step_cl.cpp 7.61 KB
Newer Older
Jake Read's avatar
Jake Read committed
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
/*
osap/drivers/step_cl.cpp

stepper in closed loop mode 

Jake Read at the Center for Bits and Atoms
(c) Massachusetts Institute of Technology 2020

This work may be reproduced, modified, distributed, performed, and
displayed for any purpose, but must acknowledge the squidworks and ponyo
projects. Copyright is retained and must be preserved. The work is provided as
is; no warranty is provided, and users accept all liability.
*/

#include "step_cl.h"

Step_CL* Step_CL::instance = 0;

Step_CL* Step_CL::getInstance(void){
    if(instance == 0){
        instance = new Step_CL();
    }
    return instance;
}

Step_CL* step_cl = Step_CL::getInstance();

// https://github.com/cmaglie/FlashStorage
// flash LUT
// FlashStorage(flash_lut, step_cl_calib_table_t);
// float __attribute__((__aligned__(256))) lut[16384];

Step_CL::Step_CL(void){}

#define CALIB_CSCALE 0.4F
36
#define CALIB_STEP_DELAY 10
37
#define CALIB_SETTLE_DELAY 1
38
39
40
#define CALIB_SAMPLE_PER_TICK 10 

#define ENCODER_COUNTS 16384
Jake Read's avatar
Jake Read committed
41
42
43
44
45
46
47
48

void Step_CL::init(void){
    stepper_hw->init(false, 0.4);
    enc_as5047->init();
    // this lut == stored lut 
    //lut = flash_lut.read();
}

49
50
51
boolean Step_CL::calibrate(void){
    // (1) first, build a table for 200 full steps w/ encoder averaged values at each step 
    float phase_angle = 0.0F;
Jake Read's avatar
Jake Read committed
52
    for(uint8_t i = 0; i < 200; i ++){ 
53
54
55
        // pt to new angle 
        stepper_hw->point(phase_angle, CALIB_CSCALE);
        // wait to settle / go slowly 
Jake Read's avatar
Jake Read committed
56
        delay(CALIB_STEP_DELAY);
57
58
59
60
61
62
63
64
65
66
67
        // do readings 
        float x = 0.0F;
        float y = 0.0F;
        for(uint8_t s = 0; s < CALIB_SAMPLE_PER_TICK; s ++){
            enc_as5047->trigger_read();
            while(!enc_as5047->is_read_complete()); // do this synchronously 
            float reading = enc_as5047->get_reading();
            x += cos((reading / (float)(ENCODER_COUNTS)) * 2 * PI);
            y += sin((reading / (float)(ENCODER_COUNTS)) * 2 * PI);
            // this is odd, I know, but it allows a new measurement to settle
            // so we get a real average 
68
            delay(CALIB_SETTLE_DELAY); 
69
70
71
72
73
74
75
76
        }
        // push reading, average removes the wraps added to readings. 
        calib_readings[i] = atan2(y, x);//(reading / (float)CALIB_SAMPLE_PER_TICK) - ENCODER_COUNTS;
        if(calib_readings[i] < 0) calib_readings[i] = 2 * PI + calib_readings[i]; // wrap the circle 
        calib_readings[i] = (calib_readings[i] * ENCODER_COUNTS) / (2 * PI);
        // rotate 
        phase_angle += 0.25F;
        if(phase_angle >= 1.0F) phase_angle = 0.0F;
Jake Read's avatar
Jake Read committed
77
    } // end measurement taking 
78
79
    // tack end-wrap together, to easily find the wrap-at-indice interval 
    calib_readings[200] = calib_readings[0];
Jake Read's avatar
Jake Read committed
80
    if(false){ // debug print intervals 
81
        for(uint8_t i = 0; i < 200; i ++){
82
83
84
85
86
            sysError("int: " + String(i) 
                        + " " + String(calib_readings[i], 4)
                        + " " + String(calib_readings[i + 1], 4));
            delay(2);
        }
Jake Read's avatar
Jake Read committed
87
    }
88
89
90
91
92
93
94
95
96
97
98
99
100
101
    // check sign of readings 
    // the sign will help identify the wrapping interval
    // might get unlucky and find the wrap, so take majority vote of three 
    boolean s1 = (calib_readings[1] - calib_readings[0]) > 0 ? true : false;
    boolean s2 = (calib_readings[2] - calib_readings[1]) > 0 ? true : false;
    boolean s3 = (calib_readings[3] - calib_readings[2]) > 0 ? true : false;
    boolean sign = false;
    if((s1 && s2) || (s2 && s3) || (s1 && s3)){
        sign = true;
    } else {
        sign = false;
    }
    sysError("calib sign: " + String(sign));

