@proceedings {082211289621, title = {Improved haptic fidelity via reduced sampling period with an FPGA-based real-time hardware platform (IMECE)}, volume = {9 PART B}, year = {2007}, note = {

Real Time Operating System (RTOS) control system;Proprietary control card;

}, pages = {1335 - 1342}, address = {Seattle, WA, United States}, abstract = {

Impedance based haptic interfaces face inherent challenges in displaying stiff virtual environments. Fidelity of a virtual environment is enhanced by stiff virtual walls combined with low damping and passive behavior of the interface. However, the stiffness of virtual walls displayed on an impedance based interface is limited by the damping inherent in the controller, the sampling rate of the control loop, and the quantization of the controller{\textquoteright}s position. Attempting to display a stiffness larger than this limiting value destroys the passivity of the interface, leading to active controller behavior and eventually closed loop instability. We propose a method of increasing the fidelity of a PHANToM Premium 1.0 commercial haptic interface by controlling it via a Field Programmable Gate Array (FPGA) both alone and with a Real Time Operating System (RTOS) control system. This custom controller enjoys several benefits over the standard control achieved via a proprietary control card in a Multitasking OS, including reduced system overhead and deterministic loop rate timing. The performance of the proposed FPGA/RTOS controller compares favorably with the performance of an FPGA/Multitasking OS controller. The FPGA/RTOS controller achieves control loop rates an order of magnitude greater than that of the proprietary controller, allowing virtual walls to be displayed with greatly increased stiffnesses, while retaining the passivity and low damping of the PHANToM interface. Copyright {\textcopyright} 2007 by ASME.

}, keywords = {Computer operating systems, Damping, Field programmable gate arrays (FPGA), Multitasking, Real time systems, Virtual reality}, attachments = {https://mahilab.rice.edu/sites/default/files/publications/56-IMECE2007-42085.pdf}, author = {Sevcik, Kevin S. and Kopp, E and O{\textquoteright}Malley, M.K.} } @article {071210493824, title = {Design of a haptic arm exoskeleton for training and rehabilitation}, journal = {IEEE/ASME Transactions on Mechatronics}, volume = {11}, number = {3}, year = {2006}, note = {

Arm exoskeletons;Apparent inertia;Design methodology;

}, pages = {280 - 289}, abstract = {

A high-quality haptic interface is typically characterized by low apparent inertia and damping, high structural stiffness, minimal backlash, and absence of mechanical singularities in the workspace. In addition to these specifications, exoskeleton haptic interface design involves consideration of space and weight limitations, workspace requirements, and the kinematic constraints placed on the device by the human arm. These constraints impose conflicting design requirements on the engineer attempting to design an arm exoskeleton. In this paper, the authors present a detailed review of the requirements and constraints that are involved in the design of a high-quality haptic arm exoskeleton. In this context, the design of a five-degree-of-freedom haptic arm exoskeleton for training and rehabilitation in virtual environments is presented. The device is capable of providing kinesthetic feedback to the joints of the lower arm and wrist of the operator, and will be used in future work for robot-assisted rehabilitation and training. Motivation for such applications is based on findings that show robot-assisted physical therapy aids in the rehabilitation process following neurological injuries. As a training tool, the device provides a means to implement flexible, repeatable, and safe training methodologies. \© 2006 IEEE.

}, keywords = {Damping, Degrees of freedom (mechanics), Joints (anatomy), Patient rehabilitation, Robot applications, Sensory perception, Stiffness}, url = {http://dx.doi.org/10.1109/TMECH.2006.875558}, attachments = {https://mahilab.rice.edu/sites/default/files/publications/47-IEEEASME_HapticArmExoskeleton.pdf}, author = {Abhishek Gupta and O{\textquoteright}Malley, M.K.} } @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 {05239144488, title = {Design of a haptic arm exoskeleton for training and rehabilitation}, volume = {73}, number = {2 PART B}, year = {2004}, note = {

Haptic arm exoskeleton;Inertia;Structural stiffness;Kinesthetic feedback;

}, pages = {1011 - 1018}, address = {Anaheim, CA, United States}, abstract = {

A high-quality haptic interface is typically characterized by low apparent inertia and damping, high structural stiffness, minimal backlash and absence of mechanical singularities in the workspace. In addition to these specifications, exoskeleton haptic interface design involves consideration of additional parameters and constraints including space and weight limitations, workspace requirements and the kinematic constraints placed on the device by the human arm. In this context, we present the design of a five degree-of-freedom haptic arm exoskeleton for training and rehabilitation in virtual environments. The design of the device, including actuator and sensor selection, is discussed. Limitations of the device that result from the above selections are also presented. The device is capable of providing kinesthetic feedback to the joints of the lower arm and wrist of the operator, and will be used in future work for robot-assisted rehabilitation and training. Copyright {\textcopyright} 2004 by ASME.

}, keywords = {Actuators, Bandwidth, Damping, Degrees of freedom (mechanics), Friction, Human computer interaction, Kinematics, Robotic arms, Robots, Sensors, Stiffness}, attachments = {https://mahilab.rice.edu/sites/default/files/publications/gupta2004asme.pdf}, author = {Abhishek Gupta and O{\textquoteright}Malley, M.K.} }