Hvilenullstilt

Hvilenullstilt is a term used in robotics and control theory to describe the reference orientation of a rigid body at rest when it is not subjected to external forces. The word is formed from hvile (rest), null (zero), and stilt (tilt) and is commonly translated as rest-zero tilt. In this sense, hvilenullstilt denotes the orientation in which roll and pitch are zero relative to a defined reference frame, while yaw may remain unconstrained.

In practice, hvilenullstilt serves as a calibration and reference state for inertial sensors and stabilization systems. When a device is aligned with hvilenullstilt, gravity points along the expected axes and tilt measurements reflect only deviations from this rest state.

Determination and use: hvilenullstilt is established by placing the device on a level surface and recording accelerometer readings. The computed roll and pitch become zero in the reference frame, with biases stored as offsets. Many systems perform periodic recalibration to track drift or mechanical changes.

Applications include unmanned aerial vehicles, robotic arms, camera gimbals, and ship or vehicle stabilization systems. As a stable reference, hvilenullstilt enables accurate tilt compensation and improves attitude estimation in noisy or dynamic environments.

Limitations: hvilenullstilt depends on the chosen reference frame and gravity. Any tilt or misalignment of the reference plane introduces errors, and yaw remains unconstrained by gravity alone. In practice, drift, temperature changes, or mounting shifts can require re-calibration to maintain accuracy.

See also: attitude estimation, IMU calibration, zero-roll, zero-pitch.