Introduction and Getting Started > Working with the supplied example models > Waste System scenario and simulation > The Waste System
The Waste System
The system requirements are as follows.
1. System Overview
Containers of toxic waste are loaded on to a conveyor belt for scanning to identify any defects in the containers, prior to long term storage. Containers passing the scan are packed into storage cages; containers failing the scan are routed to a re-packaging area.
2. Equipment
All items of equipment have built-in controllers that provide them with some degree of autonomy. For example, each item can carry out a self-test when triggered, and return a test result (as a Boolean value).
a. Main Conveyor Belt
Detects new containers via a pressure sensor and then transports the containers to the various items of equipment. Belt speed is selected by the operator via a 3-position switch. Starting and stopping of the belt motor is enacted via operator control of the Start and Stop buttons. The belt controller emits a signal each time the belt completes 1 cm of travel. This is used to determine the position of containers relative to items of equipment.
b. Bar Code Reader
When a start signal is sent to the bar code reader, it will then automatically detect the arrival of a container, read and store the bar code. It will then transmit the code number on its output line and return to idle mode.
c. Scanner
Scanning is triggered by a start signal. The scanner will then produce 4 frames of image data from 4 successive scans. Following transmission of the final frame, the scanner automatically returns to idle mode.
d. Router
The router is essentially a robotic clamp which can lift a faulty container from the belt and deposit it in a special storage area. The clamp is fitted with a set of jaws which incorporate a pressure pad that can detect the arrival of a container. The detection of a container by the jaws automatically invokes the clamping of the container and its removal from the belt. The pressure pads are activated by a start command sent to the router. On completion of routing, the router sends out a 'completed' signal. The router must now be reset, that is, the clamp re-positioned on the belt, before further routing activity can take place.
e. Cager
The cager takes each container from the end of the main belt and lays it into a packing cage for later sealing. The cager operates identically to the router.
f. System Controller
This contains the communication and control hardware, operator I/O panel and main system computer.
g. Operator I/O Panel
This contains the controls and displays required by the operator to manually control the system. Operator functions include system start and stop, in addition to changing the belt speed. System displays include system status, the number of containers detected by the belt, and the number of faulty containers found so far.
3. Normal Operation
A 'cold start' involves the operator switching on the power, and then hitting the system start button. All items of equipment should be tested (self test).
When the belt is up to speed containers are then placed on the belt. The arrival of a container is detected by the belt pressure sensor and the 'number of containers detected' display is incremented.
For every 1 cm of travel the belt signals the system controller which then determines the position of all containers on the belt relative to all items of equipment.
When a container reaches the bar code reader the system controller sends a start signal to the reader. The reader reads the bar code and sends this back to the controller.
When a container reaches the scanner, the scanner is started by the system controller. Scanning of a container takes place while the container is moving along the belt. The scanning process should categorize the container as either faulty or ok
If a container is found to be defective, the router should remove the container from the main conveyor belt and place it in a secure re-packaging area. The 'number of faulty containers' display should be incremented.
Non-defective containers are transported to the cager where containers are removed into a storage cage for sealing.
4. Diagnostics
A diagnostic panel (separate from the operator I/O panel) provides the following.
a. The display of the bar code number of the last container to be detected.
b. The display of the current status of each item of equipment.
c. A mechanism for altering the arrival rate of containers.
d. A mechanism for altering the fault rate of containers.
e. A mechanism for injecting a faulty container on to the belt.