Disturbance Observation and Control in Precision Tracking Systems

Precision tracking systems underpin a wide range of applications, from astronomical telescopes and electro-optical surveillance platforms to free-space laser communications and robotic formation control. Their performance is often limited by external and internal disturbances such as mechanical resonances, platform-induced vibrations, sensor delays and atmospheric turbulence. Disturbance observation and advanced control techniques have therefore become central to achieving high-bandwidth, high-accuracy line-of-sight stabilisation and beam pointing.

Contemporary approaches combine multi-loop feedback with model-based observers to estimate unknown perturbations in real time and compensate for them within the control law. Architectures such as disturbance observers (DOBs), error-based observers and nonlinear active disturbance rejection controllers continuously reconstruct disturbance profiles across different frequency bands. In parallel, methods like Smith predictors address time delays inherent in charge-coupled device (CCD) or photodiode sampling, while sliding mode control and internal model control frameworks enhance robustness and minimise chattering. Sensor fusion of CCDs, fibre-optic gyroscopes, accelerometers and gyroscopes further enriches state estimation, enabling control schemes to balance high-frequency disturbance rejection with low-frequency tracking precision.

These advances have delivered tangible improvements in closed-loop bandwidth and pointing stability. Mechanical resonances can now be actively suppressed, and delays compensated, yielding sub-microradian accuracy in dynamic environments. The integration of disturbance observation into electro-optical and laser communication platforms is rapidly maturing, with cross-disciplinary innovations reflecting the global demand for resilient, high-precision tracking under real-world disturbance conditions.

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Disturbance Observation and Control in Precision Tracking Systems publication trend

The graph below shows the total number of articles in disturbance observation and control in precision tracking systems across all publications each year (not limited to Nature Index journals).

Technical terms

Disturbance observer (DOB): A model-based estimator that reconstructs unknown external perturbations to enable real-time compensation within the control loop.

Smith predictor: A control architecture that isolates known time delays from the main feedback path, improving stability and bandwidth in delayed systems.

Sliding mode control (SMC): A robust nonlinear control strategy that forces system trajectories onto a predefined sliding surface, offering strong disturbance rejection.

Internal model control (IMC): A framework that embeds the plant model within the controller design, allowing prediction of system behaviour and disturbance effects.

Fast steering mirror (FSM): A precision mirror actuator used to correct line-of-sight errors at high bandwidth, often driven by multi-loop feedback and observer schemes.

Micro-electro-mechanical system (MEMS): Miniaturised mechanical and electromechanical elements that serve as sensors or actuators, valued for small size and fast response.

Kalman filter: A recursive algorithm that fuses noisy measurements and system dynamics to produce optimal state and disturbance estimates.

References

1. MEMS Inertial Sensors-Based Multi-Loop Control Enhanced by Disturbance Observation and Compensation for Fast Steering Mirror System. Sensors (2016).
2. Application of MEMS Accelerometers and Gyroscopes in Fast Steering Mirror Control Systems. Sensors (2016).
3. Inertial sensor-based multiloop control of fast steering mirror for line of sight stabilization. Optical Engineering (2016).
4. A New Mechanical Resonance Suppression Method for Large Optical Telescope by Using Nonlinear Active Disturbance Rejection Control. IEEE Access (2019).
5. Disturbance observer–based super-twisting sliding mode control for formation tracking of multi-agent mobile robots. Measurement and Control (2020).
6. Error-Based Observer of a Charge Couple Device Tracking Loop for Fast Steering Mirror. Sensors (2017).
7. Feedforward Control Based on Error and Disturbance Observation for the CCD and Fiber-Optic Gyroscope-Based Mobile Optoelectronic Tracking System. Electronics (2018).
8. Development of Sliding Mode Controller Based on Internal Model Controller for Higher Precision Electro-Optical Tracking System. Actuators (2022).
9. Experimental Study on Photodiode Array Sensor Aided MEMS Fine Steering Mirror Control for Laser Communication Platforms. IEEE Access (2021).
10. Delay-Compound-Compensation Control for Photoelectric Tracking System Based on Improved Smith Predictor Scheme. IEEE Photonics Journal (2022).