File content as of revision 1:4afc0dd95be9:

/**
 * @file main.cpp
 * @date June 9th, 2015
 * @author Weimen Li
 * @mainpage RobotBalancer
 * This program is a demo lab for MAE 433. It controls a robot to balance it.
 * @see main.cpp
 */

/* Inclusions */
#include "mbed.h"
#include "rtos.h"
#include "HBridge.hpp"
#include "QuadEnc.hpp"
#include "HC06Bluetooth.hpp"
#include "FXOS8700CQ.hpp"
#include "dsp.h"
#include "FixedRefresh.hpp"

/* Constants */
/// The CPR of the encoder.
const float encoderCPR = 100.98f * 12.0f;
/// The transmission period of the bluetooth module.
const uint32_t BTTransmitPeriodMS = 1;
/// The sampling period of the control system.
const uint32_t controlSampleRateUS = 1250;
/// The diameter of the wheels in inches
const float wheelDiameter = 1.9f;

/* Declaring objects */
/// The quad encoder of the left motor.
QuadEnc leftQuadEnc(PTB0, PTB1, encoderCPR);
/// The quad encoder of the right motor.
QuadEnc rightQuadEnc(PTC2, PTC1, encoderCPR);
/// The H-Bridge driving the left motor.
HBridge leftMotor(D9, D7);
/// The H-Bridge driving the right motor.
HBridge rightMotor(D10, D8);
/// The accelerometer on the board
FXOS8700CQ accelerometer(PTB3, PTB2, PTD0, PTD1);

/// The Bluetooth link used to transmit data.
HC06Bluetooth bluetooth(PTD3, PTD2);
/// Timer to transmit timing information.
Timer timer;

/* The acceleration commanded by control_thread and used as input for motorControl_thread() */
float setAccel;
Mutex setAccelMutex;

/* Threads */
/** @brief Bluetooth Transmission:
 * This thread reads the quadrature encoder and
 * output data and transmits it as comma-separated values over Bluetooth.
 */
void bluetooth_thread(void const *argument) {
    // Timer to control how long to wait.
    FixedRefresh refresh;
    // 64-byte buffer is used to store the data. May be expanded as needed.
    char buffer[128];
    // The accelerometer readings.
    float xAccel;
    float yAccel;
    float zAccel;
    

    while(true) {
        accelerometer.readAccelerometer(&xAccel, &yAccel, &zAccel);
        // Place the CSV information in the buffer:
        sprintf(buffer, "%f,%f,%f,%f,%f,%f\n\r", timer.read(), xAccel, yAccel, zAccel, leftMotor.read(), rightMotor.read());
        // Transmit the information.
        bluetooth.print(buffer);
        // Refresh at a specified interval.
        refresh.refresh_us(BTTransmitPeriodMS * 1000);
    }

}

/** @brief Control Thread:
 * This thread reads the current quadrature counts and actuates
 * the motor through the H-Bridge.
 */

void control_thread(void const *argument) {
    // FixedRefresh object to wait at fixed time
    FixedRefresh fixedRefresh;
    // The accelerometer readings.
    float xAccel;
    float yAccel;
    float zAccel;

    /* Feedback constants: */
    // Accelerometer feedback at n = 0;
    const float a0 = 0.15;
    // Accelerometer feedback at n = -1;
    const float a1 = 0;
    // Accelerometer feedback at n = -2;
    const float a2 = 0;
    
    /* State Variables: */
    // System's angle at n = 0
    float angle = 0;
    // System's angle at n = -1
    float angle_n1 = 0;
    // System's angle at n = -2
    float angle_n2 = 0;

    /* Filtering Constants: */
    // The block size is the number of samples processed by each tick of the digital filter.
    // Since we work sample-by-sample in real time, the block size is 1.
    const uint32_t BLOCK_SIZE = 1;
 
