A PID Loop is a control feedback loop. "PID" stands for Proportional, Integral, and Derivative  the three terms of the loop. With this website, you can simulate the effects of a PID loop on a motorized pendulum
Parameter Name  Parameter Value  Description 

P Term Gain  The gain factor for the proportional term.  
I Term Gain  The gain factor for the integral term.  
D Term Gain  The gain factor for the derivative term.  
Goal Angle  The angle the motor controller will try to put the pendulum at, from 0 to 360 degrees.  
Initial Angle  The initial angle of the pendulum, from 0 to 360 degrees.  
Pendulum Weight  The weight of the pendulum, in kg. All weight is assumed to be in the center of the weight (none in the shaft connecting it to the motor). 

Pendulum Length  The length of the pendulum, in cm. 