In this airticle, we introduce a novel aerial robot unit called TRADY, which is a tilted rotor-equipped aerial robot with autonomous in-flight assembly and disassembly ability. One TRADY unit can be combined and separated from another TRADY unit in the air autonomously, thereby extending or reducing the degree of control freedom of the aircraft. This robot is controlled by under-actuated model as a quadrotor in the unitary state, and when the two units are assembled, they are controlled by fully actuated model as a single octorotor. This system is achieve by tilted rotors with optimized tilt angles and the docking mechanism capable of both doking and undocking with high precision. Furthermore, we present a novel system configuration that allows to switch controllers between under-actuated and fully-actuated in the air, including the state transition method to compensate for discrete changes during system switchover. In the experiment with the real mahine, TRADY is able to perform aerial assembly and disassembly motion with a success rate of about 90% by using a new motion plan that employed recovery behavior from hazardous conditions. We also confine through task execution experiments that, by assembling two units, TRADY can control transition and rotation independently, and it produces more than 9 times the torque of a single unit moreover. To the best of our knowledge, this work represents the first time that a robot system has been developed that can perform both assembly and disassembly while seamlessly transitioning between fully-actuated and under-actuated models.

翻译：本文介绍了一种名为TRADY的新型空中机器人单元，这是一种配备倾转旋翼且具备自主空中组装与拆解能力的空中机器人。一个TRADY单元可自主与另一TRADY单元在空中完成结合与分离，从而扩展或缩减飞行器的控制自由度。该机器人在单体状态下采用欠驱动模型（四旋翼）进行控制；当两个单元组合后，则通过全驱动模型（八旋翼）实现控制。该系统通过优化倾转角度的旋翼以及具备高精度对接与分离能力的对接机构实现上述功能。此外，我们提出了一种新颖的系统配置方案，允许在空中完成欠驱动与全驱动控制器之间的切换，并包含一种状态转换方法以补偿系统切换过程中的离散变化。在真实样机实验中，TRADY采用了一种包含危险状态恢复行为的新型运动规划策略，成功实现了约90%成功率的空中组装与拆解动作。通过任务执行实验进一步验证，当两个单元组合后，TRADY能够独立控制平移与旋转运动，且产生的扭矩超过单个单元的9倍。据我们所知，本工作首次实现了可在全驱动与欠驱动模型间无缝切换、同时执行组装与拆解任务的机器人系统。