Feedback Control of an Exoskeleton for Paraplegics: Toward Robustly Stable Hands-free Dynamic Walking

This manuscript presents control of a high-DOF fully actuated lower-limb exoskeleton for paraplegic individuals. The key novelty is the ability for the user to walk without the use of crutches or other external means of stabilization. We harness the power of modern optimization techniques and supervised machine learning to develop a smooth feedback control policy that provides robust velocity regulation and perturbation rejection. Preliminary evaluation of the stability and robustness of the proposed approach is demonstrated through the Gazebo simulation environment. In addition, preliminary experimental results with (complete) paraplegic individuals are included for the previous version of the controller.Comment: Submitted to IEEE Control System Magazine. This version addresses reviewers' concerns about the robustness of the algorithm and the motivation for using such exoskeleton

Environmental design shapes perceptual-motor exploration, learning, and transfer in climbing

This study investigated how environmental design shapes perceptual-motor exploration, when meta-stable regions of performance are created. Here, we examined how creating meta-stable regions of performance could destabilize pre-existing skills, favoring greater exploration of performance environments, exemplified in this study by climbing surfaces. In this investigation we manipulated hold orientations on an indoor climbing wall to examine how nine climbers explored, learned, and transferred various trunk-rolling motion patterns and hand grasping movements. The learning protocol consisted of four sessions, in which climbers randomly ascended three different routes, as fluently as possible. All three routes were 10.3 m in height and composed of 20 hand-holds at the same locations on an artificial climbing wall; only hold orientations were altered: (i) a horizontal-edge route was designed to afford horizontal hold grasping, (ii) a vertical-edge route afforded vertical hold grasping, and (iii), a double-edge route was designed to afford both horizontal and vertical hold grasping. As a meta-stable condition of performance invite an individual to both exploit his pre-existing behavioral repertoire (i.e., horizontal hold grasping pattern and trunk face to the wall) and explore new behaviors (i.e., vertical hold grasping and trunk side to the wall), it was hypothesized that the double-edge route characterized a meta-stable region of performance. Data were collected from inertial measurement units located on the neck and hip of each climber, allowing us to compute rolling motion referenced to the artificial climbing wall. Information on ascent duration, the number of exploratory and performatory movements for locating hand-holds, and hip path was also observed in video footage from a frontal camera worn by participants. Climbing fluency was assessed by calculating geometric index of entropy. Results showed that the meta-stable condition of performance may have afforded utilization of more adaptive climbing behaviors (expressed in higher values for range and variability of trunk rolling motion and greater number of exploratory movements). Findings indicated how climbers learn to explore and, subsequently, use effective exploratory search strategies that can facilitate transfer of learning to performance in novel climbing environments

Learning Environments for Children with Autism - End of Year Report, July 08

This report has been written for the staff at Sunfield School, and is a continuation and update of the progress of the Learning Environments research project. It should be read as supplemental to the July 07 end of year report

Modeling and Control of the Ball and Beam Process

One of the most difficult problems that an engineer who works with modeling deals with, is the question about how to translate a physical phenomenon into a set of equations. It is usually difficult to capture all dynamics and phenomena, so one usually strives for a set of equations that describes the physical system approximately and adequately with the accuracy for the purpose. In our case, we model the dynamics relevant for control design. The topic of this thesis was to do an in-depth study of the Ball and Beam process. Two different experimental implementation of the Ball and Beam process have been considered, both available at the course lab at the Department of Automatic Control, Lund. The first step consisted of deriving the equations of motion, that is, to do the mathematical modeling of the process. In order to implement this model Modelica has been used. Modelica, which is a powerful language for modeling of physical systems, uses the tool Dymola. Another model was designed also with Modelica but with the help of the extension of the multi body library, which uses a methodology based on object orientation and symbolic manipulation of equations. With this last model it was possible to visualize an animation in real time 3D. The following step of the project was to do control design for the different models. The obtained simulations were shown in Dymola and Simulink. Finally experiments on the real process were developed, based on vision feedback

One Dimensional Motion with ICT Based Learning: Improving the Physics Teacher Candidates’ Science Process Skills and Attitudes

