Wooden Jin / BLDC_V2

bldc driver firmware based on hobbyking cheetah compact

Dependencies:   BLDC_V2 mbed-dev-f303 FastPWM3

Dependents:   BLDC_V2

Calibration/calibration.cpp@38:67e4e1453a4b, 2018-05-14 (annotated)

Committer:
benkatz
Date:
Mon May 14 20:59:02 2018 +0000
Revision:
38:67e4e1453a4b
Parent:
28:8c7e29f719c5
Child:
44:efcde0af8390
Fixed bug introduced into the calibration procedure when absolute zero offset was added

Who changed what in which revision?

UserRevisionLine numberNew contents of line
benkatz 22:60276ba87ac6 1 /// Calibration procedures for determining position sensor offset,
benkatz 22:60276ba87ac6 2 /// phase ordering, and position sensor linearization
benkatz 22:60276ba87ac6 3 ///
benkatz 22:60276ba87ac6 4
benkatz 22:60276ba87ac6 5 #include "calibration.h"
benkatz 23:2adf23ee0305 6 #include "foc.h"
benkatz 23:2adf23ee0305 7 #include "PreferenceWriter.h"
benkatz 23:2adf23ee0305 8 #include "user_config.h"
benkatz 22:60276ba87ac6 9
benkatz 23:2adf23ee0305 10 void order_phases(PositionSensor *ps, GPIOStruct *gpio, ControllerStruct *controller, PreferenceWriter *prefs){
benkatz 28:8c7e29f719c5 11
benkatz 22:60276ba87ac6 12 ///Checks phase order, to ensure that positive Q current produces
benkatz 22:60276ba87ac6 13 ///torque in the positive direction wrt the position sensor.
benkatz 22:60276ba87ac6 14 printf("\n\r Checking phase ordering\n\r");
benkatz 22:60276ba87ac6 15 float theta_ref = 0;
benkatz 22:60276ba87ac6 16 float theta_actual = 0;
benkatz 28:8c7e29f719c5 17 float v_d = .25; //Put all volts on the D-Axis
benkatz 22:60276ba87ac6 18 float v_q = 0.0;
benkatz 22:60276ba87ac6 19 float v_u, v_v, v_w = 0;
benkatz 22:60276ba87ac6 20 float dtc_u, dtc_v, dtc_w = .5;
benkatz 22:60276ba87ac6 21 int sample_counter = 0;
benkatz 22:60276ba87ac6 22
benkatz 22:60276ba87ac6 23 ///Set voltage angle to zero, wait for rotor position to settle
benkatz 25:f5741040c4bb 24 abc(theta_ref, v_d, v_q, &v_u, &v_v, &v_w); //inverse dq0 transform on voltages
benkatz 25:f5741040c4bb 25 svm(1.0, v_u, v_v, v_w, &dtc_u, &dtc_v, &dtc_w); //space vector modulation
benkatz 22:60276ba87ac6 26 for(int i = 0; i<20000; i++){
benkatz 27:501fee691e0e 27 TIM1->CCR3 = (PWM_ARR>>1)*(1.0f-dtc_u); // Set duty cycles
benkatz 27:501fee691e0e 28 TIM1->CCR2 = (PWM_ARR>>1)*(1.0f-dtc_v);
benkatz 27:501fee691e0e 29 TIM1->CCR1 = (PWM_ARR>>1)*(1.0f-dtc_w);
benkatz 22:60276ba87ac6 30 wait_us(100);
benkatz 22:60276ba87ac6 31 }
benkatz 22:60276ba87ac6 32 //ps->ZeroPosition();
benkatz 22:60276ba87ac6 33 ps->Sample();
benkatz 23:2adf23ee0305 34 wait_us(1000);
benkatz 38:67e4e1453a4b 35 //float theta_start = ps->GetMechPositionFixed(); //get initial rotor position
benkatz 26:2b865c00d7e9 36 float theta_start;
benkatz 23:2adf23ee0305 37 controller->i_b = I_SCALE*(float)(controller->adc2_raw - controller->adc2_offset); //Calculate phase currents from ADC readings
benkatz 23:2adf23ee0305 38 controller->i_c = I_SCALE*(float)(controller->adc1_raw - controller->adc1_offset);
benkatz 23:2adf23ee0305 39 controller->i_a = -controller->i_b - controller->i_c;
benkatz 23:2adf23ee0305 40 dq0(controller->theta_elec, controller->i_a, controller->i_b, controller->i_c, &controller->i_d, &controller->i_q); //dq0 transform on currents
