Motion control method for adaptive self-reconfigurable pipeline robot based on environmental perception

A motion control method for an adaptive self-reconfigurable pipeline robot based on environmental perception, comprising the following steps:

• step 1:
• placing a pipeline robot in a pipeline, using a depth camera to acquire images of the pipeline in front, recognizing a scene of the pipeline through a neural network after denoising and preprocessing on the images, segmenting planar surfaces and curved surfaces in the images according to recognition results, projecting segmentation results of regions on 2D images into a 3D space through a camera projection model, and extracting boundary lines of the pipeline;
• step 2:
• calculating a straight-pipe width, a bent-pipe curvature, a slope angle, and a step height according to features of the boundary lines to analyze passability of the robot;
• step 3:
• designing a path planner and a swing-arm planner to generate a reference trajectory and a swing-arm angle sequence of the robot, performing smoothing, and inputting the reference trajectory and the swing-arm angle sequence into a model predictive control (MPC) motion controller;
• step 4:
• estimating a position and state of the robot through an Error State Kalman Filter (ESKF) algorithm according to data from the depth camera, an inertial measurement unit (IMU), and a wheel speed sensor, and inputting estimation results and collision warning signals from Time-of-Flight (TOF) modules into the MPC motion controller in real time;
• and
• step 5:
• constructing a quadratic objective function through a kinematic model of a dual-swing-arm crawler robot in combination with the reference trajectory and the swing-arm angle sequence in the MPC motion controller, solving through an iterative method, and outputting a signal for adaptive motion control of the robot;
• wherein
• a measured length, width, and height of the pipeline robot are denoted as Ll, Lw, Lh, a radius of a driving wheel is denoted as R, a radius of a driven wheel on a swing arm is denoted as r, a wheelbase of a front swing arm is denoted as lF, a wheelbase of a rear-swing arm is denoted as lR, and a wheelbase of a traveling main body is denoted as lB, wherein the step 2 comprises:
• after obtaining an equation of each boundary line, calculating a width of the pipeline using two straight lines on a bottom surface of the pipeline in a straight-pipe scene according to geometric characteristics of the pipeline, calculating a height of the pipeline using two straight lines on a side surface of the pipeline, and identifying passability of the straight-pipe scene in front according to results of comparison with outer envelope dimensions of the robot;
• and
• calculating an angle between side boundary lines as a slope angle θs of a slope environment, wherein a coefficient of friction between the robot and a wall surface of the pipeline is denoted as μ, and when arctan(μ)<θs, the slope in front is deemed passable;
• calculating a distance between a boundary line on a step surface and a boundary line on the bottom surface of the pipeline in the step scene to obtain a step height H, and when
• l
• R
• +
• r
• +
• l
• B
• ⁢
• sin
• ⁢
• α
• 2
• -
• R
• cos
• ⁢
• α
• >
• H
• ,
• the step in front is deemed passable,
• α
• ∈
• (
• 0
• ,
• arccos
• ⁢
• R
• 2
• ⁢
• l
• B
• )
• ;
• calculating an inner curvature λin and an outer curvature λout of a pipe bend using two curved lines on the bottom surface of the pipeline in the bent-pipe scene, and then identifying passability conditions of the bent pipe:
• {
• L
• w
• <
• 1
• /
• λ
• out
• -
• 1
• /
• λ
• in
• L
• 1
• <
• 2
• ⁢
• (
• 1
• /
• λ
• out
• )
• 2
• +
• (
• 1
• /
• λ
• in
• +
• L
• w
• )
• 2
• .