A resolver sensor is the preferred choice for angular position measurement in harsh environments and for safety press controls applications. The resolver sensor resembles a rotary transformer where the output coils are oriented 90° to each other and each produces a voltage complementary to the other. The excitation coil, or the primary coil, is supplied a sine wave.
A resolver based press control uses a resolver for its position feedback. It is coupled to the shaft directly or by chain and sprocket. It provides for real time brake monitoring and actual position (absolute position) of the press to the control. CIECO manufactures an ultra rugged resolver, designed specifically to withstand shock and vibration. Beware of controls that say "resolver based" but are really encoder based. Encoders are generally not very rugged and some can lose their position when the power is removed.
CIECO Model HD13 Industrial Resolver