Abstract

A tilt table able to turn at a suitable angular velocity is required in order to correctly characterize the basic friction angle of discontinuities and to perform other tests at laboratory scale, like the study of block toppling failure mechanism with physical models. According to the ISRM Suggested Method for tilt testing, the angular velocity of the tilt plane should be kept constant at a number between 5 and 20 º/min. This conference paper explains the steps followed in order to build a motorized tilt table based on an Arduino-controlled stepper motor. Arduino is a very inexpensive free-hardware microcontroller able to read information from different sensors. In this case, an Arduino UNO R3 was used. So as to record the angular acceleration and other variables of a tilt table, an MPU-9250 sensor of 9 DOF (Degrees of Freedom) which contains an Inertial Measurement Unit (IMU) MPU-6500 (composed by an accelerometer of 3 DOF, a gyroscope of 3 DOF and a magnetometer of 3 DOF), will be attached to the newly designed tilt table and will be connected to the Arduino board. A key point on the design of the Arduino-controlled motorized tilt table was the selection of both stepper motor and gearbox in order to get enough force at the correct angular velocity. The selected stepper motor was a hybrid bipolar NEMA 34, controlled by a digital driver HB-860H/DM860H, and the selected worm gearbox is an NMR V040 with a 100:1 reduction ratio. Recording acceleration with one or more sensors will allow to use dynamic equilibrium equations in order to better understand the possible modes of failure (sliding, toppling, or both sliding and toppling) of single or multiple rigid blocks in physical models