Abstract
The fixed morphology cleaning robots lack adaptation to the unstructured environment to access and perform cleaning. Reconfigurable robots such as hTetro developed in our previous work have solved this problem, however the issues of robot's locomotion maneuverability and the associated real time control have not been resolved. This paper is aimed to validate whether a four wheel independently-controlled steering and driving (4WISD) mechanism can provide an effective solution for high maneuverability of the robot and can serve as a single mechanism for locomotion and transformation with a control strategy. After an extensive review of the existing reconfigurable robots including the hTetro platforms developed in our previous work and locomotion modules of mobile robots, the current hTetro platform with 4WISD mechanism is proposed. After it is designed and fabricated, experiments are conducted to verify its effectiveness. Experimental results show that the proposed 4WISD and the open loop kinematic control scheme deliver the high maneuverability of hTetro platform when following a circular path in various locomotion modes. The experimental results show the proposed 4WISD mechanism and kinematic controller make the hTetro platform achieve the desired maneuverability. In addition, the future work to improve the locking among the sub-modules of the robot and to further reduce the path deviation error of kinematic control is identified. Based on the work reported in this paper, the locking mechanism among the sub-modules of hTetro platform will be improved and the closed loop kinematic and dynamic control schemes will be developed to make it perform cleaning tasks in uncertain environments.
•We report a four wheel independently controlled steering and driving mechanism (4WISD) for hTetro.•The proposed single mechanism can perform both transformation and locomotion for all configurations [I, L, Z, O, T, S, J].•The proposed single mechanism also provides high maneuverability for which Predefined-Radius-Locomotion (PRL) and Fixed-Heading-Angle-Locomotion (FHAL) were demonstrated.•The design iterations ensure less interaction forces between the modules while accessing the uneven terrain.•Experiments were performed to validate the proposed design approach, and results and experimental videos are presented.