Design and Operation of Locomotion Systems examines recent advances in locomotion systems with multidisciplinary viewpoints, including mechanical design, biomechanics, control and computer science. In particular, the book addresses the specifications and requirements needed to achieve the proper design of locomotion systems. The book provides insights on the gait analysis of humans by considering image capture systems. It also studies human locomotion from a rehabilitation viewpoint and outlines the design and operation of exoskeletons, both for rehabilitation and human performance enhancement tasks. Additionally, the book content ranges from fundamental theory and mathematical formulations, to practical implementations and experimental testing procedures. Written and contributed by leading experts in robotics and locomotion systems Addresses humanoid locomotion from both design and control viewpoints Discusses the design and control of multi-legged locomotion systems

The majority of powered lower-limb exoskeletons nowadays are designed to rigidly track time-based kinematic patterns, which forces users to follow specific joint positions. This kinematic control approach is limited to replicating the normative joint kinematics associated with one specific task and user at a time. These pre-defined trajectories cannot adjust to continuously varying activities or changes in user behavior associated with learning during gait rehabilitation. Time-based kinematic control approach must also recognize the user’s intent to transition from one task-specific controller to another, which is susceptible to errors in intent recognition and does not allow for a continuous range of activities. Moreover, fixed joint patterns also do not facilitate active learning during gait rehabilitation. People with partial or full volitional control of their lower extremities should be allowed to adjust their joint kinematics during the learning process based on corrections from the therapist. To address this issue, we propose that instead of tracking reference kinematic patterns, kinetic goals (for example, energy or force) can be enforced to provide a flexible learning environment and allow the user to choose their own kinematic patterns for different locomotor tasks. In this dissertation, we focus on an energetic control approach that shapes the Lagrangian of the human body and exoskeleton in closed loop. This energetic control approach, known as energy shaping, controls the system energy to a specific analytical function of the system state in order to induce different dynamics via the Euler-Lagrange equations. By explicitly modeling holonomic contact constraints in the dynamics, we transform the conventional Lagrangian dynamics into the equivalent constrained dynamics that have fewer (or possibly zero) unactuated coordinates. Based on these constrained dynamics, the matching conditions, which determine what energetic properties of the human body can be shaped, become easier to satisfy. By satisfying matching conditions for human-robot systems with arbitrary system dimension and degrees of actuation, we are therefore able to present a complete theoretical framework for underactuated energy shaping that incorporates both environmental and human interaction. Simulation results on a human-like biped model and experimental results with able-bodied subjects across a variety of locomotor tasks have demonstrated the potential clinical benefits of the proposed control approach.

This book presents the development of a new multimodal human-robot interface for testing and validating control strategies applied to robotic walkers for assisting human mobility and gait rehabilitation. The aim is to achieve a closer interaction between the robotic device and the individual, empowering the rehabilitation potential of such devices in clinical applications. A new multimodal human-robot interface for testing and validating control strategies applied to robotic walkers for assisting human mobility and gait rehabilitation is presented. Trends and opportunities for future advances in the field of assistive locomotion via the development of hybrid solutions based on the combination of smart walkers and biomechatronic exoskeletons are also discussed.

Bioinspired Legged Locomotion: Models, Concepts, Control and Applications explores the universe of legged robots, bringing in perspectives from engineering, biology, motion science, and medicine to provide a comprehensive overview of the field. With comprehensive coverage, each chapter brings outlines, and an abstract, introduction, new developments, and a summary. Beginning with bio-inspired locomotion concepts, the book's editors present a thorough review of current literature that is followed by a more detailed view of bouncing, swinging, and balancing, the three fundamental sub functions of locomotion. This part is closed with a presentation of conceptual models for locomotion. Next, the book explores bio-inspired body design, discussing the concepts of motion control, stability, efficiency, and robustness. The morphology of legged robots follows this discussion, including biped and quadruped designs. Finally, a section on high-level control and applications discusses neuromuscular models, closing the book with examples of applications and discussions of performance, efficiency, and robustness. At the end, the editors share their perspective on the future directions of each area, presenting state-of-the-art knowledge on the subject using a structured and consistent approach that will help researchers in both academia and industry formulate a better understanding of bioinspired legged robotic locomotion and quickly apply the concepts in research or products. - Presents state-of-the-art control approaches with biological relevance - Provides a thorough understanding of the principles of organization of biological locomotion - Teaches the organization of complex systems based on low-dimensional motion concepts/control - Acts as a guideline reference for future robots/assistive devices with legged architecture - Includes a selective bibliography on the most relevant published articles

Dr Jan Veneman is employed by Hocoma AG. All other Topic Editors declare no competing interests with regards to the Research Topic subject.

