@INPROCEEDINGS{2012:Robotik_Lens_etal,
  author = {T. Lens and A. Karguth and O. von Stryk},
  title = {Safety Properties and Collision Behavior of Robotic Arms with Elastic Tendon Actuation},
  year = {2012},
  booktitle = {Proceedings of ROBOTIK},
  abstract = {Applications with physical human-robot interaction require a high level of safety even in case of software or hardware failures. This paper highlights the advantages of combining tendon actuation with transmission elasticity to maximize safety for robotic arms sharing workspaces with humans. To this end, the collision behavior of combinations of tendon or joint and elastic or stiff actuation with geared electrical motors as reliable actuators is compared using the lightweight BioRob arm as robotic platform in simulation. For the comparison a worst case scenario is assumed in which the robot arm is accelerated with maximum supply voltage over its joint range and collides with maximum end-effector velocity. The study shows that the robot arm achieves end-effector velocities as high as 6m/s and that elastic tendon actuation reduces the end-effector impact energy and force by up to 90% compared to stiff joint actuation. A considerable reduction of the gearbox stress is also achieved. In addition, the effect of motor current fuses limiting the motor torques is evaluated. It is shown that for the given high speed scenario, torque limiting devices can be effective to prevent excessive clamping forces in case of failure, but can not reduce the impact peak force without heavily compromising the robot dynamics. The main design criterion for safety should therefore be lightweight link design and compliant actuation, which can be achieved by using elastic tendon actuation. The paper concludes with the comparison of safety properties of robotic arms in research and industry.},
}

@INPROCEEDINGS{2012:IEEE-BioRob_VTS,
  author = {J. Schuy and P. Beckerle and J. Wojtusch and S. Rinderknecht and O. von Stryk},
  title = {Conception and evaluation of a novel variable torsion stiffness for biomechanical applications},
  year = {2012},
  pages = {to appear},
  booktitle = {4th IEEE RAS/EMBS Intl. Conf. on Biomedical Robotics and Biomechatronics (BioRob)},
  abstract = {Abstract—This paper proposes a novel variable torsion stiffness (VTS) aiming on biomechanical applications like prosthetic knee joints. By varying the effective length of a torsional elastic element via a relocatable counter bearing, the stiffness of a rotational joint is adjusted. This functional concept is described in detail by the authors as well as the design of such VTS joints. Additionally, analytical models for the transfer behaviour of drivetrain and stiffness control are derived. These are used for a simulative evaluation of a pendulum driven by a VTS unit. Based on the results of this simulation, the power requirements of VTS are analysed. Furthermore, an analysis of its structural strength is presented. For practical comprehensibility, the example of the design of a prosthetic knee joint is taken up for several times in this paper. Finally, the concept, modeling and design of VTS as well as the simulation results are concluded and discussed in a final assessment and in comparison to other contemporary concepts.},
}

@TECHREPORT{2012:rescue_tdp,
  author = {Thorsten Graber and Stefan Kohlbrecher and Johannes Meyer and Karen Petersen and Oskar von Stryk and Uwe Klingauf},
  title = {RoboCupRescue 2012 - Robot League Team Hector Darmstadt (Germany)},
  year = {2012},
  institution = {Technische Universität Darmstadt},
  pdf = {2012_tdp_hector.pdf},
  abstract = {This paper describes the approach used by Team Hector Darmstadt for participation in the 2012 RoboCup Rescue League competition. Participating in the RoboCup Rescue competition since 2009, the members of Team Hector Darmstadt focus on exploration of disaster sites using autonomous Unmanned Ground Vehicles (UGVs). The team has been established as part of a PhD program funded by the German Research Foundation at TU Darmstadt and combines expertise from Computer Science and Mechanical Engineering. We give an overview of the complete system used to solve the problem of reliably finding victims in harsh USAR environments. This includes hardware as well as software solutions and diverse topics like locomotion, SLAM, pose estimation, human robot interaction and victim detection. As a contribution to the RoboCup Rescue community, major parts of the used software have been released and documented as open source software for ROS.},
}

@TECHREPORT{2012:dd_tdp,
  author = {J. Kuhn and S. Kohlbrecher and K. Petersen and D. Scholz and J. Wojtusch and O. von Stryk},
  title = {Team Description for Humanoid KidSize League of RoboCup 2012 },
  year = {2012},
  institution = {Technische Universität Darmstadt},
  pdf = {2012_tdp_hum.pdf},
  abstract = {This paper describes the hardware and software design and developments of the kidsize humanoid robot systems of the Darmstadt Dribblers in 2012. The robots are used as a vehicle for research in humanoid robotics and teams of cooperating, autonomous robots. The Humanoid League of RoboCup provides an ideal testbed for investigation of topics like stability, control and versatility of humanoid locomotion, behavior control of autonomous humanoid robots and robot teams with many degrees of freedom and many actuated joints, perception and world modeling based on very limited human-like, external sensing abilities as well as benchmarking of autonomous robot performance. The methodologies developed by the Darmstadt Dribblers to address reflex and cognitive control layers, image processing, perception, world modeling, behavior and motion control, robot simulation, monitoring, debugging and bio-inspired humanoid robot bodyware are briefly discussed. },
}