Research Projects
for
H.J. Sommer III


Current Projects

Instrumentation for Farm Tractor Overturn
D.J. Murphy (AgE) and H.J. Sommer
Sponsor - NIOSH
Although roll-over protection systems (ROPS) are now mandated for farm tractors, tractor overturns cause approximately 400 deaths per year in the United States. This project will focus on new cost-effective combinations of sensors and microprocessors to detect impending side overturn, overturn of tractors with attached implements and operator display ergonomics and psychology. Click on photos or map for more details.

FY1 10/01-9/02
FY2 10/02-9/03
FY3 10/03-9/04

FY4 10/04-9/05
FY5 10/05-9/06 		Ag Progress Days
August 14-16, 2007


Maps to Test Facility
Superquadric Modeling of Pediatric Positional Plagiocephaly
H.J. Sommer
Sponsor - proposed
The occurrence of positional plagiocephaly in infants has increased dramatically since 1992 when back sleeping was recommended to reduce Sudden Infant Death Syndrome. In positional plagiocephaly, crania of infants may mold asymmetrically under gravity loading if their heads are routinely positioned in the same orientation. Unfortunately, clinical evaluations of plagiocephaly are still qualitative and treatment outcomes are concomitantly difficult to document.

To address these measurement problems, a new method for quantifying cranial shape and asymmetry has been developed to fit symmetric superquadric geometric models to three-dimensional (3D) coordinate measurements from cranial surfaces. Cranial surface asymmetry can then be quantified by deviation of the surface measurements from the inherently symmetric superquadric model. Superquadric parameters have simple geometric interpretation, are very reproducible and can be statistically significant indicators of cranial shape.

Before cranioplasty
After cranioplasty
Overturn Stability and Traction Control of Unmanned Ground Vehicles
H.J. Sommer
Sponsor - proposed
A new generation of unmanned ground vehicles (UGV) have been developed for military, disaster recovery and construction applications. While removing the human operator from the vehicle obviously increases safety of the operator, it dramatically reduces safety of the vehicle, particularly for operation over rough terrain. In particular loss of lateral traction and front/side overturn are problematic because the operator no longer has vestibular and kinesthetic feedback to assess vehicle stability. They can no longer feel vehicle attitude, vibration and motion "by the seat of the pants". Newer high speed UGVs futher exacerbate stability problems. This project will address low-cost MEMS sensor that can help UGV operators better monitor vehicle stability and traction.
Microprocessor Assessment of Postural Stability and Tremor
H.J. Sommer
Sponsor - proposed
Repeatable measurement of postural stability during quiet standing is particularly important to assess proclivity to falling in the elderly and to monitor postural effects of peripheral neuropathy in the diabetic foot. Unfortunately, traditional methods to assess postural stability such as timed stance tests and force plate center-of-pressure (COP) measurements are either subjective or expensive and not portable. To this end, dual axis MEMS accelerometers have been interfaced to microcontrollers to record supracranial accelerations and compute postural stability indicators. The same hardware is being adapated to quantify temor for assessment of neurological disorders.
Dual Beam Slip Resistance Sensor
H.J. Sommer
Sponsor - proposed
Current methods to measure slip resistance of shoes on flooring have limited reproducibility under wet or dusty contaminated conditions. This project designed a strain gage slip resistance sensor to simultaneously measure normal force and friction force under a friction coupon in contact with flooring. Design goals are manual operation and reliable estimation of slip coefficient. Current work focuses on validation against existing slipmeters and on industrial design for commercialization.

