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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)
In this paper, we developed a detailed mathematical model of dual action pneumatic actuators controlled with proportional spool valves. Effects of nonlinear flow through the valve, air compressibility in cylinder chambers, leakage between chambers, end of stroke inactive volume, and time delay and attenuation in the pneumatic lines were carefully(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)
This article deals with the collision of steel bars with external surfaces. The central issue of the article is the investigation of the fundamental concepts that are used to solve collision problems by using rigid body theory. We particularly focus on low velocity impacts of relatively rigid steel bars to test the applicability of these concepts. An(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)
I this article we developed two nonlinear force controllers based on the sliding mode control theory. We used the detailed mathematical model of a pneumatic system developed in the first part of the paper. The first controller uses the complete model, and exhibit superior performance both in the numerical simulation and experiments, but requires very(More)
In this paper we consider the most basic multi-impact system, the so called " Newton's Cradle ". The task of developing an analytical method to predict the post impact velocities of the balls in the cradle has baffled investigators in the field of impact research for many years. The impulse based rigid body body as well as the alternative compliance based(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)