Motion Planning of Runshare Boom System
With the rapid urbanization, the Aerial Work Platform (AWP) especially with long
booms and superelevation increasingly plays an important role in this process. Aerial work platforms attached greater significance to construction, fire fighting and protecting person's lives and belongings.
Firstly, a possibility of similar section design could be drawn by searching main performance parameters and design rules of the form of structures and working specifications of the modern series aerial work products. Secondly, the derivation and analysis of similar boom section design are presented by linear small deformation and nonlinear large deformation analysis method. An example is taken which requires the designed model being smaller than the original one. Full geometry similar design, similar design of equal stress between design model and protype model, similarity design of same stress in design model are respectively carried out and the forces, stress,and deformation of dangerous section of which are discussed. In the full geometry similar design, forces,stress, and deformation of the nonlinear similar design are slightly bigger than those of the linear design which intends to be unsafe. The stress of the model of nonlinear geometry similar design is greater than the original model, which means the design result is irrationable. By adjusting the section parameters of each boom, a final design can be obtained in which the stress similarity ratio is 1 or the stress could tend to be a constant.
Secondly, AWP finishes the desired movement through a different-level motion control strategy. The first control level of platform motion from work space to joint space is focused on the redundant degree of freedom planning. A simplified AWP model is built and its Jacobian matrix relative to the base frame is deduced. With obtaining the minimum Euler norm as the object, the inverse kinematics problem of redundant degree of freedom is solved based on the dividing Jacobian matrix method, in which the limit positions and velocities of telescopic and luffing motion are taken into consideration. As a result, the analysis algorithm is programmed. The motion planning in this level lays the foundation for the further hydraulic cylinder driving space control strategy.
An analytical method is introduced to deduce mapping relationship between joint space and cylinder driven space which contains the characteristic of multi-layer synchronous telescoping for prismatic joints and the cylinder driving characteristic for revolute joints. The concrete operation parameters for hydraulic control system could be achieved accordingly.
Due to requirements of the system design and motion analysis, we researched the professional design platform as AWP Design and Analysis System. With the help of the typical design prototypes, the software integrates the process from the boom section design to the boom deformation and stress analysis, then to the hierarchical control of for trajectory planning of the work platform, finally gets to the hydraulic cylinder motion error analysis. It provides a rapid and efficient computing tool for AWPs from the overall scheme design to detail structure design. The principle design process as boom section similar design, platform trajectory planning and assembling tolerance of hydraulic cylinders analysis are discussed individually.