Searchlight Beam Control for Constant Ground Speed
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Solution Overview
Problem
Existing searchlight control systems on mobile platforms fail to maintain a constant ground speed for the illumination spot, leading to variable ground speed and inefficient viewing times, especially at higher speeds, due to the constant average angular velocity of azimuth actuators.
Innovation Solution
A system comprising a searchlight apparatus mounted on a mobile platform with integrated elevation and azimuth actuators, a controller architecture, and a user input device that computes and adjusts the elevation and azimuth angles to maintain a constant ground speed by determining the required rate of change of these angles based on real-time platform status data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the azimuth actuators are rotated at a constant average angular velocity, then the control system is simple to operate, but the ground speed of the illumination spot becomes variable and inefficient
Solution Approach 1:
The patent applies dynamics by transitioning from static constant angular velocity control to dynamic variable angular velocity control. The azimuth actuator speed is continuously adjusted based on real-time calculation of required ground speed, elevation angle, and distance to target. This dynamic adaptation ensures the illumination spot maintains constant ground speed across varying operational conditions, resolving the contradiction between operational simplicity and speed consistency.
Solution Approach 2:
The patent changes the operational parameters of the azimuth actuator from fixed constant velocity to variable velocity based on multiple parameters including elevation angle, distance to illumination spot, and desired ground speed. The control system continuously modifies the angular velocity parameter to compensate for geometric relationships, ensuring constant ground speed while maintaining manageable control through automated parameter adjustment.
2Device complexity
If the azimuth actuators are rotated at a constant average angular velocity, then the actuator control is straightforward, but the viewing time efficiency decreases at higher speeds
Solution Approach 1:
The patent implements feedback control by continuously monitoring the actual ground speed of the illumination spot and comparing it to the desired constant ground speed. The system uses real-time data from elevation sensors, distance measurements, and actuator position feedback to calculate and adjust the azimuth actuator velocity. This closed-loop feedback mechanism maintains viewing time efficiency while keeping actuator control manageable through automated regulation.
Solution Approach 2:
The patent applies preliminary action by pre-calculating the required azimuth actuator velocity based on current elevation angle and distance to target before movement occurs. The control system determines the necessary speed adjustment in advance to maintain constant ground speed, allowing the actuator to execute precise movements without reactive corrections, thereby optimizing viewing time efficiency.
3Ease of manufacture
If constant average angular velocity is used for azimuth actuators, then the system is easier to implement, but control resolution and visualization quality deteriorate
Solution Approach 1:
The patent applies dynamics by implementing variable angular velocity control that adapts to elevation angle and distance conditions. At higher elevation angles where precision is more critical, the system automatically reduces azimuth actuator speed, providing finer control resolution. This dynamic speed adjustment maintains high measurement precision without requiring overly complex mechanical implementation, as the variability is achieved through software-based control algorithms.
Data Source
AI summary
Systems and methods for moving an illumination spot of a searchlight beam at a constant groundspeed. The method includes receiving state data comprising an attitude for the mobile platform. The method computes an elevation angle, theta, of the beam as a function of the attitude, an elevation actuator angle and a known mounting orientation for the searchlight. Responsive to receiving a searchlight control command from a user input device, the method determines a respective rate of change of theta, dtheta/dt, and rate of change of Psi, dPsi/dt, required to maintain the constant groundspeed of the illumination spot, as a function of the state data. The method updates theta responsive to the determined dtheta/dt and generates actuator control commands for an elevation actuator based thereon. The method updates Psi responsive to the determined dPsi/dt, and generates actuator control commands for an azimuth actuator based thereon.