Fixed-time Command Filter Tracking Control Of Continuous Stirred Tank Reactor

Continuous Stirred Tank Reactor(CSTR)is a preferred reactor for chemical,biopharmaceutical,petroleum and other process industrial production because of its simple structure,adequate reaction and flexible operation.However,CSTR system is a nonlinear,time-varying and uncertain control object.In the actual production process,when the system is affected by internal and external factors such as changes in reactant concentration and noise disturbances,the internal control steady state of CSTR system is easily disrupted,thus affecting the production efficiency and product quality of the system.Therefore,the design of a stable,safe and reliable controller for the CSTR system to ensure the accurate control of reactor concentration and temperature becomes a real problem that needs to be solved.Aiming at the precise tracking control problem of continuous stirred tank reactor system,different controller designs are proposed based on adaptive backstepping control method,fuzzy logic system and command filtering technology considering different practical applications.The main research achievements of this dissertation are as follows:(1)For the continuous stirred tank reactor system,a fixed-time command filtering adaptive backstepping control method is proposed.Use command filtering technology to introduce error compensation mechanism to solve the problem of repeated derivation of the backstepping method while eliminating the influence of filtering error and improving the control accuracy;Use fuzzy logic system to approximate the nonlinear function of CSTR system;The fixed-time technique is introduced to improve the overall convergence time of the system,to improve the limitation that the convergence time of the system is easily disturbed by the initial state variables,and to ensure that the system has a stable upper bound on the convergence time.Lyapunov stability analysis and simulation experiments are conducted to ensure the stability and feasibility of the control method.The simulations show that the control method can ensure the system has more convergence speed and higher control accuracy,which improves the control performance of the CSTR system.(2)This dissertation further considers the impact of the state unpredictability problem on the continuous stirred tank reactor system existing in practical engineering and proposes an observer-based adaptive backstepping control method with fixed-time command filtering.Design fuzzy state observer realizes online estimation of concentration and temperature of CSTR system,which reduces the hardware cost and the workload of post-maintenance brought by the use of sensors and has strong practical engineering significance.Finally,the MATLAB simulation experiment proves that the control method can achieve real-time accurate observation of the temperature and concentration of the CSTR system,and ensure that the system output signal can converge to a small neighborhood near the reference signal within a fixed time.(3)This dissertation also considers the impact of the input saturation problem on the continuous stirred tank reactor system in real engineering and redesigns the fixed-time command filtered adaptive backstepping controller.Using the saturation function to process the input signal so that the input value of the system is constrained within the specified range;simulation experimental results show that this control method can overcome the adverse effects of input saturation,while ensuring that the output signal of the CSTR system tracks to the reference signal within a fixed time,which has strong practical application value.