Design and Development of Biaxial Active Nozzle with Flexible Flow Channel for Air Floating Active Scope Camera

Abstract

Long flexible continuum robots have a high potential for search and rescue operations that explore deep layered debris. A general problem of these robots is in the control of the head motion because their thin bodies limit the space available to mount multiple actuators. This paper develops a biaxial active nozzle which can rotate the air jet direction along a roll and pitch axis in order to control the direction of reaction force and the head motion of a long flexible robot. A major challenge is how to change the air jet direction without a large resistance to the flow, which reduces the reaction force induced by the air jet. We propose a nozzle whose outlet is connected with a flexible air tube. The direction of the air jet is controlled by the smooth shape deformation of the tube. The nozzle should be compact enough to be installed on a thin robot, although the shape deformation of the tube may cause buckling. The flexible tube is modeled and simulated by a multiple link model used to derive the geometric parameters of the nozzle so that the nozzle is compact and the tube does not buckle. Based on the derived parameters, the biaxial active nozzle was developed. A basic performance experiment shows that the nozzle can change the reaction force direction by deforming the tube shape, while the magnitude of the reaction force is almost constant. We integrated the proposed nozzle with a conventional Active Scope Camera (ASC). The range where the robot can look around in a vertical exploration was significantly improved, which was three times larger than the previous ASC whose head was controlled by pneumatic actuators. The rubble field test demonstrates that the integrated ASC could move over rubble (maximum height of 200 mm) and steer the course.