In-home and remote use of robotic body surrogates by people with profound motor deficits

By controlling robots comparable to the human body, people with profound motor deficits could potentially perform a variety of physical tasks for themselves, improving their quality of life. The extent to which this is achievable has been unclear due to the lack of suitable interfaces by which to control robotic body surrogates and a dearth of studies involving substantial numbers of people with profound motor deficits. We developed a novel, web-based augmented reality interface that enables people with profound motor deficits to remotely control a PR2 mobile manipulator from Willow Garage, which is a human-scale, wheeled robot with two arms. We then conducted two studies to investigate the use of robotic body surrogates. In the first study, 15 novice users with profound motor deficits from across the United States controlled a PR2 in Atlanta, GA to perform a modified Action Research Arm Test (ARAT) and a simulated self-care task. Participants achieved clinically meaningful improvements on the ARAT and 12 of 15 participants (80%) successfully completed the simulated self-care task. Participants agreed that the robotic system was easy to use, was useful, and would provide a meaningful improvement in their lives. In the second study, one expert user with profound motor deficits had free use of a PR2 in his home for seven days. He performed a variety of self-care and household tasks, and also used the robot in novel ways. Taking both studies together, our results suggest that people with profound motor deficits can improve their quality of life using robotic body surrogates, and that they can gain benefit with only low-level robot autonomy and without invasive interfaces. However, methods to reduce the rate of errors and increase operational speed merit further investigation.Comment: 43 Pages, 13 Figure

Bayesian inference of physiologically meaningful parameters from body sway measurements

The control of the human body sway by the central nervous system, muscles, and conscious brain is of interest since body sway carries information about the physiological status of a person. Several models have been proposed to describe body sway in an upright standing position, however, due to the statistical intractability of the more realistic models, no formal parameter inference has previously been conducted and the expressive power of such models for real human subjects remains unknown. Using the latest advances in Bayesian statistical inference for intractable models, we fitted a nonlinear control model to posturographic measurements, and we showed that it can accurately predict the sway characteristics of both simulated and real subjects. Our method provides a full statistical characterization of the uncertainty related to all model parameters as quantified by posterior probability density functions, which is useful for comparisons across subjects and test settings. The ability to infer intractable control models from sensor data opens new possibilities for monitoring and predicting body status in health applications.Peer reviewe

Analysis of the Interaction Torque on the Arm Based on Via-Point Movement

To produce a desired movement, the human motor control system must regular the interaction torque generated owing to the multi-joint structure of the body. In this study, the trajectories of human movements were evaluated considering the interaction torque generated through the elbow and shoulder joints. Measurement experiments were conducted, in which the participants performed movements corresponding to a three-point task, and the results indicated that the interaction torque is correlated with certain characteristics of the trajectories of the arm movements. Moreover, the contribution of the interaction torque in realizing the task differs in the cases of dominant and non-dominant hands. In addition, through a simulation, the interaction torque of simulated trajectories was modulated to examine the corresponding effect on the arm movements. For a point-to-point movement, certain characteristics of the actual movements were reproduced in the simulated trajectories. However, for a three-point movement, the characteristics of the simulated trajectories were only partially similar to those of the measured trajectories. The findings indicate that the interaction torque notably influences the motor control, and the tuning of the interaction torque is more complex than the other criteria of motor control

Modelling, analysis and feedback control design for upright standing sways

Human body upright standing is inherently unstable, and as a bipedal creature, the body can implement several functions such as upright standing, walking and running, with the help of the central nervous system. Understanding the stability control of the human body during upright standing is important for prosthetic design and joint prostheses, walking restoration, diagnosis of nervous system diseases. Also, it is essential to anthropology, clinical research, aerospace science and kinesiology.Therefore, the objective of this work is to model the musculoskeletal system of human upright standing posture for analysis and control design of body sway. An asymmetric Gaussian function is proposed to model the force-length relationship and compared with other existing force-length models. By using least square curve fitting tools with a set of rabbit experimental data, and simulated data that represent sarcomere of the frog. Also, the implicit and explicit ordinary differential equations, are used to model muscle-tendon unit and compare the simulation results in term of singularity.In addition to, the equilibrium analysis is used to determine sway ranges during upright standing, and the equilibrium points can be used to linearize the model for feedback control design and stability analysis of the musculoskeletal system. Furthermore, a switching function is designed to model the intermittent activity of the MG muscle, where the parameters are optimised using the centre of gravity and electromyography data with Genetic Algorithm tool. The musculoskeletal system of the human body is modelled as a single inverted pendulum, which rotates around the ankle joint, in the sagittal plane only. The calf muscles especially the medial gastrocnemius activated intermittently, and soleus activated continuously are included in the model of the musculoskeletal system. The developed musculoskeletal system model is linearized in order to have clear stability analysis using Routh-Hurwitz stability criterion and eigenvalue analysis.The results show that the musculoskeletal system cannot be stabilised at the upright standing without feeding back angular velocity. The equilibrium analysis reveals how the sway range (sway points) depends on the used anatomical and anthropometry data. Finally, the stability analysis shows that during forwarding sway the calf muscles are shortening paradoxically and lengthening during backwards sway, which supports some existing experimental results. The model-based analysis which used in modelling the body upright standing, will help in analysis and understands the dynamics of the body during upright standing. Also, it assists in medical research, in clinical diagnostics and application

GA-based multi-objective optimization of active nonlinear quarter car suspension system—PID and fuzzy logic control

