Projects

Lifting FigureDrill Test Bench
A laboratory robotic system was designed and built that controls large hammer drills while they drill into concrete blocks. The system measures drilling speed and health related outcomes such as handle vibration, handle twist force, silica dust, and noise. The purpose is to compare drilling methods, bits and other factors on health and productivity. [Funded by CPWR and NIOSH]

Lifting FigureConcrete Dowel Drilling
Dowel and rod drilling involves drilling holes about 1 inch in diameter 1 - 2 feet deep into concrete in order to epoxy in rebar for structural upgrades. It is usually done manually with 30-lb pneumatic rock drills and is noisy and physically exhausting work. A Universal Drilling Jig is being developed and tested at commercial construction sites in the Bay Area. The goal is to improve productivity while reducing muscle loads, vibration exposure and exposure to silica dust. The Jig has also been used at several BART construction sites for drilling holes for large anchors as well as for setting anchors. (project page)

Lifting FigureStudies on dental tool design
Dental hygienists and dentists are at high risk for developing wrist, elbow and shoulder disorders due to poor postures and the high pinch force applied during the scraping of plaque. Dental tools of different diameter, shape, weight, and surface texture were evaluated in laboratory studies and in a 4-month randomized controlled trial of 110 dental practitioners. [Funded by NIOSH]

Lifting Figure3D CAD Reach Zones
A CAD based shoulder load model is in development that can be used during equipment and workstation design to place frequently used objects or controls to reduce shoulder fatigue and injury risk to workers. Colored 3D reach zones, representing relative fatigue and risk are linked to a mannequin to relocate equipment elements and points of operation based on the duty cycle of the task and applied hand forces. By selecting mannequins of different anthropometries or gender, the designer can consider equipment features to accommodate a wide range of workers. .

Lifting FigureProspective studies of carpal tunnel syndrome
Prospective data on 3515 production workers, followed for up to 7 years, from 50 companies were pooled from 7 research groups [UC San Francisco, SHARP, U Utah, Wisconsin U, Washington U at St Louis, U Iowa, NIOSH](Dale 2013). The study is evaluating the association of personal, sports, hobby, workplace psychosocial and workplace biomechanical factors on predicting new cases of CTS (Harris 2013). [Funded by NIOSH]

Lifting FigureTablet Design
Tablets and smart phones are used more and more for mobile business. Can the shape and texture of tablets be changed so that they are more secure and comfortable to hold in one hand? We are testing different tablet designs to evaluate their impact on productivity, comfort, and biomechanics. In the first study, 30 experienced users tested eight tablet prototypes while forearm electromyography, upper body posture, productivity and usability were evaluated. The study findings will be useful for designers of tablets and smart phones..

Lifting FigurePalm Rejection During Direct Touch
The primary objective of this research is to quantify the effects of palm rejection on direct touch performance, shoulder loading, and discomfort. Subjects performed a series of tasks involving one, two, and three simultaneous touches on a touch display, both with and without palm rejection. Results suggest that palm rejection affords some performance (speed) and comfort benefits, but little benefit to shoulder unloading..

Lifting FigureKeyboard Key Spacing
Surprisingly, the spacing of keys (e.g., 19 mm) on the conventional keyboards that we all use are based on 1950's conventions and not empirical data. Keyboards with smaller key spacing may be easier for people with smaller hands to use, could reduce the size and weight of laptops, and reduce the distance to reach to the mouse. We built and tested 8 keyboards with different key spacings on 89 experienced touch typists while measuring typing speed, error, forearm muscle activity, wrist posture and subjective preference. As it turns out, you can reduce key spacing without decreasing typing speed, even for typists with large hands..

Lifting FigurePeripheral Trackpad Size
The primary objective of this research is to quantify the effects of desktop-trackpad size on performance, posture and discomfort. Subjects performed a series of drag-and-select target acquisition tasks using three trackpads (112X63 mm to 230 X130 mm) while the dependent variables were recorded. Results suggest that trackpads with a width between 112 and 178 mm and a depth between 63 and 100 mm may provide an appropriate balance between cost, footprint, performance, and comfort..

overhead drillingOverhead Drilling Project
Of all industries, construction has the highest rate of musculoskeletal loads to the neck, back, and upper extremity. One of the most physically demanding tasks is over-shoulder work, especially overhead drilling into concrete for the attachment of anchors, bolts, etc. in order to hang pipes, ducts, wiring, and equipment. For more information see the project Web Page. Generation four of our device is up and running.
[project page]

computer postureComputer Display Position
Because the position of a computer display affects the user's posture, eye opening, and blink rate, and hence comfort, we are investigating the relationship between display position and these measures with the aim of determining optimal display positions. Particular interests include multiple and large-area displays.

Lifting FigureLower Extremity Exoskeleton Reduces Back Forces in Manual Material Handling
Manual material handling remains a physically demanding task, and existing assist devices have found limited success. The project involves a lower extremity exoskeleton device which adds a restoring moment to the subject's upper body during nonneutral postures, thus reducing forces on the low back, transmitting forces directly to the ground via the exoskeleton structure. The device has been found to effectively reduce low back forces during static tests and is being evaluated in a variety of other situations. This project is being undertaken in conjunction with the UC Berkeley Human Engineering Laboratory.

Arm SupportForearm Support Reduces Pain among Computer Users
A simple workstation modification, the addition of a forearm support, was found to reduce upper body pain and prevent musculoskeletal disorders among customer service workers who use a computer for more than 20 hours per week. In this randomized controlled trial, the 182 participating workers were followed for 1 year. Based on a cost-benefit analysis, employers could see a full return on the cost of providing arm boards to all employees within 11 months of the investment. The Morency rest forearm supports are manufactured by R&D Ergonomics of Maine. The study received the 2006 International Ergonomics Association/Liberty Mutual Prize.
[The full article is available here]

Tendon Loading In Vitro Tendon Loading
A new in vitro tendon loading system was developed to simultaneously apply different strain profiles to multiple tendons in a tissue culture environment. The system is used to evaluate the effects of precisely controlled cyclical loading on gene expression in tendons. You can watch a video article on this topic at the JOVE website.

Tendon ForceIn Vivo Tendon Force
Tendon force is measured during surgery of the hand in order to determine the relationship between fingertip force (external force) and tendon force (internal force).

Carpal TunnelCarpal Tunnel Pressure
Fluid pressure within the carpel tunnel has been measured in 37 healthy people. The purpose is to identify hand postures associated with high pressures. These postures should be avoided in designing work and hand tools.

Keyboard StudiesComputer Keyboard Studies
The effect of altering the deyboard design on hand posture, muscle load, and hand pain has been studied in laboratory and epidemiologic studies.

Fatigue StudyComputer Mouse and Fatigue of Long Duration Studies
A new method of measuring muscle fatigue was developed and validated. The technique was tested during extensive computer mouse use and recorded fatigue after 3 hours of mouse use.

Glove BoxSpace Station -- Glove Box Design
In cooperation with the Japanese Space Agency and NASA, a new design was developed for the glove box. The glove box will be used for all biological experiments on the space station.

Hand DisorderExperimental Model for Occupational Hand Disorders
To understand the direct cause of musculoskeletal disorders or diseases of the elbow, hands, and fingers, we have developed a rabbit repetitive finger flexor model. In this model, the finger is flexed for a set number of repetitions at a predetermined frequency and force. After the flexion sessions are completed, the elbow (epicondyle), carpal tunnel, and finger joints are examined by histology and biochemistry for pathology.
[read more]