Studies on a statically determinate leveling control strategy for a statically indeterminate four-leg support vehicle-borne platform

Abstract

Four outstretched legs are commonly adopted in vehicle-borne platforms, e.g., high-performance truck cranes, to support their tires off the ground before executing tasks. However, the leveling control of a four-leg support platform is a statically indeterminate problem, whose solution has particularities of uncertainty and multiplicity. Prior art methods all require iterative measurement and actuation control, resulting in problems of severe oscillation, time-consuming, poor robustness, bad control of leg loads, even weak leg, and overloading will occur. In view of afore-mentioned deficiencies, this article provides a new leveling control method for the truck crane. The statically indeterminate problem is determinately processed by measuring the mass center position of the upper load, and by distinguishing active legs and the driven leg, the fast and high precision pre-leveling is achieved at first. The limited compensating actuation length of the driven leg is then calculated, and by compensating actuation, the leveling control is accomplished. A four-leg support electro-mechanical platform is built to carry out detailed experimental researches on this strategy. Results show that the speed, stability, security, robustness of the proposed strategy are superior to the traditional highest point chasing method, and fundamentally prevents the occurrence of weak leg and overturning risk, thus has application values in related fields.