Henry Sommer

• Doctor of Philosophy
• Professor Emeritus at Pennsylvania State University

This paper presents ongoing results from a Tractor Driving Simulator study at Penn State University studying how tractor overturn events can be prevented. The simulator is used to expose subjects, in a controlled environment, to situations that would be unsafe to test in the field. Two sets of experiments are examined here. The first experiment con...

Developing devices for stability monitoring and rollover alerts is a promising possibility to prevent overturn events, which pose a severe risk to tractor operators. However, performing relevant tests with operators in the field is dangerous and impractical. As an alternative, this work identifies the challenges of simulating a tractor driving envi...

This work developed and verified a computational model to predict self-excited limit cycle yaw oscillation (SELCYO) instability of external sling payloads carried under aircraft with dual-point suspension. Inverted-V and inverted-Y slings during steady-state level flight are discussed. The primary goal was to provide a design tool for comparison of...

A novel gait and slip detection algorithm for walking robots using an inertial measurement unit was developed. An unscented Kalman filter was formulated with a simple dynamic model as a block on a slope without translations. Considerable prediction errors resulted when unmodeled dynamics (i.e., translation) occurred. These prediction errors were us...

A novel slip detection algorithm is proposed using the innovation term of the Unscented Kalman Filter (UKF). An intentional modeling error was introduced in the dynamic model of a block resting on a slope, including tilt angle and angular velocity. The model was formulated with an assumption of no translations in x- and y- directions. This model wa...

According to a 2004 National Institute for Occupational Safety and Health (NIOSH) report, approximately 250 to 350 fatalities occur each year due to incidents involving production agriculture workers and tractors. Tractor overturns account for about 150 to 200 of these deaths. The goals of this project were to study operators' understanding of trac...

The cortical bone distributions in the femoral necks of apes and humans differ as a result of different loading environments caused by the realignment of the hip abductor apparatus. Femoral neck cortical bone in extant humans is very thin superiorly and thicker inferiorly, while the cortical bone in apes tends to be more uniformly thick. The unique...

Shoulder and centreline rumble strips are used on highways in the USA to prevent single-vehicle run-off-road and opposite direction crashes. Both rumble strip types have been shown to provide positive safety benefits on a variety of roadway types. The elevated in-vehicle sound and vibration levels produced by rumble strip patterns provide the alert...

The ability of two canine pelvic osteotomy techniques to provide lateral rotation of the acetabulum was compared in vitro using an instrumented spatial linkage to measure acetabular displacement. Technique 1 was a double osteotomy and technique 2 was a triple osteotomy. We demonstrated that technique 1 provided more lateral rotation of the acetabul...

Matrix methods for kinematic analysis of spatial linkages were extended to provide jerk of joint pair variables, individual points, and individual links. Simple expressions for axode geometry were also developed. The methods were tested on revolute-sphericaluniversal-revolute and revolute-cylindrical-cylindrical-cylindrical closed loop mechanisms.

Tractor rollover incidents are responsible for the death of approximately 200 U.S. farmers every year. Tractor operators are often incapable of predicting overturn, and once a tractor reaches its critical overturn angle, operator response times are too long to allow them to take corrective action. Research conducted at the Pennsylvania State Univer...

The locations of the joint axes of the ankle complex vary considerably between subjects, yet no noninvasive method with demonstrated accuracy exists for locating these axes. The moments of muscle and ground reaction forces about the joint axes are dependent on axis locations, making knowledge of these locations critical to accurate musculoskeletal...

A new method for quantifying cranial and cerebral shape and asymmetry fits symmetric superquadric geometric models to three-dimensional coordinate measurements. Asymmetry is quantified as radial residuals of the surface data points from their best-fit superquadric models. Twenty human crania, 10 magnetic resonance imaging (MRI) exocranial surfaces,...

A low cost microprocessor sensor system was developed to help prevent overturn of agricultural tractors. Tractor roll and pitch angles are measured by a MEMS accelerometer. Roll and pitch rates are measured by MEMS rate gyros. Angle and rate signals are combined in a Kalman state-space filter to help reject noise and are externally available over a...

