The term “real-time” is used by several industries to describe time-critical technology. However, the most common usage of “real-time,” and the usage that applies to ADI, is in reference to embedded systems. Embedded systems are electronic devices designed to interface with the real world and provide control, interaction, and convenience of some form.
Embedded systems are responsible for an increasing portion of the functionality found in today’s automotive, aerospace, and defense technologies. Embedded systems use state-of-the-art microprocessors, sensors, and specifically designed software to enable technological advancements such as:
- Automobile engines offering more power while consuming less fuel
- Aircrafts offering more safety features and reduced operating cost
- Weapon systems with increased battlefield effectiveness
- Automobiles with an increased number of convenience features
- Jet engines offering more thrust and increased fuel efficiency while emitting less environmental noise
In reference to embedded systems, “real-time” denotes the required stability of the embedded system. In a real-time system, the embedded device is given a predetermined amount of time, such as 1 ms, 5 ms, or 20 ms to read input signals, such as sensors, to perform all necessary calculations, such as control algorithms, and to write all outputs, such as control actuators, and control fuel flow.
If the embedded device does not have sufficient computational power to perform its tasks, it falls behind and is said to be operating “slower than real time.” If an embedded system begins to operate slower than real time, the system may become unstable and can result in catastrophic failure.
Figure 1. General Architecture for an Embedded System controlling a Plant
The figure above illustrates the general architecture of an embedded system providing closed-loop control of a plant. In control systems terminology, “plant” refers to the dynamic system being controlled.
Go to the next topic: What are Soft and Hard Real-Time Applications?