Despite the abundant literature on obstacle crossing in humans, the question of how the central nervous system (CNS) controls postural stability during gait initiation with the goal to clear an obstacle remains unclear. Stabilizing features of gait initiation include anticipatory postural adjustments (APAs) and lateral swing foot placement. To answer the above question, 14 participants initiate...

We tested the hypothesis that area 5 of the posterior parietal cortex (PPC) contributes to interlimb coordination in locomotor tasks requiring visual guidance by recording neuronal activity in this area in three cats in two locomotor paradigms. In the first paradigm, cats were required to step over obstacles attached to a moving treadmill belt. We recorded 47 neurons that discharged in relation...

751 Trips are a commonly reported cause of falls and are reported to contribute between 35% and 53% of falls in older people (1,2). poor lower limb strength as suggested by poor leg press push off force (3), fast walking speed prior to crossing an obstacle (4), and delayed support limb loading (4) are associated with a greater risk of falling following an obstacle contact in healthy older adult...

An obstacle representation of a graph G is a set of points on the plane together with a set of polygonal obstacles that determine a visibility graph isomorphic to G. The obstacle number of G is the minimum number of obstacles over all obstacle representations of G. Alpert, Koch, and Laison [1] gave a 12-vertex bipartite graph and proved that its obstacle number is two. We show that a 10-vertex ...

in this paper, trajectory generation for the 4 dof arm of surena iii humanoid robot with the purpose of optimizing energy and avoiding a moving obstacle is presented. for this purpose, first, kinematic equations for a seven dof manipulator are derived. then, using the lagrange method, an explicit dynamics model for the arm is developed. in the next step, in order to generate the desired traject...

BACKGROUND Although the attention directed to gait does increase as an impending obstacle nears, it remains unclear whether the allocation of attentional resources differs between the precrossing phase of obstacle negotiation and the crossing phase of this task. This study compared the attentional demands associated with steady-state walking and the precrossing and crossing phases of an obstacl...

During obstacle crossing, healthy adults increase toeground/obstacle clearance from an average of 3 cm during level walking to approximately 10-15 cm over an obstacle (Chen et al., 1991; Patla et al., 1996; Chou et al., 1997) to minimize the risk of tripping. The hip, knee and ankle joints of the swing limb are modulated for phase and amplitude of flexion to ensure appropriate elevation of the ...

This study aims to investigate the effects of shoe traction and obstacle height on friction during walking to better understand the mechanisms required to avoid slippage following obstacle clearance. Ten male subjects walked at a self-selected pace during eight different conditions: four obstacle heights (0%, 10%, 20% and 40% of limb length) while wearing two different pairs of shoes (low and h...

A study is presented to examine the one-horizontal dimension effect of a shallow shelf obstacle on nonlinear long wave runup. Due to the large horizontal-vertical aspect ratio of this problem, it is not well suited for experimental analysis, and therefore this study is purely numerical. Simulations are performed for various incident wave conditions, obstacle height and widths, and final beach s...

BACKGROUND Osteoporosis is associated with changes in balance and physical performance and has psychosocial consequences which increase the risk of falling. Most falls occur during walking; therefore an efficient obstacle avoidance performance might contribute to a reduction in fall risk. Since it was shown that persons with osteoporosis are unstable during obstacle crossing it was hypothesized...