A single-phase, direct-drive electromagnetic linear actuator using a permanent-magnet field structure and a lightweight coil winding. This model drives an actual R–L electrical circuit coupled to a mass–spring–damper mechanical load, so current lag, back-EMF, and inertia all behave the way they do in a real actuator.
Live simulation — not to scale
Live telemetry — drive voltage / coil current / position vs. time
The driver applies a voltage V(t). Because the coil has inductance L and resistance R, current builds up on a delay set by V = I·R + L·dI/dt + Bl·v — it does not jump instantly to its final value.
The Lorentz force F = Bl·I acts on the coil, where Bl is the motor constant (field strength × wire length in the gap).
Moving through the field also generates a back-EMF (Bl·v) that opposes the applied voltage — this is why current dips as the coil speeds up.
Newton's law (m·dv/dt = F − damping − spring force) governs how force actually turns into motion; coil mass and any centering spring set the response time and, if present, a resonant frequency.
Reversing current reverses force direction immediately, but velocity and position change smoothly because of mechanical inertia — unlike a mechanical linkage, there is no backlash or hysteresis.
Specifications (model values)
Motor constant (Bl)3.2 N/A
Coil resistance (R)5.4 Ω
Coil inductance (L)0.38 mH
Moving mass (m)8 g
Mechanical damping (c)0.30 N·s/m
Spring constant (k, if ON)1.9 N/m
Stroke (±)6.0 mm
Peak force @ 24 V stall~14.2 N
Power sourceDC / PWM electricity
PrecisionVery high, no mechanical backlash
Model note: real voice coil actuators use much stiffer springs and run at tens to thousands of Hz. Bl, R, L, and k above are scaled down so the electrical lag, resonance, and end-stop behavior stay visible at a demonstration speed. Try setting Spring Return ON and matching Cycle Rate to about 2–3 Hz to see the resonance peak in the position trace.