benkatz 23:2adf23ee0305 41 float current = sqrt(pow(controller->i_d, 2) + pow(controller->i_q, 2));
benkatz 23:2adf23ee0305 42 printf("\n\rCurrent\n\r");
benkatz 23:2adf23ee0305 43 printf("%f %f %f\n\r\n\r", controller->i_d, controller->i_q, current);
benkatz 22:60276ba87ac6 44 /// Rotate voltage angle
benkatz 25:f5741040c4bb 45 while(theta_ref < 4*PI){ //rotate for 2 electrical cycles
benkatz 25:f5741040c4bb 46 abc(theta_ref, v_d, v_q, &v_u, &v_v, &v_w); //inverse dq0 transform on voltages
benkatz 25:f5741040c4bb 47 svm(1.0, v_u, v_v, v_w, &dtc_u, &dtc_v, &dtc_w); //space vector modulation
benkatz 22:60276ba87ac6 48 wait_us(100);
benkatz 27:501fee691e0e 49 TIM1->CCR3 = (PWM_ARR>>1)*(1.0f-dtc_u); //Set duty cycles
benkatz 27:501fee691e0e 50 TIM1->CCR2 = (PWM_ARR>>1)*(1.0f-dtc_v);
benkatz 27:501fee691e0e 51 TIM1->CCR1 = (PWM_ARR>>1)*(1.0f-dtc_w);
benkatz 25:f5741040c4bb 52 ps->Sample(); //sample position sensor
benkatz 38:67e4e1453a4b 53 theta_actual = ps->GetMechPositionFixed();
benkatz 26:2b865c00d7e9 54 if(theta_ref==0){theta_start = theta_actual;}
benkatz 22:60276ba87ac6 55 if(sample_counter > 200){
benkatz 22:60276ba87ac6 56 sample_counter = 0 ;
benkatz 22:60276ba87ac6 57 printf("%.4f %.4f\n\r", theta_ref/(NPP), theta_actual);
benkatz 22:60276ba87ac6 58 }
benkatz 22:60276ba87ac6 59 sample_counter++;
benkatz 22:60276ba87ac6 60 theta_ref += 0.001f;
benkatz 22:60276ba87ac6 61 }
benkatz 38:67e4e1453a4b 62 float theta_end = ps->GetMechPositionFixed();
benkatz 22:60276ba87ac6 63 int direction = (theta_end - theta_start)>0;
benkatz 22:60276ba87ac6 64 printf("Theta Start: %f Theta End: %f\n\r", theta_start, theta_end);
benkatz 22:60276ba87ac6 65 printf("Direction: %d\n\r", direction);
benkatz 23:2adf23ee0305 66 if(direction){printf("Phasing correct\n\r");}
benkatz 22:60276ba87ac6 67 else if(!direction){printf("Phasing incorrect. Swapping phases V and W\n\r");}
benkatz 23:2adf23ee0305 68 PHASE_ORDER = direction;
benkatz 22:60276ba87ac6 69 }
benkatz 22:60276ba87ac6 70
benkatz 22:60276ba87ac6 71
benkatz 23:2adf23ee0305 72 void calibrate(PositionSensor *ps, GPIOStruct *gpio, ControllerStruct *controller, PreferenceWriter *prefs){
benkatz 22:60276ba87ac6 73 /// Measures the electrical angle offset of the position sensor
benkatz 22:60276ba87ac6 74 /// and (in the future) corrects nonlinearity due to position sensor eccentricity
benkatz 22:60276ba87ac6 75 printf("Starting calibration procedure\n\r");
benkatz 22:60276ba87ac6 76
benkatz 25:f5741040c4bb 77 const int n = 128*NPP; // number of positions to be sampled per mechanical rotation. Multiple of NPP for filtering reasons (see later)
benkatz 25:f5741040c4bb 78 const int n2 = 50; // increments between saved samples (for smoothing motion)
benkatz 25:f5741040c4bb 79 float delta = 2*PI*NPP/(n*n2); // change in angle between samples
benkatz 25:f5741040c4bb 80 float error_f[n] = {0}; // error vector rotating forwards
benkatz 25:f5741040c4bb 81 float error_b[n] = {0}; // error vector rotating backwards
benkatz 28:8c7e29f719c5 82 const int n_lut = 128;
benkatz 28:8c7e29f719c5 83 int lut[n_lut]= {0}; // clear any old lookup table before starting.
