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System Identification and Control of a Joint-Actuated Buoy

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Trident Scholar Project rept. no. 426

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Consider the example of a small, free-floating buoy using a directional antenna to communicate with a satellite. The position of the buoy must remain stable and directed towards the satellite for effective transmission. With a joint-actuated buoy, it is mechanically possible to stabilize the free-floating buoy and the antenna. The goal of this Trident project is to perform system identification of the joint-actuated buoy prepare an animation for the response of the buoy to different inputs and create a single loop control law for the two dimensional control of the buoy to keep it vertical at all times. To complement theoretical models derived from Newtonian physics, an experimentally derived model allows non-linear effects such as drag and added mass effects to be inherently accounted for within the experimental data. Using step response testing for the top and bottom servos was the primary method used to formulate the experimental model. An animation was created to help visually comprehend the dynamics of the buoy. Next, a single loop control law was developed to control the position of the buoy in two dimensions to keep the buoy vertical at all times keeping the buoy stable while at a specified angle off of vertical was not attempted in this project due to the complexities of three dimension control with only two control surfaces.

Subject Categories:

  • Marine Engineering
  • Navigation and Guidance

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