Position estimation device for hydraulic manipulator of underwater robot and method thereof

Position Estimation Device for Underwater Robotic Hydraulic Manipulators Using Joint Hydrostatic Pressure Differential Measurement

This technology is a device that estimates the 3D position of an end-effector by measuring the hydrostatic pressure differential at the joints of an underwater robotic hydraulic manipulator to calculate the vertical displacement of each joint link, combined with yaw angle data measured by a compass.

In turbid underwater environments, camera-based position estimation is difficult, and conventional rotary encoder methods are unsuitable for the harsh operating conditions of hydraulic manipulators, leading to challenges in achieving precise position tracking.

This technology proposes a method that calculates vertical displacement using hydrostatic pressure differentials and the specific weight of water, determines the pitch angle and horizontal displacement of joint links based on these values, and derives the roll angle using an offset pressure gauge. It can be applied to underwater work robots and offshore plant maintenance, enabling accurate tracking of manipulator posture even in environments with zero visibility.

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Key Features:

• Multiple pressure gauges installed at the joint connections of the hydraulic manipulator's multiple joint links to measure hydrostatic pressure
• A compass installed on the first joint link connected to the base frame to measure the yaw angle of the manipulator
• A configuration that calculates the vertical displacement of each joint link based on the hydrostatic pressure differential between both ends of the link
• An end-position calculation unit that determines the position of the end-effector based on vertical displacement, link length, and yaw angle

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This invention was developed with support from the Smart Underwater Tunnel System Research Center of the Ministry of Science and ICT.