Session WedAT1 Pegaso A Wednesday, October 10, 2012 ... - Lirmm

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