Guest Editorial: Special Issue on Haptics in Rehabilitation and Neural Engineering

Ç THIS special issue on Haptics in Rehabilitation and Neural Engineering is focused on broadening our understanding of the role of touch in sensorimotor coordination, including rehabilitation of motor deficits and use of advanced prostheses and orthoses. The articles presented in this issue confirm that the science and technology of haptics has great potential to affect the outcomes of rehabilitation and adoption of advanced prosthetic and orthotic devices. A first topic addressed in the issue is how rehabilitation robots that employ kinesthetic or tactile feedback can lead to an enhancement of therapeutic results. The engagement of the sensorimotor system, and in particular the provision of haptic feedback to the participant during rehabilitation, is an important factor in regaining motor control. In fact, robotic devices have been shown to be effective at delivering the intensive and repetitive therapy that is known to induce brain plasticity and foster restoration of motor coordination after stroke, spinal cord injury, and other neural impairments. This area saw the largest number of submissions, and featured in the special issue. Carlo Alberto Avizzano, Massimo Satler, and Emanuele Ruffaldi present a mobile haptic interface capable of providing two degree-offreedom force rendering intended for upper limb rehabilitation in their article titled, “Portable Haptic Interface with Omni-Directional Movement and Force Capability.” The paper characterizes a novel control architecture and force feedback performance. In the paper by Sumner L. Norman, Andrew J. Doxon, Brian T. Gleeson, and William R. Provancher, “Planar Hand Motion Guidance Using Fingertip Skin-Stretch Feedback,” the authors investigated how skin stretch feedback provided to the fingerpad as corrective path feedback can accurately guide users through planar hand movements, with potential application to humanmachine interaction, such as upper-extremity rehabilitation. “Design of a Robotic Mobility System with a Modular Haptic Feedback Approach to Promote Socialization in Children” by Xi Chen, Christina Ragonesi, James C. Galloway, and Sunil K. Agrawal is a novel study in which a powered mobility device, a tracking system andmodular haptic feedback are combined within a ball-chasing game (including several children and a caregiver) with the goal of promoting socialization. In particular, an ‘assist as needed’ haptic algorithm was implemented and used with five toddlers (training group) while another five toddlers (control group) operated without force field feedback. Results showed that children in the training group drove closer to the ball possessed by a group of peers with the help of the force field and also demonstrated short-term learning. This study opens interesting possibilities of exploiting haptic channels to reduce mobility barriers and to promote socialization in children. The article “Neurocognitive RobotAssisted Therapy of Hand Function” by Jean-Claude Metzger, Olivier Lambercy, Antonella Califfi, Fabio M. Conti, and Roger Gassert is a preliminary study on the rehabilitation of hand functions in patients with neurological disorders. A two degree-of-freedom haptic device, ReHapticKnob, is used to train hand opening/closing as well as forearm rotation during exercises which involve motor, sensory as well as cognitive aspects. Unlike conventional visually guided rehabilitation tasks, high-definition haptic rendering of virtual objects was used in neurocognitive exercises. Preliminary tests on five patients suffering from different neurological disorder and different impairment levels, showed positive results in terms of feasibility and acceptance of the proposed exercises, underlining the potential of this approach to integrate haptics for intensive sensorimotor therapy of hand function. Fabien V erit e, Wael Bachta, and GuillaumeMorel, in their article, “Closed Loop Kinesthetic Feedback for Postural Control Rehabilitation,” describe the implementation of a closed-loop kinesthetic characterize responses of 11 healthy subjects using openversus closed-loop feedback. The results demonstrate that subjects are better able to control their center of pressure using closed-loop feedback. The study also investigates how other conditions (e.g., vision, secondary task) affect performance and conclude that this type of kinesthetic feedback has potential uses for rehabilitative balance training. Andrew Theriault, Mark Nagurka, and Michelle J. Johnson, in their article “Design and Development of an Affordable Haptic Robot with Force-Feedback and Compliant Actuation to Improve Therapy for Patients with Severe Hemiparesis,” focus on a safe, robust, low cost, and adaptive robotics device, suitable to be used at home and in small clinical centers. Safety, robustness and low-cost requirements are balanced via mechanical torquelimiting mechanisms. An impedance controller is also proposed that adapts its parameters to the evolving performance of its users. Finally, Stefano Mazzoleni, Luciano Puzzolante, Loredana Zollo, Paolo Dario, and Federico Posteraro present a clinical study in their paper “Mechanisms of Motor Recovery in Chronic and Subacute A. Frisoli is with PERCRO Laboratory, TeCIP Institute of Scuola Superiore Sant’Anna, via Moruzzi 1, 56123 Pisa, Italy. E-mail [email protected]. M. O’Malley is with the Department of Mechanical Engineering, Rice University, 6100 Main Street, MS 321, Houston, TX 77005-1892. E-mail: [email protected]. D. Campolo is with the School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798. E-mail: [email protected]. K. Sienko is with the Department of Mechanical Engineering, University of Michigan, 2350 Hayward St., 3116 GG Brown, Ann Arbor, MI 48109. E-mail: [email protected].