Abstract
A bio-inspired polarization sensor with lenses for navigation was evaluated in this study. Two new calibration methods are introduced, referred to as “central-symmetry calibration” (with an integrating sphere) and “noncontinuous calibration”. A comparison between the indoor calibration results obtained from different calibration methods shows that the two proposed calibration methods are more effective. The central-symmetry calibration method optimized the nonconstant calibration voltage deviations, caused by the off-axis feature of the integrating sphere, to be constant values which can be calibrated easily. The section algorithm proposed previously showed no experimental advantages until the central-symmetry calibration method was proposed. The outdoor experimental results indicated that the indoor calibration parameters did not perform very well in practice outdoor conditions. To establish the reason, four types of calibration parameters were analyzed using the replacement method. It can be concluded that three types can be easily calibrated or affect the sensor accuracy slightly. However, before the sensor is used outdoors every time, the last type must be replaced with the corresponding outdoor parameter, and the calculation needs a precise rotary table. This parameter, which is mainly affected by the spectrum of incident light, is the main factor determining the sensor accuracy. After calibration, the sensor reaches an indoor accuracy of ±0.009° and a static outdoor accuracy of ±0.05° under clear sky conditions. The dynamic outdoor experiment shows a ±0.5° heading deviation between the polarization sensor and the inertial navigation system with a ±0.06° angular accuracy.
Highlights
Polarization vision, the ability of some animals to detect the oscillation plane of an electric-field vector of light, has inspired scientists for decades
Before the least squares were used to calculate the calibration parameters, the three calibrations were distinguished by arrows with different colors
Further optimization will be performed using the results described in this paper, which makes it possible to extend the effective range of calibration parameters while maintaining a high accuracy
Summary
Polarization vision, the ability of some animals to detect the oscillation plane of an electric-field vector of light, has inspired scientists for decades. In 2004, Cochran reported that migrating songbirds recalibrate their internal magnetic compass daily from twilight polarization cues [1]. In 2006, Muheim reported that polarized light cues, in general, underlie the compass calibration of migratory songbirds [2]. The dynamic polarization vision in mantis shrimps was investigated in 2016 [3]. Polarization cues play an important role in homing ants [4]. Polarization navigation based on polarization cues (i.e., the scattered skylight) is an important application of polarization vision. Its advantages are the anti-interference and lack of error accumulations
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