An unmanned air vehicle will have the following 3-phase mission 1. Navigate to c

Question

An unmanned air vehicle will have the following 3-phase mission 1. Navigate to chemical weapons plant. Maintain radio silence 2. Circle and take pictures at 2 seconds per picture until 50 pictures are taken. 3. Navigate back to base in "friendly" country. During return flight, encrypt photos and transmit them via satellite. Mission notes: For stealth, the aircraft must not transmit during phase 1 (there is no data anyway!). On return, we may not have enough time to transmit all images. We will get them all when the vehicle lands at base. However we must transmit as many as possible in case of a crash so that we get at least n success. There is only enough memory for 51 images. No images may be erased du ring missio the mission. Therefore encryption and transmission can go on concurrently if and only if encryption goes at the same rate as transmission. The embedded processor code for this system will have several tasks with specific requirements: Task Period CPUDeadline 1 Flight Control: read sensors and adjust controls 200ms 50ms 75ms 2 Take Pictures: Transfer picture from camera to 2000ms 500ms 2000ms 3 Navigate: take GPS readi to vehicle on course and at altitude ing, compare with map, 10sec 500ms 5sec adjust course N/A 6sec N/A 5 Transmit Image: (non-real-time). This task does a N/A 60sec N/A lot of I/O so it on the 60 seconds ly requires 50% of the CPU for 6 High Level Control: Operate each phase of the 10sec 100ms 1sec of mission and SPECIFICATION Notes: "Period" is the interval between invocations of the task. If it is not given ("N/A"), then that task is rescheduled as soon as it is needed. "CPU" means the amount of CPU time required to perform the task each time it is invoked by the scheduler. Note that this is modified for task 5 "Deadline" means the time after starting the task by which it must be completed. For example, the flight control task must be completed at most 75ms after it is started. Questionl: 1.1 Which tasks Answer are running for each mission phase? 1.2 Is this a "hard real time" system? Why or why not? Answer: Question2: what will be the CPU utilization (in %) during each mission phase? Answer

Explanation / Answer

1.1. For first phase Flight control,Navigate are running. For second phase along with Flight control and Navigate, Take pictures is also running. For third phase Flight control,Navigate, Encrypt Image and Transmit is running.

1.2. It is hard real time sysytem as it does imply hard deadline on it's tasks to complete like flight controll.

2.

first: 50%

second: 55%

third: 69.33%

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