Herbert M. Reynolds

Anatomical Frames of Reference and Biomechanics

For dynamic simulation of human movement, segment axis systems are often defined by the inertial tensor unique to each simulated body segment. When empirical three-dimensional data are sought that describe either the mass distribution or the kinematic properties of the human body, anatomical frames of reference are needed for the sake of measurement methodology and data comparability. Anatomical axis systems are based on anatomical landmarks that must represent functional and stable features in the skeletal geometry. The role of anthropometric landmarks used in defining anatomical coordinate axis systems is discussed with examples from current research regarding the kinematics of the hip joint and mass distribution of the whole body. The use of anatomical frames of reference will improve the correspondence between computer simulations of the human body and the biological structure.

Computer display of multidimensional biomedical data

By combining the abstract qualities of a mathematical model with the realism of an iconic model, a computer-based image rendering tool has been developed that permits accurate visualization and quantification of three-dimensional serial slice data from anatomical structures located within the human body. Such a tool also enables an investigator to model a physical system, and then to visualize the effects that manipulation of system parameters has upon the performance of the model. Three examples of the application of computer visualization techniques to medically related projects are presented in this paper: (1) visualization of three-dimensional structure and motion in the lumbar spine; (2) visualization of three-dimensional structures in the brain and the cervical spine; and (3) visualization of the effect of changes in system parameters upon the training characteristics of an artificial neural network. These applications range in complexity from the simplicity of displaying orthogonal data, to the complexity of a ray tracing algorithm. They are presented to stimulate the imagination of readers who might find applications for such a tool in their clinical practice or research program.

Measuring body points on automobile drivers using multiple cameras

Methods are given for measuring 3D points on human drivers of automobiles. Points are natural body features marked by special targets placed on the body. The measurements are needed for improved comfort and accommodation in automotive seat design. The measurement methods required hardware instrumentation in the automobile and development of algorithms for off-line processing of the acquired data. This paper describes the use of multiple cameras to measure 3D locations within the drivers workspace. Results obtained show that measurement error in X, Y and Z coordinates is expected to be less than 1.0 mm on the lab bench and 2.0 mm in the car, and that combined 3D error is expected to be less than 2.0 mm and 3.0 mm, respectively.

The Human Machine in Three Dimensions: Implications for Measurement and Analysis

Scientists and laymen have a favorite analogy: the human body as machine. In this context, machine is “...a structure consisting of a framework and various fixed and moving parts, for doing some kind of work” (Webster’s New World Dictionary, 1974). The human skeletal system is the “framework”, while the neuromuscular system generates forces and controls movements for performing work. Modeled as a machine, the body’s skeletal linkage system acts as mechanical levers (Tichauer, 1978). Dempster (1955) defined skeletal links as straight-line distances between joint centers of rotation; for computer simulations, his interpretation suggests a stick-man model as a reasonable, straight-forward approximation. Unlike present-day machinery, however, there is poor “quality control” in the linkage system of our human machines; that is, the length of the links varies among individuals with respect to body size and even in the same individual with respect to position. Thus, the potential range of variation in body position and mobility may be maximized by behavioral and cultural variables (Maule and Weiner, 1975). Consequently, anthropometrists measuring the body are concerned with standardization of instruments, landmarks, and body configuration. These three technical areas have largely determined the parametric definition of the human machine in current models.

Porting CAESAR Data as an ERL Human Body Model

In this paper we present a method for converting the CAESAR full body scanned data into human body models for use in the ERL design software. The ERL software is a comprehensive interior automobile design tool, used in design or evaluation. The 3D CAD occupants in ERL were generated from anatomical cross sections at comparable landmarks and spinal shapes. Skeletal landmarks in the CAESAR data are used to establish segmental coordinates from which cross-sections are defined. The anatomical cross sections are used to re-generate the external shape of the body. Additional skeletal landmarks are calculated using regression equations. Segmental mass distributions are calculated based on segmental volume.

3-D Analysis & display of sequential position data in the lumbar spine

An investigation of three-dimensional lumbar position and mobility has been made by combining roentgen stereophotogrammetry with reconstructed solid images of serialized CAT scans of lumbar vertebra. The three-dimensional positions of L3, L4, and L5 in a 56-year old male, unembalmed cadaver were measured in situ with roengten stereophotogrammetry in four positions of lumbar flexion. The excised bones were cleaned and approximately 30 serialized slices in a CAT scan were obtained. These images were reconstructed using MOVIE.BYU and computer programs developed according to a protocol described in the paper. Six of nine targets in both measurement systems were located with an average difference of distance ranging from 0.4 to 1.0 mm. These computer-generated images have been used to describe local, intervertebral angular movements of .035 to .128 radians and linear movements of .00 to .12 cm as calculated by a “screw axis‘’ analysis. This investigation provides a technology that can potentially be used by both clinicians and engineers in their investgations of local spinal movements in the human body.

Systems anthropometry: development of a stereoradiographic measurement system.

Abstract A three-dimensional measurement system using stereoradiography and anatomical landmarks is described. Two sets of radiographic targets are employed to obtain a three-dimensional description of the position and mobility of the human body.

Anatomical frames of reference and biomechanics

Segment axes systems for simulations have been defined by the inertial tensor unique to each simulated body segment. When empirical three-dimensional data are sought that describe either the mass distribution or the kinematic properties of the human body, anatomical frames of reference are needed for the sake of measurement methodology and data comparability. Anatomical axes systems are based on anatomical landmarks that must represent functional and stable features in the skeletal geometry. This presentation will, therefore, discuss the role of anthropometric landmarks used in defining anatomical coordinate axes systems, and results using present preliminary anatomical frames of reference in a kinematic study of the human hip joint in a research program sponsored by the Air Force Office of Scientific Research (Contract #F49620-78-C-0012).