使用S-Function函数实现离散PID控制器，并建立simulink仿真模型

function [sys,x0,str,ts] = dPID(t,x,u,flag,kp,ki,kd) %SFUNTMPL General M-file S-function template switch flag, %%%%%%%%%%%%%%%%%% % Initialization % %%%%%%%%%%%%%%%%%% case 0, [sys,x0,str,ts]=mdlInitializeSizes; %%%%%%%%%%%%%%% % Derivatives % %%%%%%%%%%%%%%% case 1, sys=mdlDerivatives(t,x,u); %%%%%%%%%% % Update % %%%%%%%%%% case 2, sys=mdlUpdate(t,x,u); %%%%%%%%%%% % Outputs % %%%%%%%%%%% case 3, sys=mdlOutputs(t,x,u,kp,ki,kd); %%%%%%%%%%%%%%%%%%%%%%% % GetTimeOfNextVarHit % %%%%%%%%%%%%%%%%%%%%%%% case 4, sys=mdlGetTimeOfNextVarHit(t,x,u); %%%%%%%%%%%%% % Terminate % %%%%%%%%%%%%% case 9, sys=mdlTerminate(t,x,u); %%%%%%%%%%%%%%%%%%%% % Unexpected flags % %%%%%%%%%%%%%%%%%%%% otherwise DAStudio.error('Simulink:blocks:unhandledFlag', num2str(flag)); end % end sfuntmpl % %============================================================================= % mdlInitializeSizes % Return the sizes, initial conditions, and sample times for the S-function. %============================================================================= % function [sys,x0,str,ts]=mdlInitializeSizes sizes = simsizes; sizes.NumContStates = 0; sizes.NumDiscStates = 4; sizes.NumOutputs = 1; sizes.NumInputs = 1; sizes.DirFeedthrough = 0; sizes.NumSampleTimes = 1; % at least one sample time is needed sys = simsizes(sizes); % % initialize the initial conditions % x0 = [0;0;0;0]; str = []; ts = [-2 0]; % end mdlInitializeSizes function sys=mdlDerivatives(t,x,u) sys = []; % end mdlDerivatives %============================================================================= % mdlUpdate % Handle discrete state updates, sample time hits, and major time step % requirements. %============================================================================= % function sys=mdlUpdate(t,x,u) x(3)=x(2); x(2)=x(1); x(1)=u; x(4)=u+x(4); sys =x; % end mdlUpdate %============================================================================= % mdlOutputs % Return the block outputs. %============================================================================= % function sys=mdlOutputs(t,x,u,kp,ki,kd) sys=kp*x(1)+ki*0.01*x(4)+kd*(x(2)-x(3))/0.01; % end mdlOutputs % %============================================================================= % mdlGetTimeOfNextVarHit % Return the time of the next hit for this block. Note that the result is % absolute time. Note that this function is only used when you specify a % variable discrete-time sample time [-2 0] in the sample time array in % mdlInitializeSizes. %============================================================================= % function sys=mdlGetTimeOfNextVarHit(t,x,u) sampleTime = 0.01;% Example, set the next hit to be one second later. sys = t + sampleTime; % end mdlGetTimeOfNextVarHit %============================================================================= % mdlTerminate % Perform any end of simulation tasks. %============================================================================= % function sys=mdlTerminate(t,x,u) sys = []; % end mdlTerminate