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C/C++ Source or Header | 1988-05-02 | 11.0 KB | 447 lines

/********************************************************************** FILE rtsim1.c - d.c. speed control, simulation module 1 ENTRY ROUTINES tstep - advance one time step SetTimer - set count-down timer TimeUp - has count down completed? ad_init - simulates A/D initialization ad_start - simulates starting an A/D read ad_read - simulates reading A/D value ad_wread - simulates read from A/D da_init - simulates D/A initialization da_limits - returns simulation D/A output limits da_write - simulates write to D/A PRIVATE ROUTINE simul - motor plant simulation INITIALIZATION ROUTINE sim_init - initialize simulation REMARKS This module simulates the interface and motor hardware and the passage of "real" time. This module must thus provide the same interface functions as the modules controlling the hardware. To use "real" time, compile this module with the /DFTIME switch; this will cause tstep() to use ftime() calls to tell time. LAST UPDATE 1 December 1987 restructure and modify for MSC 4.00 and 5.00 Copyright(C) 1984-1987 D.M. Auslander and C.H. Tham **********************************************************************/ /*********************************************************************** I M P O R T S ***********************************************************************/ #include <stdio.h> #include "envir.h" /* environment specifications */ #ifdef FTIME /* include stuff to run simulation in */ /* real time using ftime() calls. */ #include <sys\types.h> #include <sys\timeb.h> #endif /*********************************************************************** F O R W A R D D E C L A R A T I O N S ***********************************************************************/ #ifdef ANSI void simul(void); #ifndef FTIME void runtimer(void); #endif #else void simul(); #ifndef FTIME void runtimer(); #endif #endif /********************************************************************** P R I V A T E D A T A **********************************************************************/ #define ADSCALE 512.0 /* scale speed to A/D units */ #define ADMAX 2047 /* max A/D input value */ #define ADMIN -2048 /* min A/D input value */ #define DASCALE 2047.0 /* scale D/A value to torque */ #define DAMIN -2048 /* min. output value accepted */ #define DAMAX 2047 /* max. output value accepted */ static double inertia = 1.0; /* motor system inertia */ static double speed; /* simulated motor velocity */ static double t; /* time */ static double dt; /* step size in time */ static double torque = 0.0; /* motor torque */ #ifndef FTIME static long freq = 1000L; /* timer frequency (ticks/sec) */ static long ticks; /* how many ticks to timeout */ static int tflag; /* set to 1 if timer runs out */ #endif static long millidt; /* step size dt in milliseconds */ /*********************************************************************** T I M E S I M U L A T I O N ***********************************************************************/ #ifndef FTIME /* simulate timer hardware */ /*--------------------------------------------------------------------- PROCEDURE TSTEP - advance time forward one step SYNOPSIS void tstep() LAST UPDATE 10 October 1984 ---------------------------------------------------------------------*/ void tstep() { simul(); /* compute one time step in the differential */ /* equation for the motor system. */ t += dt; /* increment time by dt */ runtimer(); /* simulate timer run */ } /*---------------------------------------------------------------------- PROCEDURE SETTIMER - set countdown timer SYNOPSIS void SetTimer(ms) long ms; PARAMETER period - count down period in milliseconds LAST UPDATE 15 January 1988 ----------------------------------------------------------------------*/ void SetTimer(ms) long ms; { ticks = ((ms * freq) + 500L) / 1000L; /* 500 is for rounding */ tflag = 0; /* timeout flag to false */ } /*--------------------------------------------------------------------- FUNCTION TIMEUP - has timer timed out? SYNOPSIS int TimeUp() RETURNS 1 if timer runs out, 0 otherwise LAST UPDATE 1 March 1985 ----------------------------------------------------------------------*/ int TimeUp() { return(tflag); } /*---------------------------------------------------------------------- PROCEDURE RUNTIMER - simulates timer run SYNOPSIS static void runtimer() LAST UPDATE 19 March 1985 ----------------------------------------------------------------------*/ static void runtimer() { if (!tflag) /* if timeout, just return, otherwise... */ { /* decrement tick count by # of ticks corresponding to dt sec */ ticks -= (long)(dt * freq + 0.5); /* 0.5 is for rounding */ if (ticks <= 