This thesis describes the implementation of a telerobotic control architecture to manipulate a standard six degree of freedom industrial robot via a unique seven degree of freedom force-reflecting exoskeleton which is located in the Human Sensory Feedback Laboratory at Wright-Patterson Air Force Base. This is the first time that the robot and exoskeleton have been interfaced. The novel Naturally-Transitioning Rate-to-Force Controller is included in the irnplementation. Background for the control architecture and modes of operation are presented as well as the specific system description and operating procedures. Peg-insertion experiments were conducted to compare the performance of rate control, Naturally-Transitioning Rate-to-Force Control, and Naturally- Transitioning Rateto-Force Control with force reflection. Task completion time and manipulator work due to contact forces and moments through Cartesian displacements were the basis for comparison, The control architecture has been completely implemented. Experimental results displayed no clear differences among the three control modes; this indicates that a reduction in system time delays and more precise gain tuning are needed.

(далее…)

Категория: Научные статьи | Нет комментариев »

Confocal microscopy methods have been employed to image the metathoracic trochanter, a small exoskeleton segment between the coxa and femur, of an adult cockroach, Periplaneta americana. The confocal images represent planar sections through the exoskeleton of the trochanter. Specia-lized software was implemented to convert the section images into a complete three-dimensional geometric model of the trochanter. The raster image data of the confocal model was exported in a vector file format. Custom software was developed to resample the vector data and to automatically create a finite element mesh. The resulting mesh contained first-order, three-dimensional, triangular plate elements and also encoded data for element thicknesses. The Algor finite element package was used to analyze the model under the conditions of several biologically pertinent experiments. Special emphasis was placed on the strain analysis of the four groups of campaniform sensilla on the trochanter. These sensory organs respond to strains in the exoskeleton and are instrumental in the control of natural walking in insects. The results were compared to data from biological experiments which confirmed hypotheses and answered questions that have been difficult to determine experimentally on the animal. Functional differentiation both between groups and within groups of sensilla was observed. Further evidence that strain measurements are used in positive feedback control of the trochanteral extensor muscles was discovered. The structure of the trochanter was analyzed in the context of the function of the campaniform sensilla. Previously undescribed quantitative stress and strain data for insect cuticle was recorded.

(далее…)

Категория: Научные статьи | Нет комментариев »

For people with muscular dystrophy and spinal muscular atrophy — conditions characterized by degenerating muscle strength — there is a need for an exoskeletal mechanism that allows the person to move their arms about freely. This paper presents a consumer-based design approach in order to construct such an assistive manipulation device and details the initial stages that have been addressed in an orthosis design project within the Applied Science and Engineering Laboratories. Two consumer meetings were held during the initial stages of the design. The results from these meetings are presented. A design principle has been established and an initial set of prototypes evaluated. These will be used to modify subsequent design iterations.

(далее…)

Категория: Научные статьи | Нет комментариев »

This paper focuses on the problem of force-feedback for the human-operator hand when manipulating virtual objects. We propose a method for the computation of feedback-forces that have to be applied on each individual phalanx and jinger of the human hand in order to display pertinent, kinesthetic information about static or dynamic chamcteristics of objects present in the virtual scene. External forces and moments of the manipulated virtual objects have to be mapped on the contact-forces space of the virtual grasp. The method is based on the solution of a nonlinear programming problem, formu-lated by performing a static analysis of a general, multiple contact points virtual grasp. A methodology for modelling interactions within a virtual environment, and performing realistic grasping and manipu-lation, is also presented.

(далее…)

Категория: Научные статьи | Нет комментариев »

The Powered Gait Orthosis (PGO) is a powered exoskeleton developed as an experimental device to provide bipedal locomotion to individuals with physical impairment. The current prototype consists of a single degree of freedom (DOF) system for each leg, providing power and proper displacement required for bipedal locomotion . It is the goal of this research to obtain the forces that are present in the device while it is in normal operation . In addition, the time ratio of the hip function generator has been varied to determine the effect that different time ratios have on system forces and required user energy. The time ratio is the relationship between the time period that the thigh is in swing phase and when it is in support phase. Knowing the forces in the system and the optimal time ratio will allow for the design and construction of a feasible device for the rehabilitation and assistance of individuals who have lost the ability to walk.

(далее…)

Категория: Научные статьи | Нет комментариев »