Advanced Control Technology Research Of Light Flight Simulator Motion Platform

Nowadays, with the rapid development of civil aviation industry, there are increasingly strong demands of pilot training. But due to high purchase price and usage costs of tranditional flight simulator, a low-cost substitution is expected to appear that can cover the basic functions of the tranditional one. In order to meet the urgent needs of civil aviation industry, we propose a concept of"Light Flight Simulator". The most exciting feature of this economic simulator is its low weight and massive usage of software modules to fulfill the functions that tranditional hardware must do. Now we finish design and manufacture of the prototype simulator. One of the most important parts of this simulator is a high performance six-dof motion platform. Its design goals are simple structure, low weight and capable of dispose within common office building. At the same time, the simulator must have good dynamic ability, supply satisfying motion feeling for pilots using electrical actuators and be capable of adapting variation of equips and pilots. Moreover, the simulator must be equipped with full software limiting measures, which can protect the hardware from accidents. This dissertation designs an integrated control system framework for light flight simulator motion platform, which covers a series of research subjects including modeling, identification, control of motion platform, washout algorithm design and optimization, motion protection system design and etc.The first part of this dissertation covers modeling, identification and control of motion platform. Firstly, three main dynamic modeling methods are compared in its computation complexity, application area and equivalence. Secondly, UKF method is proposed to identify parameters of parallel motion platform. Comparing to other identification methods, UKF method does not need transforming dynamic model to linear parameter form and have higher identification precision. Due to uncertain parameters of parallel motion platform and external disturbance, this dissertation proposes a series of adaptive control schemes to ensure the control performance of motion platform. The first controller proposed is a nonlinear adaptive sliding control scheme in task space based on dynamic model. This method divides system uncertainty into two parts: constant uncertain parameters and time-varying uncertain parameters. The control algorithm uses nonlinear adaptive controller to identify constant uncertain parameters, meanwhile, nonlinear sliding controller is used to compensate the effects of time-varying uncertain parameters and external disturbance. Due to inclusion of high-gain part in the adaptive sliding controller, it may excite unmodelled dynamics and cause chattering. So this dissertation proposed another novel adaptive fuzzy algorithm based on fuzzy disturbance observer to solve this problem. Next we step afurther and incorporate actuators'dynamics into controller design process to get an adaptive backstepping controller. This controller can ensure global stable of the whole system, good tracking ability and disturbance rejection ability. Finally due to limit actuator ability of electrical driven flight simulator parallel motion platform, this dissertation proposes a novel trajectory-tracking scheme considering actuator saturation. This scheme incorporates realtime trajectory shaping, fuzzy disturbance observer and joint space velocity observer with saturation compensation. This kind of controller structure can ensure the motion platform always operating in non-saturation region, stable and have good tracking performance under external disturbance and no-velocity measurement situation.The second part of this dissertation designs and optimizes washout algorithm for light flight simulator. Classical washout algorithm is Chosen and parameters are optimized according to the theory of matching the available workspace and demand workspace. This method ensures effective use of limit motion platform workspace to get good motion simulation effect.The third part of this dissertation designs a novel motion protection system for light flight simulator which is used to handle leg length limit and avoid interference between legs, cabin and joints. A leg length limit algorithm is developed to prevent actuators from exceeding position, velocity and acceleration limits and reduce false motion in limit region. And an interference reduction algorithm in task space based on virtual spring is proposed to handle other constraint such as interference between legs, cabin and joints. This algorithm covers virtual spring on the surface of all structure parts. As soon as the distance between structure parts is within the limit region, virtual spring force proportional to distance will push those parts away.The last part of this dissertation designs complete performance testing environment and process for light flight simulator. The test results show that motion platform has good static and dynamic motion performance.All the controllers designed by this dissertation are proven strictly and lots of simulations and experiment datas verify their validity and efficiency. The contents of this dissertation solve a series of key problems related to effectively control of flight simulator motion platform and lay a solid base to further improve the performance of motion platform. The controller software module, washout algorithm software module and motion protection software module in this dissertation have been applied in"light boat No. 1"light flight simulator prototype we designed, and have good performance in daily use.