Abstract: The principle and online testing method of force-balanced accelerometers were theoretically analyzed and experimentally studied. In engineering practice, based on the theoretical analysis of the mathematical model of the accelerometer system, the open-loop transfer function of the accelerometer system was simulated according to the specific circuit of the accelerometer system. Online testing of the system was carried out, and the mathematical model of the system was identified using a curve fitting algorithm. Keywords : force-balanced accelerometer; mathematical model; curve fitting; identification 0 Introduction The force-balanced accelerometer is an accelerometer sensor that adopts flexible support technology. It has the advantages of simple structure, small size, light weight, low cost, low threshold, and strong resistance to environmental interference. This type of accelerometer can be used in inertial navigation, inertial guidance, and inertial measurement systems. The study of the dynamic mathematical model of the force-balanced accelerometer is beneficial to the analysis of the characteristics of the accelerometer system and lays the foundation for the improvement and application of the force-balanced accelerometer. 1 Structure and Working Principle of Accelerometer The structural block diagram of the force-balanced accelerometer is shown in Figure 1. The accelerometer, which is mainly based on a flexible pendulum, is a torque-balanced accelerometer sensor. Its output is mostly expressed as electrical quantities. The torque unit is located inside the accelerometer head and consists of two permanent magnets with opposite poles and two series-connected coils. Its working principle block diagram is shown in Figure 2. The tested quartz flexural accelerometer system is a digital accelerometer system employing binary pulse-width modulation (PWM) technology. For more details, please click: