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This article deals with the rigid body collisions of planar, kinematic chains with an external surface while in contact with other surfaces. Two solution procedures that cast the impact equations in differential and algebraic forms are developed to solve the general problem. The differential formulation can be used to obtain three sets of solutions based on(More)
The main focus of the present investigation is the development of quantitative measures to assess the dynamic stability of human locomotion. The analytical methodology is based on Floquet theory, which was developed to investigate the stability of nonlinear oscillators. Here the basic approach is modified such that it accommodates the study of the complex(More)
The study reported in this article was conducted to propose a set graphical and analytical tools and assess their clinical utility by analyzing gait kinematics and dynamics of polio survivors. Phase-plane portraits and first return maps were used as graphical tools to detect abnormal patterns in the sagittal kinematics of post-polio gait. Two new scalar(More)
Additional graphical tools are needed to better visualize the joint kinematics of human locomotion. Standard plots in which the joint displacements are plotted against time or percent gait cycle do not provide sufficient information about the dynamics of the system. In this article, a study based on the two graphical tools of nonlinear dynamics to visualize(More)
The focus of this survey is the modeling and control of bipedal locomotion systems. More speciÿcally, we seek to review the developments in the ÿeld within the framework of stability and control of systems subject to unilateral constraints. We place particular emphasis on three main issues that, in our view, form the underlying theory in the study of(More)
Previous approaches to the problem of prescribing the motion of bipedal machines do not completely characterize the desired walking patterns in terms of coherent parameters. A well structured paramet-ric formulation that ties the objective functions to the resulting gait patterns has never been established. This article presents an approach that can be(More)
A general approach based on discrete mapping techniques is presented to study stability of bipedal locomotion. The approach overcomes difficulties encountered by others on the treatment of disconti-nuities and nonlinearities associated with bipedal gait. A five-element bipedal locomotion model with proper parametric formulation is considered to demonstrate(More)
This paper describes experimental studies conducted using a pneumatically driven haptic interface (PHI) system. The PHI is a unilateral exoskeletal device that tracks the motion of the shoulder and elbow. The study was carried out to evaluate the impact of an exoskeletal haptic interface on human perceptional capabilities. A population of twenty subjects(More)