Computer interfaces with visual biofeedback (BF) capabilities in robot-assisted gait training applications can help design subject-specific therapies, define tasks based on the patient's condition, and increase the training outcomes. This study presents the use of an open-source real-time computer interface as a subject-specific visual BF and monitoring tool during gait. The interface is used in combination with a low-cost Wearable integrated Sensor System for Data Acquisition (WiSSDA), which consists of a 3-D printed lower extremity exoskeleton equipped with rotary encoders and pressure-sensitive insoles that measure biometric data during the gait cycle. The system obtains the lower extremities’ joint kinematics in the sagittal plane and estimates the vertical component of the foot contact forces and the foot center of pressure. Experimental tests were performed to evaluate different gait parameters using the computer interface as visual BF to guide the subject with reference boundaries of kinematic and kinetic parameters as target trajectories. The results were used to evaluate the interface's performance for specific gait tasks. The results demonstrated the capabilities of the computer interface combined with WiSSDA for robot-assisted gait training applications using BF; providing an open-source, portable, and ambulatory device that can be used in outdoor environments. The proposed system can help bring gait rehabilitation outside the laboratory environment, eliminating the need for stationary equipment.

Biped walking involves a series of transitions between single support (SS) and double support (DS) contact configurations that can include both balanced and unbalanced states. The new concept of steppability is introduced to partition the set of unbalanced states into steppable states and falling (unsteppable) states based on the ability of a biped system to respond to forward velocity perturbations by stepping. In this work, a complete system-specific analysis of the stepping process including full-order nonlinear system dynamics is presented for the DARwIn-OP humanoid robot and a human subject in the sagittal plane with respect to both balance stability and steppability. The balance stability and steppability of each system are analyzed by numerical construction of its balance stability boundaries (BSB) for the initial SS and final DS contact configuration and the steppable unbalanced state boundary (SUB). These results are presented with center of mass (COM) trajectories obtained from walking experiments to benchmark robot controller performance and analyze the variation of balance stability and steppability with COM and swing foot position along the progression of a step cycle. For each system, DS BSBs were obtained with both constrained and unconstrained arms in order to demonstrate the ability of this approach to incorporate the effects of angular momentum and system-specific characteristics such as actuation torque, velocity, and angle limits.

The purpose of this paper is to investigate what kinds of effects the multi-segmental body with actively controlled body part have on balancing. As part of the research, a biped mechanism is simplified to multi-segmental legged model in sagittal plane where the model is comprised of a stance leg, foot and actively controlled body part. Not only the system parameters are in place but also necessary and sufficient conditions for balancing have been implemented as constraints. The algorithm that we proposed iteratively solves nonlinear constrained optimization problems. The balanced state domain is constructed by connecting velocity extrema. The proposed algorithm is used to identify the balanced state domain in a deterministic scheme using numerical optimization.

While robotic hands have been developed for manipulation and grasping, their potential as tools for performance evaluation of engineered products - particularly compliant garments that are not easily modeled - has not been broadly studied. In this research, the development of a low-cost anthropomorphic robotic hand is introduced that is designed to characterize glove stiffness in a pressurized environment. The anthropomorphic robotic hand was designed to mimic a human hand in a neutral posture corresponding to the naturally relaxed position in zero gravity, and includes the transverse arch, longitudinal arch, and oblique flexion of the rays. The resulting model also allows for realistic donning and doffing of the prototype spacesuit glove, its pressurization, and torque testing of individual joints. Solid models and 3D printing enabled the rapid design iterations necessary to successfully work with the compliant pressure garment. The performance of the robotic hand is experimentally demonstrated with a spacesuit glove for different levels of pressures, and a unique data processing method is used to calculate the required actuator torque at each finger's knuckle joint. The reliable measurement method confirmed that glove finger torque increases as the internal pressure increases. The proposed robotic design and method provide an objective and systematic way of evaluating the performance of compliant gloves.