Simulation And Control At the Boundaries Between Humans And Assistive Robots

Human-machine interaction has become an important area of research as progress is made in the fields of rehabilitation robotics, powered prostheses, and advanced exercise machines. Adding to the advances in this area, a novel controller for a powered transfemoral prosthesis is introduced that requires limited tuning and explicitly considers energy regeneration. Results from a trial conducted with an individual with an amputation show self-powering operation for the prosthesis while concurrently attaining basic gait fidelity across varied walking speeds. Experience in prosthesis development revealed that, though every effort is made to ensure the safety of the human subject, limited testing of such devices prior to human trials can be completed in the current research environment. Two complementary alternatives are developed to fill that gap. First, the feasibility of implementing impulse-momentum sliding mode control on a robot that can physically replace a human with a transfemoral amputation to emulate weight-bearing for initial prototype walking tests is established. Second, a more general human simulation approach is proposed that can be used in any of the aforementioned human-machine interaction fields. Seeking this general human simulation method, a unique pair of solutions for simulating a Hill muscle-actuated linkage system is formulated. These include using the Lyapunov-based backstepping control method to generate a closed-loop tracking simulation and, motivated by limitations observed in backstepping, an optimal control solver based on differential flatness and sum of squares polynomials in support of receding horizon controlled (e.g. model predictive control) or open-loop simulations. v The backstepping framework provides insight into muscle redundancy resolution. The optimal control framework uses this insight to produce a computationally efficient approach to musculoskeletal system modeling. A simulation of a human arm is evaluated in both structures. Strong tracking performance is achieved in the backstepping case. An exercise optimization application using the optimal control solver showcases the computational benefits of the solver and reveals the feasibility of finding trajectories for human-exercise machine interaction that can isolate a muscle of interest for strengthening

Optimal Design and Control of a Lower-Limb Prosthesis with Energy Regeneration

The majority of amputations are of the lower limbs. This correlates to a particular need for lower-limb prostheses. Many common prosthesis designs are passive in nature, making them inefficient compared to the natural body. Recently as technology has progressed, interest in powered prostheses has expanded, seeking improved kinematics and kinetics for amputees. The current state of this art is described in this thesis, noting that most powered prosthesis designs do not consider integrating the knee and the ankle or energy exchange between these two joints. An energy regenerative, motorized prosthesis is proposed here to address this gap. After preliminary data processing is discussed, three steps toward the realization of such a system are completed. First, the design, optimization, and evaluation of a knee joint actuator are presented. The final result is found to be consistently capable of energy regeneration across a single stride simulation. Secondly, because of the need for a prosthesis simulation structure mimicking the human system, a novel ground contact model in two dimensions is proposed. The contact model is validated against human reference data. Lastly, within simulation a control method combining two previously published prosthesis controllers is designed, optimized, and evaluated. Accurate tracking across all joints and ground reaction forces are generated, and the knee joint is shown to have human-like energy absorption characteristics. The successful completion of these three steps contributes toward the realization of an optimal combined knee-ankle prosthesis with energy regeneratio

Optimal Design and Control of a Lower-Limb Prosthesis with Energy Regeneration

The majority of amputations are of the lower limbs. This correlates to a particular need for lower-limb prostheses. Many common prosthesis designs are passive in nature, making them inefficient compared to the natural body. Recently as technology has progressed, interest in powered prostheses has expanded, seeking improved kinematics and kinetics for amputees. The current state of this art is described in this thesis, noting that most powered prosthesis designs do not consider integrating the knee and the ankle or energy exchange between these two joints. An energy regenerative, motorized prosthesis is proposed here to address this gap. After preliminary data processing is discussed, three steps toward the realization of such a system are completed. First, the design, optimization, and evaluation of a knee joint actuator are presented. The final result is found to be consistently capable of energy regeneration across a single stride simulation. Secondly, because of the need for a prosthesis simulation structure mimicking the human system, a novel ground contact model in two dimensions is proposed. The contact model is validated against human reference data. Lastly, within simulation a control method combining two previously published prosthesis controllers is designed, optimized, and evaluated. Accurate tracking across all joints and ground reaction forces are generated, and the knee joint is shown to have human-like energy absorption characteristics. The successful completion of these three steps contributes toward the realization of an optimal combined knee-ankle prosthesis with energy regeneratio

