View source for Trajectory Planner Smoothing Noisy GCode

GCode consisting of very short vectors and without enough digits of precision can result in GCode with sharp angles along the contour that aren't always obvious.  Here is an example of a path only ~ 0.02 inches long specified over 90 GCode Blocks:

G20<br />G01 F100.0<br />X2.4343 Y0.0289 Z0.0646<br />X2.4343 Y0.0289 Z0.0655<br />X2.4344 Y0.0289 Z0.0665<br />X2.4344 Y0.0289 Z0.0671<br />X2.4345 Y0.0290 Z0.0679<br />X2.4345 Y0.0290 Z0.0686<br />X2.4346 Y0.0290 Z0.0694<br />X2.4347 Y0.0291 Z0.0702<br />X2.4347 Y0.0291 Z0.0708<br />X2.4348 Y0.0292 Z0.0715<br />X2.4349 Y0.0292 Z0.0720<br />X2.4349 Y0.0292 Z0.0726<br />X2.4350 Y0.0293 Z0.0734<br />X2.4351 Y0.0293 Z0.0739<br />X2.4352 Y0.0294 Z0.0743<br />X2.4353 Y0.0294 Z0.0748<br />X2.4353 Y0.0295 Z0.0752<br />X2.4354 Y0.0294 Z0.0756<br />X2.4355 Y0.0294 Z0.0760<br />X2.4355 Y0.0296 Z0.0764<br />X2.4356 Y0.0296 Z0.0768<br />X2.4357 Y0.0297 Z0.0772<br />X2.4357 Y0.0297 Z0.0775<br />X2.4359 Y0.0298 Z0.0782<br />X2.4360 Y0.0299 Z0.0789<br />X2.4362 Y0.0299 Z0.0795<br />X2.4363 Y0.0300 Z0.0801<br />X2.4364 Y0.0301 Z0.0807<br />X2.4366 Y0.0302 Z0.0812<br />X2.4367 Y0.0303 Z0.0818<br />X2.4369 Y0.0303 Z0.0823<br />X2.4370 Y0.0304 Z0.0828<br />X2.4371 Y0.0305 Z0.0833<br />X2.4373 Y0.0306 Z0.0838<br />X2.4374 Y0.0307 Z0.0842<br />X2.4376 Y0.0307 Z0.0847<br />X2.4377 Y0.0308 Z0.0851<br />X2.4378 Y0.0309 Z0.0855<br />X2.4380 Y0.0310 Z0.0860<br />X2.4381 Y0.0311 Z0.0864<br />X2.4383 Y0.0311 Z0.0868<br />X2.4384 Y0.0312 Z0.0872<br />X2.4385 Y0.0313 Z0.0875<br />X2.4387 Y0.0314 Z0.0879<br />X2.4388 Y0.0315 Z0.0883<br />X2.4390 Y0.0315 Z0.0886<br />X2.4391 Y0.0316 Z0.0890<br />X2.4392 Y0.0317 Z0.0893<br />X2.4394 Y0.0318 Z0.0897<br />X2.4395 Y0.0319 Z0.0900<br />X2.4396 Y0.0319 Z0.0903<br />X2.4398 Y0.0320 Z0.0907<br />X2.4401 Y0.0322 Z0.0913<br />X2.4403 Y0.0323 Z0.0919<br />X2.4406 Y0.0325 Z0.0925<br />X2.4409 Y0.0327 Z0.0930<br />X2.4412 Y0.0328 Z0.0936<br />X2.4415 Y0.0330 Z0.0941<br />X2.4417 Y0.0331 Z0.0947<br />X2.4420 Y0.0333 Z0.0952<br />X2.4423 Y0.0334 Z0.0957<br />X2.4426 Y0.0336 Z0.0962<br />X2.4429 Y0.0338 Z0.0966<br />X2.4431 Y0.0339 Z0.0971<br />X2.4434 Y0.0341 Z0.0975<br />X2.4437 Y0.0342 Z0.0980<br />X2.4440 Y0.0344 Z0.0984<br />X2.4442 Y0.0346 Z0.0989<br />X2.4445 Y0.0347 Z0.0993<br />X2.4448 Y0.0349 Z0.0997<br />X2.4451 Y0.0350 Z0.1001<br />X2.4454 Y0.0352 Z0.1005<br />X2.4456 Y0.0353 Z0.1009<br />X2.4459 Y0.0355 Z0.1012<br />X2.4462 Y0.0357 Z0.1016<br />X2.4465 Y0.0358 Z0.1020<br />X2.4468 Y0.0360 Z0.1023<br />X2.4470 Y0.0361 Z0.1027<br />X2.4473 Y0.0363 Z0.1030<br />X2.4476 Y0.0364 Z0.1034<br />X2.4479 Y0.0366 Z0.1037<br />X2.4482 Y0.0368 Z0.1040<br />X2.4484 Y0.0369 Z0.1044<br />X2.4487 Y0.0371 Z0.1047<br />X2.4493 Y0.0374 Z0.1053<br />X2.4498 Y0.0377 Z0.1059<br />X2.4504 Y0.0380 Z0.1064<br />X2.4509 Y0.0383 Z0.1070<br />X2.4515 Y0.0386 Z0.1075<br />m30


The 3D XYZ Segment lengths are very short and plotted here:

[[File:GCode_Block_Lengths.png|none|link=]]


The XYZ deltas show significant qunatization errors caused by being so small and only the 4 decimals of precision.

[[File:XYZ_Deltas.png|none|link=]]



XY View of the 3D Path.  Grid spacing is 0.0001 which is the resolution of the GCode.  Notice the Quantization to the grid points causes 90 degree angles in some cases because the vector lengths are so small.

[[File:GCode_XY_Path.png|none]]



Here is an extreme zoom in of the GCode plotted in simulation mode which performs no Trajectory Planning or smoothing.  Note the "zig-zag" motion along the path.

[[File:GCode_Noisy_Path.png|none|link=]]


These Trajectory Planner settings shown have too small of allowed Collinear Tolerance to allow the Trajectory Planner to smooth the path.  A very small or zero tolerance forces the Trajectory Planner to closely follow the originally specified GCode path.  Because the resulting path is not smooth and angles > than the specified Break Angle limit of 15 degrees remain, exact stops occur at some points along the path.

[[File:TP_Small_BreakAngle_Small_Collinear_Settings.png|none|link=]]

<br />Here the Collinear Tolerance has been increased to 0.0005 inches to allow more smoothing and the Break Angle has been increased to 60 degrees to avoid exact stops.  The resulting motion is now smooth without stops.

[[File:TP_Good_Settings.png|none|link=]]