calibration.cpp

00001 /// Calibration procedures for determining position sensor offset, 
00002 /// phase ordering, and position sensor linearization
00003 /// 
00004 
00005 #include "calibration.h"
00006 #include "foc.h"
00007 #include "PreferenceWriter.h"
00008 #include "user_config.h"
00009 #include "motor_config.h"
00010 #include "current_controller_config.h"
00011 
00012 extern Serial pc;
00013 
00014 void order_phases(PositionSensor *ps, GPIOStruct *gpio, ControllerStruct *controller, PreferenceWriter *prefs){   
00015     
00016     ///Checks phase order, to ensure that positive Q current produces
00017     ///torque in the positive direction wrt the position sensor.
00018     pc.printf("\n\r Checking phase ordering\n\r");
00019     float theta_ref = 0;
00020     float theta_actual = 0;
00021     float v_d = .15f;                                                             //Put all volts on the D-Axis
00022     float v_q = 0.0f;
00023     float v_u, v_v, v_w = 0;
00024     float dtc_u, dtc_v, dtc_w = .5f;
00025     int sample_counter = 0;
00026     
00027     ///Set voltage angle to zero, wait for rotor position to settle
00028     abc(theta_ref, v_d, v_q, &v_u, &v_v, &v_w);                                 //inverse dq0 transform on voltages
00029     svm(1.0, v_u, v_v, v_w, &dtc_u, &dtc_v, &dtc_w);                            //space vector modulation
00030     for(int i = 0; i<20000; i++){
00031         TIM1->CCR3 = (PWM_ARR>>1)*(1.0f-dtc_u);                                        // Set duty cycles
00032         TIM1->CCR2 = (PWM_ARR>>1)*(1.0f-dtc_v);
00033         TIM1->CCR1 = (PWM_ARR>>1)*(1.0f-dtc_w);
00034         wait_us(100);
00035         }
00036     //ps->ZeroPosition();
00037     ps->Sample(DT); 
00038     wait_us(1000);
00039     //float theta_start = ps->GetMechPositionFixed();                                  //get initial rotor position
00040     float theta_start;
00041     controller->i_b = I_SCALE*(float)(controller->adc2_raw - controller->adc2_offset);    //Calculate phase currents from ADC readings
00042     controller->i_c = I_SCALE*(float)(controller->adc1_raw - controller->adc1_offset);
00043     controller->i_a = -controller->i_b - controller->i_c;
00044     dq0(controller->theta_elec, controller->i_a, controller->i_b, controller->i_c, &controller->i_d, &controller->i_q);    //dq0 transform on currents
00045     float current = sqrt(pow(controller->i_d, 2) + pow(controller->i_q, 2));
00046     pc.printf("\n\rCurrent\n\r");
00047     pc.printf("%f    %f   %f\n\r\n\r", controller->i_d, controller->i_q, current);
00048     /// Rotate voltage angle
00049     while(theta_ref < 4*PI){                                                    //rotate for 2 electrical cycles
00050         abc(theta_ref, v_d, v_q, &v_u, &v_v, &v_w);                             //inverse dq0 transform on voltages
00051         svm(1.0, v_u, v_v, v_w, &dtc_u, &dtc_v, &dtc_w);                        //space vector modulation
00052         wait_us(100);
00053         TIM1->CCR3 = (PWM_ARR>>1)*(1.0f-dtc_u);                                        //Set duty cycles
00054         TIM1->CCR2 = (PWM_ARR>>1)*(1.0f-dtc_v);
00055         TIM1->CCR1 = (PWM_ARR>>1)*(1.0f-dtc_w);
00056        ps->Sample(DT);                                                            //sample position sensor
00057        theta_actual = ps->GetMechPositionFixed();
00058        if(theta_ref==0){theta_start = theta_actual;}
00059        if(sample_counter > 200){
00060            sample_counter = 0 ;
00061         pc.printf("%.4f   %.4f\n\r", theta_ref/(NPP), theta_actual);
00062         }
00063         sample_counter++;
00064        theta_ref += 0.001f;
00065         }
00066     float theta_end = ps->GetMechPositionFixed();
00067     int direction = (theta_end - theta_start)>0;
00068     pc.printf("Theta Start:   %f    Theta End:  %f\n\r", theta_start, theta_end);
00069     pc.printf("Direction:  %d\n\r", direction);
00070     if(direction){pc.printf("Phasing correct\n\r");}
00071     else if(!direction){pc.printf("Phasing incorrect.  Swapping phases V and W\n\r");}
00072     PHASE_ORDER = direction;
00073     }
00074     
00075     
00076 void calibrate(PositionSensor *ps, GPIOStruct *gpio, ControllerStruct *controller, PreferenceWriter *prefs){
00077     /// Measures the electrical angle offset of the position sensor
00078     /// and (in the future) corrects nonlinearity due to position sensor eccentricity
00079     pc.printf("Starting calibration procedure\n\r");
00080     
00081     const int n = 128*NPP;                                                      // number of positions to be sampled per mechanical rotation.  Multiple of NPP for filtering reasons (see later)
00082     const int n2 = 50;                                                          // increments between saved samples (for smoothing motion)
00083     float delta = 2*PI*NPP/(n*n2);                                              // change in angle between samples
00084     float error_f[n] = {0};                                                     // error vector rotating forwards
00085     float error_b[n] = {0};                                                     // error vector rotating backwards
00086     const int  n_lut = 128;
00087     int lut[n_lut]= {0};                                                        // clear any old lookup table before starting.
