Summary for Improved Transducer Performance: Measurement of Force, Torque, and other Variables

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Summary of Considerations for Improved Transducer Performance

Careful initial design, both mechanically and electrically, will contribute significantly to the accuracy, stability, and repeatability of a D-I-Y transducer. Whenever feasible, for example, the spring element should be designed as a monolithic or one-piece structure from the point of load application to the reaction. Bolted assemblies commonly lead to nonlinearity and hysteresis effects, and welded ones may also cause problems due to residual stresses in the heat-affected zones.

It is always good practice to design the spring element for ease of strain gage installation. Accurate location and orientation of the gages is critical to obtaining the operating characteristics described in the preceding sections. Obviously, precise gage positioning is more apt to be achieved if the gage installation site is flat, of sufficient size, and readily accessible. Preferably, the gage installation area should be subjected to uniform strain, and at the highest strain level in the spring element (but not above about 1500

). If the strain magnitude varies over the gage site, it is advisable to install the gages with the solder-tab ends at the lowest strain level. Design consideration should also be given to assuring that the applied load acts, in both location and direction, as intended for the spring element configuration. Compensation methods for canceling off-axis load components are seldom 100 percent perfect; and the best transducer performance will be obtained from a design which minimizes such components from the beginning.