A Virtual Stringed Instrument With Haptic Feedback
Progress Report - 4/7/03
Jeff Feasel
Demos
- Here's a demo for the string sound
synthesis part. Use the keyboard (0-9 keys) to trigger the string. (Needs
DirectX and OpenGL libs)
- If you want a demo for the haptic string portion (i.e. plucking a
string with the phantom) come see me and I'll be glad to show it off.
- Right now I'm working on getting the two parts to work together.
Stay tuned.
String Sound Synth Model - Current State
- Only 1 string for now.
- Using very simple Karplus-Strong waveguide.
- Models decay crudely. Should be frequency-dependent.
- No dispersion.
- Random excitation shape. Only amplitude comes from haptic
model.
- Can not mute the string once it has started.
String Sound Synth - To Do
- More advanced waveguide model. Dispersion, freq-dependent
damping.
- Take excitation shape from the haptic model.
String Haptic Model - Current State
- Uses the PHANToM (hooray!)
- Force modelled like a spring
- Magnitude is proportional to transversal displacement only
(side-to-side, not up-and-down)
- Applied in the direction of displacement.
- Kind of a hack based on what "felt" right.
- Constants have no physical basis, yet.
- When does the string slide off the pick?
- When a maximum displacement is reached.
- A linear function of penetration depth.
- String length chosen using keyboard.
String Haptic Model - To Do
- Model the pick-string contact physically.
- Factors: Friction, incident angle.
- Decide lateral force along the pick should deicde when it will
release.
- Figure out how to handle fretting.
- Superimposed fretboard might be too much.
- Maybe just fret with the keyboard?
- A nicer UI. Not needed (you can play "by feel") but it helps
to get your bearings.