Agricultural tractors are the most common source of farm work fatalities in the U.S., with overturns the most common type of incident. For the year 2001, there were 15 tractor-related fatalities in Pennsylvania, 9 of which were due to tractor rollover. A new device using low-cost sensors and microcomputers was developed around a simplified mathemat...

A simple methodology for identification and quantification of nonlinear effects such as Coulomb friction and backlash is desired for use in condition based maintenance programs for both structural and machine based applications. Typically, structural applications are passive and undergo small vibratory motion when an external excitation is presente...

Experimental data in the form of a mobility matrix is needed for a variety of purposes including substructure synthesis, Structural Dynamics Modification (SDM) and updating of Finite Element Models (FEM). A computational based mobility matrix contains responses from both translational and rotational components. Experimentally, the rotational compon...

To determine the reliability of tibial flexural wave propagation velocity (FWPV) and the effect of overlying soft-tissues on the result. The velocity of tibial flexural wave propagation was repeatedly measured in healthy subjects. The tibia is the most frequently stress-fractured bone of runners and in military training populations. Developing tech...

A variety of experimental methods to measure rotational responses of structures have evolved. Most applications have measured frequency response functions between a translational excitation and the corresponding rotational response. The measurement of the rotational response to a moment excitation has mostly been ignored, due to the difficulty of a...

A treadmill with vibration isolation and stabilization designed for the International Space Station (ISS) was evaluated during Shuttle mission STS-81. Three crew members ran and walked on the device, which floats freely in zero gravity. For the majority of the more than 2 hours of locomotion studied, the treadmill showed peak to peak linear and ang...

Increasingly, the field of mechatronics is seen as an essential background of a practicing mechanical engineer. A course in advanced mechatronics is described which is offered as a joint graduate-undergraduate course and is intended to be a second course in mechatronics. As opposed to many mechatronics courses, this course focuses more on intellige...

A Hough transform-based computer algorithm was developed to identify sugarcane shoots as straight lines in a micropropagated Stage 2 sugarcane shoot clump image. An arc-based shoot identification method developed previously was tested after changing the lighting from fluorescent to incandescent which improved contrast between stems and leaves. This...

This paper presents kinematic analysis of a spatial closed-chain mechanism with applications in the stance phase of human gait and in postural studies. Based on a specific sequence of body-fixed rotations and an appropriate set of independent coordinates, a closed-form solution has been successfully obtained by suitably imposing the kinematic const...

Integrated healthcare material management begins with manufactures of medical/surgical supplies, uses distributors and ends at the point of use at hospitals. Recent material management philosophies in the healthcare industry, such as just-in-time and stockless systems, are yet to be fully evaluated. In order to evaluate the cost effectiveness of ea...

A three-dimensional musculoskeletal database of the lower extremities has been developed for use in human musculoskeletal models. The locations of idealized muscle attachments on the pelvis, both femurs, both tibias and fibulas, and both feet were accurately digitized for 52 dried skeletal specimens. The mean specimen heights were 177.5 cm (male) a...

Integrated healthcare material management begins with manufactures of medical/surgical supplies, uses distributors and ends at the point of use at hospitals. Recent material management philosophies in the healthcare industry, such as just-in-time and stockless systems, are yet to be fully evaluated. In order to evaluate the cost effectiveness of ea...

Ontogenetic shape changes in the skull of three species of the genus Caiman (C. latirostris, C. sclerops, and C. yacare) are compared by geometric morphometrics for three-dimensional configurations (the least-squares analysis). The technique for obtaining the landmark coordinates is a simplification of the algorithm for multidimensional scaling. Th...

Significant losses in bone density and mineral, primarily in the lower extremities, have been reported following exposure to weightlessness. Recent investigations suggest that mechanical influences such as bone deformation and strain rate may be critically important in stimulating new bone formation. It was hypothesized that velocity, cadence, and...

