Triangulation / Approximation

Hi,

__Introduction__

I'm working on electronics test system, where a certain measurement take an awfully long time. Basically its find a balance point of a circuit and checks the point is within the test limits. The circuit is a bridge which has an unknown impedance attached, then changing know values to balance out the unknown load.

The current method uses a SAR(successive approximation) method, system take an educated guess on where the point should be and try's points around it to find the balance point of the circuit.

__The problem__

The test takes an age to run as it take 10-20 attempts to find the correct values.

My idea is to use a triangulation technique to find a point that point. Basically my idea is to use 3 point, measure the magnatude of the error signal(error signal will be zero at the balance point, and increase the further from the balance point), and plot the point where the arc's cross. Sounds simple enough in theory.

However the measurements taken are not perfect(as this is the real world) and do not alway give a trivial solutions, the magantudes do not always meet up neatly to define a single point.

The question is does any have any suggestions on algorthyms that could be used to define the approximate region/crossing point of the 3 vectors even if the vectors do not actually meet.

Thanks