Exploring PID Control Loops
On the VME crates at Jefferson Lab (groups of computers used for data acquisition in particle physics experiments) adaptive fan control is sometimes needed to stabilize the temperature of the cards in the crate. This is achieved by averaging the readings from the crate's built-in temperature sensors and adjusting the fan speeds accordingly. Ideally, the temperature of the data acquisition cards in the crates should be warm and stable instead of cool and varying. Using an software environment called EPICS, we can send commands to the crate fans and receive sensor readings from them as well. Phase 1 of the project will be to graph the crate temperatures as-is and then design a control logic to throttle the fan speeds. Phase 2 will use the Raspberry Pi to provide temperature readings as input for the fan control logic on the crates that do not have built-in temperature sensors. The end goal is to achieve maximum efficiency in the crates by keeping their temperatures stable with adaptive fan control.