The field of exoskeletons has undergone an evolution from complex full-body exoskeletons that did not (yet) produce the expected results towards simpler single-joint exoskeletons that can improve the mobility of people. While full-body and single-joint exoskeletons certainly have appropriate applications, we need to get a better understanding of the distal and proximal assistive mechanisms and provide insights that are currently lacking on how to assist walking in an even simpler way than single-joint exoskeletons. This dissertation details an iterative approach toward the development of simplified and efficient assistance strategies for improving human locomotion. We first conducted an experiment to observe the human response to proximal and distal perturbations by altering the treadmill grade and footwear inclination. The results indicate that the metabolic rate is predominantly sensitive to changes in the center of mass (COM) mechanics and further motivate the development of devices that can assist walking at the level of the COM. We then developed a robotic tether system that allows applying desired cyclic force profiles as a function of step time to provide whole-body assistance during walking. By leveraging the system capabilities, we performed an experiment and simple pendulum simulation to investigate the effects of timing and magnitude for non-constant force profiles at the COM. Through these experiments and the simulation, we found that assistance at the COM during the double stance phase can efficiently reduce the metabolic rate of walking half. Surprisingly, assisting propulsion did not maximize the reduction in metabolic rate, and our pendulum model revealed that the reduction in metabolic rate can instead be explained by the assistance of COM acceleration at the beginning of the step. Ultimately, our long term goal is to develop similar strategies to populations with gait disabilities, but as a primary step, we investigated the biomechanical mechanisms to assist lower limb joints using timed forward forces at the COM. To that end, we assessed the underlying mechanisms of muscle and joint parameters that explain the effects of timing and magnitude of horizontal forces at the COM on metabolic rate. The results show that the metabolically optimal timing assisted the ankle muscles that are responsible for push-off, and the knee and hip muscles that are responsible for collision. Based on these findings, it seems possible to assist different joints by different amounts by varying the timing of forces at the COM. This could be useful in clinical populations for providing ‘targeted’ joint-specific assistance without having to switch between different exoskeletons. We expect our experimental findings to provide knowledge on optimal force profiles that could be used for treadmill exercise therapy, motorized ‘rollator’-style assistive devices for walking, and even it could even inspire new strategies for combined actions of the ankle, knee, and hip of full-body exoskeletons. Timed forces at the COM could be used to assist patients with impaired gait and facilitate proactive user participation that has been identified as a critical factor in improving locomotor outcomes for rehabilitation robotics.

This textbook provides a thorough introduction and overview of the design and engineering of state-of-the-art prosthetics and assistive technologies. Innovations in prosthetics are increasingly made by cross-disciplinary thinking, and the author introduces the application of biomedical, mechanical, electrical, computer, and materials engineering principles to the design of artificial limbs. Coverage includes the fundamentals of biomechanics, biomechanical modeling and measurements, the basics of anatomy and physiology of limb defects, and the historical development of prosthetic design. This book stimulates the innovative thinking necessary for advancing limb restoration, and will be essential reading for students, as well as researchers, professional engineers, and prosthetists involved in the design and manufacture of artificial limbs. Learning enhanced by the exercises, including physical modeling with MATLAB and Simulink; Includes appendices with relevant equations and parameters for reference; Introduction to the design and engineering of prosthetics and assistive technologies.

Human lower limbs serve important biomechanical functions, e.g., supporting human body weight, providing power for locomotion, etc. A large number of individuals, however, live with the impairment of such functions. Such functional impairment may be associated with limb loss caused by amputation, or functional degeneration associated with aging or musculoskeletal/neural pathologies (e.g. stroke). Consequently, such individuals are more likely to suffer from impaired mobility and live in a sedentary lifestyle, seriously affecting their independence and quality of life. The research in this thesis seeks to address this problem through the development of actively-powered robotic assistive devices that restore or augment the lost or weakened limb functions. Specifically, two assistive devices are presented, including a robotic knee orthosis that assists the wearer's knee motion in sit-to-stand transfer and other locomotive functions, and a robotic transtibial prosthesis that restores the lost ankle-foot functions for below-knee amputees. In the development of these devices, the design specifications were determined according to the desired locomotive functions and related biomechanical data. Subsequently, the actuation approaches were selected, along with the corresponding actuation mechanisms. The devices have been proven to provide the desired kinematic and kinetic performances through detailed analysis. In the following detailed design phase, 3D solid models were created for the robotic systems and individual components. Finite-Element Analysis was also performed to ensure the strength and rigidity of the structure under load. Finally, prototypes of the devices were fabricated and assembled, and experiments have been devised to measure their kinetic performances in use.

Predictive simulation based on dynamic optimization using musculoskeletal models is a powerful approach for studying biomechanics of human gait. Predictive simulation can be used for a variety of applications from designing assistive devices to testing theories of motor controls. However, one of the challenges in formulating the predictive dynamic optimization problem is that the cost function, which represents the underlying goal of the walking task (e.g., minimal energy consumption) is generally unknown and is assumed a priori. While different studies used different cost functions, the qualities of the gaits with those cost functions were often not provided. Therefore, this dissertation evaluates and examines different cost function forms for dynamic simulation of human walking. The problem of the walking cost function determination was cast as a bilevel optimization, which was solved using a nested evolutionary approach. The results showed cost functions based on a weighted combination of muscle-based performance criteria (e.g., metabolic cost, muscle fatigue), gait smoothness, and gait stability led to better walking solutions compared to any cost functions only based on muscle performance criteria. Further evaluations of the walking cost functions were done in the simulation cases of human walking augmented with assistive devices such as prosthesis and exoskeleton. The simulations of augmented walking were comparable to the experimental results, which suggests the potential of using the simulation approach to address problems of finding assistive device design and control.