Study On Folding Mobile Parallel Robot With Multiple Modes

Mobile robots have been widely used in disaster relief,exploring unknown area,military Investigation and family services and so on.Because of its high motion precision,compact mechanical structure,high overall stiffness and strong load capacity,mobile parallel robot has a place in mobile robots.However,in the face of complex tasks,the traditional mobile parallel robot is difficult to give full play to its structural advantages due to its small working space,single form of motion,and weak obstacle surmounting ability.Based on the purpose of robot miniaturization and improving the obstacle surmounting ability,a new type of folding multi-mode mobile parallel robot is developed to meet the demand of unknown environment detection.After folding,the robot can be miniaturized,so it is easy to store,carry and remote delivery.Using the singular position of the mechanism,the robot can realize a variety of mobile modes through mode switching,thus improving its obstacle surmounting ability and enhancing its survivability in complex environment.In this paper,the structural design of a foldable multi-mode mobile parallel robot is presented,which includes two variable platforms and four mutually nested URU branches for the requirements of folding and multi-mode movement.The change of degrees of freedom are calculated by using screw theory and the singular position is analyzed.As the working platform will be equipped with for detecting and sampling the load,the working space of parallel mechanism is solved under the condition of four degree of freedom.A solid model is manufactured in order to verify the feasibility of the mechanism design and the correctness of its degree of freedom.The robot can have seven motion modes and four folding modes through deformation.The hexagonal rolling mode,the quadrilateral rolling mode and the branch rolling mode can be realized when the full expansion is carried out.The crawling mode can be achieved by longitudinal folding,and the tumbling robot mode,walking mode and jumping mode can be implemented by the lateral folding.Both longitudinal folding and lateral folding can realize the transformation from closed loop structure to open loop structure.The kinematic analysis of each motion mode is carried out,and the ZMP of hexagon and quadrilateral rolling modes are analyzed.The gait planning of each model was carried out by using Adams software.In the crawl mode,two kinds of straight line gait and origin turn gait are planned.The hardware of the control system is designed with STM32 as the core,and the lower computer software is programmed.The upper computer interface is designed,and the wireless communication between upper and lower computer is realized.Finally,a prototype of the folding multi-mode mobile parallel robot is fabricated and related debugging experiments are completed.The results show that the designed prototype has good mobility and folding ability,and the control system is stable and reliable.