Abstract
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 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.
Highlights
We have measured the kinetic and physiological aspects of human performance using an optical motion capture system, force plate, etc., and applied kinematics and dynamics analyses to compute the joint angles andMurai et al Robomech J (2018) 5:10 technique to human whole-body motion generation is considerably difficult, because (1) humans have many more degrees of freedom and a much more complicated structure compared to robots, and (2) humans are floating systems; we need to estimate the contact forces that can become unstable, especially during dynamic motions such as sprinting [1,2,3,4]
running-specific prostheses (RSPs)-aided individuals with lower extremity amputations (ILEAs) sprinting involves humans and RSPs, as well as the kinematic and dynamic interactions between them, and its kinematics and dynamics analyses are technically complex compared with those of general rigid body systems that are often analyzed in the robotics field
We generated the RSP-aided ILEA sprinting motion, which contains the complex interactions between humans and RSPs, by developing a multilayered kinodynamics simulation, which uses a detailed digital human model and a simple motion-representation model that parametrically represents human motion mechanisms
Summary
Murai et al Robomech J (2018) 5:10 technique to human whole-body motion generation is considerably difficult, because (1) humans have many more degrees of freedom and a much more complicated structure compared to robots, and (2) humans are floating systems; we need to estimate the contact forces that can become unstable, especially during dynamic motions such as sprinting [1,2,3,4] This research solves these problems by developing a multilayered kinodynamics simulation that uses a detailed digital human model and a simple motion-representation model, which parametrically represents human motion mechanisms. We generated the RSP-aided ILEA sprinting motion, which contains the complex interactions between humans and RSPs, by developing a multilayered kinodynamics simulation, which uses a detailed digital human model and a simple motion-representation model that parametrically represents human motion mechanisms
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