Tethered Platform Trajectory Control for Maneuverability and Low Tether Force
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Solution Overview
Problem
Conventional methods for controlling tethered self-propelled platforms limit maneuverability and impose undesirable forces on the systems.
Innovation Solution
A method and system that utilize a platform leader and follower connected by a telescopically adjustable linear tether, allowing pivotal movement, to estimate a predicted position and trajectory based on current position, speed, and yaw rate, and adjust speed and yaw rate to achieve desired distances and angles, enhancing maneuverability and reducing forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional control methods are used for tethered self-propelled platforms, then the system structure is simple, but the maneuverability is limited and undesirable forces are imposed on the system
Solution Approach 1:
The system estimates the predicted position of the leader platform based on current position, speed, and yaw rate before the follower actually reaches it. This preliminary positioning allows the follower to plan its trajectory in advance, adjusting its path proactively rather than reactively, thereby improving maneuverability while minimizing disruptive forces on the tether connection
Solution Approach 2:
The control system continuously monitors the actual position, speed, and yaw rate of the leader platform, compares it with the predicted position, and uses this feedback to dynamically adjust the follower's trajectory. This closed-loop control enables real-time optimization of the follower's path, enhancing maneuverability while maintaining smooth tether forces through coordinated speed and yaw rate adjustments
2Adaptability or versatility
If the tether length is fixed, then the system structure is simple, but the linear movement between leader and follower is limited
Solution Approach 1:
The tether structure is designed with telescopic capability, allowing its length to be dynamically adjusted during operation. This dynamic length adjustment enables the system to adapt to varying operational requirements, such as changing distances between leader and follower platforms, while maintaining a relatively simple base structure that only adds the telescopic mechanism
3Manufacturing precision
If the follower directly tracks the current position of the leader, then the control response is fast, but the trajectory accuracy and maneuverability are reduced
Solution Approach 1:
By estimating the leader's predicted position based on its current state (position, speed, yaw rate), the system performs preliminary positioning before the follower actually needs to reach that point. This advance calculation allows the follower to begin trajectory adjustment earlier, improving both trajectory accuracy and effective response time
Solution Approach 2:
The system anticipates the leader's future position and prepares the follower's trajectory in advance, cushioning against potential position deviations. This proactive approach smooths out trajectory errors before they accumulate, resulting in more accurate path following without requiring abrupt corrective actions that would increase response time
Data Source
AI summary
A method of controlling tethered self-propelled platforms is provided. The method comprises providing a platform leader and a platform follower connected to the leader with a tether to define a first heading line of the leader and a first coordinate frame of the follower. Each of the leader and the follower is pivotally moveable relative to the tether, defining a leader angle and a follower angle. The method further comprises estimating a predicted position of the leader based on a current position, a current speed, and a current yaw rate of the leader. The predicted position of the leader defines a predicted heading line of the leader. The method further comprises determining a trajectory of the follower from the first coordinate frame to the predicted heading line defining a second coordinate frame of the follower. The trajectory is based on a desired distance the predicted heading line and a desired change in yaw angle of the follower. The method further comprises moving the follower along the trajectory to the second coordinate frame.