Coordinate-based landmark data are required to use many of the recent advances in morphometrics, although interlandmark distance measurements were used extensively in the past. In many cases the latter are still being used in morphometric research. The conversion of distance data to coordinate data is not straightforward because insufficient measur...

A machine vision system was developed to form a basis for single-pass quality feature inspection and grading of 'Golden Delicious' apples. The inspection criteria were based on USD A standards for fresh market apples. Image analysis algorithms were developed to assess and quantify the quality features of color, shape, and russet. Over 300 'Golden D...

A machine vision system was trained to distinguish between good and greened potatoes and yellow and green `Golden Delicious' apples. The method of using the HSI (Hue, Saturation, and Intensity) color system proved highly effective for color evaluation and image processing. The vision system achieved over 90% accuracy in inspection of potatoes and a...

Structural dynamic modification (SDM) of a fixed-free (cantilever) beam to convert it into a fixed-fixed beam with experimental modal data is presented. The SDM focuses on incorporating experimental rotational degrees-of-freedom (DOF) measured with a novel laser measurement technique. A cantilever beam is tested to develop the experimental modal da...

A Fourier-based shape separation method was developed for shape grading of potatoes using machine vision for automated inspection. The relationship between object shape and its boundary spectrum values in Fourier domain was explored for shape extraction. A new and fast method of using Green's theorem and boundary Fourier coefficients was given for...

This work addressed the relative strengths and weaknesses of the backpropagation neural network versus the Fisher discriminant function. Their performance was compared for machine vision inspection of greening, shape, andshatter bruise in two potato cultivars. The backpropagation network's number of hidden nodes were varied from zero to eight for e...

The operational principle and evaluation of a novel multi-dimensional vibration transducer is discussed in this paper. The measurement system can determine three translational and three rotational displacements of a vibrating structure by sensing the positions of three light beams reflected by a tetrahedral target. Computation of target pose from l...

The operational principle and evaluation of a novel multi-co-ordinate vibration transducer is discussed in this paper. The measurement system can determine three translational and three rotational displacements of a vibrating structure. In Part I of this paper the analytical development of the technique was discussed. In this paper the practical im...

The purpose of this study was to monitor selected aspects of the three-dimensional kinematics of the knee during walking with regular shoes and with modified shoes that induced either pronation or supination of the foot. Steinmann traction pins were inserted into the right tibia and femur of five adult men who had apparently normal lower extremitie...

A novel non-contacting system for multiaxis vibration measurements (one translation and two angular deflections) is described. The system is based on monitoring the reflections of two laser beams from a planar reflective target. By utilizing the geometry of the beams and their respective reflections: range, pitch and roll of the target can be deter...

This work discusses the utilization of experimentally measured rotational degrees-of-freedom for structural modification. The rotational degrees of freedom are measured via a dual beam laser vibrometer capable of measuring one translation (z) and two rotations (Θx, Θy) from a reflective surface on a vibrating object. Initially, measured rotational...

The measurement and utilization of rotational degrees of freedom for experimental modal analysis applications is presented in this work. The experimental data is obtained with a novel noncontacting measurement approach capable of simultaneously sensing dynamic translation (y) and two dynamic rotations (θx, θz) of a vibrating surface. The paper brie...

Least squares methods were developed to determine instant screw axis (ISA) and angular acceleration axis (AAA) parameters in experimental and analytical studies. The algorithms provide linear relationships for rigid body velocity and acceleration descriptors based on position, velocity, and acceleration data for individual points on the body. Weigh...

Three-dimensional kinematics of the tibiofemoral joint were studied during normal walking. Target markers were fixed to tibia and femur by means of intra-cortical traction pins. Radiographs of the lower limb were obtained to compute the position of the target markers relative to internal anatomical structures. High-speed cine cameras were used to m...

An iterative algorithm has been developed to determine threedimensional camera coordinates for landmarks on a rigid body, using two-dimensional image coordinates of the landmarks from a single camera. The landmarks may be coplanar or noncoplanar. The algorithm has been generalized for any number of landmarks (N ≥ 3). Monte Carlo simulation results...

