Control Systems · MCTE4450 · Spring 2026

DC-Motor Modeling & Speed Control

Control SystemsSystem IdentificationNI-DAQLabVIEWMATLAB

Brief

Identify a real DC motor, then close the loop on its speed.

Rather than simulate an idealized motor, this project is grounded entirely in hardware measurements: identify the motor from a real step test, build a model from the data, then design and validate a speed controller on the same rig — and report only numbers that came off the bench.

System Identification

A 0.1 V step gives a clean first-order plant.

A 0.1 V step drives the motor while the tacho-generator output is logged through NI-DAQ at 100 samples/s. The response is first-order, so the plant reduces to a single gain and time constant.

Quantity	Value
DC gain, K	36.52 (tacho-V / input-V)
Time constant, τ	0.070 s
Open-loop pole	−14.3 rad/s
Identified model	G(s) = 36.52 / (0.070 s + 1)

Closed-Loop Control

Proportional feedback makes the motor ~3.5× faster.

Driving the closed loop with a 1.979 V square-wave reference (2 s period), the controlled motor tracks each step. Feedback collapses the time constant and tightens the response:

Metric	Open loop	Closed loop
Time constant	0.070 s	0.020 s
Rise time (10–90%)	—	0.030 s
Speed regulation	—	20–28% under load

LabVIEW front panel showing the closed-loop speed rig tracking a square-wave reference: the motor output follows the commanded steps each period. — Closed-loop rig tracking a square-wave speed reference in LabVIEW — output follows each commanded step.

Analysis & Write-up

Theory applied to measured parameters, reported IEEE-style.

The Final Value Theorem predicts the steady-state output and the Routh-Hurwitz criterion confirms closed-loop stability — both applied to the identified parameters rather than textbook values. The full study is documented as an IEEE-format paper, with every figure traceable to a hardware experiment.