Design, manufacturing, and rough terrain analysis of a collision resilient foldable, adjustable wheeled miniature robot: FAWSCY

Abstract

FAWSCY: Foldable Adjustable Wheeled Stringy Clumsy Robot is a foldable, collision resilient, adjustable wheeled robot which can run through different ter-rains and inclined surfaces, to inspect areas which are unavailable to humans due to dimensional limitations or hazardousness level; to attend search and rescue missions to cover more area in a shorter duration and to be a part of somatic activities with elders and kids. Hence, it is desired to be non-harmful to itself and its environment in case of any collisions or falls, and persistent on its run under various conditions and terrains as any insect or lizard can. FAWSCY is an incremental work that till attaining its final version, several legs and wheels; and electronic components and their combinations are investi-gated. First, c-legs are tested due to its advantages on rough terrains, yet they lack sensor implementation by its constant oscillatory movement. Then ninja stars are tested the robot yet they are so rigid that they sunder from the body in presence of a collision or undesired tracking. Afterwards, the bellow design is modified to be enforced as a wheel and it is the most promising wheel configu-ration since it can damp all longitudinal, lateral and vertical forces during the impact of a collision and fall. Also, it has appreciable rough terrain performance. However, as well as being soft it is also quite strong that it cannot be controlled for different length configurations for a miniature untethered scale. Therefore, it is not applicable for FAWSCY. On its final adjustable wheel, a novel wicker modular wheel design which exhibits similar behaviour with the bellow design, and its adjusting mechanism are proposed. On the other hand, Raspberry Pi is chosen to be the main processor, and by experiments and investigation through different motors, sensors and control strategies, a two part single board design is finalized. The body of FAWSCY is also kirigami-inspired and formed by foldable sheets to cover and maintain integrity of its parts and components. After the design is completed, its performance and capabilities are assessed. First, its indoor run performance, wheel adjustment mechanism, collision resilient properties, obstacle scaling and response to inclination are investigated. The robot is assessed to be suitable for indoor environments, stairs and inclinations without getting disintegrated and harming other living subjects. Then, rough terrain experiments are conducted which resulted in success on grass, gravel and soil terrains with diverse wheel length configurations.