Recent Projects

Identification of Dynamic Nonlinearities in Robots for Predictive Maintenance
H.J. Sommer
Sponsor - PSU ARL
Identification of dynamic nonlinearities in robot joint drives using the Hilbert transform and internal excitation is being studied for predictive maintenance. Over long periods of operation, backlash and Coulomb friction in joints increase due to wear. If these nonlinearities can be monitored at periodic intervals, robot maintenance schedules can be predicted more reliably. The differences between the Fourier and Hilbert transforms of joint drive performance on a SCARA industiral manipulator will be correlated to artificially induced changes in backlash and friction. Numerical simulations, experiments on a simple spring-mass-damper and experiments on a prototype two-link manipulator have shown that Fourier versus Hilbert transform differences relative to baseline can identify the presence, magnitude and location of changes in Coulomb friction.
Locomotion in Microgravity
P.R. Cavanagh (CELOS) and H.J. Sommer
Sponsor - NASA Johnson Space Center
Significant losses in bone density and mineral content in the lower extremities have been reported following prolonged weightlessness. Recent investigations suggest that mechanical influences such as bone loading and strain rate may be critically important to stimulate new bone formation. A ground-based microgravity simulator was developed to investigate which factors affect limb loading during tethered treadmill exercise. The microgravity simulator incorporates a supine suspension system, an instrumented vertical treadmill and a gravity replacement harness to load the subjects horizontally into the treadmill. Ongoing tests using the simulator address exercise protocols as countermeasures for hypokinetic osteoporosis. This work supports the Treadmill Vibration Isolation System (TVIS), a free-floating powered exercise treadmill, as part of ongoing Risk Mitigation Experiments (RME) on STS-81 and the International Space Station (ISS).
Measurement of Six Degree-of-Freedom TVIS Motion
H.J. Sommer, P.R. Cavanagh (CELOS) and D.R Lemmon (CELOS)
Sponsor - Krug Life Sciences for NASA Johnson Space Center
The Treadmill Vibration Isolation System (TVIS) is a free-floating powered exercise treadmill designed to mitigate hypokinetic osteoporosis of the lower limbs during prolonged spaceflight. Two studies were conducted to measure all six degrees-of-freedom (6DOF) of TVIS motion during use on STS-81 and during ground tests at NASA Houston. Measurement of TVIS motion on STS-81 employed nonlinear stereophotogrammetry using sequences of video images from camcorders. Ground tests used a novel 6DOF Instrumented Spatial Linkage (ISL) developed and constructed at Penn State.
Sling Forces on Aircraft Caused by External Payloads
H.J. Sommer and J.M Cimbala
Sponsor - Boeing Helicopter
Aerodynamic drag on external payloads carried by slings under aircraft can impair aircraft handling and reduce stability, particularly due to self-excited yaw oscillations of the payload. Laboratory wind tunnel drag testing on scale models of typical external payloads was combined with analytical modeling of sling motion to predict sling forces and yaw instability. The predictions were validated by wind tunnel tests of scale models of external loads suspended with scaled slings.
Directed Seismic Vibration for Crowd Dispersal
H.J. Sommer
Sponsor - ARL Institute for Non-Lethal Defense Technology
A feasibility study of inducing ground vibration to disperse crowds was conducted. Capabilities of commercial-off-the-shelf (COTS) technologies including vibroseis trucks used in geological prospecting and industrial compactors and breakers used in heavy construction were compared to seismic vibration levels required to frighten personnel yet not cause collateral damage to pavement and structures.

