SignalGenerator

SignalGenerator produces a test waveform — sine, block, triangle, sawtooth, two smooth profiles, or Gaussian noise — for commissioning, system identification and frequency-response work.

Every setting is faded in, not stepped. Amplitude, frequency, phase, offset, the enable, and the waveform itself each ramp to their new value over a configurable time. Changing the signal type mid-run cross-fades between the two shapes, so nothing this block does puts a discontinuity into a moving machine.

flowchart LR
    i1(["enable"]) --> B["SignalGenerator"]
    i2(["signalType"]) --> B
    i3(["frequency"]) --> B
    i4(["amplitude"]) --> B
    i5(["phase"]) --> B
    i6(["offset"]) --> B
    i7(["dwellTime"]) --> B
    i8(["noiseAmplitude"]) --> B
    i9(["resetEnableSwitch"]) --> B
    B --> o1(["output — the generated signal"])
    B --> o2(["allOutputs — all seven types at once"])
    B --> o3(["sincos — sine and cosine of the phase"])
    B --> o4(["isStable"])
    B --> o5(["stableCycleCnt"])
    B --> o6(["enableIsOn"])
    B --> o7(["enableIsOff"])
    B --> o8(["time — the phase, 0 to 2 pi"])

frequency is in rad/s, not hertz — 6.283 is 1 Hz. amplitude is the peak, so a sine swings ±amplitude around offset. For the noise type, amplitude is a 3σ bound: about 99.7% of samples fall inside it and the rest are clipped, so the noise’s RMS is roughly a third of what you set.

Nothing here survives a controller restart. Every signal setting is a live input, not a stored parameter, and the block comes back with amplitude and frequency at 0 — a flat line at offset. That is deliberate: a generator that resurrected itself at full amplitude would be dangerous. Keep your test settings somewhere else.

Wait for isStable before trusting a measurement. With the default five-second fades, a value you write now is not fully applied until five seconds later.

Signals

Inputs

Outputs

Parameters

These four are persistent and survive a restart.

Setup

1. Set offset to where the machine should sit at rest, and amplitude and frequency to 0.

2. Set enable true. output should move to offset over enableFadeTime and enableIsOn should go true.

3. Choose signalType. Start with 5, QUINTIC, or 4 — both are gentle on mechanics and neither excites a resonance the way a block wave does.

4. Raise amplitude from 0 in steps, watching the machine. Remember each step takes newSettingFadeTime to apply.

   Step 4 moves the machine. The fade means the full amplitude arrives seconds after you write it, so raise it in small steps and wait for isStable between them rather than writing a large value and watching.

5. Set frequency. Convert from hertz by multiplying by 6.283.

6. Wait for isStable, then take your measurement. Use stableCycleCnt to confirm you have enough complete periods.

7. To stop, set enable false. The output ramps down to offset — it does not step.

Tuning

1. Choose the waveform for what you are measuring. Sine for frequency response one point at a time; noise for a whole band at once; a smooth profile when the mechanics matter more than the spectrum.
2. Set newSettingFadeTime shorter — one second, say — while sweeping through many frequencies, so each point settles quickly. Set it longer on a delicate machine.
3. Sweep by writing each new frequency and waiting for isStable, then counting periods on stableCycleCnt. That is the intended workflow and the two outputs exist for it.
4. Use sincos as the correlation reference if you are computing a gain and phase yourself — it is the generator’s own phase, with no measurement lag.
5. Use dwellTime when you want to hold at the extremes rather than pass through them, for example to check settling at both ends of travel.
6. Add noiseAmplitude on top of a sine to test how a loop rejects noise while tracking.
7. Watch allOutputs to compare shapes before committing to one — no need to switch and wait for a cross-fade.

Read how gentle a waveform is off how rounded its turns are.

A starting point for a gentle 1 Hz excitation, quick to retune:

signalType         = 5
frequency          = 6.283
amplitude          = 0.01
phase              = 0.0
offset             = 0.0
dwellTime          = 0.0
noiseAmplitude     = 0.0
newSettingFadeTime = 1.0
enableFadeTime     = 2.0
enable             = true

Raise amplitude from there as Setup step 4 describes.

Limits and errors

The block raises no errors or warnings and logs nothing. Every failure above shows as a value on a trace, not as a message.

Verified against motorcortex-control3 3.30.0 (bc348fd).