What does a digital twin without sensor latency do to a tuned controller?

research/latency-twin

What a twin without sensor latency does to a tuned controller: exact stable-gain interval shrinks with delay, the zero-delay LQR gain tolerates one step (1.6× cost) and is unstable from two, retuned static gains cost 1.1–2.6×, wrong-delay predictors are mostly unstable, and delay identification needs ≈2z²(1+1/snr) samples.

8 tests

What it found

A scalar unstable plant is controlled by the LQR gain designed in a twin with no measurement delay. The exact stable-gain interval shrinks with the real delay (upper edge 1 at one step, 0.59 at two), so the twin-tuned gain (0.70) tolerates one step at 1.6× the delay-aware cost and is unstable from two; a retuned static gain costs 1.1–2.6× for delays 1–5, and a predictor built for the wrong delay is unstable in nearly every off-diagonal case tested. Identifying the delay from an i.i.d. probe takes about 2z²(1+1/snr) samples. Stylised: scalar plant, integer delay, known dynamics.

A figure from its own output

Figure produced by research/latency-twin: cost_vs_delay — latency-twin/experiments/cost_vs_delay.svg, written by the project's own experiment code.

Paper, code and results

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Produced with AI assistance (Claude). Results are from the code in this repository and are simulated or stylised unless the abstract says otherwise; nothing here implies affiliation with or endorsement by any lab, researcher or company cited. MIT licensed.