Ati Industrial Automation, Inc.

Andrew Glusiec

David Fleissner

Travers Thurman

A torque sensor comprises a transducer plate having a center area and periphery connected by a plurality of spokes and instrumentation beams. The transducer plate exhibits mechanical compliance under axial torque, but stiffness under off-axis loads. Strain gages attached to instrumentation beams detect deformation caused by axial torques. The instrumentation beams may be asymmetric, allowing strain gages to be placed in regions of high sensitivity to axial torques and low sensitivity to off-axis loads. The strain gage responses from some off-axis loads are designed to be coupled to, or linearly dependent on, the strain gage responses of other off-axis loads. This reduces the number of strain gages necessary to resolve the loads. The spokes and beams are cost-effectively formed by removing adjacent transducer plate material in simple shapes.

Torque sensor using coupled loads and fewer strain gages

Strain gages on a robotic force/torque sensor are individually temperature compensated prior to resolving the gage outputs to estimate force and torque loads on the sensor. Thermal sensors are mounted proximate each strain gage, and the initial gate and thermal sensor outputs at a known load and temperature are obtained. The force/torque sensor then undergoes warming, and strain gage and thermal sensor outputs are again obtained. These gage and thermal sensor outputs are processed to calculate coefficients to a temperature compensation equation, such as by using a least squares algorithm. Each strain gage output is compensated using the temperature compensation equation, and the temperature-compensated outputs of the strain gages are then combined to resolve temperature-compensated force and torque values.

Robotic force/torque sensor with improved temperature compensation

A force/torque sensor includes a plurality of serpentine or spiral deformable beams connecting a TAP and MAP. These classes of shapes increase the overall length of the deformable beams, which reduces their stiffness. In addition to the deformable beams is a plurality of straight overload beams, each connected at a first end to one of the TAP and MAP, and separated from the other of the TAP and MAP at the second end by an overload gap of a predetermined width. Over a first range of forces and torques, strain gages on the deformable beams transduce compressive and tensile strains into electrical signals, which are processed to resolve the forces and torques. Over a second range of forces and torques greater than the first range, the overload beams close the overload gap, establishing rigid contact to both the TAP and MAP. The stiffness of the sensor in the second range of forces and torques is greater than over the first range.

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Andrew Glusiec