Reactionless rotary drive mechanism

Abstract

An articulating probe head includes motors 12 and 18 for driving respective output shafts 14 and 20 about respective orthogonal axes z and x to move a stylus 22 over the surface of a workpiece under the control of a controller 26. At least one of the motors is inertia balanced by mounting the stator 32 of the motor on bearings 42 to allow it to rotate in opposition to the rotation of the rotor 34. Control of the speed of the spinning stator is achieved by connecting it to the winding assembly 46 of an additional “back-to-earth” motor 47 the magnet assembly 48 of which is connected to the housing. The motor 47 acts as a brake to prevent overspeeding of the rotatable stator, and can have power supplied to it to ensure that the stator does not slow down excessively when the main motor is running at constant angular velocity. Control of the power supply to the motors is achieved by the controller 26.

Dependencies are inferred from the claim text.