    /* FIR Coefficients buffer generated using fir1() MATLAB function. */
    const uint32_t NUM_TAPS = 241;
    const float32_t firCoeffs32[NUM_TAPS] = { 
    +0.0000825832f, +0.0000894684f, +0.0000968224f, +0.0001047243f, +0.0001132540f, 
    +0.0001224923f, +0.0001325206f, +0.0001434207f, +0.0001552749f, +0.0001681654f, 
    +0.0001821744f, +0.0001973838f, +0.0002138753f, +0.0002317296f, +0.0002510270f, 
    +0.0002718465f, +0.0002942661f, +0.0003183624f, +0.0003442106f, +0.0003718838f, 
    +0.0004014538f, +0.0004329897f, +0.0004665588f, +0.0005022258f, +0.0005400529f, 
    +0.0005800994f, +0.0006224218f, +0.0006670735f, +0.0007141047f, +0.0007635622f, 
    +0.0008154892f, +0.0008699254f, +0.0009269065f, +0.0009864647f, +0.0010486275f, 
    +0.0011134190f, +0.0011808585f, +0.0012509612f, +0.0013237379f, +0.0013991947f, 
    +0.0014773333f, +0.0015581504f, +0.0016416385f, +0.0017277849f, +0.0018165723f, 
    +0.0019079784f, +0.0020019764f, +0.0020985340f, +0.0021976146f, +0.0022991768f, 
    +0.0024031731f, +0.0025095530f, +0.0026182598f, +0.0027292324f, +0.0028424053f, 
    +0.0029577080f, +0.0030750656f, +0.0031943982f, +0.0033156220f, +0.0034386488f, 
    +0.0035633859f, +0.0036897366f, +0.0038176002f, +0.0039468720f, +0.0040774439f, 
    +0.0042092041f, +0.0043420363f, +0.0044758227f, +0.0046104412f, +0.0047457665f, 
    +0.0048816721f, +0.0050180266f, +0.0051546986f, +0.0052915523f, +0.0054284511f, 
    +0.0055652573f, +0.0057018292f, +0.0058380268f, +0.0059737056f, +0.0061087236f, 
    +0.0062429351f, +0.0063761952f, +0.0065083597f, +0.0066392822f, +0.0067688185f, 
    +0.0068968232f, +0.0070231529f, +0.0071476642f, +0.0072702146f, +0.0073906644f, 
    +0.0075088735f, +0.0076247053f, +0.0077380240f, +0.0078486968f, +0.0079565924f, 
    +0.0080615841f, +0.0081635462f, +0.0082623558f, +0.0083578955f, +0.0084500499f, 
    +0.0085387062f, +0.0086237583f, +0.0087051028f, +0.0087826382f, +0.0088562714f, 
    +0.0089259110f, +0.0089914715f, +0.0090528717f, +0.0091100354f, +0.0091628926f, 
    +0.0092113772f, +0.0092554288f, +0.0092949932f, +0.0093300194f, +0.0093604643f, 
    +0.0093862908f, +0.0094074663f, +0.0094239628f, +0.0094357608f, +0.0094428463f, 
    +0.0094452091f, +0.0094428463f, +0.0094357608f, +0.0094239628f, +0.0094074663f, 
    +0.0093862908f, +0.0093604643f, +0.0093300194f, +0.0092949932f, +0.0092554288f, 
    +0.0092113772f, +0.0091628926f, +0.0091100354f, +0.0090528717f, +0.0089914715f, 
    +0.0089259110f, +0.0088562714f, +0.0087826382f, +0.0087051028f, +0.0086237583f, 
    +0.0085387062f, +0.0084500499f, +0.0083578955f, +0.0082623558f, +0.0081635462f, 
    +0.0080615841f, +0.0079565924f, +0.0078486968f, +0.0077380240f, +0.0076247053f, 
    +0.0075088735f, +0.0073906644f, +0.0072702146f, +0.0071476642f, +0.0070231529f, 
    +0.0068968232f, +0.0067688185f, +0.0066392822f, +0.0065083597f, +0.0063761952f, 
    +0.0062429351f, +0.0061087236f, +0.0059737056f, +0.0058380268f, +0.0057018292f, 
    +0.0055652573f, +0.0054284511f, +0.0052915523f, +0.0051546986f, +0.0050180266f, 
    +0.0048816721f, +0.0047457665f, +0.0046104412f, +0.0044758227f, +0.0043420363f, 
    +0.0042092041f, +0.0040774439f, +0.0039468720f, +0.0038176002f, +0.0036897366f, 
    +0.0035633859f, +0.0034386488f, +0.0033156220f, +0.0031943982f, +0.0030750656f, 
    +0.0029577080f, +0.0028424053f, +0.0027292324f, +0.0026182598f, +0.0025095530f, 
    +0.0024031731f, +0.0022991768f, +0.0021976146f, +0.0020985340f, +0.0020019764f, 
    +0.0019079784f, +0.0018165723f, +0.0017277849f, +0.0016416385f, +0.0015581504f, 
    +0.0014773333f, +0.0013991947f, +0.0013237379f, +0.0012509612f, +0.0011808585f, 
    +0.0011134190f, +0.0010486275f, +0.0009864647f, +0.0009269065f, +0.0008699254f, 
    +0.0008154892f, +0.0007635622f, +0.0007141047f, +0.0006670735f, +0.0006224218f, 
    +0.0005800994f, +0.0005400529f, +0.0005022258f, +0.0004665588f, +0.0004329897f, 
    +0.0004014538f, +0.0003718838f, +0.0003442106f, +0.0003183624f, +0.0002942661f, 
    +0.0002718465f, +0.0002510270f, +0.0002317296f, +0.0002138753f, +0.0001973838f, 
    +0.0001821744f, +0.0001681654f, +0.0001552749f, +0.0001434207f, +0.0001325206f, 
    +0.0001224923f, +0.0001132540f, +0.0001047243f, +0.0000968224f, +0.0000894684f, 
    +0.0000825832f
    };

