372 research outputs found
The Design and Characterization of a Soft Haptic Interface for Rehabilitation of Impaired Hand Function
abstract: The human hand comprises complex sensorimotor functions that can be impaired by neurological diseases and traumatic injuries. Effective rehabilitation can bring the impaired hand back to a functional state because of the plasticity of the central nervous system to relearn and remodel the lost synapses in the brain. Current rehabilitation therapies focus on strengthening motor skills, such as grasping, employ multiple objects of varying stiffness and devices that are bulky, costly, and have limited range of stiffness due to the rigid mechanisms employed in their variable stiffness actuators. This research project presents a portable cost-effective soft robotic haptic device with a broad stiffness range that is adjustable and can be utilized in both clinical and home settings. The device eliminates the need for multiple objects by employing a pneumatic soft structure made with highly compliant materials that act as the actuator as well as the structure of the haptic interface. It is made with interchangeable soft elastomeric sleeves that can be customized to include materials of varying stiffness to increase or decrease the stiffness range. The device is fabricated using existing 3D printing technologies, and polymer molding and casting techniques, thus keeping the cost low and throughput high. The haptic interface is linked to either an open-loop system that allows for an increased pressure during usage or closed-loop system that provides pressure regulation in accordance with the stiffness the user specifies. A preliminary evaluation is performed to characterize the effective controllable region of variance in stiffness. Results indicate that the region of controllable stiffness was in the center of the device, where the stiffness appeared to plateau with each increase in pressure. The two control systems are tested to derive relationships between internal pressure, grasping force exertion on the surface, and displacement using multiple probing points on the haptic device. Additional quantitative evaluation is performed with study participants and juxtaposed to a qualitative analysis to ensure adequate perception in compliance variance. Finally, a qualitative evaluation showed that greater than 60% of the trials resulted in the correct perception of stiffness in the haptic device.Dissertation/ThesisMasters Thesis Biomedical Engineering 201
Exploring affective design for physical controls
Physical controls such as knobs, sliders, and buttons are experiencing a revival as many computing systems progress from personal computing architectures towards ubiquitous computing architectures. We demonstrate a process for measuring and comparing visceral emotional responses of a physical control to performance results of a target acquisition task. In our user study, participants experienced mechanical and rendered friction, inertia, and detent dynamics as they turned a haptic knob towards graphical targets of two different widths and amplitudes. Together, this process and user study provide novel affect- and performance-based design guidance to developers of physical controls for emerging ubiquitous computing environments. Our work bridges extensive human factors work in mechanical systems that peaked in the 1960’s, to contemporary trends, with a goal of integrating mechatronic controls into emerging ubiquitous computing systems. Author Keywords Haptic display, physical control, design process, affect
ReachMAN to help sub-acute patients training reaching and manipulation
Conventional rehabilitation after stroke, consisting in one-to-one practice
with the therapist, is labor-intensive and subjective. Furthermore, there is
evidence that increasing training would benefit the motor function of stroke
survivors, though the available resources do not allow it. Training with
dedicated robotic devices promises to address these problems and to promote
motivation through therapeutic games. The goal of this project is to
develop a simple robotic system to assist rehabilitation that could easily be
integrated in existing hospital environments and rehabilitation centers. A
study was first carried out to analyze the kinematics of hand movements
while performing representative activities of daily living. Results showed
that movements were confined to one plane so can be trained using a robot
with less degrees-of-freedom (DOF). Hence ReachMAN, a compact 3 DOF
robot based on an endpoint based approach, was developed to train reaching,
forearm pronosupination and grasping, independently or simultaneously.
