US Patent 10895445 Articulated arm coordinate measuring machines with active counterbalance

Rotary assemblies for arm segments of an articulated arm coordinate measuring machines are provided. The rotary assemblies include a drive assembly having an output shaft passing therethrough. The drive assembly includes a motor subassembly and an output subassembly having a gear assembly and a shaft engagement element. The motor subassembly is configured to drive the gear assembly and the shaft engagement element to drive the output shaft. In some embodiments, a motor controller is operably coupled to the motor subassembly. The motor assembly provides a torque on an arm segment about a second axis in response to a signal from the motor controller.