PidController.h

00001 /**
00002  * @author James Batchelar
00003  *
00004  * @section LICENSE
00005  *
00006  *
00007  * Permission is hereby granted, free of charge, to any person obtaining a copy
00008  * of this software and associated documentation files (the "Software"), to deal
00009  * in the Software without restriction, including without limitation the rights
00010  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
00011  * copies of the Software, and to permit persons to whom the Software is
00012  * furnished to do so, subject to the following conditions:
00013  *
00014  * The above copyright notice and this permission notice shall be included in
00015  * all copies or substantial portions of the Software.
00016  *
00017  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
00018  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
00019  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
00020  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
00021  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
00022  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
00023  * THE SOFTWARE.
00024  *
00025  * @section DESCRIPTION
00026  *
00027  * PID Controller with Integral Clamping
00028  * 
00029  * 
00030  *     
00031  */
00032 
00033 #ifndef PidController_H
00034 #define PidController_H
00035 #include "mbed.h"
00036 
00037 //-- Constants used in system
00038 const int RATE = 100;        //--(ms) Time that Calculate mehtod is being called       
00039 const int AUTOMATIC = 0;    //-- In automatic then PID Controls Output
00040 const int MANUAL = 1;       //-- In Manual then User Controls Output directly
00041 
00042 //-- Constructor 
00043 
00044 class PidController{
00045     public:
00046         // Public Methods
00047     
00048         // Constructor
00049         PidController();
00050         
00051         /** Performs the PID Calculation
00052         * @param SP - Setpoint (target value) units depends on what PID is controlling
00053         * @param PV - Process Variable (feedback/ measure value) units depends on what PID is controlling
00054         * @return Returns If Controller is in Automatic then returns PID controlled signal. In manual returns the user SP.
00055         */
00056         float Calculate(float SP, float PV);
00057         
00058         /** Update Internal Settings
00059         * @param Bias - Added to the PID Calculation
00060         * @param PropGain - Proportional Gain
00061         * @param IntGain - Integral Gain
00062         * @param DiffGain - Differential Gain
00063         * @param OutputMin - Minimum Limit for the Output (units are same as setpoint)
00064         * @param OutputMax - Maximum Limit for the Output (units are same as setpoint)
00065         * @param OutputScale - Multiplier at End of PID loop to convert from engineering units to signal (eg PWM duty cycle)   
00066         */    
00067         void UpdateSettings(float Bias, float PropGain, float IntGain, float DiffGain, float OutputMin, float OutputMax);
00068         
00069         /** Update Internal Settings
00070         * @param OutputMin - Minimum Limit for the Output (units are same as setpoint)
00071         * @param OutputMax - Maximum Limit for the Output (units are same as setpoint)
00072         */    
00073         void UpdateSettings(float OutputMin, float OutputMax);
00074         
00075         /** Get the controller mode
00076         * @return 1 = AUTOMATIC, 0 = MANUAL(User has direct contol on output).
00077         */
00078         int GetMode(void){return (int)mode;}
00079         
00080         /** Set the controller in Manual Mode (PID turned off SP is writted directly to output)
00081         */
00082         void SetManual(void){mode = MANUAL;}
00083         
00084         /** Set the controller in Automatic Mode (PID turned on)
00085         */
00086         void SetAutomatic(void){mode = AUTOMATIC;}
00087         
00088         /** Enable Diagnostics for HMI
00089         */
00090         void StartDiag(void);
00091         
00092         /** Disable Diagnostics for HMI
00093         */
00094         void EndDiag(void);
00095         
00096         /** Check to see if the controller is collecting diagnostics data
00097         * @return true then a diagnostics message is been created.
00098         */
00099         bool DiagnosticsEnabled(void){return collectDiagnostics;}
00100         
00101         /** Check to see if the controller is collecting diagnostics data
00102         * @param Data - Starting address of target recieve buffer (must be at least 25char long)
00103         */
00104         void GetDiagnosticsMessage(char *data);
00105         
00106     private:
00107         bool mode;
00108         //-- For Diagnostics to GUI
00109         bool collectDiagnostics;
00110         uint16_t elapsedTime;
00111         char diagMsg[28];
00112         
00113         //-- Settings
00114         float bias;
00115         float minLimit, maxLimit;
00116         float K_p,K_i,K_d;
00117         
00118         //-- For PID Calculations
00119         float error;
00120         float accumError;
00121         float prevError;
00122         
00123         //-- Private Helper functions
00124         void float_to_byte(char *data, float *val);
00125         void int_to_byte(char *data, uint16_t val);
00126         };
00127     
00128 #endif
00129     
00130     
00131     
00132 
00133 
00134