Quanser 6 DOF Hexapod Laboratory Manual page 32

The Northridge earthquake had a maximum displacement of 16.92 cm and this was scaled down to 2.5 cm (as
set by x_max). In order to achieve the same acceleration, the time of the generated trajectory is compressed
from 39.98 to 15.37 seconds.
7. Once the script is ran, the make_quake_xyz.m Simulink Model can be used to replay the earthquake on the 6
DOF Hexapod. See Section 2.6 for the procedure to run the tremor on the table.
Files used for Earthquake Scaling
Three functions are called in make_quake_xyz.m to create the scaled position command from the recorded earth-
quake data:
1. init_earthquake_data.m: this script extracts the sampling time information of the recorded earthquake, dt, and
compiles the acceleration data from the AT2 file, which is the four column format, into an array called acc_data.
2. construct_quake_trajectory.m: creates a trajectory containing the recorded earthquake acceleration data, [t,a].
3. q_scale.p: goes through a scaling algorithm and outputs the time of the trajectory t, the scaled position setpoint
in centimeters xd_cm, the desired acceleration ad, and the duration of the tremor tf.
These are listed and explained in Table 4.2 as well.
HEXAPOD Laboratory Guide 32