Optimal Design and Control of a Lower-Limb Prosthesis with Energy Regeneration

The majority of amputations are of the lower limbs. This correlates to a particular need for lower-limb prostheses. Many common prosthesis designs are passive in nature, making them inefficient compared to the natural body. Recently as technology has progressed, interest in powered prostheses has expanded, seeking improved kinematics and kinetics for amputees. The current state of this art is described in this thesis, noting that most powered prosthesis designs do not consider integrating the knee and the ankle or energy exchange between these two joints. An energy regenerative, motorized prosthesis is proposed here to address this gap. After preliminary data processing is discussed, three steps toward the realization of such a system are completed. First, the design, optimization, and evaluation of a knee joint actuator are presented. The final result is found to be consistently capable of energy regeneration across a single stride simulation. Secondly, because of the need for a prosthesis simulation structure mimicking the human system, a novel ground contact model in two dimensions is proposed. The contact model is validated against human reference data. Lastly, within simulation a control method combining two previously published prosthesis controllers is designed, optimized, and evaluated. Accurate tracking across all joints and ground reaction forces are generated, and the knee joint is shown to have human-like energy absorption characteristics. The successful completion of these three steps contributes toward the realization of an optimal combined knee-ankle prosthesis with energy regeneratio

Design Optimization of an Above-Knee Prosthesis with Energy Regeneration

Above-knee amputees who use a prosthetic leg typically have to compensate for its shortcomings with unnatural hip motions. This compensation eventually leads to adverse health issues such as arthritis. We propose an active prosthesis to improve performance. The motor in our prosthetic knee allows the patient to move his hip normally, thus reducing the possibility of ancillary health issues. To improve the efficiency of the prosthesis, we use the braking phase of the prosthesis to regenerate energy. By storing energy in a supercapacitor during braking, the prosthesis lasts longer between each charge than it would without regenerative braking. We are considering two knee motor designs—a gear drive and a ball screw drive. Both designs appear to have the potential for regeneration. Several parameters characterize the prosthesis design. We use biogeography-based optimization (BBO) to determine these parameters. We are currently optimizing the prosthesis design to achieve accurate tracking of the knee angle. Future optimization criteria will include efficient energy use and generation.https://engagedscholarship.csuohio.edu/u_poster_2013/1009/thumbnail.jp

State Estimation For An Agonistic‐Antagonistic Muscle System

Research on assistive technology, rehabilitation, and prosthetics requires the understanding of human machine interaction, in which human muscular properties play a pivotal role. This paper studies a nonlinear agonistic‐antagonistic muscle system based on the Hill muscle model. To investigate the characteristics of the muscle model, the problem of estimating the state variables and activation signals of the dual muscle system is considered. In this work, parameter uncertainty and unknown inputs are taken into account for the estimation problem. Three observers are presented: a high gain observer, a sliding mode observer, and an adaptive sliding mode observer. Theoretical analysis shows the convergence of the three observers. Numerical simulations reveal that the three observers are comparable and provide reliable estimates

Towards a heuristic model for experiential AI:analysing the Zizi Show in the new real

Based on the rapid pace of evolving creative practice in AI arts, we identify and respond to an urgent need to develop frameworks for analysing the critical dimensions (including social/political) of this emerging field. This paper offers a comprehensive case study of The Zizi Show, by Jake Elwes, developed as part of The New Real and Experiential AI programme at the Edinburgh Futures Institute within the University of Edinburgh. Based on this case study analysis, we propose the structuring of distinct project characteristics into four categories (socio-cultural and institutional aspects; technology and media; experience and affect; and audience and impact) which form the basis for a heuristic model. The statements/descriptors collected in each category serve to capture creative and design strategies that can lead design processes from cultural and technological perspectives, enable projects’ cross-examination and evaluation and surface blindspots in the creative process