Jake Read's avatar
Jake Read committed
102
    // (2) build the table, walk all encoder counts... 
103
104
105
    // now to build the actual table... 
    // want to start with the 0 indice, 
    for(uint16_t e = 0; e < ENCODER_COUNTS; e ++){
Jake Read's avatar
Jake Read committed
106
107
        // find the interval that spans this sample
        boolean bi = false; 
108
        int16_t interval = -1;
109
        for(uint8_t i = 0; i < 200; i ++){
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
            if(sign){ // +ve slope readings, left < right 
                if(calib_readings[i] < e && e <= calib_readings[i + 1]){
                    interval = i;
                    break;
                }
            } else { // -ve slope readings, left > right 
                if(calib_readings[i] > e && e >= calib_readings[i + 1]){
                    interval = i;
                    break;
                }
            }
        }
        // log intervals 
        if(interval >= 0){
            // sysError(String(e) + " inter: " + String(interval) 
            //                 + " " + String(calib_readings[interval]) 
            //                 + " " + String(calib_readings[interval + 1]));
        } else {
128
            // no proper interval found, must be the bi 
129
            // find the opposite-sign interval 
130
            for(uint8_t i = 0; i < 200; i ++){
131
132
133
                boolean intSign = (calib_readings[i + 1] - calib_readings[i]) > 0 ? true : false;
                if(intSign != sign){
                    interval = i;
Jake Read's avatar
Jake Read committed
134
                    bi = true; // mark the bad interval
135
136
137
                    break;
                }
            }
Jake Read's avatar
Jake Read committed
138
139
140
141
142
143
            if(!bi){
                // truly strange 
                sysError("missing interval, exiting");
                return false;
            }
            /*
144
145
146
147
            sysError("bad interval at: " + String(e) 
                    + " " + String(interval)
                    + " " + String(calib_readings[interval]) 
                    + " " + String(calib_readings[interval + 1]));
Jake Read's avatar
Jake Read committed
148
            */
149
        }
150
151
152

        // (3) have the interval (one is bad), 
        // find real angles (ra0, ra1)
153
154
        float ra0 = 360.0F * ((float)interval / 200);          // real angle at left of interval 
        float ra1 = 360.0F * ((float)(interval + 1) / 200);    // real angle at right of interval 
155
156
157
158
159
160
        // interval spans these readings (er0, er1)
        float er0 = calib_readings[interval];
        float er1 = calib_readings[interval + 1];

        // (4) for the bad interval, some more work to do to modify interp. points 
        float spot = e;
Jake Read's avatar
Jake Read committed
161
        if(bi){
162
163
164
165
166
167
            if(sign){ // wrap the tail *up*, do same for pts past zero crossing 
                er1 += (float)ENCODER_COUNTS;
                if(spot < er0) spot += (float)ENCODER_COUNTS;
            } else { // wrap the tail *down*, do same for pts past zero crossing 
                er1 -= (float)ENCODER_COUNTS;
                if(spot > er0) spot -= (float)ENCODER_COUNTS;
Jake Read's avatar
Jake Read committed
168
169
            }
        }
170
171
172
173
174
175

        // (5) continue w/ (ra0, ra1) and (er0, er1) to interpolate for spot 
        // check we are not abt to div / 0: this could happen if motor did not turn during measurement 
        float intSpan = er1 - er0;
        if(intSpan < 0.01F && intSpan > -0.01F){
            sysError("near zero interval, exiting");
176
177
178
            return false;
        }
        // find pos. inside of interval 
179
        float offset = (spot - er0) / intSpan;
Jake Read's avatar
Jake Read committed
180
        // find real angle offset at e, modulo for the bad interval 
181
182
183
        float ra = (ra0 + (ra1 - ra0) * offset);
        // wrap to 360 degs, 
        /*
Jake Read's avatar
Jake Read committed
184
185
186
187
188
        if(ra < 0.0F){
            ra += 360.0F;
        } else if (ra > 360.0F){
            ra -= 360.0F;
        }
189
        */
190
        // log those 
Jake Read's avatar
Jake Read committed
191
192
        if(bi){
            sysError("e: " + String(e) + " ra: " + String(ra, 4) + " BI");
193
194
195
196
            //     + " span: " + String(intSpan) + " offset: " + String(offset));
            // sysError("i0: " + String(interval) + " " + String(calib_readings[interval])
            //     + " i1: " + String(calib_readings[interval + 1])
            //     + " BI");
Jake Read's avatar
Jake Read committed
197
198
199
200
        } else {
            sysError("e: " + String(e) + " ra: " + String(ra, 4));
        }
        delay(10);
201
    } // end sweep thru 2^14 pts 
Jake Read's avatar
Jake Read committed
202
    sysError("calib complete");
203
    return true; // went OK 
Jake Read's avatar
Jake Read committed
204
}