UAV Terrain-Following Altitude Control Using Predicted Position
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Solution Overview
Problem
Unmanned aerial vehicles (UAVs) face challenges in maintaining a target altitude over undulating terrain due to noise in range data from ground altimeters, leading to delays in altitude control and the need for extra margin in target altitudes, limiting their ability to fly over uneven areas effectively.
Innovation Solution
An aircraft equipped with sensors for altitude, position, and speed detection, an altitude actuator, memory for terrain data, and an electronic controller that estimates future positions and controls altitude based on terrain data, allowing precise altitude maintenance without relying on ground altimeters or range finders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ground altimeter is used to detect altitude relative to ground, then altitude detection is enabled, but noise in range data causes delays in altitude control and requires extra margin in target altitudes
Solution Approach 1:
The system pre-acquires terrain elevation data for the entire flight area before the UAV flight. This preliminary action allows the ground controller to have advance knowledge of terrain features, enabling the UAV to maintain precise altitude over undulating terrain without relying on real-time ground altimeter measurements that suffer from noise and delay.
2Reliability
If ground altimeter is used for terrain following control, then altitude maintenance is possible, but numerous waypoints with target altitudes are needed for undulating ground
Solution Approach 1:
The system uses pre-acquired terrain elevation data that copies the actual terrain topology. Instead of relying on numerous discrete waypoints to represent the terrain, the continuous terrain data model allows the ground controller to calculate appropriate altitude adjustments at any position along the flight path, significantly reducing the number of waypoints needed while maintaining reliable terrain following capability.
3Measurement precision
If ground altimeter range data is processed to eliminate noise, then measurement accuracy improves, but control response time decreases
Solution Approach 1:
The terrain elevation data is acquired and processed in advance before the UAV flight. This preliminary processing eliminates the need for real-time noise filtering during flight, allowing the system to use the clean, pre-processed terrain data for immediate altitude control calculations without sacrificing response speed.
4Reliability
If extra margin is added to target altitude, then navigation safety improves, but altitude control precision deteriorates
Solution Approach 1:
The system implements closed-loop feedback control where the ground controller continuously monitors the UAV's actual position and altitude, compares it with the terrain data and target altitude, and sends corrective control commands. This feedback mechanism allows the UAV to maintain precise altitude control while ensuring navigation safety, eliminating the need for conservative altitude margins.
Data Source
AI summary
An aircraft includes at least one sensor, an altitude actuator, a memory device, and an electronic controller. The at least one sensor is configured to detect altitude of the aircraft, current position of the aircraft and speed of the aircraft. The altitude actuator is configured to change the altitude of the aircraft. The memory device is configured to store predetermined terrain data of an area. The electronic controller is configured to estimate a future position of the aircraft based on a detected current position of the aircraft and a detected speed of the aircraft. The electronic controller is further configured to control the altitude actuator based on the future position, a detected altitude of the aircraft and the predetermined terrain data.