ReachMAN's exercises were developed using games based on software
thereby facilitating active participation from patients. Visual, haptic and
performance feedback were provided to increase motivation. Tuneable levels
of difficulty were provided to suit patient's ability. A pilot study with three
subjects was first conducted to evaluate the potential use of ReachMAN as
a rehabilitation tool and to determine suitable settings for training. Following
positive results from a pilot study, a clinical study was initiated to
investigate the effect of rehabilitation using ReachMAN. Preliminary results
of 6 subjects show an increase in patients upper limb motor activity, range
of movements, smoothness and reduction in movement duration. Subjects
reported to be motivated with the robot training and felt that the robot
helped in their recovery. The results of this thesis suggest that a compact
and simple robot such as ReachMAN can be used to enhance recovery in
sub-acute stroke patients
Robot-Assisted Rehabilitation of Forearm and Hand Function After Stroke
Ph.DDOCTOR OF PHILOSOPH
Feasibility Study of a Wearable Haptic knob System
In this study, we develop an event-based wearable haptic knob system that can be used in three-dimensional space. The first step involves building custom-built brakes and attaching them to a human forearm to achieve a wearable haptic knob. The display is built using a carbon-fiber frame. As our system is experiment-based, target torque curves are collected by a force sensor before using the torque representation. We confirm the effectiveness of our developed display through three operations, namely doorknob rotation, valve closing, and valve opening by the test subject. In the first step, the rotational axis was fixed on a table. These results are then used to develop the perfect wearable haptic system that includes a rotational axis in the display
The Grasp Perturbator: Calibrating human grasp stiffness during a graded force task
In this paper we present a novel and simple handheld device for measuring in vivo human grasp impedance. The measurement method is based on a static identification method and intrinsic impedance is identified inbetween 25 ms. Using this device it is possbile to develop continuous grasp impedance measurement methods as it is an active research topic in physiology as well as in robotics, especially since nowadays (bio-inspired) robotics can be impedance-controlled. Potential applications of human impedance estimation range from impedance-controlled telesurgery to limb prosthetics and rehabilitation robotics. We validate the device through a physiological experiment in which the device is used to show a linear relationship between finger stiffness and grip force
Effects of Haptic Feedback on the Wrist during Virtual Manipulation
As an alternative to thimble devices for the fingertips, we investigate
haptic systems that apply stimulus to the user's forearm. Our aim is to provide
effective interaction with virtual objects, despite the lack of co-location of
virtual and real-world contacts, while taking advantage of relatively large
skin area and ease of mounting on the forearm. We developed prototype wearable
haptic devices that provide skin deformation in the normal and shear
directions, and performed a user study to determine the effects of haptic
feedback in different directions and at different locations near the wrist
during virtual manipulation. Participants performed significantly better while
discriminating stiffness values of virtual objects with normal forces compared
to shear forces. We found no differences in performance or participant
preferences with regard to stimulus on the dorsal, ventral, or both sides of
the forearm.Comment: 7 pages, submitted conference paper for IEEE Haptics Symposium 202
Effects of Haptic Feedback on the Wrist during Virtual Manipulation
We propose a haptic system for virtual manipulation to provide feedback on
the user's forearm instead of the fingertips. In addition to visual rendering
of the manipulation with virtual fingertips, we employ a device to deliver
normal or shear skin-stretch at multiple points near the wrist. To understand
how design parameters influence the experience, we investigated the effect of
the number and location of sensory feedback on stiffness perception.
Participants compared stiffness values of virtual objects, while the haptic
bracelet provided interaction feedback on the dorsal, ventral, or both sides of
the wrist. Stiffness discrimination judgments and duration, as well as
qualitative results collected verbally, indicate no significant difference in
stiffness perception with stimulation at different and multiple locations.Comment: 2 pages, work-in-progress paper on haptics symposium, 202
From humans to robots: The role of cutaneous impairment in human environmental constraint exploitation to inform the design of robotic hands
Human hands are capable of a variety of movements, thanks to their extraordinary biomechanical structure and relying on the richness of human tactile information. Recently, soft robotic hands have opened exciting possibilities and, al the same time, new issues related to planning and control. In this work, we propose to study human strategies in environmental constraint exploitation to grasp objects from a table. We have considered both the case where participants' fingertips were free and with a rigid shell worn on them to understand the role of cutaneous touch. Main kinematic strategies were quantified and classified in an unsupervised manner. The principal strategies appear to be consistent in both experimental conditions, although cluster cardinality differs. Furthermore, as expected, tactile feedback improves both grasp precision and quality performance. Results opens interesting perspective for sensing and control of soft manipulators
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