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QNET Gantry Laboratory Manual
1. Laboratory Objectives
In industry, the crane is often used to transport items from one place to another. The gantry
experiment involves developing a control system for a crane travelling on a moving
platform. In this case, the crane is represented by the suspended pendulum and the rotary
arm behaves as the moving platform that transports the crane at different locations. The
problem is to develop a controller that enables the platform, or in this case the arm of the
rotary pendulum system, to track a commanded position while minimizing the motions of
the crane, or pendulum, as it is being transported.
In this laboratory, the equations representing the motions of the rotary pendulum will be
derived using a technique known as Lagrange. The resulting nonlinear dynamics are then
then linearized and converted to a state-space model. The linear state-space representation
of a system is different than Laplace and is used more prominently in the control research
field. The obtained model is then used to design a closed-loop controller using the LinearQuadratic Regulator technique. It is used to minimize or dampen the movements of the
suspended pendulum while the rotary arm tracks the reference angle given. Practically
speaking, the algorithm developed regulates the movements of the gantry and keeps the
crane steady in the vertical down position such that items can be transported in a safely.
Regarding Gray Boxes:
Gray boxes present in the instructor manual are not intended for the students as they
provide solutions to the pre-lab assignments and contain typical experimental results
from the laboratory procedure.
2. References
[1] NI-ELVIS User Manual.
[2] QNET-ROTPEN User Manual.
3. ROTPEN Plant Presentation
3.1. Component Nomenclature
As a quick nomenclature, Table 1, below, provides a list of the principal elements
composing the Rotary Pendulum (ROTPEN) Trainer system. Every element is located and
identified, through a unique identification (ID) number, on the ROTPEN plant represented
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