasks are de- fined. Tasks in respect of timeoptimal control,mini- mizingjoint loadsandmaximizing thevertical torque of the torsoarepresented. Thedynamicoptimalcon- trol problem is transformed into a static paramet- ric optimization problem by using B-spline curves. The optimization is carried out with the Sequential QuadraticProgrammingalgorithm. 1. Introduction Ingeneral, roboticsystemsashumanoidsarecom- plex structures which are able to interact with their environment. The research on humanoid robots is a major and challenging part in the field of robotics. Various humanoid robotic systems have been de- veloped in the past, see e.g. [5, 7]. Moreover, a humanoid walking machine is developed at the Jo- hannesKeplerUniversityLinz [6]. Fig. 1 shows the modularsetupof thehumanoidbymeansofsubmod- ules. In this configuration, the systempossesses of 6 degrees of freedom (DOFs) per leg and 1DOF per arm. Figure1: Schematic representation of thebiped v0,2 q2 x y z q3 g q1 ωF,2 r23 Figure 2: Schematic representation of the analyzed armsystem Especially thearmplaysan important role regard- ing interaction ormanipulation of an object. More- over, arms are used to counterbalance the torque about the vertical axis. In order to achieve a higher degreeofmobility of thearmsubmodule, anewarm system is developed. The system consists of 3 actu- ators and structural elements which aremodeled as rigidbodies. Theshoulder is represented by2DOFs and the elbowhas1DOF.That setup is an approach toward the 7DOFs armmodule as presented in [1]. In this paper thearmmodule shown inFig. 2 is con- sidered (whichwill replace the rigid arm inFig. 1). Thepaperfocusesonoptimizationofelementaryarm motionswith respect tovariousgoals. Start andfinal configurations of the armsystemwill be regarded as known fromthehumangait. As shown inFig. 2, the arm system is spatial fixed for all further investiga- 59