TMR Voting Against Single-Event Upsets: Ensuring Spacecraft Reliability

What Triple Modular Redundancy (TMR) Is

Triple Modular Redundancy is a fault-tolerant design technique used to ensure the reliability of spacecraft circuits. In TMR, three identical modules perform the same function and their outputs are compared by a majority voter. If one module fails due to a single-event upset (SEU), the other two correct its output, maintaining system integrity.

TMR is particularly useful in space missions where radiation from cosmic rays can cause single-bit upsets that would otherwise corrupt data or command sequences.

How TMR Works

In a TMR setup, each module processes the same input and generates an output. The outputs are then compared by a majority voter. If two out of three modules agree on an output, it is passed to the system; if there is disagreement, additional checks or error correction mechanisms can be employed.

This redundancy ensures that even if one module experiences a single-event upset, the other two will still provide correct data, preventing errors from propagating.

Why TMR Is Effective Against Single-Event Upsets

Single-Event Upsets occur when high-energy particles strike semiconductor devices and cause temporary or permanent changes in their state. In a single module, an SEU can corrupt data or commands, leading to system failures.

TMR mitigates this risk by ensuring that any SEU affecting one of the three modules is caught and corrected by the other two, maintaining overall system reliability.

Comparing TMR with Unprotected Modules

When comparing a TMR setup to an unprotected single module, it becomes clear that TMR significantly reduces the likelihood of errors. The majority voter in TMR ensures that only outputs from at least two modules are accepted, effectively filtering out SEUs.

This is particularly evident when simulating cosmic ray strikes and varying mission clock speeds, where TMR demonstrates its robustness against single-event upsets.

Frequently asked questions

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Everything above runs in your browser — open TMR Voting Against Single-Event Upsets and change the parameters while it is running. Nothing is installed, nothing is uploaded, the whole model lives in one tab.