Background The primary function of a suspension system is to isolate the vehicle body from road irregularities thus providing the ride comfort and to support the vehicle and provide stability. The suspension system has to perform conflicting requirements; hence, a passive suspension system is replaced by the active suspension system which can supply force to the system. Active suspension supplies energy to respond dynamically and achieve relative motion between body and wheel and thus improves the performance of suspension system. Methods This study presents modelling and control optimization of a nonlinear quarter car suspension system. A mathematical model of nonlinear quarter car is developed and simulated for control and optimization in Matlab/Simulink® environment. Class C road is selected as input road condition with the vehicle traveling at 80 kmph. Active control of the suspension system is achieved using FLC and PID control actions. Instead of guessing and or trial and error method, genetic algorithm (GA)-based optimization algorithm is implemented to tune PID parameters and FLC membership functions’ range and scaling factors. The optimization function is modeled as a multi-objective problem comprising of frequency weighted RMS seat acceleration, Vibration dose value (VDV), RMS suspension space, and RMS tyre deflection. ISO 2631-1 standard is adopted to assess the ride and health criterion. Results The nonlinear quarter model along with the controller is modeled and simulated and optimized in a Matlab/Simulink environment. It is observed that GA-optimized FLC gives better control as compared to PID and passive suspension system. Further simulations are validated on suspension system with seat and human model. Parameters under observation are frequency-weighted RMS head acceleration, VDV at the head, crest factor, and amplitude ratios at the head and upper torso (AR_h and AR_ut). Simulation results are presented in time and frequency domain. Conclusion Simulation results show that GA-based FLC and PID controller gives better ride comfort and health criterion by reducing RMS head acceleration, VDV at the head, CF, and AR_h and AR_ut over passive suspension system

Design Of Feedback Control For Active Mass Dampers Of Excited Structures

Annually, our world experiences thousands of seismic events that are the cause of hundreds of structural disasters and human fatalities. The objective of the presented research is to contribute to the world’s social, economic, and environmental needs by designing an optimized feedback control for active mass dampers (AMDs) by reducing oscillations. The optimal design will meet the required specifications and maintain a structure’s quasi-ideal, static position throughout a seismic event. The system’s equation of motion (EOM) is derived by using the Lagrangian Method and the free-body diagram. All the simulated and experimental responses of the AMD-1 system are obtained using MATLAB and Simulink. The experimental data is collected from various tests performed on a single-story building model. The techniques utilized for improvement of the AMD’s feedback control include parameter estimation, eigenvalue assignment, and linear quadratic regulation (LQR). As success is achieved with the AMD feedback control, future research can focus on idealizing the AMD’s performance in a system with multiple degrees of freedom

Design Of Feedback Control For Active Mass Dampers Of Excited Structures

Annually, our world experiences thousands of seismic events that are the cause of hundreds of structural disasters and human fatalities. The objective of the presented research is to contribute to the world’s social, economic, and environmental needs by designing an optimized feedback control for active mass dampers (AMDs) by reducing oscillations. The optimal design will meet the required specifications and maintain a structure’s quasi-ideal, static position throughout a seismic event. The system’s equation of motion (EOM) is derived by using the Lagrangian Method and the free-body diagram. All the simulated and experimental responses of the AMD-1 system are obtained using MATLAB and Simulink. The experimental data is collected from various tests performed on a single-story building model. The techniques utilized for improvement of the AMD’s feedback control include parameter estimation, eigenvalue assignment, and linear quadratic regulation (LQR). As success is achieved with the AMD feedback control, future research can focus on idealizing the AMD’s performance in a system with multiple degrees of freedom

Design Of Feedback Control For Active Mass Dampers Of Excited Structures

Annually, our world experiences thousands of seismic events that are the cause of hundreds of structural disasters and human fatalities. The objective of the presented research is to contribute to the world’s social, economic, and environmental needs by designing an optimized feedback control for active mass dampers (AMDs) by reducing oscillations. The optimal design will meet the required specifications and maintain a structure’s quasi-ideal, static position throughout a seismic event. The system’s equation of motion (EOM) is derived by using the Lagrangian Method and the free-body diagram. All the simulated and experimental responses of the AMD-1 system are obtained using MATLAB and Simulink. The experimental data is collected from various tests performed on a single-story building model. The techniques utilized for improvement of the AMD’s feedback control include parameter estimation, eigenvalue assignment, and linear quadratic regulation (LQR). As success is achieved with the AMD feedback control, future research can focus on idealizing the AMD’s performance in a system with multiple degrees of freedom

Cardiovascular autonomic nervous system responses and orthostatic intolerance in astronauts and their relevance in daily medicine

Background: The harsh environmental conditions during space travel, particularly weightlessness, impose a major burden on the human body including the cardiovascular system. Given its importance in adjusting the cardiovascular system to environmental challenges, the autonomic nervous system has been in the focus of scientists and clinicians involved in human space flight. This review provides an overview on human autonomic research under real and simulated space conditions with a focus on orthostatic intolerance. Methods: The authors conducted a targeted literature search using Pubmed. Results: Overall, 120 articles were identified and included in the review. Conclusions: Postflight orthostatic intolerance is commonly observed in astronauts and could pose major risks when landing on another celestial body. The phenomenon likely results from changes in volume status and adaptation of the autonomic nervous system to weightlessness. Over the years, various non-pharmacological and pharmacological countermeasures have been investigated. In addition to enabling safe human space flight, this research may have implications for patients with disorders affecting cardiovascular autonomic control on Earth