SAMPLE / PREDICT / COMPARE

Give tracking its own path

Keep feedback gain fixed. Change reference feedforward and compare target tracking with the separate disturbance response.

02 / CHECK YOUR PREDICTION

Did the result match your prediction?

Choose a measurable prediction before changing a setting. Record the current result, change one condition, then check. This compares complete recordings, not the replay cursor.

MeasureMy prediction after one change

Prediction and baseline stay in memory for this page only. Use Start a new prediction to choose a new baseline.

Observe and compare

2ẏ=−y+K(u+d), u=kₚ(βr−y)+Fr · Y/R=K(kₚβ+F)/(2s+1+Kkₚ), Y/D=K/(2s+1+Kkₚ)

Inspect time (s)

t=0 s · y=0 · yᵣ=0 · y𝒹=0 · u=2

Cyan solid: total y. White dashed: reference-only yᵣ. Amber dotted: disturbance-only y𝒹. Thin gray: r=1. At 6 s the disturbance begins. The cursor reports command u separately.

Pinned dashed traces compare the primary signal (continuous x or total y); the list preserves the settings. Up to three comparisons stay in page memory.

Explain what changed

Continue in Lecture Room →

Read the related Field Journal →

MathWorks — Two-degree-of-freedom PID controllers

Change one condition

kₚ

Actual gain K

Input disturbance d

Normalized plant. τ=2 s, nominal gain=1, r=1 from t=0, input disturbance at 6 s. Continuous P control, no integral action or saturation.

Observe and compare

2ẏ=−y+K(u+d), u=kₚ(βr−y)+Fr · Y/R=K(kₚβ+F)/(2s+1+Kkₚ), Y/D=K/(2s+1+Kkₚ)

Inspect time (s)

t=0 s · y=0 · yᵣ=0 · y𝒹=0 · u=2

Cyan solid: total y. White dashed: reference-only yᵣ. Amber dotted: disturbance-only y𝒹. Thin gray: r=1. At 6 s the disturbance begins. The cursor reports command u separately.

Pinned dashed traces compare the primary signal (continuous x or total y); the list preserves the settings. Up to three comparisons stay in page memory.