Variable Pitch Instrument Platform for Satellite Image Coverage
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Solution Overview
Problem
Remote sensing vehicles face issues with incomplete coverage and data gaps due to bowtie-shaped swaths and pixel underlap when scanning at Nadir elevation, as well as limitations in time delay and integration (TDI) dwell, which are exacerbated by the static nature of the sensor platform relative to the host bus.
Innovation Solution
A method involving a variable pitch instrument platform dynamically coupled to the host bus platform in at least one degree of freedom, allowing for independent payload pointing and scanning, enabling changes in pitch angle to decouple scanning from host bus attitude, thereby varying ground-scan-distance and improving data coverage and resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the sensor platform is kept static relative to the host bus during scanning, then the satellite bus attitude control is simplified, but pixel underlap and incomplete coverage occur in successive swaths
Solution Approach 1:
The sensor platform is segmented from the host bus, creating an independent variable pitch instrument platform that can be controlled separately. This allows the sensor to adjust its pitch angle independently to eliminate pixel underlap and ensure complete coverage, while the host bus maintains its simplified attitude control.
Solution Approach 2:
The sensor platform transitions from a static configuration to a dynamic one with variable pitch capability. The pitch angle can be adjusted during operation to optimize swath overlap and coverage, resolving the contradiction between simplified control and complete coverage.
2Reliability
If the sensor platform is made variable with adjustable pitch angle, then coverage and overlap issues are resolved, but the device complexity and control difficulty increase
Solution Approach 1:
The variable pitch capability is implemented as a separate, modular instrument platform that can be independently controlled. This segmentation allows the complexity to be isolated to a specific subsystem rather than affecting the entire satellite bus, making the system more manageable despite the added capability.
3Measurement precision
If the host bus attitude is changed to adjust sensor pointing, then payload pointing is achieved, but other ancillary sensors on the host bus are negatively affected
Solution Approach 1:
The sensor platform is separated from the host bus, allowing independent control of payload pointing without affecting ancillary sensors. The variable pitch instrument platform adjusts pointing accuracy for the primary payload while the host bus maintains its standard attitude, preventing negative impacts on other sensors.
Solution Approach 2:
The variable pitch instrument platform acts as an intermediary between the host bus and the sensor, providing fine pointing adjustments without requiring changes to the host bus attitude. This intermediary mechanism protects ancillary sensors from disruption while achieving precise payload pointing.
4Device complexity
If TDI dwell is tied to gross satellite bus motion, then the control system is simplified, but scanning flexibility and adaptability are limited
Solution Approach 1:
The control system is segmented into two independent levels: gross satellite bus motion control and fine sensor platform pitch control. This allows TDI dwell to be controlled at the sensor platform level with high flexibility, while the host bus maintains its simplified control architecture.
Solution Approach 2:
The system transitions from a static, unified control approach to a dynamic, multi-level control architecture. The variable pitch instrument platform enables dynamic adjustment of scanning parameters independent of bus motion, providing adaptability without complicating the overall control system.
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
Operating a remote sensing vehicle 250 comprising a host bus platform 252 and a variable pitch instrument platform 254 movably coupled to the host bus platform in at least one degree of freedom. The method comprises establishing a pointing position and scanning a target surface with the variable pitch instrument platform. The variable pitch instrument platform is dynamically movable relative to the host bus platform to vary the pointing position of the variable pitch instrument platform, thereby decoupling payload pointing from the host bus platform. A method is provided of varying ground- sample-distance value with a remote sensing vehicle. A remote sensing vehicle comprises a host bus platform and a variable pitch instrument platform for scanning or data collection of a target surface, and an dynamic coupling device (e.g., a gimbal(s)) movably coupling the variable pitch instrument platform to the host bus platform in at least one degree of freedom.