Special Section: Theory and Design of Reconfigurable Mechanisms and Robots

Abstract

Advanced robotic systems are expected to be smartly reconfigurable to adapt to new needs for versatile operations in rapidly changing unknown, uncertain environments. The evolution has led to worldwide research interest in developing reconfigurable mechanisms and robots as intelligent-mechanical systems which have the ability to change their mobility, configurations, kinematics, and dynamics performance for various application scenarios in industrial automation, healthcare, space, field exploration, maintenance, domestic operations, human assistance, and augmentation. This Special Section features 14 papers that highlight the latest theories, designs, analyses, and deployments of reconfigurable mechanisms and robots with contributions from papers presented in the IEEE/IFToMM International Conference on Reconfigurable Mechanisms and Robots (ReMAR 2021) [1] as well as an Open Call for Papers.Mechanism and robot reconfiguration stems from geometric constraint changes based on innovative design and control operation. Systematic design synthesis theory and use-oriented design methodologies are critical to generating more reconfigurable mechanism and robot concepts. Reconfiguration has been extended from basic reconfigurable joints and linkages, to various mechanisms, and to various robot functions including ground mobile motion, flying navigation, manipulation, soft robotics, and sensing interaction. Fundamental modeling and analysis of those newly developed designs are the basis to verify the reconfiguration process and guide application-based development with experimental validation. In this special issue, reconfiguration highlights numerous exemplars in the form of modular manipulators, deployable linkages, reconfigurable grippers, origami mechanisms, and reconfigurable parallel mechanisms with both rigid links and cable-driven designs.Modular design enables flexible manipulator design and reconfiguration. Ju et al. present a cable-driven manipulator with a lightweight and expandable structure based on a modular U-joint unit for flexible environment adaptability. A fast heuristic inverse kinematics model is developed for the hyper-redundant system and provides a reference solution for other reconfigurable redundant designs. A similar modular cable-driven continuum arm is developed by Sitler and Wang for free-floating underwater manipulation onboard a remotely operated vehicle (ROV). In addition to the flexible arm design based on the modular unit, a reconfigurable dual arm configuration is also realized for crawling gait, dexterous, and seafloor manipulation. Modular units-based serial chain arm could be redundant and self-reconfigurable, requiring intensive dynamic calculations in simulation. To reduce the computational load, Fass et al. present a general novel analytical approach to formulate the Newton–Euler dynamics of self-reconfigurable chains in a single vectorized differential equation which enables efficient parallel computing.Reconfigurable linkages provide a fundamental basis for mechanism reconfiguration in a wide range of application scenarios. Tang et al. present a novel quadruped robot using a single-loop metamorphic mechanism to enable the ability of transforming between different working modes. This paves the way for developing versatile mobile robots using reconfigurable linkages. By applying Hoberman’s linkage as the modular design, Zhang et al. present a snake-inspired swallowing robot that can synchronously deploy and fold both axially and radially. The work creatively demonstrates an application of reconfigurable linkages in bio-inspired robot designs. To match demands of rapid development in the automotive industry, Lyu et al. present a reconfigurable modular fixture with high modularity and flexibility. The design method has a potential in generating more flexible fixture systems in industrial applications with frequent object size changes.Robot grasping requires high flexibility and adaptability in inter