Diff: PID.h

Revision:

3:93fb84c4e9bc

Parent:

2:d6f14bb935da

Child:

5:d01614d14cd1

--- a/PID.h	Tue May 22 17:15:51 2018 +0000
+++ b/PID.h	Wed May 23 15:08:15 2018 +0000
@@ -25,49 +25,8 @@
  *
  * @section DESCRIPTION
  *
- * motion control PID speed controler library.
- *
- *  This library require a tuning (mostly base on try/modify) and will not give 
- *  a correct performance until you have tuned all 3 parameters Kp, Ki and Kd.
- *
- * @note :
- *      You must provide a 16 bits Timer definition that allow the use of a quadrature encoder (pins A & B must be connected respectively to pin 1 and 2 of the timer.
- *
- *      Typicaly on Nucleo F446RE TIM3 and TIM4 are perfect to do this job.
- *      In this case simply use TIM3 or TIM4 as timer parameter 
- *
- *      You must also provide the number of pulses generated by the QE for a 1mm displacement of the wheel.       
- *
- *      You may also add 2 or 3 outputs to drive a PWM full bridge :
- *          - 2 outputs for DIR/PWM full bridge
- *          - 3 outputs for IN+/IN-/PWM full bridge.
- *      Or you may not define any outputs.
+ * motion control.
  *
- *      In this case the PID controler must use a specific function that will output a PWM value that user must transform to match the full bridge.
- *      Value evolve from 1 (full PWM fortward) to -1 (full PWM backward).
- *      This value can also be found in the global variable : _PwmValue
- * 
- * @note :
- *      As this motion control system is implemented in a microcontroler it is important to understand that there is a loop time for the motion control system and that this loop time MUST be constant.
- *      Kp, Ki and Kd are dependent of the loop time. changing loop time mean changing the corrector's coefficients.
- *      We use a Ticker to control loop time.
- *
- *      The looptime can be set by software as long as it remain constant during the whole use of PID controler. Loop time is set to 1ms by default.
- *
- *      Take care not to increase too mutch this time (or you will fail to to control the motion) and to always keep enought time for computation to take place during this loop.
- *
- * @note :
- *      The PID is initialized with Ki = 0, Kd = 0 and Kp = 1
- *       -  Increasing Kp will shorten your response time but will also create
- *          instability (at beggining overshoots, then instability).
- *       -  Adding a bit of Ki will allow your system to bring to 0 the static
- *          error (ie : will make the error, between the set point and your
- *          mesurment, tend to 0) but might create instability and increase
- *          setting time.
- *       -  Adding a bit of Kd will stabilize the response (with almost no bad
- *          effect, as long as Kd remains small).
- *
- * more info can be found here : https://en.wikipedia.org/wiki/PID_controller 
  */
 
 #ifndef PID_H
@@ -82,6 +41,22 @@
 /**
  * PID Motion control system (speed control).
  *  refere to wikipedia for more explainations : https://en.wikipedia.org/wiki/PID_controller
+ *
+ * @note This library require a tuning (mostly base on try/modify) and will not give a correct performance until you have tuned all 3 parameters Kp, Ki and Kd for each wheels of the robot
+ *
+ * @note You must use a QE (quadrature Encoder) connected to a 16 bits timer to get proper motion control. Pins A & B of the QE must be connected respectively to pin 1 and 2 of the timer. Typicaly on Nucleo F446RE TIM3 and TIM4 are perfect to do this job. In this case simply use TIM3 or TIM4 as timer parameter. 
+ *
+ * @note You must also specify the number of pulses generated by the QE for a 1mm displacement of the wheel. This is the scale parameter       
+ *
+ * @note Outputed PWM value evolve from 1 (full PWM fortward) to -1 (full PWM backward). This value can also be found in the global variable : _PwmValue. The PWM value is based on a 1.3 m/s maximum speed.
+ * 
+ * @note As this motion control system is implemented in a microcontroler it is important to understand that there is a loop time for the motion control system and that this loop time MUST be constant. Kp, Ki and Kd are dependent of the loop time. Changing loop time means changing all the corrector's coefficients. Library use a Ticker to control loop time. The looptime can be set by software as long as it remain constant during the whole use of PID controler. Loop time is set to 1ms by default.
+ *
+ * @note The PID is initialized with Ki = 0, Kd = 0 and Kp = 1
+ *       -  Increasing Kp will shorten your response time but will also create instability (at beggining overshoots, then instability).
+ *       -  Adding a bit of Ki will allow your system to bring to 0 the static error (ie : will make the error, between the set point and your mesurment, tend to 0) but might create instability and increase setting time.
+ *       -  Adding a bit of Kd will stabilize the response (with almost no bad effect, as long as Kd remains small).
+ * @note More info can be found here : https://en.wikipedia.org/wiki/PID_controller 
  */
 class PID {
 
