Tilt-X: Enabling Compliant Aerial Manipulation through a Tiltable-Extensible Continuum Manipulator
Authors: Anuraj Uthayasooriyan, Krishna Manaswi Digumarti, Jack Breward, Fernando Vanegas, Julian Galvez-Serna, Felipe Gonzalez
Organizations: QUT Centre for Robotics, Queensland University of Technology, Brisbane, QLD Australia 4000 · School of Electrical Engineering and Robotics, Queensland University of Technology, Brisbane, QLD Australia 4000 · REF,Queensland University of Technology, Brisbane, QLD Australia 4000
Aerial manipulators extend the reach and manipulation capabilities of uncrewed multirotor aerial vehicles for inspection, agriculture, sampling, and delivery. Continuum arm aerial manipulation systems offer lightweight, dexterous, and compliant interaction opportunities. Existing designs allow manipulation only below the UAV which restricts their deployability in multiple directions and through clutter. They are also sensitive to propeller downwash. Addressing these limitations, we present Tilt-X, a continuum arm aerial manipulator that integrates a tilting mechanism, a telescopic stage, and a cable-driven continuum section. We present its design and kinematic model and validate it through flight demonstrations. Tilt-X enables a volumetric workspace with up to 75 mm extension and planar orientations between 0∘ to 90∘. Experiments comparing end effector pose with and without downwash quantitatively measure its accuracy, providing critical evidence to guide the design and control of reliable aerial manipulators. Results show stabilisation of end effector pose as the manipulator extends out of the propeller influence zone.
Figures & tables
Fig. 2 : The electrical (a) and mechanical (b) architecture of the Tilt-X system showing the various components. (c) an illustration of the tilt and telescoping mechanism that forms the basis of our design.
Fig. 3 : Forward kinematics map from the actuator-space ( q1 - q5 : motor angles) to configuration-space (curvature κ , bending plane angle ϕ , arc length ℓ , tilt angle α , linear extension β ) to task-space pose of the end effector THE .
Fig. 4 : (a) A schematic of the system showing the key coordinate frames - {W} : world, {U} : UAV, {H} : hinge on the UAV, {B} : base of the Tilt-X, {T} : tip of the telescopic mechanism, and {E} : tip of the continuum section. (b) The position of the cables 1-3 relative to the bending plane on the triangular base. (c) The routing of the cables through a pulley system at the hinge is on the bottom right.
Fig. 5 : Workspace of the Tilt-X system. (a) Isometric view colored by radial distance. (b) Front view (X–Z). (c) Top view (X–Y). (d) Side view (Y–Z).
Fig. 6 : (a) Bench-top experimental setup, (b) setup to evaluate wall effect in which a board is placed next to the UAV, (c) setup to evaluate ground effect in which the UAV approaces close to a board and (d) the location of test points around the UAV used for comparing model with experiments.
Exp.
Propeller
Influence
Tilt α
Tilt α
ON/OFF
(wall/ ground)
β = 0 mm
β = 75 mm
1
OFF
N/A
0∘ , 30∘ , 90∘
0∘ , 30∘ , 90∘
2
ON
Free
0∘ , 30∘ , 90∘
0∘ , 30∘ , 90∘
3
ON
Wall
-
90∘
4
ON
Ground
-
0∘ , 30∘
TABLE I : Conditions in the Bench-top Experiments
Fig. 7 : The x,y,z positions of the end effector when only the continuum section is actuated with no tilt present, at an extension of 75 mm.
Fig. 8 : Variation of Euclidean error of positions of the end effector compared to the model when only the continuum section is actuated while no tilt present.
Fig. 9 : Position error under 100% throttle level with reference to the mean position at no throttle. The lines represent the mean and the shading shows the standard deviation.
Fig. 10 : Orientation error under 100% throttle level with reference to the mean orientation at no throttle. The lines represent the mean and the shading shows the standard deviation.