Cranes and torque measuring system and method

The present invention discloses a crane and torque measuring system and method, wherein the torque measuring system, the crane comprising: a projection device, mounted within the boom crane for structured light projected onto the top of the boom arm; an optical sensor mounted in the crane boom, a top structure for reflecting light back through sensing arm of the boom; and a control means connected to the optical sensor signals, the control means for the sensing result of the optical sensor, the deformation curve of the boom axis, and an actual torque value calculated according to the curve of the crane. Its high torque measuring system and the crane system of the present invention provides a precision, anti-interference, the size of the torque can be obtained directly, less accumulation of errors.