Research On Walking-Rolling Biped Parallel Mechanisms With Multiple Modes

ABSTRACT:The design concept of parallel mechanisms with multiple modes, which are integrated with locomotion and operation modes, is proposed in this thesis. Based on the design concept, four types of locomotion modes and two types of operation modes are defined and refined to form the method of mode integration for the purposes of improving the capacity to carry heave payload and traverse complex terrain. The walking-rolling biped parallel mechanisms with multiple modes composed of U-P-U (universal joint-prismatic joint-universal joint) kinematic chain and U-R-U (universal joint-revolute joint-universal joint) kinematic chain are constructed and analyzed, and the mechanisms as the typical configurations are studied systematically by carrying out the theory analysis, dynamic simulation, prototypes manufacturing and experimental research.Based on the study of4U parallelogram mechanism,6U mechanism and3-UPU parallel mechanism, a walking-rolling biped4-UPU parallel mechanism with multiple modes is proposed as the main research object. And then, by considering the specific application, a biped walking2-UPU+2-UU parallel mechanism is presented. After that, in order to extending the operation and locomotion modes, a walking-rolling biped4-URU parallel mechanism with multiple modes is developed. The main research works include:(1) Comparing and analyzing the three kinds of biped walking4U parallelogram mechanisms, the differences and relations of the configurations caused by the different configurations of kinematic pairs are summarized, with it, a novel biped walking4U parallelogram mechanism is obtained. According to the analysis of the rolling principle of the proposed rolling6U mechanism, two new rolling6U parallel mechanisms are gotten by using different configuration methods of kinematic pairs. Furthermore, a rolling3-UPU parallel mechanism with multiple modes is proposed by adopting a new configuration of kinematic chain. The locomotion feasibility and mode switching strategies of four rolling modes are studied by analyzing the degree of freedom and singularity positions. And, the influence of rolling capability caused by the change of the step length is discussed.(2) Based on locomotion modes and operation modes, a walking-rolling biped4-UPU parallel mechanism with multiple modes is proposed, and three kinds of locomotion modes and two kinds of operation modes are studied, respectively. The actuation strategies, mode switching, turning operation, and gait characters are discussed in the locomotion modes. And the posture adjustment, center of gravity adjustment, touching ground, and so on are analyzed in the operation mode of fixed manner. In addition, the auxiliary function of collaborative operation is researched in the locomotion modes, such as, reset function and self-rescue capability when it overturned. Furthermore, the relation between the step length and velocity is discussed by analyzing mechanism characteristics, and the property of overcoming the typical terrain is analyzed.(3) Considering the high stiffness, load carrying capability and the requirement of overcoming the rugged terrain, a biped walking2-UPU+2-UU parallel mechanism with load-carrying capacity is proposed, which can be applied for load-carrying transport. The equation of the design parameters of the two feet is calculated according to the locomotion characteristics and the load-carrying space of the mechanism. What’s more, analyzing the relation between the drive force and structure parameters under the condition of crawling, it is found that the crawling gait can deduce driving force compared with the walking gait.(4) According to the characteristics of biped4-UPU parallel mechanism with multiple modes and the design requirement of the mechanism, the different types of chains are used to construct the mechanism. And then, the function of locomotion modes and operation modes are developed. Taking biped4-URU parallel mechanism with multiple modes as example, the locomotion mode of four-footed jumping and the operation mode of ascending and descending of the platform are analyzed.To sum up, the systematic research is carried out based on proposing the design concept of walking-rolling parallel mechanism with locomotion and operation modes. A new technological approach is provided for the mobile robots equipping with carrying heave payload and traversing complex terrain capabilities.