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improved low speed regime handling and better overall effective acceleration calculation

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Dietz0r
2025-01-03 16:40:30 +01:00
committed by GitHub
parent 5a05201041
commit 5ffa6bcb81
1 changed files with 13 additions and 3 deletions
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16
planner.c
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@@ -549,9 +549,19 @@ bool plan_buffer_line (float *target, plan_line_data_t *pl_data)
#if ENABLE_JERK_ACCELERATION
// Calculate effective acceleration over block. Since jerk acceleration takes longer to execute due to ramp up and
// ramp down of the acceleration at the start and end of a ramp we need to adjust the acceleration value the planner
// uses so it still calculates reasonable entry and exit speeds. We do this by adding 2x the time it takes to reach
// full acceleration to the trapezoidal acceleration time and dividing the programmed rate by the value obtained.
block->acceleration = block->programmed_rate / ((block->programmed_rate / block->max_acceleration) + 2.0f * (block->max_acceleration / block->jerk));
// uses so it still calculates reasonable entry speeds, exit speeds and times to decelerate/accelerate.
// 2 general cases emerge:
// -slow speed regime: uncomplete jerk ramp (max_acceleration is not reached)
// -high speed regime: complete jerk ramp + time at max_axcel to reach desired programmed_rates
// Profiles are calculated as symmetrical (calculate to 1/2 programmed rate, then double)
float time_to_max_accel = block->max_acceleration / block->jerk; // unit: min - time it takes to reach max acceleration
float speed_after_jerkramp = 0.5f * block->jerk * time_to_max_accel * time_to_max_accel; // unit: mm / min - velocity after one completed jerk ramp up - Vt = V0 + A0T + 1/2 jerk*T
if (0.5*block->programmed_rate > speed_after_jerkramp)
// Profile time = 2x (1 complete jerk ramp + additional time at max_accel to reach desired speed)
block->acceleration = block->programmed_rate / (2.0f *(time_to_max_accel + (0.5f * block->programmed_rate - speed_after_jerkramp) / block->max_acceleration));
else
// Max Accel is not reached. time_to_halfvelocity = sqrt( 0.5 programmed_rate * 2 / jerk) -> derived from Vt = V0 + A0T + 1/2 jerk*T (v0 and a0t == 0 in this case)
block->acceleration = block->programmed_rate / (2.0f * sqrt(block->programmed_rate / block->jerk));
#endif
// TODO: Need to check this method handling zero junction speeds when starting from rest.