Complete SE³ underwater robot control with arbitrary thruster configurations

Abstract

Abstract-We present a control algorithm for autonomous underwater robots with modular thruster configuration. The algorithm can handle arbitrary thruster configurations. It maintains the robot's desired attitude while solving for translational motion. The attitude can be arbitrarily chosen from the special orthogonal group SO 3 allowing the robot all possible orientations. The desired translational velocities can be chosen from R 3 allowing the robot to follow arbitrary trajectories underwater. If the robot is not fully holonomic then the controller chooses the closest possible solution using least squares and outputs the error vector.We verify the controller with experiments using our autonomous underwater robot AMOUR. We achieve roll errors of 1.0 degree (2.1 degrees standard deviation) and pitch errors of 1.5 degrees (1.8 degrees standard deviation). We also demonstrate experimentally that the controller can handle both nonholonomic and fully holonomic thruster configurations of the robot. In the later case we show how depth can be maintained while performing 360 degree rolls. Further, we demonstrate an input device that allows a user to control the robot's attitude while moving along a desired trajectory.

Using optical communication for remote underwater robot operation

“…It also logs both the data from the optical modem as well as the robot's current position which it receives from the IMU. Finally, the IMU uses the Modular Thruster Control Algorithm [1] to compute thruster updates.…”

“…We presented the latest version of our underwater robot system and the human input device in [1]. To the best of our knowledge, this paper presents the first results for remotely controlling an underwater vehicle in real-time using a wireless optical link in shallow waters where ambient light is present.…”

“…The HID is a handheld Inertial Measurement Unit (IMU) that we described in detail in [1]. We first present the optical modem hardware and then the underwater robot.…”

“…The IMU uses the Modular Thruster Control Algorithm presented in [1] to orient and position the robot into the desired attitude. …”

Estimation of Thruster Configurations for Reconfigurable Modular Underwater Robots

“…Other hovering underwater robots that maneuver predominantly using thrusters include the University of Hawaii ODIN-III robot [1], the CSIRO Starbug robot [3] and the Bluefin Robotics HAUV [10]. The Modular Thruster Control Algorithm developed in our previous work [2] provides attitude and position control for modular robots and can handle arbitrary thruster configurations. However, the algorithm requires knowledge of the thrusters' locations.…”