Abstract: The relative position of two members is determined based upon a detected relative intensities of first and second colors of light. The intensity balance associated with relative occlusion of first and second color filter portions on one member by a mask on the other member. An exemplary use is in rotational position sensing within a limited rotation range. With a given compliance between the two members, the position sensing can be used as a proxy for torque sensing.

Abstract: The attitude of a tiltable body is tracked and controlled on the basis of signals outputted from gyros and tilt sensors. The signals outputted from the gyros are transformed and integrated to produce estimated position information in the form of a modified quaternion in which the yaw component is constrained to a zero value. Modified quaternion information in the same form is also generated from signals outputted from the tilt sensor and is used to detect and correct an error component in the estimated position information. Gyro drift is also corrected based on the output of the tilt sensor.