@@ -90,48 +65,48 @@
     /**
      * Constructor (standard) with full bridge control
      *
-     * @param _TIM : the Mbed 16 bits timer used to connect the A&B output of QE
-     * @param outPWM : the Mbed pin used to send PWM on the full bridge
-     * @param outA : the Mbed pin used to send direction to the full bridge
-     * @param outB : the Mbed pin used to send direction (in case of 3 pins full bridge)
-     * @param scale : the number of pulses on the QE for 1mm displacement of the wheel
-     * @param loopTime : the time between 2 computations
+     * @param _TIM (TIM_TypeDef*) : the Mbed 16 bits timer used to connect the A&B output of QE
+     * @param outPWM (PinName) : the Mbed pin used to send PWM on the full bridge
+     * @param outA (PinName) : the Mbed pin used to send direction to the full bridge
+     * @param outB (PinName) : the Mbed pin used to send direction (in case of 3 pins full bridge)
+     * @param scale (double) : the number of pulses on the QE for 1mm displacement of the wheel
+     * @param loopTime (double) : the time between 2 computations
      */
-    PID(TIM_TypeDef * TIM, PinName outPWM, PinName outA, PinName outB, double scale = 31.8309886184, double loopTime = 0.001);
+    PID(TIM_TypeDef * TIM, PinName outPWM, PinName outA, PinName outB, double scale = 63.661977236758, double loopTime = 0.001);
 
     /**
      * Set the Kp value
      *
-     * @param  Kp value
-     * @return  the value of Kp
-     * @note  can also be accessed using the global variable _Kp
+     * @param  Kp (float) : value of Kp
+     * @return The value of Kp (float)
+     * @note  Can also be accessed using the global variable _Kp
      */
     float setProportionnalValue (float KpValue);
     
     /**
      * Set the Ki value
      *
-     * @param  Ki value
-     * @return  the value of Ki
-     * @note  can also be accessed using the global variable _Ki
+     * @param  Ki (float) : value of Ki
+     * @return The value of Ki (float)
+     * @note  Can also be accessed using the global variable _Ki
      */
     float setintegralValue (float KiValue);
     
     /**
      * Set the Kd value
      *
-     * @param  Kd value
-     * @return  the value of Kd
-     * @note  can also be accessed using the global variable _Kd
+     * @param  Kd (float) : value of Kd
+     * @return The value of Kd (float)
+     * @note  Can also be accessed using the global variable _Kd
      */
     float setDerivativeValue (float KdValue);
     
     /**
      * compute the PWM value of a motion controled system
      *
-     * @param  Set point value (in mm/s)
+     * @param  Setpoint value (in mm/s)
      * @return  PWM value (between -1 and 1)
-     * @note    this function is provided for users that don't use a 3 wires full bridge
+     * @note    This function is provided for users that don't use a 3 wires full bridge
      */
     float computePWM (float setPoint); 
     
@@ -146,8 +121,8 @@
      * Get position of the wheel (in step of the Quadrature Encoder)
      *
      * @note One step is a fouth of a period of A or B signal
-     * @note position is updated each time a motion computation take place
-     * @return the number of step from beggining
+     * @note Position is updated each time a motion computation take place
+     * @return The number of step from beggining
      */
     long getPosition (void);
     
@@ -155,16 +130,16 @@
     long    _Position;
     /**
      * Global Variable to indicate that required speed is unreachable (=1 if speed is unreachable)
-     * @note    must be cleared by user
+     * @note    Must be cleared by user
      */
     int     RobotIsStuck;  
 
 protected :
 
+    Ticker                  _tick;
     Nucleo_Encoder_16_bits  _encoder;
-    Ticker                  _tick;
+    PwmOut                  _pwm;
     DigitalOut              _outA, _outB;
-    PwmOut                  _pwm;
 
 private :