Yildirim Hurmuzlu

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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)
The focus of this survey is the modeling and control of bipedal locomotion systems. More speci6cally, we seek to review the developments in the 6eld 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 parametric formulation that ties the objective functions to the resulting gait patterns has never been established. This article presents an approach that can be(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 rigid body collisions of a special class of planar kinematic chains with rough and flat surfaces is studied. The common aspect of this class of problems is the configuration of the chain immediately before impact. One end of the mechanism strikes the surface while the other end is resting on the surface before contact and both ends are free to detach(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)