Power-efficient adaptive behavior through a shape-changing elastic robot

The adaptive morphology of a robot, such as shape adaptation, plays a significant role in adapting its behaviors. Shape adaptation should ideally be achieved without considerable cost, like the power required to deform the robot’s body, and therefore, it is reasonably considered as the last resort in classical rigid robots. However, the last decade has seen an increasing interest in soft robots: robots that can achieve deformability through their inherent material properties or structural compliance. Nevertheless, the dynamics of these types of robots is often complex and therefore it is difficult to substantiate whether the cost like the required power for changing its shape will be worthwhile to achieve the desired behavior. This article presents an approach in the development and analysis of a shape-changing locomoting robot, which relies on the ability of elastic beams to deform and vibrate. Through a proper use of elastic materials and the robot’s vibration-based dynamics, it will be shown both analytically and experimentally how shape adaptation can be designed such that it leads to desirable behaviors, with better power efficiency compared to when the robot solely relies on changing its control input. The results encourage emerging direction in robotics that investigates approaches to change robots’ behaviors through their adaptive morphology. </jats:p

Evaluation of gait symmetry in poliomyelitis subjects : Comparison of a conventional knee ankle foot orthosis (KAFO) and a new powered KAFO.

Background: Compared to able-bodied subjects, subjects with post polio syndrome and poliomyelitis demonstrate a preference for weight-bearing on the non-paretic limb, causing gait asymmetry. Objectives: The purpose of this study was to evaluate the gait symmetry of the poliomyelitis subjects when ambulating with either a drop- locked knee ankle foot orthosis (KAFO) or a newly developed powered KAFO. Methods: Seven subjects with poliomyelitis who routinely wore conventional KAFOs participated in this study, and received training to enable them to ambulate with the powered KAFO on level ground, prior to gait analysis. Results: There were no significant differences in the gait symmetry index (SI) of step length (P=0.085), stance time (P=0.082), double limb support time (P=0.929) or speed of walking (p=0.325) between the two test conditions. However, using the new powered KAFO improved the SI in step width (P=0.037), swing time (P=0.014), stance phase percentage (P=0.008) and knee flexion during swing phase (p≤0.001) compared to wearing the dropped locked KAFO. Conclusion: The use of a powered KAFO for ambulation by poliomyelitis subjects affects gait symmetry in the base of support, swing time, stance phase percentage and knee flexion during swing phase

Determining level of postural control in young adults using force-sensing resistors

A force-sensing platform (FSP), sensitive to changesof the postural control system was designed. The platform measuredeffects of postural perturbations in static and dynamic conditions.This paper describes the implementation of an FSP usingforce-sensing resistors as sensing elements. Real-time qualitativeassessment utilized a rainbow color scale to identify areas withhigh force concentration. Postprocessing of the logged data providedend-users with quantitative measures of postural control.The objective of this research was to establish the feasibility of usingan FSP to test and gauge human postural control. Tests wereconducted in eye open and eye close states. Readings obtained weretested for repeatability using a one-way analysis of variance test.The platform gauged postural sway by measuring the area of distributionfor the weighted center of applied pressure at the foot.A fuzzy clustering algorithm was applied to identify regions of thefoot with repetitive pressure concentration. Potential applicationof the platform in a clinical setting includes monitoring rehabilitationprogress of stability dysfunction. The platform functions as aqualitative tool for initial, on-the-spot assessment, and quantitativemeasure for postacquisition assessment on balance abilities

Real-time stability measurement system for postural control

A method for assessing balance, which was sensitive to changes in the posturalcontrol system is presented. This paper describes the implementation of a force-sensing platform,with force sensing resistors as the sensing element. The platform is capable of measuringdestabilized postural perturbations in dynamic and static postural conditions. Besidesproviding real-time qualitative assessment, the platform quantifies the postural control ofthe subjects. This is done by evaluating the weighted center of applied pressure distributionover time. The objective of this research was to establish the feasibility of using the forcesensingplatform to test and gauge the postural control of individuals. Tests were conductedin Eye Open and Eye Close states on Flat Ground (static condition) and the balance trainer(dynamic condition). It was observed that the designed platform was able to gauge the swayexperienced by the body when subject’s states and conditions changed

Real-time stability measurement system for postural control

A method for assessing balance, which was sensitive to changes in the postural control system is presented. This paper describes the implementation of a force-sensing platform, with force sensing resistors as the sensing element. The platform is capable of measuring destabilized postural perturbations in dynamic and static postural conditions. Besides providing real-time qualitative assessment, the platform quantifies the postural control of the subjects. This is done by evaluating the weighted center of applied pressure distribution over time. The objective of this research was to establish the feasibility of using the force-sensing platform to test and gauge the postural control of individuals. Tests were conducted in Eye Open and Eye Close states on Flat Ground (static condition) and the balance trainer (dynamic condition). It was observed that the designed platform was able to gauge the sway experienced by the body when subject�s states and conditions changed

Measuring Human Balance on an Instrumented Dynamic Platform: A Postural Sway Analysis

A system to monitor the trajectory and distribution of Center of Pressure (CoP) oscillations in real-time was designed. The system used a custom built force plate that measured sway area and sway velocity based on the measured CoP. A stable posture is reflected by a controlled CoP oscillation, where the oscillation lies within the limits of stability. Large magnitudes of CoP oscillations (large sway area) indicate weak proprioception strength and a heightened risk of falls. Experiments carried out involved self-induced perturbations that destabilized postural control among volunteers with active and inactive lifestyles. The observed results from the experiment indicate that individuals with active lifestyle have better postural control than individuals with inactive lifestyle. Subjectswith active lifestyles demonstrated greater sway velocities, while maintaining a small sway area

Stereo vision human motion detection and tracking in uncontrolled environment

Stereo vision in detecting human motion is an emerging research for automation, robotics, and sports science field due to the advancement of imaging sensors and information technology. The difficulty of human motion detection and tracking is relatively complex when it is applied to uncontrolled environment. In this paper, a hybrid filter approach is proposed to detect human motion in the stereo vision. The hybrid filter approach integrates Gaussian filter and median filter to reduce the coverage of shadow and sudden change of illumination. In addition, sequential thinning and thickening morphological method is used to construct the skeleton model. The proposed hybrid approach is compared with the normalized filter. As a result, the proposed approach produces better skeleton model with less influential effect on shadow and illumination. The output results of the proposed approach can show up to 86% of average accuracy matched with skeleton model. In addition, obtains approximately 94% of sensitivity measurement in the stereo vision. The proposed approach using hybrid filter and sequential morphology could improve the performance of the detection in the uncontrolled environment

Assessment of Gait Symmetry and Gait Normality Using Inertial Sensors : In-Lab and In-Situ Evaluation

Quantitative gait analysis is a powerful tool for the assessment of a number of physical and cognitive conditions. Unfortunately, the costs involved in providing in-lab 3D kinematic analysis to all patients is prohibitive. Inertial sensors such as accelerometers and gyroscopes may complement in-lab analysis by providing cheaper gait analysis systems that can be deployed anywhere. The present study investigates the use of inertial sensors to quantify gait symmetry and gait normality. The system was evaluated in-lab, against 3D kinematic measurements; and also in-situ, against clinical assessments of hip-replacement patients. Results show that the system not only correlates well with kinematic measurements but it also corroborates various quantitative and qualitative measures of recovery and health status of hip-replacement patientsAccelGai