Effects of the Mechanical Closed-Loop Between the Body and the Ground on the Postural Balance of Gaits

People and animals adapt their gait to the environment as they perform activities in a variety of environments. However, there are cases where the parts of the body necessary for walking are damaged in some way, resulting in walking difficulties. An example is paralysis caused by a stroke. A split-belt treadmill is occasionally used for the investigation to analyze how the stroke effects on the motion. However, the mechanical properties of the split-belt treadmill on the body have not been clarified. It is also unknown how the mechanical closed-loop between the body and the environment, generated by synchronizing the movements of the two belts, affects the gait. In this study, we investigated that the effect of the mechanical closed-loop structure between the body and the environment on walking using the robot and the mechanical effect of the floor reaction force on the body. Further, we conducted walking experiments using the developed robot, obtained body and environmental information, and analyzed the results. As the result, it was observed that the motion data differed based on the coupling of the treadmill. In other words, it was suggested that the mechanical closed-loop structure certainly influenced the physical balances on walking motion. Furthermore, it is confirmed that the coupling of treadmills increases the body’s sway. Although our results are given from a robotic experiment, it is expected that these measures would be one of the important index in human rehabilitations.

Descending and Ascending Signals That Maintain Rhythmic Walking Pattern in Crickets

The cricket is one of the model animals used to investigate the neuronal mechanisms underlying adaptive locomotion. An intact cricket walks mostly with a tripod gait, similar to other insects. The motor control center of the leg movements is located in the thoracic ganglia. In this study, we investigated the walking gait patterns of the crickets whose ventral nerve cords were surgically cut to gain an understanding of how the descending signals from the head ganglia and ascending signals from the abdominal nervous system into the thoracic ganglia mediate the initiation and coordination of the walking gait pattern. Crickets whose paired connectives between the brain and subesophageal ganglion (SEG) (circumesophageal connectives) were cut exhibited a tripod gait pattern. However, when one side of the circumesophageal connectives was cut, the crickets continued to turn in the opposite direction to the connective cut. Crickets whose paired connectives between the SEG and prothoracic ganglion were cut did not walk, whereas the crickets exhibited an ordinal tripod gait pattern when one side of the connectives was intact. Crickets whose paired connectives between the metathoracic ganglion and abdominal ganglia were cut initiated walking, although the gait was not a coordinated tripod pattern, whereas the crickets exhibited a tripod gait when one side of the connectives was intact. These results suggest that the brain plays an inhibitory role in initiating leg movements and that both the descending signals from the head ganglia and the ascending signals from the abdominal nervous system are important in initiating and coordinating insect walking gait patterns.