benkatz 28:8c7e29f719c5 84 ps->WriteLUT(lut);
benkatz 22:60276ba87ac6 85 int raw_f[n] = {0};
benkatz 22:60276ba87ac6 86 int raw_b[n] = {0};
benkatz 22:60276ba87ac6 87 float theta_ref = 0;
benkatz 22:60276ba87ac6 88 float theta_actual = 0;
benkatz 28:8c7e29f719c5 89 float v_d = .25; // Put volts on the D-Axis
benkatz 22:60276ba87ac6 90 float v_q = 0.0;
benkatz 22:60276ba87ac6 91 float v_u, v_v, v_w = 0;
benkatz 22:60276ba87ac6 92 float dtc_u, dtc_v, dtc_w = .5;
benkatz 22:60276ba87ac6 93
benkatz 22:60276ba87ac6 94
benkatz 22:60276ba87ac6 95 ///Set voltage angle to zero, wait for rotor position to settle
benkatz 25:f5741040c4bb 96 abc(theta_ref, v_d, v_q, &v_u, &v_v, &v_w); // inverse dq0 transform on voltages
benkatz 25:f5741040c4bb 97 svm(1.0, v_u, v_v, v_w, &dtc_u, &dtc_v, &dtc_w); // space vector modulation
benkatz 22:60276ba87ac6 98 for(int i = 0; i<40000; i++){
benkatz 27:501fee691e0e 99 TIM1->CCR3 = (PWM_ARR>>1)*(1.0f-dtc_u); // Set duty cycles
benkatz 24:58c2d7571207 100 if(PHASE_ORDER){
benkatz 27:501fee691e0e 101 TIM1->CCR2 = (PWM_ARR>>1)*(1.0f-dtc_v);
benkatz 27:501fee691e0e 102 TIM1->CCR1 = (PWM_ARR>>1)*(1.0f-dtc_w);
benkatz 22:60276ba87ac6 103 }
benkatz 22:60276ba87ac6 104 else{
benkatz 27:501fee691e0e 105 TIM1->CCR1 = (PWM_ARR>>1)*(1.0f-dtc_v);
benkatz 27:501fee691e0e 106 TIM1->CCR2 = (PWM_ARR>>1)*(1.0f-dtc_w);
benkatz 22:60276ba87ac6 107 }
benkatz 22:60276ba87ac6 108 wait_us(100);
benkatz 22:60276ba87ac6 109 }
benkatz 22:60276ba87ac6 110 ps->Sample();
benkatz 23:2adf23ee0305 111 controller->i_b = I_SCALE*(float)(controller->adc2_raw - controller->adc2_offset); //Calculate phase currents from ADC readings
benkatz 23:2adf23ee0305 112 controller->i_c = I_SCALE*(float)(controller->adc1_raw - controller->adc1_offset);
benkatz 23:2adf23ee0305 113 controller->i_a = -controller->i_b - controller->i_c;
benkatz 23:2adf23ee0305 114 dq0(controller->theta_elec, controller->i_a, controller->i_b, controller->i_c, &controller->i_d, &controller->i_q); //dq0 transform on currents
benkatz 23:2adf23ee0305 115 float current = sqrt(pow(controller->i_d, 2) + pow(controller->i_q, 2));
benkatz 26:2b865c00d7e9 116 printf(" Current Angle : Rotor Angle : Raw Encoder \n\r\n\r");
benkatz 25:f5741040c4bb 117 for(int i = 0; i<n; i++){ // rotate forwards
benkatz 22:60276ba87ac6 118 for(int j = 0; j<n2; j++){
benkatz 22:60276ba87ac6 119 theta_ref += delta;
benkatz 25:f5741040c4bb 120 abc(theta_ref, v_d, v_q, &v_u, &v_v, &v_w); // inverse dq0 transform on voltages
benkatz 25:f5741040c4bb 121 svm(1.0, v_u, v_v, v_w, &dtc_u, &dtc_v, &dtc_w); // space vector modulation
benkatz 27:501fee691e0e 122 TIM1->CCR3 = (PWM_ARR>>1)*(1.0f-dtc_u);
benkatz 25:f5741040c4bb 123 if(PHASE_ORDER){ // Check phase ordering
benkatz 27:501fee691e0e 124 TIM1->CCR2 = (PWM_ARR>>1)*(1.0f-dtc_v); // Set duty cycles
benkatz 27:501fee691e0e 125 TIM1->CCR1 = (PWM_ARR>>1)*(1.0f-dtc_w);
benkatz 22:60276ba87ac6 126 }
benkatz 22:60276ba87ac6 127 else{
benkatz 27:501fee691e0e 128 TIM1->CCR1 = (PWM_ARR>>1)*(1.0f-dtc_v);
benkatz 27:501fee691e0e 129 TIM1->CCR2 = (PWM_ARR>>1)*(1.0f-dtc_w);