00088     ps->WriteLUT(lut); 
00089     int raw_f[n] = {0};
00090     int raw_b[n] = {0};
00091     float theta_ref = 0;
00092     float theta_actual = 0;
00093     float v_d = .15f;                                                             // Put volts on the D-Axis
00094     float v_q = 0.0f;
00095     float v_u, v_v, v_w = 0;
00096     float dtc_u, dtc_v, dtc_w = .5f;
00097     
00098         
00099     ///Set voltage angle to zero, wait for rotor position to settle
00100     abc(theta_ref, v_d, v_q, &v_u, &v_v, &v_w);                                 // inverse dq0 transform on voltages
00101     svm(1.0, v_u, v_v, v_w, &dtc_u, &dtc_v, &dtc_w);                            // space vector modulation
00102     for(int i = 0; i<40000; i++){
00103         TIM1->CCR3 = (PWM_ARR>>1)*(1.0f-dtc_u);                                        // Set duty cycles
00104         if(PHASE_ORDER){                                   
00105             TIM1->CCR2 = (PWM_ARR>>1)*(1.0f-dtc_v);
00106             TIM1->CCR1 = (PWM_ARR>>1)*(1.0f-dtc_w);
00107             }
00108         else{
00109             TIM1->CCR1 = (PWM_ARR>>1)*(1.0f-dtc_v);
00110             TIM1->CCR2 = (PWM_ARR>>1)*(1.0f-dtc_w);
00111             }
00112         wait_us(100);
00113         }
00114     ps->Sample(DT);   
00115     controller->i_b = I_SCALE*(float)(controller->adc2_raw - controller->adc2_offset);    //Calculate phase currents from ADC readings
00116     controller->i_c = I_SCALE*(float)(controller->adc1_raw - controller->adc1_offset);
00117     controller->i_a = -controller->i_b - controller->i_c;
00118     dq0(controller->theta_elec, controller->i_a, controller->i_b, controller->i_c, &controller->i_d, &controller->i_q);    //dq0 transform on currents
00119     float current = sqrt(pow(controller->i_d, 2) + pow(controller->i_q, 2));
00120     pc.printf(" Current Angle : Rotor Angle : Raw Encoder \n\r\n\r");
00121     for(int i = 0; i<n; i++){                                                   // rotate forwards
00122        for(int j = 0; j<n2; j++){   
00123         theta_ref += delta;
00124        abc(theta_ref, v_d, v_q, &v_u, &v_v, &v_w);                              // inverse dq0 transform on voltages
00125        svm(1.0, v_u, v_v, v_w, &dtc_u, &dtc_v, &dtc_w);                         // space vector modulation
00126         TIM1->CCR3 = (PWM_ARR>>1)*(1.0f-dtc_u);
00127         if(PHASE_ORDER){                                                        // Check phase ordering
00128             TIM1->CCR2 = (PWM_ARR>>1)*(1.0f-dtc_v);                                    // Set duty cycles
00129             TIM1->CCR1 = (PWM_ARR>>1)*(1.0f-dtc_w);
00130             }
00131         else{
00132             TIM1->CCR1 = (PWM_ARR>>1)*(1.0f-dtc_v);
00133             TIM1->CCR2 = (PWM_ARR>>1)*(1.0f-dtc_w);
00134             }
00135             wait_us(100);
00136             ps->Sample(DT);
00137         }
00138        ps->Sample(DT);
00139        theta_actual = ps->GetMechPositionFixed();
00140        error_f[i] = theta_ref/NPP - theta_actual;
00141        raw_f[i] = ps->GetRawPosition();
00142         pc.printf("%.4f   %.4f    %d\n\r", theta_ref/(NPP), theta_actual, raw_f[i]);
00143        //theta_ref += delta;
00144         }
00145     
00146     for(int i = 0; i<n; i++){                                                   // rotate backwards
00147        for(int j = 0; j<n2; j++){
00148        theta_ref -= delta;
00149        abc(theta_ref, v_d, v_q, &v_u, &v_v, &v_w);                              // inverse dq0 transform on voltages
00150        svm(1.0, v_u, v_v, v_w, &dtc_u, &dtc_v, &dtc_w);                         // space vector modulation
00151         TIM1->CCR3 = (PWM_ARR>>1)*(1.0f-dtc_u);
00152         if(PHASE_ORDER){
00153             TIM1->CCR2 = (PWM_ARR>>1)*(1.0f-dtc_v);
00154             TIM1->CCR1 = (PWM_ARR>>1)*(1.0f-dtc_w);
00155             }
00156         else{
00157             TIM1->CCR1 = (PWM_ARR>>1)*(1.0f-dtc_v);
00158             TIM1->CCR2 = (PWM_ARR>>1)*(1.0f-dtc_w);
00159             }
00160             wait_us(100);
00161             ps->Sample(DT);
00162         }
00163        ps->Sample(DT);                                                            // sample position sensor
