Subsections
Variable delay
Linear
The Variable Transport Delay block can be used to simulate a variable
time delay. The block might be used to model a system with a pipe
where the speed of a motor pumping fluid in the pipe is variable. The
block accepts two inputs: the first input is the signal that passes
through the block; the second input is the time delay.
Set delay parameters |
|
Max delay |
1 |
initial input |
0 |
Buffer size |
1024 |
- Max delay:It defines the largest value the time delay input
can have.The value cannot be negative.
- initial input:The output generated by the block until the
simulation time first exceeds the time delay input.
- Buffer size: The number of points the block can store.
- always active: no
- direct-feedthrough: yes
- zero-crossing: no
- mode: no
- number/sizes of inputs: 2 / -1 1
- number/sizes of outputs: 1 / -1
- number/sizes of activation inputs: 0 /
- number/sizes of activation outputs: 0 /
- continuous-time state: no
- discrete-time state: no
- name of computational function: variable_delay
scilab/macros/scicos_blocks/linear/VARIABLE_DELAY.sci
#include "scicos_block.h"
#include <math.h>
#include "../machine.h"
#if WIN32
#define NULL 0
#endif
extern void sciprint __PARAMS((char *fmt,...));
void variable_delay(scicos_block *block,int flag)
{/* rpar[0]=max delay, rpar[1]=init value, ipar[0]=buffer length */
double* pw,del,t,td;
int* iw;
int i,j,k;
if (flag == 4){/* the workspace is used to store previous values */
if ((*block->work=
scicos_malloc(sizeof(int)+sizeof(double)*
block->ipar[0]*(1+block->insz[0])))== NULL ) {
set_block_error(-16);
return;
}
pw=*block->work;
pw[0]=-block->rpar[0]*block->ipar[0];
for(i=1;i< block->ipar[0];i++){
pw[i]=pw[i-1]+block->rpar[0];
for(j=1;j< block->insz[0]+1;j++){
pw[i+block->ipar[0]*j]=block->rpar[1];
}
}
iw=(int *) (pw+block->ipar[0]*(1+block->insz[0]));
*iw=0;
}else if (flag == 5){
scicos_free(*block->work);
} else if (flag==1) {
if (get_phase_simulation()==1) do_cold_restart();
pw=*block->work;
iw=(int *) (pw+block->ipar[0]*(1+block->insz[0]));
t=get_scicos_time();
del=min(max(0,block->inptr[1][0]),block->rpar[0]);
td=t-del;
if(td<pw[*iw]){
sciprint("delayed time=%f but last stored time=%f \r\n", td, pw[*iw]);
sciprint("Consider increasing the length of buffer in variable delay block\r\n");
}
if (t>pw[(block->ipar[0]+*iw-1)%block->ipar[0]]){
for(j=1;j< block->insz[0]+1;j++){
pw[*iw +block->ipar[0]*j]=block->inptr[0][j-1];
}
pw[*iw]=t;
*iw=(*iw+1)%block->ipar[0];
}else{
for(j=1;j< block->insz[0]+1;j++){
pw[(block->ipar[0]+*iw-1)%block->ipar[0] +block->ipar[0]*j]=block->inptr[0][j-1];
}
pw[(block->ipar[0]+*iw-1)%block->ipar[0]]=t;
}
i=0;j= block->ipar[0]-1;
while (j-i>1) {
k=(i+j)/2;
if (td<pw[(k+*iw)%block->ipar[0]]) {
j=k;
}else if (td>pw[(k+*iw)%block->ipar[0]]) {
i=k;
}else{
i=k;
j=k;
break;
}
}
i=(i+*iw)%block->ipar[0];
j=(j+*iw)%block->ipar[0];
del=pw[j]-pw[i];
if(del!=0.0){
for (k=1;k<block->insz[0]+1;k++){
block->outptr[0][k-1]=((pw[j]-td)*pw[i+block->ipar[0]*k] +
(td-pw[i])*pw[j+block->ipar[0]*k])/del;
}
}else{
for (k=1;k<block->insz[0]+1;k++){
block->outptr[0][k-1]=pw[i+block->ipar[0]*k];
}
}
}
}
Ramine Nikoukhah
2004-06-22