Kinds Of Feet Research Articles

Mechanical Performances of Typical Robot Feet Intruding into Sands

Four kinds of feet with typical structures, referred to as the hemispherical foot, the semicylindrical foot, the rectangular foot and the circular foot, respectively, were designed and manufactured to study the foot–terrain interaction mechanics for legged robots. Three kinds of quartz sand were selected to study how particle size, shape and compactness affected the physical properties of the substrate and the intrusion performance of mechanical feet. The media with smaller particle sizes had higher bulk densities and lower angles of stability, but no obvious rule was found for particle shapes of quartz sand with different sizes. The intrusion resistive forces and pressures of the hemispherical foot on these three kinds of quartz sand were all less compared with the other three mechanical feet. The particle disturbance areas and motion trends were compared under these four kinds of mechanical feet using discrete element method simulations. The intrusion resistive forces of these mechanical feet first increased and then decreased with the increasing particle sizes of the quartz sand. Moreover, the intrusion resistive forces of these mechanical feet on spherical particles were smaller compared with irregular particles. The corresponding resistive forces of the mechanical feet were characterized based on the compactness of the quartz sand. According to the intrusion test data, the classic pressure–sinkage model was modified, and the relationships between intrusion resistive force and mechanical foot depth were obtained.

Apparent mass distribution at the feet of standing subjects exposed to whole-body vibration

This study was carried out to investigate the influence of the body posture and of the foot support on the apparent mass distribution at the feet of standing subjects exposed to whole-body vibration. The apparent mass was measured at the driving point through a capacitive pressure sensor matrix, which allowed to separate the contributions of the different foot regions. The overall value was also determined using a conventional measurement system based on piezoelectric load cells. Ten male subjects performed 15 tests with three kinds of feet supports (flat rigid, anatomic rigid and flat soft) in five different postures. Static components of the pressure measurements were exploited to identify which fraction of the weight is supported by the rearfoot, the midfoot and the forefoot in the various test configurations. Factorial design of experiments on different response variables showed that the apparent mass is affected by the posture but not by the type of feet contact surface; conversely, the presence of insoles varies with the apparent mass distribution on the different feet parts. Practitioner Summary: The response of standing subjects to whole-body vibration has always been considered as a global parameter measured at the driving point, neglecting the local phenomena occurring in different foot parts. We have experimentally identified the apparent mass distribution of subjects in different standing postures and with different foot supports.

A Study on Stability of Limit Cycle Walking Model with Feet: Parameter Study

In this paper, two kinds of feet, namely, curved and flat feet, are added to limit cycle walking model to investigate its stability properties. Although both models are already proposed and are investigated, most previous works are focused on efficiency and gait behaviors. Only the stability properties of the simplest walking model conceived Garcia et al. are well defined. Therefore, there is still a need for a precise research on the effect of feet, especially in the view of local stability, bifurcation route to chaos, global stability, falling boundary and energy balance line. Therefore, this article revisits the stability analysis of limit cycle walking model with various foot shape. To analyze the effects of feet, we re-derive the equation of motion of modified models by adding one more parameter of foot shape than the simplest walking model. Also, the falling boundary and energy balance line of modified models are derived to get proper initial conditions for stable walking and to explain global stability. Simulation results show us that the curved feet can enlarge both stable walking range and area of basin of attraction while the case of flat feet depends on foot shape parameter.

The foot and footwear.

Coming from a country where the majority of people walk in unshod feet and where shoes are an expensive luxury, I would like to offer some unconventional thoughts which might provide a global overview of the problems involved in the design of footwear and foot and ankle orthoses. I was brought up with the traditional concept of the foot being merely a static tripod or a semi-rigid support for superincumbent body weight. The arches of the foot were held to be very important and fie height of the longitudinal arch was correlated with a superior kind of foot. We owe it to Hicks (1961) of Birmingham who taught us to clearly differentiate between a beam, an arch and a truss, and the role of muscles and the plantar aponeurosis in the weight bearing and balancing mechanism of the foot. But the foot can no longer be viewed as a mere weight-bearing device meant only for standing. It has evolved, as the bioengineering team at the University of California (1947) has been telling us over the last two decades, as a dynamic mechanism functioning as an integral part of the locomotor system. The human foot is primarily meant for walking and it is important to understand its behaviour in the walking cycle. The foot is a remarkably mobile mechanism, adapting itself to the contours of the ground as well as responding to the forces transmitted via the suprapedal segments from above. By supinating and pronating, it causes the weight fine to follow a curved pathway leading to an even load distribution on the metatarsal heads. It becomes supple as it is grounded from heel strike to foot flat, and rigid as it prepares itself for heel rise and the final take-off. There is a locking mechanism in the foot, operated

Progressive Talipes Equinovalgus Due to Trauma or Degeneration of the Posterior Tibial Tendon and Medial Plantar Ligaments

Summary Two patients with talipes equinovalgus secondary to laceration of the posterior tibial tendon have been presented. One patient with a seven year old lesion was managed by transfer of the flexor hallucis longus and reconstruction and advancement of the medial ligaments. The anatomic and functional result was essentially a normal foot. A second patient with a laceration of the posterior tibial tendon was managed by tendon transfer of the adjacent flexor digitorum longus without reconstruction of ligaments, because only five months had elapsed between injury and repair. In this patient also normal anatomic and physiologic relationships were re-established. Six patients with progressive talipes equinovalgus unrelated to specific trauma were managed by various operative procedures. Plication of the posterior tibial tendon was insufficient to eliminate pain completely and restore the longitudinal arch. Reinforcement by an adjacent flexor hallucis longus or flexor digitorum longus tendon alone was insufficient to re-establish a foot that was totally pain-free with an adequate longitudinal arch but did produce a better result than plication of the tendon alone. The evidence favors managing this kind of foot by plication and reinforcement of the medial plantar calcaneonavicular ligament, and by reinforcement of the diseased posterior tibial tendon with the flexor hallucis longus or flexor digitorum longus. If this treatment is done before degenerative joint changes occur, satisfactory function should be re-established and triple arthrodesis should be avoided.