Education nowadays is demanded to produce students who have beneficial skills of the 21st century in dealing with problems in the era of information and digital technology. Therefore, it is necessary to change the emphasis of learning patterns. In this paper, the results of the application of 21st-century skills in learning Basic Physics 1 in the Physics Education Study Program, UIN Sunan Gunung Djati Bandung using a scientific approach is presented. Learning activities were conducted based on low budget materials and ICT in the form of tracker software. The results showed that students were skilled in using tracker (90%), had science processing skills (excellent 5.2%, good 74.0%, and fair 20.8%), and fostered curiosity (92.0%), careful attitude (92.2%), caring for the environment (73.0%), honest (93.0%), and cooperative (97.0%

A Mobile App Delivering a Gamified Battery of Cognitive Tests Designed for Repeated Play (OU Brainwave): App Design and Cohort Study

Background: Mobile phone and tablet apps are an increasingly common platform to collect data. A key challenge for researchers has been participant “buy-in” and participant attrition for designs requiring repeated testing. Objective: The objective of this study was to develop and asses the utility of 1 – 2 minute versions of both classic and novel cognitive tasks within a user focussed and driven mobile phone and tablet app designed to encourage repeated play. Methods: A large sample (N = 13,979 at first data collection) participated in multiple, self-paced, sessions of working memory (N-back), spatial cognition (Mental rotation), sustained attentional focus (Persistent Vigilance task), and split attention (Multiple object tracking) tasks along with an implementation of a novel action learning task. A full morningness-eveningness questionnaire was also included. Data was collected across an 18 month period. While the app prompted reengagement at set intervals, each participant was free to repeatedly complete each task as many times as they wished. Results: We found a significant relationship between morningness and age (r = 0.298, n = 12755, p Conclusions: Using extremely short testing periods and permitting participants to decide their own level of engagement - both in terms of which gamified task they played, and how many sessions they completed - we were able to collect a substantial and valid dataset. We suggest that the success of OU brainwave should inform future research oriented apps - particularly in issues around balancing participant engagement with data fidelity

The Use of a Sensory Integration Program for Children with Behavioral and Attention Deficits

One of the challenges facing occupational therapy practitioners today is incorporating treatment approaches into psychosocial and school environments that address the needs of children who have difficulties maintaining an optimal level of arousal, who have a decreased attention span, who are non-engaged and have maladaptive behaviors and impulsivity, and who may have anger management difficulties. These characteristics may coexist with the diagnosis of a sensory integrative dysfunction. As a result, the authors anticipate an increasing demand for the implementation of sensory integration programming in a psychosocial or school setting. An extensive literature review was completed to gain a full understanding of how sensory systems work and their impact on a child\u27s ability to function. The literature reviewed identified that SI programming can be beneficial in both psychosocial and school settings. Also identified through the literature review were: populations in which sensory integration programming has been a successful treatment approach, the effects of sensory dysfunction on behavior and academics, methods of how to effectively implement sensory integration interventions into a treatment plan, and widely accepted assessments used to identify sensory integration dysfunction. The purpose of this scholarly project was to develop a sensory integration program that can be easily implemented in a psychosocial or school setting. Based on the results of the current research and literature review, the Can You Regulate? program manual was developed. It was designed to educate professionals working in the psychosocial and school settings and to provide them with the appropriate tools to implement the program. The manual is divided into sections and provides an introduction to sensory integration programming and sensory integration treatment tools to be used in the Can You Regulate? program

Model-Based Control of a Large-Scale Ball-on-Plate System With Experimental Validation

A ball-on-plate system is a widespread education oriented laboratory experiment for automation in mechatronics. The setup combines elements of mechanical, electrical and control engineering and is an adequate setup for learning the combination of theory and practice. This paper presents an example of a workshop result on automatic control in mechatronics. The aim of the workshop is to develop and compare model-based approaches for ball position control in a given large-scale ball-on-plate system. The result includes the derivation of a non-linear state space model of the system. The equations are linearized in the center of the horizontal plate as an operating point in order to apply cascade control, linear-quadratic optimal control and PI optimal state feedback control. The algorithms are implemented on a microcontroller and tested in the experimental setup. The results show a successful control development which achieves the control goal with good performance in terms of command response