Chris,
I'm trying to understand velocity calculation, and I can't come up with
current formula,
I ended up with this, could you please tell what am I missing?
Thanks in advance,
Alex.
void tcRunCycle(TP_STRUCT *tp, TC_STRUCT *tc, double *v, int
*on_final_decel) {
- double discr, maxnewvel, newvel, newaccel=0;
+ double dtg, maxnewvel, newvel, newaccel=0;
if(!tc->blending) tc->vel_at_blend_start = tc->currentvel;
-
- discr = 0.5 * tc->cycle_time * tc->currentvel - (tc->target -
tc->progress);
- if(discr > 0.0) {
+ dtg = tc->target - tc->progress;
+ // compare with disance over cycle with constant desceleration to 0.
+ if(dtg <= tc->currentvel * tc->cycle_time / 2.0)
// should never happen: means we've overshot the target
newvel = maxnewvel = 0.0;
- } else {
- discr = 0.25 * pmSq(tc->cycle_time) - 2.0 / tc->maxaccel * discr;
- newvel = maxnewvel = -0.5 * tc->maxaccel * tc->cycle_time +
- tc->maxaccel * pmSqrt(discr);
+ else {
+ // time to cover dtg with maxaccel and zero end speed
+ double time = pmSqrt(2.0 * dtg / tc->maxaccel);
+ newvel = maxnewvel = tc->maxaccel * (time - tc->cycle_time);
}
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