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In addition to my question How to physically wire a (ADXL345) accelerometer for Input Shaping (Resonance Compensation) support on for a Ender 3 V2 printer?.

Does an accelerometer in a Marlin-based Input Shaping setup compensate in real-time (during print) for vibration? Or is it a one time (for example before print) measurement to determine a level of vibration and use that as the compensation scheme during a print, as in "not adapting to unexpected vibration"? Similar to how bed leveling is used.

If it does not do real-time compensation, what is the benefit of having an accelerometer compared to doing Input Shaping test prints instead?

Bob Ortiz
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Input shaping in 3D printers is typically implemented prior to the actual printing operation, not in real-time. It's based on the known characteristics of the printer rather than dynamic adjustments made during printing. This requires to be set-up and determined before printing. The printer's firmware is where you can define input-shaping.

3D printer firmware based input shaping

The resonant frequencies of the printer are determined through test prints and input into the firmware. The firmware then automatically applies the necessary adjustments to the motion commands during the printing process (it reads the G-code and applies the algorithms on motion changes). This is still not real-time adjustment; it's a predefined modification based on the printer's known characteristics.

Real-time or not?

Input shaping is not a real-time control system that dynamically adjusts to changing conditions during a print. Instead, it's a method of optimizing the printer's motion commands based on its known mechanical properties and behavior (hardware determined). Why not real-time? Real-time control for input shaping in 3D printing would be complex and would require additional sensors and processing capabilities (controller board). The printer would need to continuously monitor its own vibrations and adjust its movements on the fly, which is not typically feasible with current consumer level 3D printing technology.

0scar
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