OBJECTIVES To investigate the effects of height, surface firmness, and visual reference on standing balance in construction workers. DESIGN Controlled laboratory study with balanced repeated measures. PARTICIPANTS Twenty four construction workers. SETTING Test subjects performed standing tasks at ground level as well as at 3 m and 9 m high balconies on firm or deformable surfaces with clo...

This study assesses lateral tipping motion-induced interruptions (MIIs) in a simulated motion environment. The objective is to revisit MII occurrence and sway motion relationship by focusing on the frequency and acceleration of the lateral motion stimulus. Results verify that MIIs increase with increasing peak sway acceleration, but the effect of sway frequency is not as clear as that of accele...

Separate studies have demonstrated that vibration and fatigue of ankle muscles alter postural control. The purpose of the present experiment was to investigate the effect of ankle muscle vibration on the regulation of postural sway in bipedal stance following ankle muscle fatigue. Center of foot pressure displacements were recorded using a force platform. Results showed a similar increase in po...

Generally, both horizontal and vertical boom motion must be used to suppress the load sway caused by horizontal boom motion of a rotary crane. However, it would be less energy intensive and also safer if a control scheme could be developed that only used horizontal boom motion, i.e., without the need for any vertical boom motion. In addition, if load sway can be suppressed without measuring it,...

Postural balance is impaired in individuals with pathology of the anterior superior vermis of the cerebellum. Chronic alcoholism, with its known vermian pathology, provides a viable model for studying the relationship between cerebellar pathology and postural stability. Decades of separate study of recovering alcoholics and post-mortem neuroanatomical analysis have demonstrated vermian patholog...

INTRODUCTION We compared changes in balance control due to chronic inflammatory demyelinating polyneuropathy (CIDP) and non-inflammatory (non-inf) polyneuropathy (PNP) to each other and with respect to healthy controls (HCs). Differences in patients' subjective impressions of balance capabilities were also compared. METHODS Balance control of 11 CIDP patients (mean age 61.1±(sd) 11, 8 male) a...

Postural sway during quiet stance is attenuated by actively maintained contact of the index finger with a stationary surface, even if the level of applied force (<1 N) cannot provide mechanical stabilization. In this situation, changes in force level at the fingertip lead changes in center of foot pressure by approximately 250 ms. These and related findings indicate that stimulation of the fing...

STUDY DESIGN Trunk sway occurring during clinical stance and gait tasks was compared between a group of subjects with a chronic whiplash injury, resulting from an automobile collision, and a normal collective. OBJECTIVES To examine if population specific trunk sway patterns for stance and gait could be identified for chronic whiplash injury patients. SUMMARY OF BACKGROUND DATA Our previous ...

Undisturbed human standing is primarily characterized by sway of the whole body about the ankle joints and is regulated primarily by the calf muscles. Traditionally, in accord with normal ideas of postural control, ankle stiffness, enhanced by spindle mediated muscle stretch reflexes, has been considered to be important for maintaining the upright human stance. This idea predicts that during fo...

In this paper, a nonlinear anti-sway control law for overhead cranes is investigated. The crane model itself is adopted from the literature; however, a new nonlinear decoupling control law that provides superior position-regulation and swaysuppression characteristics is proposed in this paper. The derived control law uses the sway angular rate as well as the sway angle as feedback. The performa...