Looks like this might get lost, so I hope to help get it going.... I would imagine that the most difficult part would be getting the mechanical engineering / handling correct.
1) Is this your own mechanics ? 2) How are you managing damping of the system? i.e. When the tray 'hits' the load cell. 3) Are you sure it's not resonant / resonating ? Have you tested for resonance ? See damping. 4) Can you correlate actuals with data at lower speeds ? Post signal data as an example. Suggestions =========== I would suggest that you post a picture (It's worth a thousand words) or two and some sample data, then you might get a fuller answer.