Torque sensor using coupled loads and fewer strain gages

A torque sensor, comprising:

• a transducer plate having an axis and configured to be attached between first and second objects;
• and
• four strain gages attached to the transducer plate, each strain gage connected to a strain gage circuit;
• whereby the transducer plate configuration, strain gage placement, and strain gage circuits are such that a strain gage response for two different pairs of force and torque are each linearly dependent, whereby the strain gage response under the force of each pair differs from strain gage response under the torque of that pair by a multiple, and the four strain gage responses comprise a four by four linear system, from which at least a torque about the axis is directly determined from the strain gage responses and a decoupling matrix.

A method of manufacturing a torque sensor, comprising:

• providing a generally circular, generally planar transducer plate having a center area with a perpendicular center axis z, and a periphery;
• forming one or more first mounting holes proximate the center area, the first mounting holes configured to be attached to a first object;
• forming one or more second mounting holes proximate the periphery, the second mounting holes configured to be attached to a second object;
• forming a plurality of voids through the transducer plate between the center area and periphery, wherein adjacent voids define spokes connecting the center area and periphery;
• forming one or more radial slots through the transducer plate between the center area and periphery, each radial slot adjacent at least one void, wherein the transducer plate between a radial slot and a void defines an instrumentation beam connecting the center area and periphery, each instrumentation beam oriented generally radially along its entire length, and having the same thickness as the transducer plate along its entire length;
• attaching a strain gage to an instrumentation beam;
• and
• connecting the strain gage to a strain gage circuit outputting a voltage dependent on a strain-dependent resistance of the strain gage.