Contact — depth & pressure drill

Drag the base handle

You do not move the tip directly. You drag the base plate; a two-bone arm carries the tip toward a soft surface. Dragging toward the surface moves the tip along the approach vector: first it closes the gap (depth), then — once it touches — it penetrates the compliant pad (pressure). Depth and pressure are independent: you can rest exactly on the surface with zero pressure, or jam pressure at the wrong depth. Both are hidden — the only guide is the warmer/colder strip and the two bars. Left-drag the plate (forgiving grab) · right-drag or hold Space to orbit · wheel zooms.

Contact match

— pick a target —

left-drag the pink plate (forgiving grab) · right-drag / Space+drag to orbit · wheel zoom · targets hidden — read the bars

press New target to begin

Not aligned
hold depth & pressure in-band to lock

0LOCKS

—BEST ERROR

—LAST LOCK

Press New target. A hidden depth and a hidden pressure band appear. Drag the base plate toward the pad until both bars read narrow, then hold.

Why did I miss?

Error is split so a miss is legible — is your depth wrong (where you're touching), or your pressure wrong (how hard)?

Assists & options

Reveal target depth & band (training wheels)

Show tip Show linkage

Show pad deformation

Keyboard controls

Click the 3D view first (it takes focus). ←→↑↓ orbit · Home reset view · wheel zoom.
Drag the pink base plate to drive the arm toward the pad. The tip is the referent of all feedback — always.

What this drill teaches

Two sub-skills, made independent by a compliance model: a soft-contact spring at the pad surface. Depth is where the tip sits along the approach vector (before/at/past first contact). Pressure is the spring force from penetrating past first contact, rising nonlinearly (F = k·penetration^1.6) so it is a continuous, hill-climbable signal rather than a hit/no-hit binary. You can rest exactly at the target depth with zero pressure (barely touching), or drive hard pressure at the wrong depth — the two bars tell you which one is off. Target depth and target pressure band are randomized per attempt, static within it. Max two uncertainty sources: hidden target + indirect linkage.