@proceedings {082211289622, title = {Disturbance observer based closed loop force control for haptic feedback}, volume = {9 PART B}, year = {2007}, note = {

Disturbance observer;Haptic feedback;Pseudostatic interactions;

}, pages = {1343 - 1349}, address = {Seattle, WA, United States}, abstract = {

Most commonly used impedance-type haptic interfaces employ open-loop force control under the assumption of pseudostatic interactions. Advanced force control in such interfaces can increase simulation fidelity through improvement of the transparency of the device, and can further improve robustness. However, closed loop force-feedback is limited both due to the bandwidth limitations of force sensing and the associated cost of force sensors required for its implementation. In this paper, we propose the use of a nonlinear disturbance observer for estimation of contact forces during haptic interactions. This approach circumvents the traditional drawbacks of force sensing while exhibiting the advantages of closed-loop force control in haptic devices. The feedback of contact force information further enables implementation of advanced robot force control techniques such as robust hybrid impedance and admittance control. Simulation and experimental results, utilizing a PHANToM Premium 1.0A haptic interface, are presented to demonstrate the efficacy of the proposed approach. Copyright {\textcopyright} 2007 by ASME.

}, keywords = {Computer simulation, Force control, Haptic interfaces, Robotics, Robustness (control systems)}, attachments = {https://mahilab.rice.edu/sites/default/files/publications/50-gupta-imece07.pdf}, author = {Abhishek Gupta and O{\textquoteright}Malley, M.K. and Volkan Patoglu} } @article {06199869875, title = {Shared control in haptic systems for performance enhancement and training}, journal = {Journal of Dynamic Systems, Measurement and Control, Transactions of the ASME}, volume = {128}, number = {1}, year = {2006}, note = {

Virtual environments;Mass-spring-damper;System dynamics;Shared control;

}, pages = {75 - 85}, chapter = {75}, abstract = {

This paper presents a shared-control interaction paradigm for haptic interface systems, with experimental data from two user studies. Shared control, evolved from its initial telerobotics applications, is adapted as a form of haptic assistance in that the haptic device contributes to execution of a dynamic manual target-hitting task via force commands from an automatic controller. Compared to haptic virtual environments, which merely display the physics of the virtual system, or to passive methods of haptic assistance for performance enhancement based on virtual fixtures, the shared-control approach offers a method for actively demonstrating desired motions during virtual environment interactions. The paper presents a thorough review of the literature related to haptic assistance. In addition, two experiments were conducted to independently verify the efficacy of the shared-control approach for performance enhancement and improved training effectiveness of the task. In the first experiment, shared control is found to be as effective as virtual fixtures for performance enhancement, with both methods resulting in significantly better performance in terms of time between target hits for the manual target-hitting task than sessions where subjects feel only the forces arising from the mass-spring-damper system dynamics. Since shared control is more general than virtual fixtures, this approach may be extremely beneficial for performance enhancement in virtual environments. In terms of training enhancement, shared control and virtual fixtures were no better than practice in an unassisted mode. For manual control tasks, such as the one described in this paper, shared control is beneficial for performance enhancement, but may not be viable for enhancing training effectiveness. Copyright \© 2006 by ASME.

}, keywords = {Control equipment, Damping, Data reduction, Haptic interfaces, Robotics, Robots}, issn = {0022-0434}, doi = {10.1115/1.2168160 }, url = {http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal\&id=JDSMAA000128000001000075000001\&idtype=cvips\&gifs=yes}, attachments = {https://mahilab.rice.edu/sites/default/files/publications/52-00\%20-\%20JDSMC\%20Shared\%20control.pdf}, author = {O{\textquoteright}Malley, M.K. and Abhishek Gupta and Gen, Matthew and Yanfang Li} } @proceedings {7780496, title = {Passive and active assistance for human performance of a simulated underactuated dynamic task}, year = {2003}, note = {

simulated underactuated dynamic task;machine-mediated training;virtual fixtures;active assist;haptic feedback;visual feedback;

}, pages = {348 - 55}, address = {Los Angeles, CA, USA}, abstract = {

Machine-mediated training of dynamic task completion is typically implemented with passive intervention via virtual fixtures or active assist by means of record and replay strategies. During interaction with a real dynamic system however, the user relies on both visual and haptic feedback real-time in order to elicit desired motions. This work investigates human performance in a Fitts{\textquoteright} type targeting task with an underactuated dynamic system. Performance, in terms of number of hits and between-target tap times, is measured while various passive and active control modes are displayed concurrently with the haptic feedback from the simulated system{\textquoteright}s own dynamic behavior. It Is hypothesized that passive and active assist modes that are implemented during manipulation of simulated underactuated systems could be beneficial in rehabilitation applications. Results indicate that human performance can be improved significantly with the passive and active assist modes

}, keywords = {Haptic interfaces, Virtual reality}, url = {http://dx.doi.org/10.1109/HAPTIC.2003.1191308}, attachments = {https://mahilab.rice.edu/sites/default/files/publications/omalley2003HAPTICS.pdf}, author = {O{\textquoteright}Malley, M.K. and Abhishek Gupta} } @proceedings {7971173, title = {Skill transfer in a simulated underactuated dynamic task}, year = {2003}, note = {

underactuated dynamic system;Fitts{\textquoteright} type;skill transfer;haptic feedback;

}, pages = {315 - 20}, address = {Millbrae, CA, USA}, abstract = {

Machine-mediated teaching of dynamic task completion is typically implemented with passive intervention via virtual fixtures or active assist by means of record and replay strategies. During interaction with a real dynamic system however, the user relies on both visual and haptic feedback in order to elicit desired motions. This work investigates skill transfer from assisted to unassisted modes for a Fitts{\textquoteright} type targeting task with an underactuated dynamic system. Performance, in terms of between target tap times, is measured during an unassisted baseline session and during various types of assisted training sessions. It is hypothesized that passive and active assist modes that are implemented during training of a dynamic task could improve skill transfer to a real environment or unassisted simulation of the task. Results indicate that transfer of skill is slight but significant for the assisted training modes

}, keywords = {computer based training, Haptic interfaces, learning (artificial intelligence), Virtual reality}, url = {http://dx.doi.org/10.1109/ROMAN.2003.1251864}, attachments = {https://mahilab.rice.edu/sites/default/files/publications/omalley2003ieeeskilltrans.pdf}, author = {O{\textquoteright}Malley, M.K. and Abhishek Gupta} }