Also found in: Dictionary, Thesaurus.
The algorithms and computers utilized to steer a vehicle along a path. The types of vehicles include airplanes, rockets, missiles, ships, torpedoes, drones, and material transport vehicles within factories and so forth. The means of steering depend on the vehicle and can be the rudder, elevators, and other control surfaces on an airplane, the rudder on a ship, the control surfaces on a missile or on a torpedo, the gimbal angle of the motor on a rocket, and others. In every case the guidance system utilizes knowledge of the difference between where the vehicle should be and where it is. The difference between these two vectors is processed by the guidance algorithm. The output is a steering command intended to reduce the error between the desired and the actual paths. See Control systems, Flight controls, Ship powering, maneuvering, and seakeeping
Several important performance attributes contribute to the effectiveness of the system. These attributes are governed by the guidance system and by the other system components, including the vehicle itself and its dynamic behavior.
A primary concern is accuracy. Whether the goal is to insert a satellite into synchronous orbit or to try to intercept an enemy aircraft with an air-to-air missile, the accuracy of the sensor and the properties of the guidance system are the principal factors.
Another concern is speed of response. Here the dynamics of the vehicle itself can be a limiting factor. The guidance system must compensate to the extent possible in providing a fast, responsive system. The system should be able to recover from errors as quickly as possible and return to the desired path. In the case of homing on a target, this is crucial if the target can maneuver. Coupled with the need for a quick response is the simultaneous need for a stable response.
Another important feature of the system is its robustness. The guidance system design is based on a mathematical model of the vehicle, the autopilot, and the sensor. The guidance system must provide good overall performance despite this.
Reliability is also important. In many cases, backup components are provided for redundancy. This is frequently the case for the digital computer of the guidance system, especially for crewed space flight. See Reliability, availability, and maintainability