This letter presents two long continuum robots, inserted through small holes, and working collaboratively in a crammed space to manipulate an extreme-temperature (>2000 °C) flame for coating repair on aeroengines without the need of their disassembly. One robot (Adder) carries a thermal spray nozzle while the other (Observer) carries cameras and a flame ignitor, supporting the locomotion and operation of the Adder, which was demonstrated on a real aeroengine offering advantages in both operational time and repair costs.

Continuum robots (CRs) outperform the conventional rigid-link manipulators in aspects of hyper-redundant and compliant features. They provide universal and efficient solutions to access to constrained environments, e.g., aero engines and industrial vessels. In this article, a slender tendon-driven CR (length/diameter: 715/12.7 mm) is introduced for in situ maintenance of aero engine combustors. Two control challenges, the piecewise-constant-curvature (PCC) assumption mismatch and sections coupling issues, are discussed to explain the defect of model-based kinematic controllers on specific designs. Then, inspired by the tug of war, a novel local model-less controller utilizing a fuzzy logic algorithm is proposed for the feedback control of a single section. This implements the control policies directly from the task space to the actuation space, avoiding the model mismatch of the PCC assumption owing to the explicit call of arc parameters. Experiments on a single section of the tendon-driven CR, in comparison with PCC-based method, validate the stability and universality of the developed controller, which can reach $ \pm 1 - $ mm overall positioning accuracy and $ \pm 0.5$ - mm positional accuracy for 75% of the test points in both X and Y directions. Further, a set of trails on two distal sections of a long robot demonstrate that the controller can also effectively minimize the section coupling issue.

In-situ aeroengine maintenance works (e.g. inspection, repair) are highly beneficial as it 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. However, feeding in/out via inspection ports and performing a multi-axis movement of an end-effector in a very constrained environment such as aeroengine combustion chamber is a fairly challenging task. This paper presents the design and development of a highly slender (i.e., low diameter-to-length ratio) dual-structure continuum robot with 16 degrees of freedom (DoFs) to provide the feeding motion needed to navigate into confined environments and then perform a required configuration shape for further repair operation. This continuum robot is a compact system and presents a set of innovative mechatronic solutions such as: (i) two-stage tendon-driven structure with bevelled disk design to perform required configuration shape and to provide selective stiffness for the ability of taking high payloads; (ii) various compliant joints to enable different flexibility requirement in each stage; (iii) three commanding cables for each 2-DoF section to minimise the number of actuators with a precise actuation. To be able to achieve the desired configuration shape, a kinematic model has been established and the configuration-cable kinematics has been implemented. Finally, the continuum robot has been built and tested for performing the predefined configuration shape.

Current robotic laser weeding systems mostly rely on serial mechanisms with one or two actuated axes, which can barely meet the requirements of high precision and dynamic performances. In this article, a novel laser weeding gimbal is proposed based on a two-degree-of-freedom 5-revolute rotational parallel manipulator to perform a dynamic intrarow laser weeding operation. Comprehensive analyses consisting of kinematics, workspace, singularity, and dynamics are carried out to evaluate the performance of the proposed design. Finally, experimental tests were conducted both in lab and field environments and the results are provided, in which the positioning accuracy has been evaluated as in average errors of 0.62 mm in position at the distance of 535 mm, and the dynamic weeding efficiency is around 0.72 s/weed with a dwell time of 0.64 s at the tracking speed of 0.1 m/s. The effectiveness of the proposed dynamic intrarow weeding mechanism has been evaluated in a real field trial.

Current research on walking robots strives to achieve a higher efficiency, a better load capacity, and an increased adaptability. Parallel kinematic manipulators (PKMs) are characterized by high payload and accuracy, but conventional PKMs with fixed configurations are limited to constrained workspaces in known structured environments. In this article, we propose a parallel reconfigurable walking machine tool that overcomes these limits by adapting its configuration and gaits to different scenarios. A lightweight and compact positioning system with shape memory alloy actuation is presented to achieve reconfiguration capabilities. Furthermore, kinematic, stability, and force analyses are reported to determine the optimal walking gaits in three different scenarios (with inclined slopes at different angles) and four robot configurations. Finally, a set of experiments with the physical prototype validates the proposed models. The results show that symmetric configurations present a better performance at lower ground inclinations (0.5% error), whereas asymmetric configurations can climb on slope conditions that would prevent the use of conventional PKMs (18% or 10°).