Session WedAT1 Pegaso A Wednesday, October 10, 2012 ... - Lirmm
Session WedAT1 Pegaso A Wednesday, October 10, 2012 ... - Lirmm
Session WedAT1 Pegaso A Wednesday, October 10, 2012 ... - Lirmm
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<strong>Session</strong> WedFT5 Gemini 2 <strong>Wednesday</strong>, <strong>October</strong> <strong>10</strong>, <strong>2012</strong>, 16:15–17:30<br />
Contact Modeling<br />
Chair Rui Cortesao, Univ. of Coimbra<br />
Co-Chair<br />
16:15–16:30 WedFT5.1<br />
Synthesis and Stabilization of Complex Behaviors<br />
through Online Trajectory Optimization<br />
Yuval Tassa, Tom Erez and Emanuel Todorov<br />
Computer Science & Engineering, University of Washington, USA<br />
• Online trajectory optimization<br />
method and software platform.<br />
• iterative-LQG trajectory optimizer.<br />
• Fast, in-house physics engine with<br />
novel contact models.<br />
• Full humanoid behavior generated in<br />
7 x slower than realtime, simpler<br />
problems already in real-time.<br />
• Nothing is precomputed, no heuristic<br />
approximations to the Value function<br />
are used.<br />
Humanoid getting up<br />
16:45–17:00 WedFT5.3<br />
Robust Sensing of Contact Information for<br />
Detection of the Physical Properties of an Object<br />
Takashi Takua, Ken Takamine, and Tatsuya Masuda<br />
Department of Electrical and Electronic Systems Engineering,<br />
Osaka Institute of Technology, Japan<br />
• Robust sensing that estimate the contact information, reaction force from<br />
the object and consequent joint displacement during pushing the object, is<br />
proposed<br />
• Using certain kinetic and kinematic relationships on 1-DoF joint<br />
mechanism and physical property of the McKibben pneumatic actuator,<br />
the relationships among magnitude of the force on the contact point, the<br />
joint angle, and the inner pressure of the actuator are derived.<br />
• The relationship is evaluated using<br />
physical 1-DoF joint mechanism, and,<br />
elasticity of the object is estimated by<br />
using the relationships.<br />
• Experiments show that the robust<br />
sensing of the contact information<br />
that avoids attaching the sensors on<br />
the contact point and the joint can be<br />
obtained, and that physical property<br />
of the object can be estimated.<br />
17:15–17:30 WedFT5.5<br />
Comparison of Position and Force-Based<br />
Techniques for Environment Stiffness<br />
Estimation in Robotic Tasks<br />
Fernanda Coutinho and Rui Cortesão<br />
Institute of Systems and Robotics, University of Coimbra, Portugal<br />
• In this paper, we compare the results of position-based stiffness<br />
estimation algorithms with those obtained by COBA.<br />
• COBA is an online stiffness estimation algorithm based on force data<br />
only.<br />
• COBA avoids some problems that can negatively affect the<br />
performance of position-based algorithms.<br />
16:30–16:45 WedFT5.2<br />
Trajectory optimization for domains with contacts<br />
using inverse dynamics<br />
Tom Erez and Emanuel Todorov<br />
Computer Science, UW-Seattle, USA<br />
• Trajectory optimization in domains with contact (e.g., ground reaction<br />
forces) is notoriously hard due to the discontinuities at impact.<br />
• We use a soft contact model that can be used with both forward and<br />
inverse dynamics, thereby formulating a continuous optimization problem.<br />
• The algorithm was applied to a 3D simulated humanoid running domain<br />
with 31 degrees of freedom. After ~2500 Newton steps (~<strong>10</strong> minutes on a<br />
standard desktop) a complex running gait emerges.<br />
• Almost all computation time is spent on finite-differencing the dynamics.<br />
Since this bottleneck is trivially parallelizable, our approach stands to<br />
benefit from Moore’s law and any other improvements in parallel CPU<br />
architecture.<br />
17:00–17:15 WedFT5.4<br />
Modeling and Simulation of Friction Forces during<br />
Needle Insertion Using Local Constraint Method<br />
Lijuan Wang, Zhongkui Wang, and Shinichi Hirai<br />
Department of Robotics, Ritsmeikan University, Japan<br />
• In the modern clinical practice, accurate<br />
orientation inside soft tissue is difficult to<br />
achieve, because of complicated tissue<br />
deformations and the interaction forces.<br />
• A dynamic model of needle insertion with<br />
friction forces is proposed based on the<br />
Finite Element Method (FEM).<br />
• The relative velocity and contact length are<br />
considered as the main factors of friction<br />
forces during needle insertion.<br />
• Simulations using Local Constraint Method<br />
(LCM) are proposed. Local constraints and<br />
friction forces are calculated and applied<br />
onto the tissue frame to avoid remeshing.<br />
<strong>2012</strong> IEEE/RSJ International Conference on Intelligent Robots and Systems<br />
–174–<br />
A series of Local Regions along<br />
the needle insertion path.