This work addresses a new method for more rapid and reliable measurement of cranial and cerebral asymmetry, which have been hypothesized to correlate with cerebral lateralization. Cerebral laterality itself has been related to speech aphasia, dyslexia, stuttering, autism, hormone levels during development, and some immune system disorders. This new...

A systems analysis was performed on a baked apple product line in a fruit processing plant. The purpose of the analysis was to determine the energy usage of the processing line and to improve productivity through automation. The energy usage audit focused on the baking oven within the line, since the oven consumed more energy than other component....

Research is described on the development of an automated inspection system which uses digital images and artificial intelligence techniques. Procedures have been developed for evaluating size, shape, and color of apples, potatoes, and mushrooms. Current emphasis is being placed on developing algorithms for detection of surface defects. A major effo...

This paper discusses a novel noncontacting measurement approach, capable of simultaneously sensing one dynamic translation and two dynamic angular rotations, and its application for experimental modal analysis. The transducer system is based on the positional measurement of two laser beams reflected from a planar target. Using the geometric orienta...

Least-squares algorithms for computing instant screw axis (ISA) and angular acceleration axis (AAA) parameters from position, velocity, and acceleration measurements for discrete landmarks on a rigid body are described. Instantaneous velocity and acceleration for each landmark are approximated using digital filtering and finite difference derivativ...

A measurement system is described that employs noncontacting transducers to investigate vibratory displacements and rotations. The system is based on the positional measurement of two collimated laser beams reflected from a planar target/photodetector. The transducer is used for an experimental modal analysis of a simple cantilever beam, and the sy...

Today's engineering graduates are expected to be familar not only with the numerical and computational aspects of computers, but also with their use in an experimental setting. Pennsylvania State University is preparing its mechanical engineering students for this reality by offering them wide exposure to PCs in a variety of laboratories and suppor...

Tractor overturns are a major cause of death in farm operations. The overturns are the result of interactions between the tractor operator, the tractor and the environment. Numerous variables involved in tractor overturn have been identified. Previous stability analyses have resulted in attempts to design devices to warn or prevent tractor rollover...

Three male paraplegics volunteered to push their wheelchairs on a motor driven treadmill, for a total of 80 min each, at a work rate of 60-65% of their VO2 maximum, determined on an earlier test session. At 20 min intervals 16 mm high-speed film of the subjects was taken for three consecutive push cycles. The digitized film was used to compute the...

Many analytical biomechanics methods require extensive three-dimensional descriptions of anatomical geometry. In particular, researchers requiring the three-dimensional coordinates of specific boney landmarks (e.g. tendon and ligament attachments) are often forced to extrapolate such measurements from an experimental specimen set to their subject g...

Instrumented spatial linkages (ISL's) are finding wide applications in biomechanics for measuring all six degrees of freedom of relative location and attitude between two anatomical bodies moving through limited ranges of motion. The objective of this paper is to present a calibration scheme which will re-evaluate initial estimates of various kinem...

This paper describes a general technique for fitting a spatial kinematic model to an in-vivo anatomical joint under typical physiological loading conditions. The method employs a nonlinear least squares algorithm to minimize the aggregate deviation between postulated model motion and experimentally measured anatomical joint motion over multiple joi...

This paper describes a general technique for fitting a kinematic model to an in-vivo anatomical joint under typical physiological loading conditions. The method employs a nonlinear least squares algorithm to minimize the aggregate deviation over multiple joint positions between postulated model performance and experimentally measured anatomical joi...

Researchers requiring osteometric spatial coordinates of tendon and ligament attachments, condylar maps, etc. , are often confronted with a shortage of published data and are consequently forced to extrapolate measurements from a statistically small specimen set to their subject. This work presents a unified approach to two major problems inherent...

Printout. Thesis (M.S.)--University of Illinois at Urbana-Champaign, 1977. Includes bibliographical references (leaf 66).

Thesis supervisor: H.J. Sommer. Thesis (B.S.)--Pennsylvania State University, 2002. Library holds archival microfiches negative and service copy.