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Prototype and coordination system of the overactuated UAV platform. Each of the four traditional quadcopters is mounted on a two-DOF passive gimbal with equal distance to the center of main frame to generate three-dimensional thrust force.

Prototype and coordination system of the overactuated UAV platform. Each of the four traditional quadcopters is mounted on a two-DOF passive gimbal with equal distance to the center of main frame to generate three-dimensional thrust force.

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Article
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Multirotor copters with full six Degree of Free-dom(DoF) maneuvering are often overactuated. The control allocation of overactuated UAV platforms can have an infinite number of solutions due to their redundancy. The most common allocation framework is based on Force Decomposition(FD), which provides a robust least-square solution and is easy to imp...

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Context 1
... this paper, we will implement all three frameworks on our overactuated multirotor UAV platform to comprehensively evaluate their robustness in simulation and verify their performance in experiment. This platform (Fig. 1) has a similar highlevel dynamics compared to the twist-and-tilt rotor quadcopter platforms presented in [11] and [12]. We compare the performance of the three frameworks under kinematic-singularity in tracking a vertical rotation ...
Context 2
... overactuated UAV platform to evaluate three allocation frameworks ( Fig. 1) consists of four traditional mini quadcopters attached to the central frame via passive gimbal joints with two DoF that are perpendicular to each other, and the joint angles are independently controlled by torques of each quadcopter [13]. The passive joints have unlimited ranges of angulation, so the thrust vector generated by the ...
Context 3
... have unlimited ranges of angulation, so the thrust vector generated by the quadcopter can be pointed at any direction. Under the control framework, each quadcopter provides thrust force with variable magnitude and direction defined by the two-DoF gimbal, resulting in a system with 12 DoF in total. The corresponding coordinate frames are shown in Fig. ...

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Citations

... However, the limited range of the tensioned cables or spherical joints used to connect quadcopters and the tool frame significantly constrains the achievable attitudes. Our group has proposed modular vectored thrust units made of quadcopters and passive mechanisms without angle range limits or constraints for two realizations, one DoF hinge [28,29] or two DoF gimbal [30,31,32]. These modular vectored thrust units overcome the constraints of the limited orientations between the quadcopters and the main frame in [25,26,27], and enable creating new multirotor aerial platforms for unique capabilities and performance. ...
... Using eight DoF input to represent the six DoF virtual inputs and has multiple solutions, including the leastsquare allocation (24) widely used in previous works [21,30,31]. Actually, it can be observed from (20) that adding any components from the nullspace of ...
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... Overactuated aerial vehicles were considered in [19] and the thrust allocation problem was examined using a quad-copter on a dual-axes gimbal configuration followed by singularity avoidance methods. ...
... The controller (22) stabilizes the system dynamics(19) for small deflections. ...
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... As introduced in Section I, the unmodeled dynamics are not considered in the nominal controller framework and they can only be compensated by the integral operation of the tracking controller. Therefore, even if additional inputs are included or the allocation is changed to another allocation method [13][14][15]25], as long as the goal is to solve for the control inputs from Eq. (30), the control performance will be difficult to improve. Based on these reasons, we decided to use the auxiliary inputs to formulate a compensation loop. ...
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