0L) /* time has run out */ tflag = 1; } } #else /* else use "real" time */ /*--------------------------------------------------------------------- PROCEDURE TSTEP - advance time forward one step SYNOPSIS void tstep(void) REMARKS This routine runs the simulation and then waits dt seconds (millidt is dt converted to milliseconds) using ftime() library calls. Thus, dt determines how often the simulation is run and is more or less independent of the sampling time. LAST UPDATE 18 January 1988 ---------------------------------------------------------------------*/ void tstep() { struct timeb start; /* starting time */ struct timeb now; /* current time */ simul(); ftime(&start); do { ftime(&now); } while (((now.time - start.time) * 1000) + now.millitm - start.millitm < millidt); } #endif /* else ifndef FTIME */ /*********************************************************************** A / D S I M U L A T I O N These routines dummies the routines in dash8.c which drives the Metrabyte DASH8 A/D board. The channel parameter is ignored. ***********************************************************************/ void ad_init() { speed = 0.0; } void ad_start(channel) int channel; { /* nothing */ } int ad_read(channel) int channel; { int rval; /* return value */ rval = ADSCALE * speed; /* scale and convert to int type */ if (rval > ADMAX) /* apply converter limits */ rval = ADMAX; else if (rval < ADMIN) rval = ADMIN; return(rval); } int ad_wread(channel) int channel; { return(ad_read(channel)); } /*********************************************************************** D / A S I M U L A T I O N These routines dummies the routines in dac2.c which drives the Metrabyte DAC02 D/A board. The channel parameter is ignored. The DAC2 is a 12-bit digital-to-analog converter configured for bipolar output. Thus, the output parameter values range from -2048 to 2047. Only lower 12 bits will be used, treating those 12 bits as a 2's complement signed number. Thus if the output value is negative, the lower 12 bits will be preserved and all higher order bits will be converted to 1's. Note the use of ~0xfff instead of 0xf000, this makes the program more portable across machines with different integer sizes. ***********************************************************************/ void da_init() { torque = 0.0; } void da_limits(lo, hi) int *lo, *hi; { *lo = DAMIN; *hi = DAMAX; } void da_write(channel, value) int channel, value; { if (value < 0) /* OR with a binary number having 0's for */ value |= ~0xfff; /* the lower 12 bits and 1's elsewhere */ else value &= 0xfff; /* for positive values, just save the */ /* lower 12 bits. */ torque = value / DASCALE; /* rescale for motor drive torque. */ } /********************************************************************** P R I V A T E R O U T I N E S The following routines are declared "static". These routines can be directly accessed only by routines inside this file; they are not "visible" to routines outside this file. Hence they are private to this file. Private routines enhances data security and helps avoid unexpected name conflicts in large programming projects. ***********************************************************************/ /*---------------------------------------------------------------------- PROCEDURE SIMUL - simulates motor plant SYNOPSIS static void simul() REMARKS Solve the motor system differential equation. This version uses the Euler method for integration; it isn't very efficient, but its easy to program! LAST UPDATE 12 January 1988 add friction term to make it more interesting ----------------------------------------------------------------------*/ static void simul() { double friction; friction = speed / 10.0; /* this is quite arbitrary */ speed += (torque - friction) * dt / inertia; } /*********************************************************************** I N I T I A L I Z A T I O N R O U T I N E ***********************************************************************/ /*---------------------------------------------------------------------- PROCEDURE INIT - system initialization SYNOPSIS sim_init(cline) char *cline; PARAMETER cline - user's input command line REMARKS In a "real" real-time program, this function would be used to set up interrupts, set clock modes, etc. In this simulation version, it sets time to zero and sets the motor simulation initial conditions. LAST UPDATE 18 October 1984 ----------------------------------------------------------------------*/ sim_init(cline) char *cline; { sscanf(cline, "%lf", &dt); /* get the step size. */ #if DEBUG printf("<init> dt = %lf\n", dt); #endif t = 0.0; /* reset time */ millidt = (long)(dt * 1000 + 0.5); speed = 0.0; /* motor is initially at rest */ torque = 0.0; }