24 research outputs found
A Soft Continuum Robot with Self-Controllable Variable Curvature
This paper introduces a new type of soft continuum robot, called SCoReS,
which is capable of self-controlling continuously its curvature at the segment
level; in contrast to previous designs which either require external forces or
machine elements, or whose variable curvature capabilities are discrete --
depending on the number of locking mechanisms and segments. The ability to have
a variable curvature, whose control is continuous and independent from external
factors, makes a soft continuum robot more adaptive in constrained
environments, similar to what is observed in nature in the elephant's trunk or
ostrich's neck for instance which exhibit multiple curvatures. To this end, our
soft continuum robot enables reconfigurable variable curvatures utilizing a
variable stiffness growing spine based on micro-particle granular jamming for
the first time. We detail the design of the proposed robot, presenting its
modeling through beam theory and FEA simulation -- which is validated through
experiments. The robot's versatile bending profiles are then explored in
experiments and an application to grasp fruits at different configurations is
demonstrated.Comment: Accpeted for IEEE Robotics and Automation letters in January 2024,
Imperial's open access research REF 2029 open access polic
An approach for smooth trajectory planning of high-speed pick-and-place parallel robots using quintic B-splines
This paper presents a new, highly effective approach for optimal smooth trajectory planning of high-speed pick-and-place parallel robots. The pick-and-place path is decomposed into two orthogonal coordinate axes in the Cartesian space and quintic B-spline curves are used to generate the motion profile along each axis for achieving C4-continuity. By using symmetrical properties of the geometric path defined, the proposed motion profile becomes essentially dominated by two key factors, representing the ratios of the time intervals for the end-effector to move from the initial point to the adjacent virtual and/or the via-points on the path. These two factors can then be determined by maximizing a weighted sum of two normalized single-objective functions and expressed by curve fitting as functions of the width/height ratio of the pick-and-place path, so allowing them to be stored in a look-up table to enable real-time implementation. Experimental results on a 4-DOF SCARA type parallel robot show that the residual vibration of the end-effector can be substantially reduced thanks to the very continuous and smooth joint torques obtained