Old Projects

Standardized Testing of White Food-grade Belts
P.N. Walker (AgE), H.J. Sommer and M. Toda (PENNTAP)
Sponsor - Hershey Foods
An industry survey of current ASTM, ISO, DIN and internal test standards will be used as a basis for competitive evaluation of belt suppliers.
In-vivo Poroelastic Material Properties of the Subcalcaneal Pad
H.J. Sommer, P.R. Cavanagh (CELOS) and H. Katoozian (CELOS)
Sponsor - PSU internal
Finite element analyses (FEA) of the foot/shoe interface have been developed to facilitate design of therapeutic footwear. To be effective however, FEA require accurate material properties. This project is a pilot study to use DANTE MRI to visualize a tagged grid within the subcalcaneal fat pad as a known surface loading is applied. Numerical comparison of the deformed DANTE grid to homologous FEA deflections will then allow iterative estimation of in-vivo material properties using Levenberg-Marquardt algorithms. To date, the technique has been tested on hyperelastic foam coupons. Current efforts focus on construction of a loading apparatus that can be used within MRI machines.
Solid Strut Motion Platform
H.J. Sommer
Sponsor - PSU internal
Stewart-Gough platforms use six extensible struts between the base and platform to control six degrees-of-freedom (DOF) of platform motion. Traditional applications include ride simulators and mulitaxis machining. A novel solid strut platform (SSP) has been built for passive biomechanics testing and a powered SSP prototype is under construction. Current efforts focus on workspace/velocity design considerations and vibration suppression using redundant Stewart-Gough actuators.
Experimental Angular Velocity, Acceleration and Jerk from Landmark Trajectories
H.J. Sommer
Sponsor - PSU internal
Least-squares methods were developed to determine the Instantaneous Helical Axis (IHA) for angular velocity and instantaneous angular acceleration and angular jerk from experimental measurement of landmark trajectories. These algorithms are used in biomechanics to determine rotation of body segments from photogrammetric measurement of markers attached to the segments. Additionally, relative kinematics between segments and instantaneous invariants of motion were defined.
Three Dimensional Normative Databases of Muscle Origins and Insertions of the Lower Extremities
H.J. Sommer and T.M. Kepple (NIH)
Sponsor - NIH
In-vivo lines of action for muscles can be predicted by filming the motion of external markers attached to palpable landmarks on subjects during locomotion. This requires a database of three-dimensional (3D) locations of muscle origins and insertions relative the palpable landmarks. Unfortunately, the number of skeletal specimens used to accumulate existing databases of 3D origin and insertion locations for the lower extremities were relatively limited. To this end, 3D locations of muscle attachments on the pelvis, femur, tibia/fibula, and foot were accurately digitized for 52 dried skeletal specimens from the Terry Collection of the Smithsonian National Museum of Natural History. Thirteen specimens each were selected within four gender/race categories with representative stature. Normative 3D databases developed from these landmark data statistically extend currently available 3D databases by an order of magnitude. These new data better describe expected gender/race variation and provide better effective lines of action for muscle which wrap over boney structures.
Single Beam Laser Vibrometer
H.J. Sommer and M.W. Trethewey
Sponsor - NSF
Prior work on multiple beam laser vibrometers for simultaneously measuring range, pitch and roll of a moving reflective target was extended to use a single laser beam and two transparent position sensing photodetectors. Calibration of the new single beam vibrometer with traditional Marquardt methods and with artificial neural networks compared favorably to previous dual beam vibrometer precision and accuracy. Additional electronics were developed to modulate the laser beam and remove the effects of background illumination.
Machine Vision Inspection of Apples, Potatoes and Mushrooms
P.H. Heinemann (AgE), C.T. Morrow (AgE) and H.J. Sommer
Sponsor - State Horticultural Association of PA
A variety of novel lighting techniques and machine vision algorithms were developed to grade apples, potatoes and mushrooms. Grading was based on optical inspection and numerical quantification of overall shape, size, color and surface blemishes. The shape/size/color/blemish data were then combined to assign an overall quality grade. Traditional linear classifiers, expert system rules and artificial neural networks methods for assigning grades were compared to USDA inspectors with excellent correlation. The current laboratory hardware and PC based software are now being upgraded for on-line field use.
Adjustable Prosthetic Sockets using Shape Memory Alloys
H.J. Sommer
Sponsor - PSU internal
Between 60 to 80 percent of amputees typically report inadequate fit between their residual limb and their prosthetic sockets particularly as the residual limb atrophies. While this lack of fit can be addressed by thicker and thicker stump socks, many amputees require adjustment or complete replacement of the socket every two to five years. This project demonstrated the technical feasibility of using socket walls with embedded Nitinol shape memory alloy wire. The wire was stretched to ten percent plastic elongation before being wrapped around the outer socket wall. Subsequent electrical heating of the wire was able to produce four percent diametral reduction of the socket to allow on-line refitting