Navigation: fix calculations of ground speeds and navigation progress #2532
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…f ground speeds and navigation progress - add fabs and explicit type conversion respectively to fix calculation errors Fixes issue #2531
gautierhattenberger
requested changes
May 25, 2020
sw/airborne/modules/nav/nav_smooth.c
Outdated
| @@ -170,7 +170,7 @@ static void compute_ground_speed(float airspeed, | |||
| /* g^2 -2 scal g + c = 0 */ | |||
| float scal = wind_east * cos(alpha) + wind_north * sin(alpha); | |||
| float delta = 4 * (scal * scal - c); | |||
| ground_speeds[i] = scal + sqrt(delta) / 2.; | |||
| ground_speeds[i] = scal + sqrt(fabs(delta)) / 2.; | |||
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This is not the proper way I think. The navigation routine should just fail if delta is negative.
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In the latest commit, I changed to return false on calculation failure.
| @@ -592,7 +592,7 @@ void nav_route(struct EnuCoor_i *wp_start, struct EnuCoor_i *wp_end) | |||
| INT32_VECT2_RSHIFT(pos_diff, pos_diff, INT32_POS_FRAC); | |||
| uint32_t leg_length2 = Max((wp_diff.x * wp_diff.x + wp_diff.y * wp_diff.y), 1); | |||
| nav_leg_length = int32_sqrt(leg_length2); | |||
| nav_leg_progress = (pos_diff.x * wp_diff.x + pos_diff.y * wp_diff.y) / nav_leg_length; | |||
| nav_leg_progress = (pos_diff.x * wp_diff.x + pos_diff.y * wp_diff.y) / (int32_t)nav_leg_length; | |||
gautierhattenberger
approved these changes
May 26, 2020
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Fixes issue #2531