The force balance sensor is geared towards DC and low-frequency acceleration measurements, such as those found in the motion of vehicles, aircraft, and ships. These sensors have the capacity to measure levels from as low as 0.0001 g up to 200 g across a frequency range from DC to 1000 Hz. Additionally, due to their innate sensitivity to gravity, making specific modifications or introducing special features to the force balance accelerometers makes them excellent instruments for measuring inclination angles. This kind of sensor, generally known as an inclinometer, is practical for applications such as borehole mapping, gun sight control, platform levelling, pipeline levelling and other low-level seismic measurement applications.
The force-balance sensor offers several advantages that produce excellent performance in many applications. Internal displacements within any accelerometer generate inaccuracies and errors typically in the form of disproportionate levels of hysteresis, stickiness, non‐linearity, and non‐repeatability.
LVDT, potentiometric, variable reluctance and similar kinds of sensors all have the potential to cause these errors, which results from the fact that the sensing element must travel over some distance to generate a measurable change in output.
Conversely, the output signal from a force balance accelerometer is not contingent on the displacement of some internal element being a linear function of acceleration. Internal displacements remain comparatively small, generally less than one ten-thousandth of an inch.
In addition to minimizing static error, the minute displacements relative to the force balance sensor contribute to the relatively high natural frequency this type of sensor possesses. A strain gage sensor does not necessitate excessive internal displacements but is vulnerable to effects of temperature, creep, and aging, which can result in instability.
Opposed to other low-frequency accelerometers, which need viscous media, dashpots or similar mechanical damping techniques, the force balance sensor’s dynamic response can be damped and adjusted with ease to a specific value by way of electronic networks.
The damping ratio can be calibrated to near critical for a maximum usable response or to a higher degree, or limited response and sensitivity to high frequencies.
Generally, in open-loop types of transducers, the ratio is either controlled by means of viscous media or uncontrolled, as in the case of piezoelectric devices. In the former case, it is not possible to control the damping ratio by any tight tolerances due to viscosity changes vs. temperature.
Several strain gage, potentiometric or LVDT type accelerometers incorporate thermostatically controlled heaters in an attempt to stabilize damping characteristics.
Additionally, in most cases, the force balance accelerometer is completely self-controlled, which means additional signal conditioning is not necessary, which means they have the capacity to directly interface with spectrum analysers, oscilloscopes, data acquisition systems, digital voltmeters and displays. The full-scale output is typically in the order of several volts and necessities no additional amplification.