Design, Characterization, and Control of a Size Adaptable In-pipe Robot for Water Distribution Systems

TL;DR

This paper presents a comprehensive design, characterization, and control framework for a size-adaptable in-pipe robot capable of operating in high-pressure, high-flow water distribution pipelines, with validated simulation and experimental results.

Contribution

It introduces a novel LQR-PID controller, characterizes the spring mechanism under extreme conditions, and provides an end-to-end power management method for the robot.

Findings

The robot maintains stability with velocity margins of -4 to +3 degrees/sec.

Experimental results show the robot accurately tracks desired velocities in PVC pipes.

The control system reduces initial state errors to near zero within four iterations.

Abstract

Leak detection and water quality monitoring are requirements and challenging tasks in Water Distribution Systems (WDS). In-line robots are designed for this aim. In our previous work, we designed an in-pipe robot [1]. In this research, we present the design of the central processor, characterize and control the robot based on the condition of operation in a highly pressurized environment of pipelines with the presence of high-speed flow. To this aim, an extreme operation condition is simulated with computational fluid dynamics (CFD) and the spring mechanism is characterized to ensure sufficient stabilizing force during operation based on the extreme operating condition. Also, an end-to-end method is suggested for power considerations for our robot that calculates minimum battery capacity and operation duration in the extreme operating condition. Finally, we design a novel LQR-PID based controller based on the system auxiliary matrices that retain the robot stability inside the pipeline against disturbances and uncertainties during operation. The ADAMS-MATLAB co-simulation of the robot-controller shows the rotational velocity with -4 degree/sec and +3 degree/sec margin around x, y, and z axes while the system tracks different desired velocities in pipelines (i.e. 0.12m/s, 0.17m/s, and 0.35m/s). Also, experimental results for four iterations in a 14-inch diameter PVC pipe show that the controller brings initial values of stabilizing states to zero and oscillate around it with a margin of 2 degrees and the system tracks desired velocities of 0.1m/s, 0.2m/s, 0.3m/s, and 0.35m/s in which makes the robot dexterous in uncertain and highly disturbed the environment of pipelines during operation.