Variable Capacitance Accelerometer With Microprocessor Temperature Compensation
Endevco introduced a variable capacitance accelerometer featuring onboard, microprocessor-controlled temperature compensation. The model 7290D has high thermal stability and global accuracy for measurement of low-level accelerations in laboratory test and measurement, automotive, and aerospace applications including military and commercial flight testing. Gas damping and internal over-range stops are used by an anisotropically etched, silicon sensing element to withstand shock and acceleration loads. The use of gas damping in the sensing element also results in very small thermally induced changes in frequency response. Other features include dynamic accuracy of 2.5 percent over the entire mil-spec temperature range of -55°C to +125°C (defined as the root of the sum of the squares of thermal sensitivity shift, non-linearity, hysteresis, and transverse sensitivity); signal conditioning to operate with a nominal excitation of 8V DC to 30V DC, and high-level, low-impedance output. The ±2.25V differential output (single-ended output is optional) is DC-coupled at a bias of approximately 2.5V. A custom ASIC provides programmable temperature compensation; compensation and adjustments are incorporated within the accelerometer so post-processing is not required; and the compensation is accomplished via a five-point, piecewise, linear-fit algorithm for thermal sensitivity shift and thermal zero shift. A transducer electronic data sheet conforming to IEEE 1451.4 is also included to store serial number and calibration information.