Introduction. In-pipe robots enable non-destructive diagnostics of internal pipeline surfaces in water, oil-and-gas, and process industries, where access is limited and inspection conditions vary substantially. Reliable operation requires adaptive locomotion that maintains traction and stability across diameter changes, bends, joints, and deposits while providing predictable sensor standoff and scan coverage. This paper presents a structural and parametric synthesis approach for designing adaptive locomotion mechanisms for in-pipe robots intended for internal pipeline surface diagnostics.
Methods. A structural–parametric synthesis framework was developed to formalize the pipeline environment as a set of geometric and contact constraints (diameter range, curvature, obstacles, allowable normal forces), generate candidate locomotion structures (multi-module wheeled/tracked and clamping–propulsion hybrid concepts) with explicit compliance and reconfiguration elements, and perform parametric synthesis via constrained multi-objective optimization. Design variables include linkage geometry, module spacing, wheel/track radii, compliant element stiffness, and clamping preload. Objective functions minimize slip risk and energy demand while maximizing traversability (minimum negotiable bend radius and step height) and diagnostic quality indicators (sensor standoff stability and coverage uniformity). The models incorporate quasi-static contact mechanics with Coulomb friction and a simplified actuator capacity model.
Results. Our method produces Pareto-optimal designs that balance traversability, traction margin, and diagnostic stability. Synthesized mechanisms demonstrate improved passability of diameter transitions and elbows while maintaining bounded contact forces compatible with pipeline integrity constraints. Compared with baseline fixed-geometry concepts, adaptive designs yield higher traction margins, reduced sensitivity to friction variability, and more stable sensor standoff, which directly improves the repeatability of surface diagnostic measurements.
Conclusions. Structural and parametric synthesis provides a systematic route for designing adaptive in-pipe locomotion mechanisms tailored to specific pipeline networks and diagnostic tasks. The resulting design maps and Pareto sets support evidence-based mechanism selection and parameter tuning, improving mobility robustness and measurement quality for internal pipeline surface diagnostics.
