manabu kosaka / Mbed 2 deprecated BLDCmotor

UVW 3 phases Brushless DC motor control

Dependencies:   QEI mbed-rtos mbed

Fork of DCmotor by manabu kosaka

fast_math.cpp@12:a4b17bb682eb, 2012-12-21 (annotated)

Committer:
kosaka
Date:
Fri Dec 21 22:06:56 2012 +0000
Revision:
12:a4b17bb682eb
Child:
13:791e20f1af43
121222a

Who changed what in which revision?

UserRevisionLine numberNew contents of line
kosaka 12:a4b17bb682eb 1 #include "mbed.h"
kosaka 12:a4b17bb682eb 2 #include "fast_math.h"
kosaka 12:a4b17bb682eb 3
kosaka 12:a4b17bb682eb 4 unsigned short sin60[DEG60+1]; // sin table from 0 to 60 deg. (max precision error is 0.003%)
kosaka 12:a4b17bb682eb 5
kosaka 12:a4b17bb682eb 6 long _sin(unsigned short th){ // return( 65535*sin(th) ), th=rad*DEG60/(PI/3)=rad*(512*3)/PI (0<=rad<2*PI)
kosaka 12:a4b17bb682eb 7 // init_sin60();
kosaka 12:a4b17bb682eb 8 // if( th>2.*PI ){ th -= 2*PI*(float)((int)(th/(2.*PI)));}
kosaka 12:a4b17bb682eb 9 // th_int = (unsigned short)(th/(PI/3.)*(float)DEG60+0.5); // rad to deg
kosaka 12:a4b17bb682eb 10 // sin = (float)_sin(th)/65535.;
kosaka 12:a4b17bb682eb 11 unsigned short f_minus;
kosaka 12:a4b17bb682eb 12 long x;
kosaka 12:a4b17bb682eb 13
kosaka 12:a4b17bb682eb 14 if( th>=DEG60*3){ f_minus = 1; th -= DEG60*3;} // if th>=180deg, th = th - 180deg;
kosaka 12:a4b17bb682eb 15 else{ f_minus = 0;} // else , f_minus = on.
kosaka 12:a4b17bb682eb 16
kosaka 12:a4b17bb682eb 17 if( th<DEG60 ){ // th<60deg?
kosaka 12:a4b17bb682eb 18 x = sin60[th]; // sin(th)
kosaka 12:a4b17bb682eb 19 }else if( th<DEG60*2 ){ // 60<=th<120deg?
kosaka 12:a4b17bb682eb 20 x = sin60[DEG60*2-th] + sin60[th-DEG60]; // sin(th)=sin(th+60)+sin(th-60)=sin(180-(th+60))+sin(th-60) because sin(th+60)=s/2+c*root(3)/2, sin(th-60)=s/2-c*root(3)/2.
kosaka 12:a4b17bb682eb 21 }else{// if( th<180 ) // 120<=th<180deg?
kosaka 12:a4b17bb682eb 22 x = sin60[DEG60*3-th]; // sin(60-(th-120))=sin(180-th)
kosaka 12:a4b17bb682eb 23 }
kosaka 12:a4b17bb682eb 24 if( f_minus==1 ){ x = -x;}
kosaka 12:a4b17bb682eb 25 return(x);
kosaka 12:a4b17bb682eb 26 }
kosaka 12:a4b17bb682eb 27
kosaka 12:a4b17bb682eb 28 long _cos(unsigned short th){ // return( 65535*sin(th) ), th=rad*DEG60/(PI/3)=rad*(512*3)/PI (0<=rad<2*PI)
kosaka 12:a4b17bb682eb 29 th += DEG60*3/2;
kosaka 12:a4b17bb682eb 30 if( th>=DEG60*6 ){ th -= DEG60*6;}
kosaka 12:a4b17bb682eb 31 return( _sin(th) );
kosaka 12:a4b17bb682eb 32 }
kosaka 12:a4b17bb682eb 33
kosaka 12:a4b17bb682eb 34 void init_fast_math(){ // sin0-sin60deg; 0deg=0, 60deg=512
kosaka 12:a4b17bb682eb 35 int i;
kosaka 12:a4b17bb682eb 36
kosaka 12:a4b17bb682eb 37 for( i=0;i<=DEG60;i++ ){ // set sin table from 0 to 60 deg..
kosaka 12:a4b17bb682eb 38 // sin60[i] = (unsigned short)(sin((float)i/512.*PI/3.));
kosaka 12:a4b17bb682eb 39 sin60[i] = (unsigned short)(65535.*sinf((float)i/(float)DEG60*PI/3.));
kosaka 12:a4b17bb682eb 40 }
kosaka 12:a4b17bb682eb 41 }
kosaka 12:a4b17bb682eb 42
kosaka 12:a4b17bb682eb 43 #if 0
kosaka 12:a4b17bb682eb 44 //float norm(float x[0], float x[1]){ // ２ノルムを計算
kosaka 12:a4b17bb682eb 45 // return(sqrt(x[0]*x[0]+x[1]*x[1]));
kosaka 12:a4b17bb682eb 46 //}
kosaka 12:a4b17bb682eb 47 float sqrt2(float x){ // √xのx=1まわりのテイラー展開 √x = 1 + 1/2*(x-1) -1/4*(x-1)^2 + ...
kosaka 12:a4b17bb682eb 48 // return((1+x)*0.5); // 一次近似
kosaka 12:a4b17bb682eb 49 return(x+(1-x*x)*0.25); // 二次近似
kosaka 12:a4b17bb682eb 50 }
kosaka 12:a4b17bb682eb 51 #endif