Design and development of a snake robot with mixed mode locomotion

Abstract

Small robots have a great potential to access confined spaces where humans cannot go. However, the mobility of the robot with wheel and track systems is severely limited in chaotic environments. Alternatively, biomimetic robots for instance snake robot using biologically inspired gait for locomotion can provide better access in many situations, but they are usually slow and can easily get snag or stuck caused by lack of motion flexibility. Serpentine, concertina, sidewinding and rectilinear are main four types of common snake robot locomotion gaits stimulated from biological snake. Nevertheless, these modes of locomotion are only suitable for a unique type of space of working environment. This individual gait most of the time fails to work effectively on the snake robots when they are required to work in different cluttered environment with different measures of complexity. As an example for consideration, motion type of the snake robot in open space should be different from the limited space such as in a narrow passage. To resolve this problem, mixed mode locomotion is proposed in this study by synchronizing two different gaits: serpentine gait for open workspace and wriggler gait for narrow space environment through development of a gait transition algorithm. This study includes the investigation on kinematics analysis followed by dynamics analysis while considering related structural constraints for both gaits. Based on the analyses a new snake robot prototype has been developed and consequently experiments have been conducted to validate the proposed locomotion strategy. In the prototype design, a new designed of scales has been introduced as frictional elements and this prototype is designed to meet geometric constraints for both gaits under consideration. Experimental results show that the new snake robot is capable of switching its gait efficiently from one to another. It also shows that the serpentine gait is able to run at a higher speed compared to the wriggler gait. However, the current study is limited to 20 snake motion without sensory feedback. To improve motion capabilities as well as flexibility of snake robots, further research is recommended with 30 motion capability.