Error correction method for binocular stereo vision in temperature-humidity coupling field based on fixed target array

To address the issue of extrinsic parameter drift in binocular cameras induced by thermo-hygroscopic deformation of metallic camera supports within wide-range temperature–humidity coupled environments during aircraft structural climatic strength testing, as well as the inability of existing self-calibration methods to adapt to coupled high/low-temperature and high/low-humidity conditions, this paper proposes a real-time error correction method for binocular vision based on a fixed target array mounted on a high-stiffness foundation. A mathematical model of pose deviation is constructed incorporating thermal expansion, moisture expansion, and cross-coupling terms, and an extrinsic parameter error propagation equation under temperature–humidity disturbances is derived. An auxiliary correction camera is introduced to observe the fixed targets, and the EPnP algorithm is employed to solve for the support pose deviation, enabling dynamic compensation of the binocular system extrinsic parameters. Validation is conducted through simulations and nine sets of environmental chamber experiments, with a grating scale (accuracy: 0.5 μm) serving as the reference benchmark; the experiments cover low-temperature, high-temperature, and full-range comprehensive thermal cycling conditions. The simulation and experimental results demonstrate that the uncorrected system exhibits an average measurement error of 0.065 mm, exceeding the permissible error of 0.03 mm under all operating conditions. After applying the proposed correction method, the mean absolute error (MAE) across all conditions ranges from 0.0209 mm to 0.0253 mm, with a maximum single-point error of 0.0278 mm; the measurement standard deviation is substantially reduced and data repeatability is markedly enhanced, with simulation error improvement rates of 64.2%–65.8%. The proposed scheme requires only one additional correction camera and a fixed target array, without necessitating extra temperature or displacement sensors, thus offering low hardware cost and ease of integration, and is capable of satisfying the high-precision three-dimensional deformation measurement requirements for climatic strength testing of large-scale aircraft structures.