DocumentCode :
2701281
Title :
Stable, adaptive interaction and contact transition control of a high inertia haptic interface for haptic simulation in gait rehabilitation
Author :
Hussein, Sami ; Büchel, Moritz ; Krüger, Jörg
Author_Institution :
Rehabilitation Robot. Group, Tech. Univ. of Berlin, Berlin, Germany
fYear :
2011
fDate :
9-13 May 2011
Firstpage :
4176
Lastpage :
4181
Abstract :
In robot assisted rehabilitation the development of sophisticated training strategies using force and impedance control methods is an important field of research. The objective of the presented work is to provide a haptic control framework for end-effector based gait rehabilitation robots, which allows for the training of arbitrary foot trajectories of daily life and the design of sophisticated, patient-adaptive training environments. Due to the end-effector design principle the machine carries the patient´s full bodyweight during the whole training cycle which implies excessively high forces at the interaction ports. To allow for a guided movement under the described conditions the machine features powerful drives and a massive, stiff mechanical structure. This results in exceptionally high device inertia comparable to heavy-duty industrial robots and normally not common in haptic displays. To ensure stable interaction with a passive user and a known range of stiff and viscose virtual environments an adaptive virtual coupling controller is developed. To minimize the complexity of design procedure, a linear, discrete-time coupled and contact transition stability analysis is derived, taking into account the known target range of environments. The developed haptic controller was implemented and tested experimentally on the robotic walking simulator HapticWalker. It was shown to interact stably with virtual environments within the defined stiffness bounds. Further a set of lower target impedance parameters was evaluated in free motion without contact. An algorithm for the adaptation of the target damping was suggested to improve transparency during free motion while still ensuring a stable contact transition and interaction with stiff environment objects. The feasibility of the adaptive coupling controller was proven in free motion and walking experiments on the HapticWalker with the simulation static and dynamic virtual environments.
Keywords :
adaptive control; digital simulation; discrete time systems; end effectors; force control; haptic interfaces; linear systems; medical robotics; patient rehabilitation; stability; adaptive virtual coupling controller; contact transition control; contact transition stability analysis; dynamic virtual environments; end-effector design principle; force control method; gait rehabilitation robots; haptic control framework; haptic simulation; high inertia haptic interface; impedance control method; linear discrete-time coupled stability analysis; patient-adaptive training environments; robot assisted rehabilitation; robotic walking simulator HapticWalker; stable adaptive interaction; static virtual environments; target damping; Foot; Haptic interfaces; Impedance; Legged locomotion; Stability analysis; Virtual environments;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Robotics and Automation (ICRA), 2011 IEEE International Conference on
Conference_Location :
Shanghai
ISSN :
1050-4729
Print_ISBN :
978-1-61284-386-5
Type :
conf
DOI :
10.1109/ICRA.2011.5980396
Filename :
5980396
Link To Document :
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