There are several possible sources of error, many of which correspond to fabrication and assembly. In the process of evaluating on the bench such error sources are easier to identify, thereby making bench testing a good and necessary practice to embrace before proceeding to mass production. The following list shows all possible error sources identified for this particular design including the ones accounted for in the preliminary design:

• Fabrication Limitation and mechanical tolerance
• Operating outside of the linear region
• Device offsets
• Roll, Yaw, and Pitch
• Magnet Variation
• Device Variation and Temperature Drift
• External Fields
• Nearby Material Influence
• Bench Setup Error
• Supply Tolerance
• Measurement precision

The most notable errors for the 2-magnet-2-sensor thumbstick prototyped in this application note resulted in data curve that exhibited hysteresis. One significant error source was the mechanical hysteresis stemming from material selection and fabrication tolerance, while the other was the magnetic properties of the nearby materials. These errors were quite significant when not accounted for and do affect the post processing calibration and calculation results. Prior to addressing the mechanical hysteresis, the hardware data in Figure 2-20 exhibited noticeable hysteresis and resulted in the large error observed in Figure 2-21. Other notable errors include offset and fulcrum slippage.