Development of a slender continuum robotic system for on-wing inspection/repair of gas turbine engines

Abstract

Abstract-The maintenance works (e.g. inspection, repair) of aero-engines while still attached on the airframes requires a desirable approach since this can significantly shorten both the time and cost of such interventions as the aerospace industry commonly operates based on the generic concept "power by the hour". However, navigating and performing a multi-axis movement of an end-effector in a very constrained environment such as gas turbine engines is a challenging task. This paper reports on the development of a highly flexible slender (i.e. low diameter-to-length ratios) continuum robot of 25 degrees of freedom capable to uncoil from a drum to provide the feeding motion needed to navigate into crammed environments and then perform, with its last 6 DoF, complex trajectories with a camera equipped machining end-effector for allowing in-situ interventions at a low-pressure compressor of a gas turbine engine. This continuum robot is a compact system and presents a set of innovative mechatronics solutions such as: (i) twin commanding cables to minimise the number of actuators; (ii) twin compliant joints to enable large bending angles (±90deg) arranged on a tapered structure (start from 40mm to 13mm at its end); (iii) feeding motion provided by a rotating drum for coiling/uncoiling the continuum robot; (iv) machining end-effector equipped with vision system. To be able to achieve the in-situ maintenance tasks, a set of innovative control algorithms to enable the navigation and end-effector path generation have been developed and implemented. Finally, the continuum robot has been tested both for navigation and movement of the end-effector against a specified target within a gas turbine engine mock-up proving that: (i) max. deviations in navigation from the desired path (1000mm length with bends between 45° and 90°) are ±10 mm; (ii) max. errors in positioning the end-effector against a target situated at the end of navigation path is 1 mm. Thus, this paper presents a compact continuum robot that could be considered as a step forward in providing aero-engine manufacturers with a solution to perform complex tasks in an invasive manner.

A Novel Discrete Wire-Driven Continuum Robot Arm with Passive Sliding Disc: Design, Kinematics and Passive Tension Control

“…He modified Walker's kinematic formulation for multi-section manipulators and relations using cable length variation [19]. Kinematics based on cable length variation were also proposed by X. Dong on twin-pivot continuum robot arm for gas turbine inspection [20]. Furthermore, Koganezawa proposed a simple kinematic solution for discrete cable driven manipulators by using homogeneous transformation matrices multiplication to compute the end effector position.…”

Design and Development of a Slender Dual-Structure Continuum Robot for In-Situ Aeroengine Repair

“…where θ s1 and θ s2 are the slope angles of two planes, respectively and the ∆θ i is the segment bending angle with the bending angle θ i which can be obtained by (1). Furthermore, the total change in length of the cable in the i th section (body) can be obtained by taking into account the disk number in each body section, N body .…”

“…In-situ aeroengine repair can significantly reduce currently accepted maintenance cycle which is extensive and costly due to the need to remove engines from the wing of an aircraft to fully strip and overhaul. Over the past decade, robots have been integrated into many service operations around the world and have enabled or improved many new in-situ aeroengine repair technologies [1]. Currently, most employed devices are either rigid-segmented boreblending tools [2] with one DoF or flexible ones with two DoFs to perform bending movement in two directions [3].…”

Robots Hiper-Redundantes: Clasificación, Estado del Arte y Problemática

“…Además, presenta una estructura mecánica innovadora, ya que hace uso de una duplicidad de cables para minimizar el número de actuadores, y de una duplicidad de articulaciones, para permitir grandes ángulos de rotación sobre sí mismo. Para lograr las tareas de mantenimiento, un conjunto de algoritmos de control innovadores permite su navegación y la generación de la trayectoria de su efector final (Dong, Axinte et al 2017) (Tabla 2).…”