Understanding the characteristics of ground reaction forces (GRFs) on both limbs during sprinting in unilateral amputees wearing running-specific prostheses would provide important information that could be utilized in the evaluation of athletic performance and development of training methods in this population. The purpose of this study was to compare GRFs between intact and prosthetic limbs during sprinting in unilateral transfemoral amputees wearing running-specific prostheses. Nine sprinters with unilateral transfemoral amputation wearing the same type of prosthesis performed maximal sprinting on a 40-m runway. GRFs were recorded from 7 force plates placed in the center of the runway. Peak forces and impulses of the GRFs in each direction were compared between limbs. Peak forces in vertical, braking, propulsive, and medial directions were significantly greater in intact limbs than those in prosthetic limbs, whereas there were no significant differences in peak lateral force between limbs. Further, significantly less braking impulses were observed in prosthetic limbs than in intact limbs; however, the other measured impulses were not different between limbs. Therefore, the results of the present study suggest that limb-specific rehabilitation and training strategies should be developed for transfemoral amputees wearing running-specific prostheses.

In this work, we perform the challenging task of a humanoid robot standing up from a chair. First we recorded demonstrations of sit-to-stand motions from normal human subjects as well as actors performing stylized standing motions (e.g. imitating an elderly person). Ground contact force information was also collected for these motions, in order to estimate the human's center of mass trajectory. We then mapped the demonstrated motions to the humanoid robot via an inverse kinematics procedure that attempts to track the human's kinematics as well as their center-of-mass trajectory. In order to estimate the robot's center-of-mass position accurately, we additionally used an inertial parameter identification technique that fit mass and center-of-mass link parameters from measured force data. We demonstrate the resulting motions on the Carnegie Mellon/Sarcos hydraulic humanoid robot.

Surpassing the world record in athletic performance requires extensive use of kinematic and dynamic motion analyses to develop novel body usage skills and training methods. Performance beyond the current world record has not been realized or measured; therefore, we need to generate it with dynamics consistency using forward dynamics simulation, although it is technologically difficult because of the complexity of the human structure and its dynamics. This research develops a multilayered kinodynamics simulation that uses a detailed digital human model and a simple motion-representation model to generate the detailed sprinting performances of individuals with lower extremity amputations (ILEAs) aided by carbon-fiber running-specific prostheses (RSPs), which have complex interactions with humans. First, we developed a digital human model of an ILEA using an RSP. We analyzed ILEA sprinting based on experimental motion measurements and kinematics/dynamics computations. We modeled the RSP-aided ILEA sprinting using a simple spring-loaded inverted pendulum model, comprising a linear massless spring, damper, and mass, and we identified the relevant parameters from experimentally measured motion data. Finally, we modified the sprint motion by varying the parameters corresponding to the RSP characteristics. Here, the forward dynamics have been utilized to simulate detailed whole-body sprinting with different RSP types (including simulated RSPs not worn by the subject). Our simulations show good correspondence with the experimentally measured data and further indicate that the sprint time can be improved by reducing the RSP viscosity and increasing stiffness. These simulation results are validated by the experimentally measured motion modifications obtained with different types of RSPs. These results show that the multilayered Article tilte: Kindly check and confirm the edit made in the Article tilte.kinodynamics simulation using the detailed digital human model and the simple motion-representation model has the capacity to generate complex phenomena such as RSP-aided ILEA sprinting that contains complex interactions between the human and the RSP. This simulation technique can be applied to RSP design optimization for ILEA sprinting.