A Comparison of Adaptive LQG and Nonlinear Controllers for Vehicle Suspension Systems

A design feature of many computer-controlled suspension systems, is their ability to adapt control law parameters to suit prevailing road conditions. Here, for systems employing high bandwidth actuators and state variable feedback control, the benefits of such adaptation are shown to be at best marginal. An optimal adaptive LQG system is compared with a fixed structure nonlinear feedback controller in the context of a simple quarter-vehicle suspension model. Performance comparisons are made, and trends considered under more realistic conditions. In consequence the overall usefulness of this type of adaptation is called into question.     

Application of Learning Automata to Controller Design in Slow-Active Automobile Suspensions

This study considers a new design methodology in the context of active vehicle suspension control. The approach combines concepts from Stochastic Optimal Control with those of Learning Automata. A learning automaton effectively learns optimal control on-line in the vehicle, in an appropriate stochastic “test-track” environment. For practical application, the overwhelming advantage of this approach is that no explicit modelling is required, and considerable time savings may be expected in system development. This simulation study considers the on-line learning of optimal control in a low-bandwidth active suspension system, where control feedback is confined to a body-mounted accelerometer at each corner of the vehicle. It is shown that learning can successfully take place under a range of conditions, including the case when there is substantial transducer noise. The performance of the resulting control system is shown to depend heavily on the nature of the learning environment.     

船队运力过剩的解决方案

我想就航运界普遍担忧的运力过剩问题谈谈自己的看法. 首先来看一组数据:根据克拉克森统计,今年1～10月份全球新接订单合计9512万载重吨,同比增长162%.而截至2010年9月初,油轮、货轮和集装箱船的订单占现有船队的比例分别高达28.5%、54.5%和24.9%.今年1～9月份,中国新船订单5071万载重吨,是去年同期1692万载重吨的三倍.中国承接的新船订单占了全球订单总量的45.6%.航运市场今后如何消化这么庞大的运力?这是航运界需要审慎对待的问题.