Abstract:

Hyper-redundant manipulators (HRMs) are used in non-invasive on-site maintenance tasks of aeroengines owing to their excellent dexterity and adaptability.
However, it is challenging for them to achieve the obstacle avoidance planning in confined environment compared to conventional manipulators. This work presents a 3Ddynamic safety envelope (3DSE) based collision avoidance strategy to tackle this challenge. First, unlike conventional obstacle expansion-based methods that are computationally expensive and conservative, 3DSE is proposed and applied to establish collision constraints. Then, the motion in confined spaces is divided into trajectory tracking and blade detection processes. To address the issue of HRM’s inability to fully track the trajectory, the continuous motion trajectory is discretized, and 3DSE is employed to update the trajectory nodes. The blade detection process when the base is fixed is modeled as an inverse kinematics
(IK) problem of HRM, and a heuristic serpentine scanning method based on 3DSE and regional adaptation is proposed. An 18 degrees-of-freedom HRM prototype is built to experimentally validate the mechanical design and the performance of the proposed method. The results show that it well completes the traversing and fault detection of multistage blades in confined space.