benkatz 22:60276ba87ac6 130 }
benkatz 22:60276ba87ac6 131 wait_us(100);
benkatz 22:60276ba87ac6 132 ps->Sample();
benkatz 22:60276ba87ac6 133 }
benkatz 22:60276ba87ac6 134 ps->Sample();
benkatz 38:67e4e1453a4b 135 theta_actual = ps->GetMechPositionFixed();
benkatz 22:60276ba87ac6 136 error_f[i] = theta_ref/NPP - theta_actual;
benkatz 22:60276ba87ac6 137 raw_f[i] = ps->GetRawPosition();
benkatz 22:60276ba87ac6 138 printf("%.4f %.4f %d\n\r", theta_ref/(NPP), theta_actual, raw_f[i]);
benkatz 22:60276ba87ac6 139 //theta_ref += delta;
benkatz 22:60276ba87ac6 140 }
benkatz 26:2b865c00d7e9 141
benkatz 25:f5741040c4bb 142 for(int i = 0; i<n; i++){ // rotate backwards
benkatz 22:60276ba87ac6 143 for(int j = 0; j<n2; j++){
benkatz 22:60276ba87ac6 144 theta_ref -= delta;
benkatz 25:f5741040c4bb 145 abc(theta_ref, v_d, v_q, &v_u, &v_v, &v_w); // inverse dq0 transform on voltages
benkatz 25:f5741040c4bb 146 svm(1.0, v_u, v_v, v_w, &dtc_u, &dtc_v, &dtc_w); // space vector modulation
benkatz 27:501fee691e0e 147 TIM1->CCR3 = (PWM_ARR>>1)*(1.0f-dtc_u);
benkatz 24:58c2d7571207 148 if(PHASE_ORDER){
benkatz 27:501fee691e0e 149 TIM1->CCR2 = (PWM_ARR>>1)*(1.0f-dtc_v);
benkatz 27:501fee691e0e 150 TIM1->CCR1 = (PWM_ARR>>1)*(1.0f-dtc_w);
benkatz 22:60276ba87ac6 151 }
benkatz 22:60276ba87ac6 152 else{
benkatz 27:501fee691e0e 153 TIM1->CCR1 = (PWM_ARR>>1)*(1.0f-dtc_v);
benkatz 27:501fee691e0e 154 TIM1->CCR2 = (PWM_ARR>>1)*(1.0f-dtc_w);
benkatz 22:60276ba87ac6 155 }
benkatz 22:60276ba87ac6 156 wait_us(100);
benkatz 22:60276ba87ac6 157 ps->Sample();
benkatz 22:60276ba87ac6 158 }
benkatz 25:f5741040c4bb 159 ps->Sample(); // sample position sensor
benkatz 38:67e4e1453a4b 160 theta_actual = ps->GetMechPositionFixed(); // get mechanical position
benkatz 22:60276ba87ac6 161 error_b[i] = theta_ref/NPP - theta_actual;
benkatz 22:60276ba87ac6 162 raw_b[i] = ps->GetRawPosition();
benkatz 22:60276ba87ac6 163 printf("%.4f %.4f %d\n\r", theta_ref/(NPP), theta_actual, raw_b[i]);
benkatz 22:60276ba87ac6 164 //theta_ref -= delta;
benkatz 22:60276ba87ac6 165 }
benkatz 22:60276ba87ac6 166
benkatz 22:60276ba87ac6 167 float offset = 0;
benkatz 22:60276ba87ac6 168 for(int i = 0; i<n; i++){
benkatz 25:f5741040c4bb 169 offset += (error_f[i] + error_b[n-1-i])/(2.0f*n); // calclate average position sensor offset
benkatz 22:60276ba87ac6 170 }
benkatz 25:f5741040c4bb 171 offset = fmod(offset*NPP, 2*PI); // convert mechanical angle to electrical angle
benkatz 23:2adf23ee0305 172
benkatz 22:60276ba87ac6 173
benkatz 25:f5741040c4bb 174 ps->SetElecOffset(offset); // Set position sensor offset
benkatz 23:2adf23ee0305 175 __float_reg[0] = offset;
benkatz 23:2adf23ee0305 176 E_OFFSET = offset;
benkatz 22:60276ba87ac6 177
benkatz 22:60276ba87ac6 178 /// Perform filtering to linearize position sensor eccentricity
benkatz 22:60276ba87ac6 179 /// FIR n-sample average, where n = number of samples in one electrical cycle
benkatz 22:60276ba87ac6 180 /// This filter has zero gain at electrical frequency and all integer multiples
benkatz 25:f5741040c4bb 181 /// So cogging effects should be completely filtered out.
