Optimized Trajectories for Motion Control

FAQ about Input Shaping

  • How is Input Shaping® different from conventional low pass or notch filtering?

    Conventional low pass filters and notch filters are designed using frequency domain techniques. They will suppress a steady state sinusoidal frequency or range of frequencies but they can have unexpected or undesirable behavior during input transients. An Input Shaper™ is designed using optimization theory to create a custom time domain input with both time and frequency domain constraints. It is designed specifically to suppress vibration excited by motion transients.

  • Can an Input Shaper™ be designed without an analytical model of the closed loop system?

    Yes, this is one of the benefits of Input Shaping™. The only information needed to design an Input Shaper is the frequency or frequencies of the vibrations. This information is usually collected experimentally.

  • Why is Input Shaping® better than S-curves?

    S-curves and other complex acceleration profiles are based on the assumption that rapid changes in acceleration cause vibrations. Input Shaping® technology makes it possible to make rapid changes in acceleration without exciting vibrations. S-curve vibration suppression is highly dependent on the move length, maximum acceleration and maximum velocity. Input Shaping® yields consistent vibration suppression for any move length, at any velocity, and at any acceleration.

  • What if the system has multiple vibration frequencies?

    Input Shaping® can also suppress multiple frequencies. From a practical perspective it is easier to start by measuring the lowest frequency vibration. Once an Input Shaper™ has been implemented for the lowest frequency, higher frequency vibrations become more apparent. There is no theoretical limit to the number of frequencies that can be suppressed using Input Shaping®, however very few systems will require more than 3 frequencies.