Download General Purpose Petri Net Simulator

26. Measuring Robot Usage
The flexible manufacturing cell at the Narvik Institute of Technology (NIT), Norway, consists
of a CNC vertical machining center (Mori Seiki), a CNC horizontal machining center (Mori
Seiki), an ABB IRB2000 robot, and a conveyor belt; figure 12 shows the system.
Conveyor belts
(both for incoming
and outgoing)
ing center (VMC)
CNC vertical
machining center
(VMC)
ABB IRB2000
Robot
CNC horizontal
machining center
(HMC)
Figure-46.
Flexible Manufacturing Cell at Narvik Institute of Technology (NIT)
Here is the operational specification of the system, somewhat simplified for our modeling
purposes:
1. To start a cycle, a raw part must be available on the incoming conveyor belt, and the
robot is also available.
2. The robot moves a raw part from the conveyor and loads it at the horizontal machining
center (HMC).
3. The milling operation is performed at HMC while the robot backs off (returns).
4. The robot unloads the work piece from HMC, loads it to the vertical machining center
(VMC) and returns.
5. The drilling operation is performed at VMC, and simultaneously the robot perform step 2.
6. The robot unloads the finished part from VMC, deposits it on the conveyor and returns.
In steady-state steps 2-6 repeat. Note that the specifications are very similar to the one given
in Zhou and Robbi (1994). Well, it has to be similar, considering the simple systems we and
they have, there is only one way to do it.
26.1.1 The Petri net model
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