A Novel Motion Compensation Approach Based on Symmetric Triangle Wave Interferometry for UAV SAR Imagery

Abstract

The combination of synthetic aperture radar (SAR) with unmanned aerial vehicles (UAVs) is attractive for acquiring high-resolution images without the restrictions of time and weather. However, because UAVs are lightweight and small in size, the UAV SAR system is very sensitive to turbulence, resulting in serious trajectory deviations and remaining residual motion errors (RMEs), such as residual range cell migration (RCM) and aperture phase errors (APEs). In this paper, a novel motion compensation (MoCo) strategy is developed based on the symmetric triangle linear frequency modulated continuous wave (STLFMCW) signal. The STLFMCW signal model is first presented, which reveals the relevance between the positive-negative frequency modulations and motion errors. The residual RCMs and relative phase errors are estimated directly through the phase differential interferometry of up-ramp and down-ramp chirp signals, instead of the traditional approach of relying on the range-shift gradient of adjacent range profiles. The proposed approach is independent of conventional prominent point processing (PPP) and calculates the range deviation to avoid the accumulation of errors, thereby achieving high precision and efficiency. Experiments based on simulated and measured data sets validate the proposed approach.

A W-Band Active Phased Array Miniaturized Scan-SAR with High Resolution on Multi-Rotor UAVs

“…In this section, a new motion compensation method is proposed based on the symmetrical triangle LFM continuous wave signal. This method was proposed by our team and has been introduced in detail in the literature [36,37]. Here, it is applied to optimize the proposed APA mini-SAR.…”

A Novel Multiport DC-DC Converter for Enhancing the Design and Performance of Battery–Supercapacitor Hybrid Energy Storage Systems for Unmanned Aerial Vehicles

“…Accordingly, the applications of electric UAVs powered by electric power sources are expected to have more expansions, especially for the photovoltaic (PV)-powered UAVs that became widely popular due to their increased flight endurance [5][6][7]. Advanced applications of electric UAVs in advanced remote sensing techniques using synthetic aperture radar (SAR) as a payload [8,9] introduce more challenges for the design of UAVs power system, which is required to supply the high-power pulses consumed by these payloads whilst being restricted by the weight/volume limits imposed on UAVs' subsystems. For instance, the limited surfaces and weight available for installing the PV cells on UAVs' structure limit its power and energy harvesting capabilities; hence the power system should rely on an energy storage system (ESS) to supply the high load power peaks.…”