Watchdog timer
A hardware or software timer that resets or triggers a safe-state action if not periodically refreshed by the running program. In the co-processor architecture, the microcontroller implements a watchdog on the SBC communication link: if no setpoint is received within the timeout window, the MCU enters a safe state and waits. Three safe-state patterns are in common use, and the correct choice depends on the robot's physical dynamics: (1) Torque-off / coast: the MCU disables motor driver enable signals, removing drive current and allowing the mechanism to coast to rest; appropriate for wheeled mobile robots on flat ground where coasting to a stop is safe. (2) Active braking: the MCU commands zero velocity to the motor driver while keeping the driver enabled, actively decelerating the mechanism; appropriate when a coasting mobile robot could roll into a hazard or when a moving arm must decelerate under control. (3) Hold-last-safe position: the MCU freezes its output at the last known-safe setpoint, keeping a joint or end-effector stationary; appropriate for collaborative arms holding a part, where dropping the load is more dangerous than remaining stationary. After the watchdog fires, the MCU must also implement a re-arm handshake before accepting new setpoints: it should require at least one valid setpoint message from the SBC (confirming the SBC has recovered) before exiting the safe state, rather than automatically resuming motion the moment any message arrives. A common pattern is to require a specific "resume" command or a sequence of zero-velocity setpoints before restoring normal motion, preventing a half-initialized SBC from issuing stale high-speed commands on first reconnect.
Defined in 2 GAGE programs, which carry 4 distinct definitions of it. The wording above is taught in Foundations of Robotics and Physical AI.
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 hardware or software timer that resets or triggers a safe-state action if not periodically refreshed by the running program. In the co-processor architecture, the microcontroller implements a watchdog on the SBC communication link: if no setpoint is received within the timeout window, the MCU enters a safe state and waits. Three safe-state patterns are in common use, and the correct choice depends on the robot's physical dynamics: (1) Torque-off / coast: the MCU disables motor driver enable signals, removing drive current and allowing the mechanism to coast to rest; appropriate for wheeled mobile robots on flat ground where coasting to a stop is safe. (2) Active braking: the MCU commands zero velocity to the motor driver while keeping the driver enabled, actively decelerating the mechanism; appropriate when a coasting mobile robot could roll into a hazard or when a moving arm must decelerate under control. (3) Hold-last-safe position: the MCU freezes its output at the last known-safe setpoint, keeping a joint or end-effector stationary; appropriate for collaborative arms holding a part, where dropping the load is more dangerous than remaining stationary. After the watchdog fires, the MCU must also implement a re-arm handshake before accepting new setpoints: it should require at least one valid setpoint message from the SBC (confirming the SBC has recovered) before exiting the safe state, rather than automatically resuming motion the moment any message arrives. A common pattern is to require a specific "resume" command or a sequence of zero-velocity setpoints before restoring normal motion, preventing a half-initialized SBC from issuing stale high-speed commands on first reconnect.
An independent hardware or software mechanism that monitors whether a system is behaving as expected (for example, whether a compute subsystem is still responding) and takes a defined safe action, such as a reset or a controlled stop, if it is not. A watchdog timer is a common engineering response to a tightly coupled interface where one subsystem's failure could otherwise propagate silently into another.
A hardware or software timer that triggers a safety action, typically an emergency stop, if it is not reset within a specified period. Used to detect controller failures. A watchdog timer set at 5 milliseconds will trigger if no control command arrives within 5 milliseconds of the previous one.
A hardware or software mechanism that expects periodic confirmation signals ("heartbeats") from a monitored process or circuit; if the expected signal fails to arrive within a set time window, the watchdog assumes a fault has occurred and triggers a defined safe response.
Where it is taught
The exact lessons this term appears in. The first module of every program is free with a free account.
- Why production robotics runs on C++ for speed and control · Programming for Robotics with C++, Foundations of Robotics and Physical AI
- Microcontrollers versus single-board computers · Electronics and Hardware Foundations, Foundations of Robotics and Physical AI
- Thinking in systems, not isolated parts · Engineering Thinking and Elegant Minimalism, Engineering Judgment and Professional Formation
- Designing so that one failure does not become a disaster · Failure Analysis, Learning From How Robots Break, Engineering Judgment and Professional Formation
Where it shows up at work
A definition is where Watchdog timer starts. The lessons above teach it inside the competencies below, which are what job descriptions ask for and what the GAGE credential records. Every link here is drawn from the same careers map that builds a role's readiness check.
Designs tests for factuality, robustness, fairness, safety and abuse resistance with rubrics, baselines and thresholds, and says what a score misses.
One lesson on this page teach it as a primary outcome.
Plans for a vendor failure, an unsafe model change or a suspended service: rollback, manual fallback, data export and safe decommissioning.
One lesson on this page teach it as a primary outcome.
Designs safeguards, family protocols and reporting paths for older adults, minors and people who cannot challenge an automated outcome.
One lesson on this page teach it as a primary outcome.
Roles that hire for it
Each role page shows the full competency set, what the seat decides, and a readiness check against your own evidence.
- Chief Technology Officer, AI engineering editionneeds it at depth
- Model Risk Managerneeds it at depth
- AI Evaluation Specialistneeds it at depth · 6 open postings this week
- AI Model Validatorneeds it at depth
- AI Product Manager, responsible product editionneeds it at depth · 3 open postings this week
- Ethical AI Specialistneeds working knowledge · 5 open postings this week
How job descriptions say it
Postings rarely use the textbook word. These are the phrases the careers map reads as asking for the competencies above.
Where the frameworks place it: NIST AI RMF MEASURE 1 and 2; NIST AI 600-1; DORA; NIS2.
One interview question about it
Design the evaluation for a customer-service model before launch. What do you test, against what data, and what result blocks the release?
Asked of candidates for ai evaluation and testing design. Answering it in your own words is exactly how a GAGE topic is passed, and the credential records the pass where an employer can check it.
If you come from another field
Some backgrounds already carry this competency, and the readiness check gives credit for it.
- Model risk, credit risk and quantitative analysis carries it as work you can show: Test design and benchmark selection are the craft.
- A computer science or software engineering degree carries it as a claim to back up: Testing is second nature; AI evaluation design is a new shape of it.
- A data science, statistics or analytics degree carries it as a claim to back up: Evaluation design for a governance decision is a new frame for a known skill.
Terms it appears with
Not an alphabetical neighbourhood: these are the terms taught in the same lessons, ranked by how often they appear together.