Hybrid mobile robot is the system that will practically combine legged walking and skated driving in the same system. Therefore, this robot has own problems of inverse kinematics that are not considered in typical walking robots. In this paper, I fully categorized the inverse kinematics problems for hybrid mobile robot with general motion by walking and driving on an inclined plane, including switching end-effectors between foots and blades. I also solved the inverse kinematics for each case of problems. I here actively adopted the coordinate transformation derived from the inclined plane to cope with the random motion of foots and blades on the plane. I then presented several examples of the inverse kinematics problems with specific situations, and verified the validity of the analysis method from the results.

[Purpose] To investigate the correlation between joint position sense (JPS) during hip abduction and static/dynamic balance abilities. [Method] The study enrolled 22 healthy college undergraduates and a smartphone application known as Clinometer was used to measure JPS during hip abduction using the passive setting/active reproduction. Balance ability was measured at levels 12, 7, and 3 of the Biodex Balance System. The JPS error during hip abduction was correlated with balance ability in relation to sway level. [Results] Error in JPS during hip abduction was moderately correlated with all balance scores at all sway levels (r≥0.38, p≤0.04 for all), except for the anterior-posterior balance at levels 12 and 3 (r≤0.24, p≥0.30 for both). [Conclusion] A significant correlation existed between JPS during hip abduction and balance ability, regardless of sway level. Therefore, adequate sensory training of the hip joint is needed during balance training.

In soccer, sports science aims to prevent injuries and improve performance by biomechanically analyzing a series of the kick processes. In order to understand the kick processes biomechanically, studies on kinematic, kinetic, and EMG have been conducted. However, these studies have limitations due to absence of integrated theory defining interactions between the segments. In the present work, we propose a model to understand dynamic characteristics of the kicking leg based on the biomechanical features of the instep kick. Five healthy men participated in an experiment to perform four-level instep kick. We collected kinematic and kinetic information of the hip and knee joints. Based on the passive dominance of the knee joint, we devised the knee joint torque model proportional to angle and angular velocity. RMSE between simulated and real torque was 4.17%, and exhibited a tendency to decrease linearly with the kick speed. Henceforth, it is apparent that the faster the kick, the greater the load on the hip; and the slower the kick, the greater the load on the knee joint. We anticipate that this model will be applied to the kick monitoring equipment and for the prevention of injuries by measuring the load.