Feedback-Controlled Linear Actuator System to Simulate Laboratory Analogs of Landslides

Micah Pratt, Kayla Booth, Vihaan Mallela, Vashan Wright 

This study describes a scientific apparatus that induces granular flow by tilting an acrylic sample container under user-prescribed constant angular velocity and acceleration profiles. The system consists of a transparent sample container mounted within a motorized frame driven by a linear actuator that we control using pulse-width modulation with feed-forward compensation. Additional components of the device enable control of the sample volume fraction, image acquisition to determine the onset of failure, measurement of the spatiotemporal evolution of traction shear stress, and acoustic monitoring of the granular material. Mechanical testing demonstrates low noise levels and reliable reproduction of reference tilt profiles, with constant angular velocity and acceleration maintained to within 1 degree. The device can achieve a set target angle within 2 degrees, with this overshoot being related to the inertia of the device. We demonstrate the capabilities of the device using two experiments that show [1] slide initiation angle varies systematically with volume fraction and decreases with increasing angular velocity and angular acceleration and [2] that the magnitude and size traction shear stress clusters increase leading up to failure. The device is therefore well suited for fundamental studies of what controls whether, when, and how failure occurs in granular materials, particularly in the context of landslide modeling.