Study On Climbing Snakelike Robot

The research of snakelike robots is a branch of bionic robots'research. There are a good many of prototypes in the world till present. The locomotion modes of the prototypes are serpentine crawl, sideslip, side roll, et al on a plane. And most of them have the abilities of raising their heads, climb up steps, crossing low obstacles, et al in the three-dimensional space. Especially in recent years, the new developed snakelike robots have more aimed and versatile functions. Some of them can climb up to a level of several meters in the vertical direction. The climbing that realized till now includes inner-climbing and outer-climbing. The inner-climbing refers to the climbing that proceeds in the inner space or surface of climbing object, such as in a pipe or between two walls. The snakelike robots stake on the inner surface of the climbing object by shaping as brackets, then they can move up and down by track driving, inchworm locomotion, rolling et al. The outer-climbing refers to the climbing that proceeds on the outer surface of the climbing object. The snakelike robots twist on the climbing object and climbing up and down by certain locomotion gait. The inner-climbing is much easier to be realized for most of snakelike robots while the outer-climbing is not. The realizing of outer-climbing mostly depends on the structure and the appearance design of the snakelike robot. It is strongly required that the snakelike robot has agility locomotion ability in three-dimension space and it can attach on the surface of the climbing object steadily and will not drop.Only one experiment of snakelike robot realized outer-climbing in the world. And theoretical study on it is blank. This paper will focus on the outer-climbing of snakelike snake. To develop a kind of climbing snakelike robot that has great advantage in vertical outer-climbing, it presents a new mode of structure. A climbing snakelike robot that based this structure mode has simple structure, is easy to be controlled and could steadily attach on the surface of the climbing object more agility and easier. Then it analyzes the mechanism of the static balance of the basic pose while climbing snakelike robot climbing a tree, which provides theoretical rules for developing a climbing snakelike robot or choose climbing object. Following is planning a spatial inchworm locomotion gait for it to climb a trunk which bases the inchworm locomotion gait on a plane. Then it analyzes the kinematics mechanism of the gait, presents the locomotion equations of the wave. Base on the locomotion equations, the snakelike robot could realize the climbing on a trunk.The studies in this paper mainly focus on followings.(1) Presents a new and modular structure design of execution unit, which has rather great agility in three-dimension space.against the problems that exist in the study of climbing snakelike robots at present, this paper presents a design named P-R module, who is similar to parallel and orthogonal link ways, but the operating space of the module is similar to a universal joint. So a snakelike robot that links by P-R modules both can act as a parallel linked one or a orthogonal linked one. But on the other hand, it nearly equal to a universal joint linked one in function. And it has simple structure and is easy controllable, so it is much easy to be made than universal joints linked one. A climbing snakelike robot based P-R modules has simple structure and is easy to be controlled, it could steadily attach on the surface of the climbing object more agility and easier, so it has unique dominance on vertical climbing.(2) Study on the mechanism of static balance of climbing snakelike robot climbing a trunk.CSR that based on P-R modules has good agility. It can climb trees. The pose that it twists on a trunk steadily and forms an isometric spiral is the basic pose of climbing trees. Analyzing the helical track, it gains the relationship of the obliquity of helical curve and each P, R joints'rotation. Then in the course of practise, only to know the obliquity of the helical curve that CSR rolling on the trunk, by controlling the rotation of each joints, CSR will form the corresponding shape and attach on the surface of the trunk.Studing on the mechanical equilibrium that CSR on the trunk, it gain the function relationship between the parameters of CSR and the trunk, analyzing the soecufuc relationships between every two parameters, it gained the border value of each parameters, which provide theoretical rules for developing a climbing snakelike robot or choose climbing object.(3) Gait plan.It is planed a three-link formed motion wave inchworm locomotion gait for CSR climbing trees. In the procession of climbing, only P-joints engage in the delivery procession of locomotion wave. It plans the full procession of motion wave deliver, and gives the position and rotation of each joint. In the procession of motion wave pass, CSR will arrive to another isometric spiral position from a former one. The two isometric spiral have the same obliquity, but they are not coincidence. CSR moves from one to another to realize climbing.For CSR, the three-link formed motion wave inchworm locomotion gait is a kind of simple action, strong stability, wide suitable use and energy conservation gait.(4) Study on the mechanics of climbing locomotion.It analyzes the inchworm locomotion in three-dimension space whose motion wave is formed with three links by four-link mechanism. The relationship of angular displacement of relative angles between two adjacent links, the relative change rate of the angular displacement, the equations of initial angular of the motion wave and the length of one step are presented.By analyzing the figures of simulation, it is gained that the spatial inchworm locomotion gait is suitable for the snakelike robot to adopt while climbing trees because of the smooth change of the spatial angulars'rotational velocity. But because these are spatial angulars that formed by twisting, and only P-joints engage in the delivery procession of locomotion wave, the relative angles between two adjacent links that form the locomotion wave could not sampling as arbitrary as they are just on a plane. The three-link locomotion wave can transfer continuously only when each of the relative angles varies in its specific range.(5) Simulations and prototype experiments.Simulations by software ADAMS and prototype experiments are presented to demonstrate and validate the concepts and the modeling assumptions.This paper studies on the climbing snakelike robot. From the optimization of the structure design to the realization of the behavior of climbing a tree, it gives rather full and deep studies. These studies provide valuable preferences for wider and deeper climbing snakelike robot research.