Figure 8
The four panels in a two-by-two grid are labeled “(a)”, “(b)”, “(c)”, and “(d)”, each showing a line graph with a legend labeled “Normal”, “Slowdown”, “Jamming”, and “Abnormal Door Closing”, respectively. In all panels, the horizontal axis is labeled “Time step” and ranges from 0 to 400 in (a) and (b) in increments of 100 units, from 0 to 400 in (c) in increments of 200 units, and from 0 to 300 in (d) in increments of 100 units. The vertical axis is labeled “Velocity (meters per second)” and ranges from negative 2 to 2 in increments of 1 unit in (a), (b), and (d), and from negative 1 to 1 in (c). In panel “(a)”, the velocity increases from near 0 to above 2 in early time steps, then drops to 0 and remains stable before decreasing sharply to around negative 2 near time step 300 and finally returning toward 0. In panel “(b)”, the velocity follows a similar pattern with an initial rise above 2, a flat region at 0, then a drop to around negative 2 after time step 300, followed by a gradual return toward 0. In panel “(c)”, the velocity rises to around 1, stabilizes briefly, then drops to near 0, followed by a gradual decline to around negative 1 near time step 350, and then fluctuates slightly while remaining below 0. In panel “(d)”, the velocity increases to above 2 in the early phase, quickly drops to 0, remains flat for a period, then decreases sharply to near negative 2 around time step 250, and ends with slight fluctuations below 0. Note: All numerical data values are approximated.Elevator door operating curves under different states. (a) Normal. (b) Slowdown. (c) Jamming. (d) Abnormal door closing. Source(s): Figure created by authors