A Low-Cost Robotic Solar-Tracking Platform for Radiance and Irradiance Measurements in Earth Observation
Accurate measurements of solar irradiance (incoming sunlight) and radiance (light coming from a specific direction) are fundamental in Earth Observation (EO). They are used in atmospheric correction, surface reflectance retrieval, and validation of satellite products.
Most ground-based radiometric measurements rely on fixed sensors or manual alignment, which can introduce errors when the sun position changes or when measurements need to be taken at different viewing angles. This limits their use for dynamic EO validation experiments and field campaigns.
Recent developments in robotics and low-cost electronics allow the use of motorised gimbals that can automatically orient sensors toward the sun or predefined directions. By combining simple solar-position models with robotic control, a compact and affordable solar-tracking system can be developed for EO applications.
This MSc project focuses on building and testing such a robotic system, with a clear application to Earth observation radiometry.
Research Objective and Questions
The main objective of this research is to develop and evaluate a low-cost robotic solar-tracking system that improves ground-based radiance and irradiance measurements for Earth observation applications. The study will assess whether active robotic tracking leads to more stable and accurate measurements compared to traditional fixed-angle setups.
Four research questions are formulated and will be addressed during this MSc research:
- How accurately can a robotic gimbal track the sun using simple solar-position models and basic sensors?
- Does robotic tracking reduce variability in irradiance and radiance measurements compared to a static sensor?
- How do small pointing errors of the gimbal affect radiometric measurements?
- Can the system reliably measure direct solar irradiance and directional sky radiance under different conditions?
Methodology
System Setup
- Motorised pan-tilt gimbal (2-axis)
- Embedded controller (e.g. Arduino or Raspberry Pi)
- Sensors:
- Orientation sensor (IMU)
- Radiance or irradiance sensor (photodiode or compact radiometer)
Solar Tracking Approach
- Sun position calculated from date, time, and location
- Gimbal controlled to point toward:
- The sun (irradiance measurement)
- Selected sky directions (radiance measurement)
- Simple PID control for tracking
Measurements & Analysis
- Convert sensor output to radiometric quantities
- Compare:
- Static sensor measurements
- Actively tracked measurements
- Evaluate:
- Tracking accuracy
- Measurement stability
- Sensitivity to pointing errors
Expected Results
- A functional robotic solar-tracking measurement system
- Quantitative comparison between:
- Static and tracked radiance/irradiance measurements
- Assessment of how robotic control quality affects EO radiometric data
- Recommendations for using low-cost robotic trackers in EO field campaigns
Relevance
This research directly supports various themes in Earth Observation missions and algorithm development, such as
- In-situ measurements for EO validation
- Radiometry and atmospheric correction
- Sensor calibration and field experimentation
For students with a robotics background, the project:
- Builds on control systems and sensors
- Introduces EO radiometric concepts in an applied, hands-on way
- Serves as a bridge between robotics engineering and Earth observation science
The topic fits the TE profile of MSE.