00164        theta_actual = ps->GetMechPositionFixed();                                    // get mechanical position
00165        error_b[i] = theta_ref/NPP - theta_actual;
00166        raw_b[i] = ps->GetRawPosition();
00167        pc.printf("%.4f   %.4f    %d\n\r", theta_ref/(NPP), theta_actual, raw_b[i]);
00168        //theta_ref -= delta;
00169         }    
00170         
00171         float offset = 0;                                  
00172         for(int i = 0; i<n; i++){
00173             offset += (error_f[i] + error_b[n-1-i])/(2.0f*n);                   // calclate average position sensor offset
00174             }
00175         offset = fmod(offset*NPP, 2*PI);                                        // convert mechanical angle to electrical angle
00176         
00177             
00178         ps->SetElecOffset(offset);                                              // Set position sensor offset
00179         __float_reg[0] = offset;
00180         E_OFFSET = offset;
00181         
00182         /// Perform filtering to linearize position sensor eccentricity
00183         /// FIR n-sample average, where n = number of samples in one electrical cycle
00184         /// This filter has zero gain at electrical frequency and all integer multiples
00185         /// So cogging effects should be completely filtered out.
00186         
00187         float error[n] = {0};
00188         const int window = 128;
00189         float error_filt[n] = {0};
00190         float cogging_current[window] = {0};
00191         float mean = 0;
00192         for (int i = 0; i<n; i++){                                              //Average the forward and back directions
00193             error[i] = 0.5f*(error_f[i] + error_b[n-i-1]);
00194             }
00195         for (int i = 0; i<n; i++){
00196             for(int j = 0; j<window; j++){
00197                 int ind = -window/2 + j + i;                                    // Indexes from -window/2 to + window/2
00198                 if(ind<0){
00199                     ind += n;}                                                  // Moving average wraps around
00200                 else if(ind > n-1) {
00201                     ind -= n;}
00202                 error_filt[i] += error[ind]/(float)window;
00203                 }
00204             if(i<window){
00205                 cogging_current[i] = current*sinf((error[i] - error_filt[i])*NPP);
00206                 }
00207             //printf("%.4f   %4f    %.4f   %.4f\n\r", error[i], error_filt[i], error_f[i], error_b[i]);
00208             mean += error_filt[i]/n;
00209             }
00210         int raw_offset = (raw_f[0] + raw_b[n-1])/2;                             //Insensitive to errors in this direction, so 2 points is plenty
00211         
00212         
00213         pc.printf("\n\r Encoder non-linearity compensation table\n\r");
00214         pc.printf(" Sample Number : Lookup Index : Lookup Value : Cogging Current Lookup\n\r\n\r");
00215         for (int i = 0; i<n_lut; i++){                                          // build lookup table
00216             int ind = (raw_offset>>7) + i;
00217             if(ind > (n_lut-1)){ 
00218                 ind -= n_lut;
00219                 }
00220             lut[ind] = (int) ((error_filt[i*NPP] - mean)*(float)(ps->GetCPR())/(2.0f*PI));
00221             pc.printf("%d   %d   %d   %f\n\r", i, ind, lut[ind],  cogging_current[i]);
00222             wait(.001);
00223             }
00224             
00225         ps->WriteLUT(lut);                                                      // write lookup table to position sensor object
00226         //memcpy(controller->cogging, cogging_current, sizeof(controller->cogging));  //compensation doesn't actually work yet....
00227         memcpy(&ENCODER_LUT, lut, sizeof(lut));                                 // copy the lookup table to the flash array
00228         pc.printf("\n\rEncoder Electrical Offset (rad) %f\n\r",  offset);
00229         
00230         if (!prefs->ready()) prefs->open();
00231         prefs->flush();                                                         // write offset and lookup table to flash
00232         prefs->close();
00233 
00234 
00235     }