University of California, Irvine

CS 513

Due Date: September 14, 2020, Time: 11:59.59pm AoE Total Points: 100 Problem 1. (Synchronous Reactive Components) [20 points] Event-based synchronous components: In this problem, we will design a synchronous reactive component to set the cruising speed of a vehicle. The synchronous assumption can be cumbersome if we want some components to not operate in some rounds. A useful modeling choice is the use of events. An event is a s2ecial input/output variable that can be absent or present, and an event variable has a value only if the event is present. The syntax we use for events is similar to the input/output guards in ESM representations of asynchronous processes: e? is true if event e is present, and e!v means that the output event gets the value v. (a) [10 points] We will design the SetSpeed component in the cruise-control system CruiseController. The SetSpeed component takes the following input/outputs: 1. event(bool) cruise on off: input modeling user request to toggle the cruise control. 2. event(nat) set cruise speed: input modeling current speed of the vehicle. 3. event inc: input modeling user request to increase cruising speed. 4. event dec: input modeling user request to decrease cruising speed. 5. event(nat) cruiseSpeed: output, if present, indicates current cruising speed. 6. bool status: output is 1 when cruise control is on, and 0 when off. There are two constants called min speed and max speed that we will use within the component. The operation of the component depends on if it is on or off. If the component if off, the component receiving the cruise on off event turns it on, and if it is on, receiving cruise on off turns it off. 1 Component is ON: When the component is on, if the component receives a set cruise speed event1 , with the speed within the range [min speed, max speed], then the component “remembers” the speed set cruise speed. If it is not within this range, the speed is set to the closest legal speed in the above range. As long as the component remains on, it outputs this value on the cruiseSpeed variable in each subsequent round. You can imagine this as the variable being the input to a downstream ControlSpeed module that is responsible for regulating the vehicle speed, and to the Display module to show the set speed to the driver. If a dec event is received, then the cruising speed is decremented (restricting the lowest speed to min speed), and when the inc event is received, the cruising speed is incremented (restricting the highest speed to max speed). Furthermore, as long as it is on, in each round, it outputs the Boolean value 1 on the output variable status.