Patent ID: 8485014

Claim:
A paramagnetic gas sensor apparatus comprising: a test body held by a support enabling rotation of the test body about an axis of rotation; a set of magnets for generating a magnetic field that generates a first disturbing torque, acting on the test body in a first direction about the axis of rotation, in response to a test stimulus; an electrical conductor element for location in the magnetic field, for generating a second torque when an electrical current flows within the electrical conductor element, acting on the test body in a second direction opposite the first direction, in response to a control signal; a controller for varying the control signal until the test body achieves a balanced null position; and a signal measurement unit for measuring the control signal required to achieve the balanced null position; further comprising: an orientation detector for measuring the orientation of the apparatus relative to an acceleration or gravitational field; a processing unit to calculate, from the measured control signal and measured orientation, a required compensation for the effects of mechanical imbalance; and means for applying the compensation to a measured control signal to determine a modified control signal required to balance the first disturbing torque.