You are hired to develop a software system for motion detection and garage door control. The system should turn the garage door lights on automatically when it detects motion within a given perimeter. The garage door opener should be possible to control either by a remote radio transmitter or by a manual button switch. The opener should include the following safety feature. An electric eye sensor, which projects invisible infrared light beams, should be used to detect if someone or something passes under the garage door while it closes. If the beam is obstructed while the door is going down, the door should not closethe system should automatically stop and reverse the door movement.

The relevant hardware parts of the system are as follows (see Figure):

- motion detector

- external light bulb

- motor for moving the garage door

- electric eye sensor

- remote control radio transmitter and receiver

- manual opener button switch

Assume that all the hardware components are available and you only need to develop a software system that controls the hardware components.

a) Identify the actors for the system and their goals

b) Derive only the use cases relevant to the system objective and write brief or casual text description of each

c) Draw the use case diagram for the system

d) For the use case that deals with the remote-controlled garage door opening, write a fully dressed description

e) Draw the system sequence diagram(s) for the use case selected in (d)

f) Show the operation contracts for the operations of the use case selected in (d)

Manual Opener Switch Remote Receiver External Light Motion Detector Electric Eye Motor Motion detection perimeter Remote Transmitter