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The tonic postural system guarantees the stability of the human body in upright stance and during locomotion. It is considered as a complex organization which involves several internal systems and has multiple sources of information. In this paper, we provide a review of techniques and materials for human stability assessment. The primary tools to record and evaluate human sways in static posture...
Wheel-quadrupled combines individual benefits of wheeled robot and legged robot and has excellent adaption to terrain, which has become research highlights of robot fields these years. In this paper, the basic static walking pattern of robot is determined, and the attitude angles and the position of COG (center of gravity) are adjusted to enhance the stability and ability of robot to traverse the...
Classic biped walking controllers assume a perfectly flat, rigid surface on which the robot walks. While walking over unknown terrain, robots need to sense and estimate the ground location. Errors in this estimation result in an unexpected early or late ground contact of the swing foot. In this paper, we analyze how these errors affect walking stability. Based on simulation results, we propose a strategy...
Passive dynamic walking robot can walk with low energy consumption and exhibits human-like natural gait. However, because the walking performance greatly or fully depends on the mechanical structural parameters, their walking stability is quite low compared to active walking robot. In other words, proper mechanical parameters are one of the key factors to achieve stable walking for a passive dynamic...
Gait and balance disorders are among the most common causes of falls in older adults. Most falls occur as a result of unexpected hazards while walking. In order to improve the effectiveness of current fall-prevention programs, new balance training paradigms aim to strengthen the control of the compensatory responses required after external perturbations. The aim of this study was to analyze the adaptions...
This paper presents some theoretical and experimental physio-pathological aspects of certain behaviors on patient bipodal posture. In the first part of paper, aspects of ocular physio-pathology are presented in relation to the level and form of impaired visual function of the patient. Experimental structure and the evaluation are issues presented in the second part of the paper. Experimental structure...
The lift-and-carry of non-rigid objects is challenging for both people and bipedal robots. Examples include lifting and carrying jugs, jerry cans or bags that are respectively filled with water, gasoline or sand. Carrying such objects often makes it difficult to walk due to the shifting center-of-mass. As such, tripping and falling are risks. Such lift-and-carry is a common material handling task...
Motor control strategies can be described by muscle synergies, a model of functional muscle recruitment to perform a movement. However, stability of muscle synergies during locomotion has not yet been investigated. The objective of this work was the evaluation of the stability of muscle synergies while walking at normal (NS) and fast (FS) speed. Each walking condition was tested during a prolonged...
Quantifying dynamic postural stability from inertial sensor data is clinically very relevant for treatment and therapy monitoring in neuromuscular diseases, e.g. Parkinson's disease (PD). We extract peak accelerations in movement direction during the loading phase and in vertical direction at ground contact from gravity-free acceleration signals captured at the patient's feet as novel markers of dynamic...
In this paper, we propose to study the orbitally exponential stabilization of underactuated bipedal robotic walking with an impulse effect through time-dependent output feedback control. In gait characterization, symmetric periodic gaits are considered and defined. Input-output linearization is then utilized to synthesize an output feedback controller, which drives the directly controlled joints to...
Most existing bipedal dynamics models are built on an assumption of no foot slip. We relax such assumption and present hybrid zero dynamics model and properties for bipedal walking with foot slip. When foot slips, the biped hybrid zero dynamics (HZD) preserve rich features such as high dimensionality and transitions between slip and non-slip dynamics. We present the closed-form of the HZD for human...
Individuals with lower limb amputation have a high fall risk, which could be partially due to a lack of stabilizing control in conventional prostheses. Inspired by walking robots, we hypothesized that modulating prosthetic ankle push-off could help improve amputee balance. We developed a three-dimensional walking model, found limit cycles at two speeds, and designed state-feedback controllers that...
This paper introduces a novel control system of bipedal robots on uneven terrain. Since this method does not require to measure Zero Moment Point (ZMP), the tracking performance of the controller is not deteriorated by the noise on a measured ZMP. Moreover, the robot withstands frequent perturbations because of its two-degree-of-freedom structure. The robot is stabilized by Center of Mass (COM) regulation...
In this paper, we investigate the local stability of a flat-foot limit cycle walking model with compliant ankle joints, and analyze the effects of ankle stiffness and foot inertial and geometric parameters on disturbance rejection. These results can provide a further understanding of local behaviors of different phases in one step and guidelines for stiffness control and flat foot design towards stable...
This paper presents motion planning of a biped robot using leg-mounted ultrasonic sensors. An inverted pendulum model was used for modeling and simulation of kinematics. The experiments were conducted using a biped prototype. Each leg of the biped consists of four active joints; two for the hip joint, and one each for the knee and ankle joints. Overall, eight joints are controlled to execute biped...
The zero moment point (ZMP) control method is usually used in stable biped walking. A novel preview control of ZMP is proposed in the paper. First, the dynamics of a biped robot is modeled as a running cart on the table which gives a convenient representation to treat ZMP. Second, the walking pattern generation process is describes in details and a presented preview controller is introduced to reduce...
The purpose of this paper is to present the model of a Humanoid robot inspired by Poppy, modified for heavier load capacity and the balancing of humanoid in multiple work environments. The design has been modified in order to use MX-64 servos with more torque capacity than MX-28 servos which were used in original design. We have also redesigned the ankle joint and feet to make it a more accurate human...
Human walking is a complex locomotion that benefits from falling like attribute to perform forward movement. "Zero Moment Point" method (ZMP) is one of the most simple and practical criteria in the field of bipedal walking to assure the dynamic balance. However, this method is highly conservative and bipedal walking according to this criterion is not optimal in comparison with actual human...
The remarkable ability of goats to maintain stability during climbing cliffs or trees provides a valuable opportunity to understand some of the secrets of stable legged locomotion on unstructured terrains. This paper, for the first time, presents analytical and experimental explanations as to how the morphological computation at the goat hoof makes a significant contribution to slip reduction on both...
From the viewpoint of evolution, vertebrates first accomplished locomotion via motion of the spine. Legs evolved later, to enhance mobility, but the spine remains central. Contrary to this, most robots have rigid torsos and rely primarily on movement of the legs for mobility. The force distributing properties of tensegrity structures presents a potential means of developing compliant spines for legged...
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