Stay still for 3 seconds
Hold the phone sideways with the screen down and your forearm level. After 3 seconds, that posture becomes the session's neutral starting point.
Motion logic
How does it count one movement?
Wrist Trainer finds a stable relative starting point, then uses phone posture, your target angle, and hold duration to decide when an extension or flexion count is complete.
Start with stability
Calibrate, move, then return to neutral.
Derive relative angle
The accelerometer supplies a gravity reference and the gyroscope provides short-term compensation for the phone's relative angle.
Keep both directions separate
Extension and flexion use independent counts. Clearly invalid or off-axis samples are rejected instead of being forced into a count.
The count condition
Reach the target, then hold it.
A count completes only after the relative angle reaches your target and the hold duration setting is satisfied.
- Move toward the target slowly. The target is a session setting, not a universal medical prescription.
- Hold the target. A per-second haptic cue helps show that the hold is still progressing.
- Finish with three parts. Completion gives a three-part haptic cue; devices without haptics still show visual feedback.
- Return to neutral for the next rep. The next count unlocks only after the neutral zone, reducing threshold jitter.