Knee-Assistive Robotic Exoskeleton (KARE-1) Using a Conditionally Singular Mechanism for Industrial Field Applications

With the aging demographic of today’s society, the need for robotic exoskeletons is expected to increase as they can compensate for declining physical strength in the physically impaired. In this study, an assistive robotic exoskeleton for the knee joint with fairly low energy consumption is proposed for industrial applications. The knee-assistive robotic exoskeleton (KARE-1) was designed to support a human body during production line tasks. The KARE-1 is based on a four-bar link mechanism with a rotary actuator and gas spring to accommodate a high power-to-weight ratio. By taking advantage of the utilized singular configuration of the four-bar linkage, this novel design is able to efficiently support the weight of the human body. The selected singular configuration allows this device to support the knee joint in the load-bearing stages of static sitting as well as during the motion between standing and sitting. The proposed device is further able to move freely along with the knee during walking movements. The proposed design was verified through a series of numerical simulations and through human subject testing at an industrial workplace.

Walking-Stair Climbing Control for Powered Knee Prostheses

Recent progresses in powered lower-limb prostheses have the potential of enabling amputee users to conduct energetically demanding locomotive tasks, which are usually beyond the capability of traditional unpowered prostheses. Realizing such potential, however, requires responsive and reliable control of the power provided by prosthetic joints. In this paper, an integrated walking-stair climbing control approach is presented for transfemoral prostheses with powered knee joints. Leveraging the similarities between walking and stair climbing, this new approach adopts the general finite-state impedance control framework. Furthermore, important modifications are introduced to model the biomechanical characteristics that are beyond the capability of standard impedance control. The transition between the walking and stair-climbing modes is triggered through the real-time measurement of the spatial orientation of the user’s thigh, which provides a reliable indicator of the user’s intention of making such transition. This new control approach has been implemented on a powered knee prosthesis, and its effectiveness was demonstrated in human subject testing.

Reducing Parkinsonian Hand Tremor With a Novel Dynamic Eating Utensil

The work presented here details the modeling, fabrication, testing, and analysis of a dynamic eating utensil designed to reduce hand tremors in subjects with Parkinson’s disease. Most of the current work addressing this problem has been invasive, using medicine or electrical brain stimulation for example. Here, an analysis is presented on the nature of the tremor. This is then used to develop a multi degree-of-freedom analytic model for the forearm/wrist/utensil system. Experiments were performed to identify model form and parameters and theory is presented which allowed for optimized system design. A physical model of the hand/wrist system was developed for testing utensil prototypes in controlled experiment. Ultimately iterative human subject testing validated the design decisions, providing both hard data and survey results to shape the final product. In addition to general performance, special consideration is given to the engineering design parameters and those established by the candidates for ease of use. Specifically, the device presented here outperforms its predecessors in cost, manufacturability, and usability. Additionally, an option for easy user tuning makes the device appropriate for a large host of tremor sufferers. Quantitative and qualitative results indicating the overall effectiveness are presented with the design.

Estimating the Performance of Sound Restoration Hearing Protectors by Using the Speech Intelligibility Index

Despite advances in engineering noise controls and the use of administrative controls, miners are still dependent on hearing protection devices for prevention of noise-induced hearing loss. However, miners often raise concerns about the audibility of spoken communication when wearing conventional hearing protectors. Electronic technologies that selectively process and restore sounds from outside of hearing protectors have been suggested as a partial remedy to the audibility problem. To assess the potential benefits of this technology for miners, NIOSH tested the impact of nine electronic sound restoration hearing protectors on speech intelligibility in selected mining background noises. Because of the number of devices and potential settings of those devices, it was necessary to narrow the choices before conducting human subject testing. This was done by testing the nine devices on an acoustic test fixture (ATF) to acquire one-third-octave-band data, and then calculating the speech intelligibility index (SII) to determine estimates of performance across device, noise and setting. The estimates of speech intelligibility obtained with the SII are highly correlated with the intelligibility of speech under adverse listening conditions such as noise, reverberation, and filtering. The results of fixture based testing indicate that performance varies little between most devices, with few showing exceptionally good or poor estimated speech intelligibility. The most significant differences in estimated performance using the devices were between the different noise sources used, regardless of device or setting. The findings of this research were used to select the devices and settings for subsequent human subject based speech intelligibility testing. The human subject testing results largely concurred with the findings from the acoustic test fixture testing and calculation of speech intelligibility index. Specifically, variations in background noise led to the greatest differences in speech intelligibility.

Forensic Engineering Use Of Walkway Traction Testing

Pedestrian Fall Events Are Frequently Linked To Slippery Walkway Surfaces. Friction Is The Measured Quantity At Issue In Traction Testing Which Has Been Conducted Using Various Devices For Over 80 Years. The Various Available Devices (Called Tribometers) Each Have Their Advocates, Resulting In A Certain Amount Of Controversy. Robust Analysis Of Walkway Traction Requires An Understanding Of Individual Tribometer Characteristics And Knowledge Of Potential Limitations In The Ability To Test Certain Surfaces & Contaminants. It Is Also Necessary To Understand The Status Of Relevant Traction Testing Standards And To Be Familiar With Current Research Which Links Tribometer And Human Subject Testing To Provide Required Friction Values For Safe Pedestrian Ambulation.

Biomechanical Efficiency of Wrist Guards as a Shock Isolator

Despite the use of wrist guards during skate- and snowboard activities, fractures still occur at the wrist or at further proximal locations of the forearm. The main objectives of this study were to conduct a human subject testing under simulated falling conditions for measurement of the impact force on the hand, to model wrist guards as a shock isolator, to construct a linear mass-spring-damper model for quantification of the impact force attenuation (Q-ratio) and energy absorption (S-ratio), and to determine whether wrist guards play a role of an efficient shock isolator. While the falling direction (forward and backward) significantly influenced the impact responses, use of wrist guards provided minimal improvements in the Q- and S-ratios. It was suggested based on the results under the submaximal loading conditions that protective functions of the common wrist guard design could be enhanced with substantial increase in the damping ratio so as to maximize the energy absorption. This would bring forth minor deterioration in the impact force attenuation but significant increase in the energy absorption by 19%, which would help better protection against fall-related injuries of the upper extremity.