Upper Limb work-related musculoskeletal disorders (WMSDs) present a significant health risk to industrial workers. To address this, rigid-body exoskeletons have been widely used in industrial settings to mitigate these risks while exosuits offer advantages such as reduced weight, lower inertia, and no need for precise joint alignment, However, they remain in the early stages of development, especially for reducing muscular effort in repetitive and forceful tasks like heavy lifting and overhead work. This study introduces a multiple degrees-of-freedom cable-driven upper limb bilateral exosuit for human power augmentation. Two control schemes were developed and compared: an IMU based controller, and a myoelectric controller to compensate for joint torque exerted by the wearer. The results of preliminary experiments showed a substantial reduction in muscular effort with the exosuit's assistance, with the myoelectric control scheme exhibiting reduced operational delay. In parallel, the neuromusculoskeletal modeling and simulator (NMMS) has been widely applied in various fields. Most of the research works implements the PD-based internal model of human’s central nervous system to simulate the generated muscle activation. However, the PD-based internal models in recent works are tuned by the empirical data which requires empirical data from human subject experiments. In this dissertation, an off-policy DRL algorithm, Deep Deterministic Policy Gradient was implemented to tune the PD-based internal model of human’s central nervous system. Compared to the conventional approaches, the DRL-based auto-tuner can learn the optimal policy through trial-and-error which doesn’t require human subject experiment and empirical data. The experiment this work showed promising results of this DRL-based auto-tuner for internal-model of human’s central nervous system.

During walking, arm swing helps maintain postural balance and stability, but it does not aid in body propulsion. Human bipedal locomotion makes the upper limbs passively swing without engaging much upper limb muscle force or effort. The central idea of this thesis is to capture the kinetic energy of the arm swing during walking and transfer it to the lower limbs via a wearable exosuit to reduce the lower limb muscle efforts during walking. The Arm-Leg Interactive Coupling Exosuit (ALICE) is designed with cable-pulley system to harness shoulder and elbow movements to support the hips and ankles during walking. ALICE employs two coupling methods, shoulder-hip coupling and elbow-ankle coupling. The shoulder is coupled with the hip contralaterally, while the elbow is coupled with the ankle ipsilaterally to match the natural walking pattern. Therefore, shoulder flexion results in hip flexion, and elbow flexion initiates plantarflexion of the ankle during toe-off. The proposed concept was validated through human subject experiments involving 15 healthy young adults who walked on a treadmill for 5 minutes with and without the device. Walking kinematics, muscle activity, foot pressure, and metabolic cost were recorded to compare differences in walking biomechanics and energetics between three conditions - BL, S1 (device worn but disengaged) and S2 (device worn and engaged). A repeated measures analysis of variance (ANOVA) followed by post hoc analysis was used to identify the effects of shoulder-hip coupling, elbow-ankle coupling, and their combined effects. The results indicate that the proposed concepts indeed generate the expected outcomes of reducing lower limb muscle activity in exchange for the increased effort of upper limb muscles.

In this thesis, design, integration and validation of Serial and Parallel Elastic Cable Actuator (SPECA) is presented with an aim to enhance human-device interaction in cable-driven systems of wearable robots and to optimize actuator force and power delivery to the user. Adding springs in series and in parallel to the cables acted on the mechanical joint for motion or force control have been shown individually to reduce mechanical power consumption and therefore electrical power consumption. SPECA combines both serial elastic (SE) and parallel elastic (PE) components to explore the compounded effects on a dual cable driven system controlled by a single actuator. A bi-articulating winch attached to the actuator allows control of two cables to achieve a bidirectional control of a revolute joint. Expanding the control of the single actuator, the dual cables route to a mechanical clutch that can engage up to two external winches, or four cables, simultaneously. SPECA is built as an isolated system with only the two winches of the clutch leading to end effectors creating a design capable of being integrated into many cable driven systems. A Simulink model is developed of a simple two degree of freedom (DOF) system to confirm that SE and PE elements not only increase the effective range of a system but lower the mechanical power. SPECA undergoes static and dynamic experiments to explore SE and PE in an applied system confirming the conclusions of the model along with recommendations based on observed characteristics from the experiments. SPECA serves as an exploratory and modular proof of concept for the integration of SE and PE components into many cable driven systems.