benkatz 22:60276ba87ac6 182
benkatz 22:60276ba87ac6 183 float error[n] = {0};
benkatz 23:2adf23ee0305 184 const int window = 128;
benkatz 22:60276ba87ac6 185 float error_filt[n] = {0};
benkatz 23:2adf23ee0305 186 float cogging_current[window] = {0};
benkatz 22:60276ba87ac6 187 float mean = 0;
benkatz 25:f5741040c4bb 188 for (int i = 0; i<n; i++){ //Average the forward and back directions
benkatz 22:60276ba87ac6 189 error[i] = 0.5f*(error_f[i] + error_b[n-i-1]);
benkatz 22:60276ba87ac6 190 }
benkatz 22:60276ba87ac6 191 for (int i = 0; i<n; i++){
benkatz 22:60276ba87ac6 192 for(int j = 0; j<window; j++){
benkatz 25:f5741040c4bb 193 int ind = -window/2 + j + i; // Indexes from -window/2 to + window/2
benkatz 22:60276ba87ac6 194 if(ind<0){
benkatz 25:f5741040c4bb 195 ind += n;} // Moving average wraps around
benkatz 22:60276ba87ac6 196 else if(ind > n-1) {
benkatz 22:60276ba87ac6 197 ind -= n;}
benkatz 22:60276ba87ac6 198 error_filt[i] += error[ind]/(float)window;
benkatz 22:60276ba87ac6 199 }
benkatz 23:2adf23ee0305 200 if(i<window){
benkatz 23:2adf23ee0305 201 cogging_current[i] = current*sinf((error[i] - error_filt[i])*NPP);
benkatz 23:2adf23ee0305 202 }
benkatz 22:60276ba87ac6 203 //printf("%.4f %4f %.4f %.4f\n\r", error[i], error_filt[i], error_f[i], error_b[i]);
benkatz 22:60276ba87ac6 204 mean += error_filt[i]/n;
benkatz 22:60276ba87ac6 205 }
benkatz 25:f5741040c4bb 206 int raw_offset = (raw_f[0] + raw_b[n-1])/2; //Insensitive to errors in this direction, so 2 points is plenty
benkatz 28:8c7e29f719c5 207
benkatz 28:8c7e29f719c5 208
benkatz 23:2adf23ee0305 209 printf("\n\r Encoder non-linearity compensation table\n\r");
benkatz 23:2adf23ee0305 210 printf(" Sample Number : Lookup Index : Lookup Value : Cogging Current Lookup\n\r\n\r");
benkatz 25:f5741040c4bb 211 for (int i = 0; i<n_lut; i++){ // build lookup table
benkatz 22:60276ba87ac6 212 int ind = (raw_offset>>7) + i;
benkatz 22:60276ba87ac6 213 if(ind > (n_lut-1)){
benkatz 22:60276ba87ac6 214 ind -= n_lut;
benkatz 22:60276ba87ac6 215 }
benkatz 22:60276ba87ac6 216 lut[ind] = (int) ((error_filt[i*NPP] - mean)*(float)(ps->GetCPR())/(2.0f*PI));
benkatz 23:2adf23ee0305 217 printf("%d %d %d %f\n\r", i, ind, lut[ind], cogging_current[i]);
benkatz 26:2b865c00d7e9 218 wait(.001);
benkatz 22:60276ba87ac6 219 }
benkatz 23:2adf23ee0305 220
benkatz 25:f5741040c4bb 221 ps->WriteLUT(lut); // write lookup table to position sensor object
benkatz 23:2adf23ee0305 222 //memcpy(controller->cogging, cogging_current, sizeof(controller->cogging)); //compensation doesn't actually work yet....
benkatz 25:f5741040c4bb 223 memcpy(&ENCODER_LUT, lut, sizeof(lut)); // copy the lookup table to the flash array
benkatz 23:2adf23ee0305 224 printf("\n\rEncoder Electrical Offset (rad) %f\n\r", offset);
benkatz 22:60276ba87ac6 225
benkatz 23:2adf23ee0305 226 if (!prefs->ready()) prefs->open();
benkatz 25:f5741040c4bb 227 prefs->flush(); // write offset and lookup table to flash
benkatz 25:f5741040c4bb 228 prefs->close();
benkatz 23:2adf23ee0305 229
benkatz 23:2adf23ee0305 230
benkatz 22:60276ba87ac6 231 }