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

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 (±90°) arranged on a tapered structure (start from 40 mm to 13 mm 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 (1000 mm 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

Design, modelling and validation of a novel extra slender continuum robot for in-situ inspection and repair in aeroengine

The file archived on this repository is a preprint, arXiv:1910.04572v1 [cs.RO], available at: https://doi.org/10.48550/arXiv.1910.04572 (submission history: Mingfeng Wang [v1] Wed, 9 Oct 2019 10:37:12 UTC (1,745 KB)). It has not been certified by peer review. The version of record published by Elsevier is available at https://doi.org/10.1016/j.rcim.2020.102054.In-situ aeroengine maintenance works are highly beneficial as it can significantly reduce the current maintenance cycle which is extensive and costly due to the disassembly requirement of engines from aircraft. However, navigating in/out via inspection ports and performing multi-axis movements with end-effectors in constrained environments (e.g. combustion chamber) is fairly challenging. A novel extra-slender (diameter-to-length ratio < 0.02) dual-stage continuum robot (16 degree-of-freedom) is proposed to navigate in and out confined environments and perform required configuration shapes for repair operations. Firstly, the robot design presents several innovative mechatronic solutions: (i) dual-stage tendon-driven structure with bevelled disks to perform required shapes and to provide selective stiffness for carrying high payloads; (ii) various rigid-compliant combined joints to enable different flexibility and stiffness in each stage; (iii) three commanding cables for each 2-DoF section to minimise the number of actuators with precise actuation. Secondly, a segment-scaled piecewise-constant-curvature-theory based kinematic model and a Kirchhoff-elastic-rod-theory based static model are established by considering the applied forces/moments (friction, actuation, gravity and external load), where the friction coefficient is modelled as a function of bending angle. Finally, experiments were carried out to validate the proposed static modelling and to evaluate the robot capabilities of performing the predefined shape and stiffness

Developing Intuitive, Closed-Loop, Teleoperative Control of Continuum Robotic Systems

This thesis presents a series of related new results in the area of continuum robot teleoperation and control. A new nonlinear control strategy for the teleoperation of extensible continuum robots is described. Previous attempts at controlling continuum robots have proven difficult due to the complexity of their system dynamics. Taking advantage of a previously developed dynamic model for a three-section, planar, continuum manipulator, we present an adaptation control-inspired law. Simulation and experimental results of a teleoperation scheme between a master device and an extensible continuum slave manipulator using the new controller are presented. Two novel user interface approaches to the teleoperation of continuum robots are also presented. In the first, mappings from a six Degree-of-Freedom (DoF) rigid-link robotic arm to a nine degree-of-freedom continuum robot are synthesized, analyzed, and implemented, focusing on their potential for creating an intuitive operational interface. Tests were conducted across a range of planar and spatial tasks, using fifteen participant operators. The results demonstrate the feasibility of the approach, and suggest that it can be effective independent of the prior robotics, gaming, or teleoperative experience of the operator. In the second teleoperation approach, a novel nine degree-of-freedom input device for the teleoperation of extensible continuum robots is introduced. As opposed to previous works limited by kinematically dissimilar master devices or restricted degrees-of-freedom, the device is capable of achieving configurations identical to a three section continuum robot, and simplifying the control of such manipulators. The thesis discusses the design of the control device and its construction. The implementation of the new master device is discussed and the effectiveness of the system is reported

Real-time method for tip following navigation of continuum snake arm robots

This paper presents a novel technique for the navigation of a snake arm robot, for real-time inspections in complex and constrained environments. These kinds of manipulators rely on redundancy, making the inverse kinematics very difficult. Therefore, a tip following method is proposed using the sequential quadratic programming optimization approach to navigate the robot. This optimization is used to minimize a set of changes to the arrangement of the snake arm that lets the algorithm follow the desired trajectory with minimal error. The information of the Snake Arm pose is used to limit deviations from the path taken. Therefore, the main objective is to find an efficient objective function that allows uninterrupted movements in real-time. The method proposed is validated through an extensive set of simulations of common arrangements and poses for the snake arm robot. For a 24 DoF robot, the average computation time is 0.4 s, achieving a speed of 4.5 mm/s, with deviation of no more than 25 mm from the ideal path

Projeto de um dispositivo robótico de cadeia aberta em ambiente de simulação

TCC(graduação) - Universidade Federal de Santa Catarina. Centro Tecnológico. Engenharia de Controle e Automação.O Instituto SENAI de Inovação em Sistemas Embarcados apresenta-se como uma entidade que oferece soluções em diversos segmentos estratégicos tais como indústrias aeroespacial, automotiva, de energia, óleo e gás, automação e TIC. Este PFC está inserido em um projeto do tipo PoC do inglês, Proof of Concept que vem sendo desenvolvido no SENAI. Por conta de uma demanda, o instituto ficou responsável pela construção de um manipulador robótico, o qual deveria possuir oito graus de liberdade, na atual etapa o manipulador apresentará apenas três, e com a capacidade de exercer uma quantidade significativa de torque em seu efetuador final, além disso sua estrutura deveria ser compacta o suficiente para que esse mesmo manipulador se deslocasse através de ambientes restritos. Atualmente já são empregados robôs na linha de montagem da empresa contratante, mas esses robôs são manipuladores industriais antropomórficos comuns, entretanto há problemas envolvidos com o tamanho desses manipuladores, dessa forma há uma necessidade da empresa em se possuir robôs com uma configuração não tão usual. Este trabalho de PFC está focado em dois aspectos: o primeiro na implementação da programação de movimentação do robô com alguns algoritmos de geração de trajetória e o segundo na construção de uma plataforma customizada para esta função. Esta plataforma ainda está em fase de construção, e implementa muitas funções de forma genérica, isso para que possa ser usada não apenas neste projeto.The SENAI Institute for Embedded Systems Innovation is an entity that offers solutions in several strategic segments such as aerospace, automotive, energy, oil and gas, automation and ICT industries. This PFC is part of a PoC project, Proof of Concept, which has been developed in SENAI. Due to a demand, the institute was responsible for the construction of a robotic manipulator, which should have several degrees of freedom and with the capacity to exert a significant amount of torque in its end effector, in addition its structure should be compact enough for that same handler to move through restricted environments. Robots are currently employed on the assembly line of the contracting company, but these robots are common anthropomorphic industrial manipulators, however there are problems involved with the size of these manipulators, so there is a need for the company to own robots with a not so usual configuration. This work of PFC is focused in two aspects: the first in the implementation of the programming of movement of the robot with some algorithms of generation of trajectory and the second in the construction of a platform customized for this function. This platform is still under construction, and implements many functions in a generic way, so that it can be used not only in this project