Hardware interlock
A physical, electromechanical safety mechanism that prevents a dangerous condition independent of software logic, for example a mechanism that makes it physically impossible to fire a high-power beam unless a required component is correctly positioned. Hardware interlocks are valued because they do not share failure modes with the software they back up. This does not make a hardware interlock immune to failure of its own: a mechanical part can wear, jam, or be miswired during maintenance, and a physical safeguard still needs a periodic inspection regime. The real advantage is independence, not infallibility. A hardware interlock and a software check are unlikely to fail from the same cause at the same time, which is the actual property worth engineering for.
Defined in 2 GAGE programs, which carry 2 distinct definitions of it. The wording above is taught in Engineering Judgment and Professional Formation.
How each discipline defines it
The same term does different work depending on who is using it. These are the definitions as each program teaches them, unedited.
A physical, electromechanical safety mechanism that prevents a dangerous condition independent of software logic, for example a mechanism that makes it physically impossible to fire a high-power beam unless a required component is correctly positioned. Hardware interlocks are valued because they do not share failure modes with the software they back up. This does not make a hardware interlock immune to failure of its own: a mechanical part can wear, jam, or be miswired during maintenance, and a physical safeguard still needs a periodic inspection regime. The real advantage is independence, not infallibility. A hardware interlock and a software check are unlikely to fail from the same cause at the same time, which is the actual property worth engineering for.
A physical mechanism that prevents a system from entering a dangerous state regardless of software state. In the context of the Therac-25 case (Leveson and Turner, 1993), the absence of hardware interlocks allowed a software timing defect to produce dangerous actuator behavior. In robotics, hardware interlocks include limit switches, current fuses, and mechanical stops.
Terms it appears with
Not an alphabetical neighbourhood: these are the terms taught in the same lessons, ranked by how often they appear together.