Look for an effect pedal that uses an LFO to automatically control your LP filter and allows you to set the frequency of the oscillations. Obviously, a manual resonance control will also come in handy if you want your sweeps to be defined.
What this basically is, is a wah pedal... except you're not manually controlling it. I know you're thinking 'auto-wah', but auto-wah uses additional parameters like threshold and other things. If you can get an auto-wah pedal that actually lets you change all its parameters extensively, you'll have what you're looking for.
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