    /* Filter Object */
    // The filter object used to perform the filtering.
    FIR_f32<NUM_TAPS, BLOCK_SIZE> fir(firCoeffs32);
    // The filtered z Acceleration
    float32_t zAccelFiltered;
    
    while (true) {
        // Read the state from the accelerometer:
        accelerometer.readAccelerometer(&xAccel, &yAccel, &zAccel);
        // Filter the accelerometer state:
        fir.process(&zAccel, &zAccelFiltered);

        // Acquire the system's angle:
        // angle = atan2f(yAccel, zAccel);
        arm_sqrt_f32(2*zAccelFiltered, &angle);
        if(yAccel < 0) {
            angle = -angle;
        }

        // Control Law to regulate system:
        float output = a0 * angle + a1 * angle_n1 + a2 * angle_n2;
        // Set the output for motorControl_thread to handle.
        setAccelMutex.lock();
        setAccel = output;
        setAccelMutex.unlock();

        // Update the state variables
        angle_n1 = angle;
        angle_n2 = angle_n1;

        // Thread::wait(100);
        fixedRefresh.refresh_us(controlSampleRateUS);
    }
}


/**
 * @brief This thread controls the motors to have a specified acceleration, with the value
 * coming from control_thread.
 */
void motorControl_thread(void const* argument) {
    // Control variable constants
    const float kConst = 1;
    const float iConst = 1;

    // Left Wheel State Variables
    float leftPosition = 0;
    float prevLeftPosition = 0;
    float leftPositionDeriv = 0;
    float prevLeftPositionDeriv = 0;
    float leftPositionDDeriv = 0;
    float leftErrorInt = 0;

    // Right Wheel State Variables
    float rightPosition = 0;
    float prevRightPosition = 0;
    float rightPositionDeriv = 0;
    float prevRightPositionDeriv = 0;
    float rightPositionDDeriv = 0;
    float rightErrorInt = 0;

    FixedRefresh refresh;

    while(true) {
        // Calculate new values for the state variables. Note that the steps are performed in reverse.
        leftPositionDDeriv = leftPositionDeriv - prevLeftPositionDeriv;
        rightPositionDDeriv = rightPositionDeriv - prevRightPositionDeriv;
        leftPositionDeriv = leftPosition - prevLeftPosition;
        rightPositionDeriv = rightPosition - prevRightPosition;
        leftPosition = leftQuadEnc.getRevs();
        rightPosition = rightQuadEnc.getRevs();

        // Get the commanded acceleration:
        setAccelMutex.lock();
        float localSetAccel = setAccel;
        setAccelMutex.unlock();

        // Calculate the error:

        float leftError = localSetAccel - leftPositionDDeriv;
        float rightError = localSetAccel - rightPositionDDeriv;

        // Calculate the output:
        float leftOutput = kConst * leftError + iConst * leftErrorInt;
        float rightOutput = kConst * leftError + iConst * rightErrorInt;
        leftErrorInt += leftError;
        rightErrorInt += rightError;
        // Write the output:
        leftMotor.write(leftOutput);
        rightMotor.write(rightOutput);
        // Update the previous state variable values:
        prevLeftPosition = leftPosition;
        prevRightPosition = rightPosition;
        prevLeftPositionDeriv = leftPositionDeriv;
        prevRightPositionDeriv = rightPositionDeriv;
        refresh.refresh_us(1250);
    }
}

/** @brief Main thread:
 * This thread performs any additional initialization necessary for the declared objects.
 * Then, it starts the threads.
 */
int main() {
    /* Initialize objects */
    // Set the offset value for the accelerometer.
    accelerometer.setOffset(0.012, -0.032, 0.032);
    // Start the global timer.
    timer.start();

    /* Initialize threads. */
    // Thread priority is set as normal.
    Thread thread(bluetooth_thread, NULL, osPriorityNormal);
    // Thread priority is set as above normal: If the control_thread and bluetooth_thread
    // ever want to happen at the same time, control_thread wins.
    //Thread thread2(control_thread, NULL, osPriorityAboveNormal);
    Thread thread3(motorControl_thread, NULL, osPriorityAboveNormal);
    while (true) {
        // Main thread does nothing else, so we tell it to wait forever.
        Thread::wait(osWaitForever);
    }
}