Simulating the GRF of Humanoid Robot Vertical Jumping Using a Simplified Model with a Foot Structure for Foot Design

There are many theories and tools for human or robot motion simulation, but most of them require complex calculations. The LNZN model (a simplified model named by the proposers) simplifies the human model and facilitates simulation of the Ground Reaction Force (GRF) of body landing by spring damping model and ignoring joint rotation movements, which can reduce the amount of computation obviously. In this paper, the LNZN model of human running is selected as the basis and is modified to obtain the LNZN model of a robot, which expands the application of the LNZN model. According to the structure of the human foot, a foot structure is then added to the simplified model to reduce the GRF. We also applied driving forces to the new model to simulate the whole high jump motion of the robot to expand the functions of the LNZN model. The obtained GRF data were anastomotic to the actual experimental results. In addition, the effects of variables, such as the mass, hardness, and damping, of the foot on the GRF at the moment of landing were also explored. Finally, based on the guidelines obtained for the design of the robot’s foot structure, we fabricated new robot’s feet and installed them on the actual robot and achieved a better cushioning effect than the original foot in experiments.