Abstract
This paper investigates a method to achieve computationally efficient path generation and tracking, suitable for manned operations. To provide an adequate level of comfort to the passengers, path geometric continuity of the second order (\(G^2\)) is used. Thus, generalized 3D \(G^2\) Dubins paths are proposed as a template, later approximated with algebraic polynomial splines of the third order. This allows to leverage the strengths of both Dubins paths and spline-based methods. The proposed splines pseudo-parametrization avoids explicit numerical evaluation of elliptic integrals, while achieving a good approximation of arc-length parametrization. The method is first applied to planar maneuvers, and then extended to complete 3D ones, such as climbing turns. The strategy leads to facilitated 4D planning, that can be either velocity or time-based, re-planning is a local problem, and path tracking convergence is enhanced. The technique has been demonstrated on a certifiable fly-by-wire platform both in laboratory tests and in flights, including landings. Flight results will be shown and discussed at the end of the paper.
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Abbreviations
- \(\chi\), \(\gamma\) :
-
Aircraft’s ground track and flight path angles
- \(\phi\), \(\theta\) :
-
Aircraft’s bank and pitch angles
- p, q :
-
Aircraft’s bank and pitch rates
- u :
-
Non-normalized spline parameter
- r :
-
Pseudo-normalized spline parameter
- \(\bar{r}_k\) :
-
Root at timestep k
- \(\bar{r}^n\) :
-
Candidate root at iteration n
- \(r_1\) :
-
Candidate root for quadratic minimization
- \(\varvec{S}(u)\) :
-
A non arc-length parametrized spline
- \(\varvec{\tilde{S}}(r)\) :
-
A pseudo-parametrized spline
- \(x_s\), \(y_s\), \(z_s\) :
-
Spline’s components along coordinate x,y or z
- \(\varvec{p}\) :
-
A point in 3D space
- \(\varvec{\tau }\) :
-
Tangent vector in 3D space
- \(\kappa\) :
-
Curve curvature
- l(u):
-
Spline arc length
- \(\hat{L}\) :
-
Estimated spline length
References
Airbus Group: Future of Urban Mobility. My Kind of Flyover. [Online]. http://www.airbusgroup.com/int/en/news-media/corporate-magazine/Forum-88/My-Kind-Of-Flyover.html (2017)
Uber Elevate: Fast-Forwarding to a Future of On-Demand Urban Air Transportation. [Online]. https://www.uber.com/elevate.pdf (2017)
Guenter, B., Parent, R.: Computing the arc length of parametric curves. IEEE Comput. Graphics Appl. 10(3), 72–78 (1990)
Wang, F.-C., Wright, P., Barsky, B., Yang, D.: Approximately arc-length parametrized C3 quintic interpolatory splines. J. Mech. Des. 121(3), 430–439 (1999)
Wang, H., Kearney, J., Atkinson, K.: Arc-length parameterized spline curves for real-time simulation. In: Proceedings of 5th International Conference on Curves and Surfaces, pp. 387–396 (2002)
Farouki, R.T., Sakkalis, T.: Pythagorean hodographs. IBM J. Res. Dev. 34(5), 736–752 (1990)
Shanmugavel, M., Tsourdos, A., Zbikowski, R., White, B.A.: 3D path planning for multiple UAVS using pythagorean hodograph curves. In: AIAA Guidance, Navigation, and Control Conference and Exhibit, Hilton Head, South Carolina, pp. 20–23 (2007)
Rathbun, D., Kragelund, S., Pongpunwattana, A., Capozzi, B.: An evolution based path planning algorithm for autonomous motion of a UAV through uncertain environments. In: Digital Avionics Systems Conference. Proceedings. The 21st, vol. 2. IEEE, pp. 8D2–8D2 (2002)
Lian, F.L., Murray, R.: Real-time trajectory generation for the cooperative path planning of multi-vehicle systems. In: Decision and Control, 2002, Proceedings of the 41st IEEE Conference on, vol. 4. IEEE, pp. 3766–3769 (2002)
Conte, G., Duranti, S., Merz, T.: Dynamic 3D path following for an autonomous helicopter. In: Proceedings of of the IFAC Symposium on Intelligent Autonomous Vehicles, pp. 5–7 (2004)
Lorenz, S., Adolf, F.M.: A decoupled approach for trajectory generation for an unmanned rotorcraft. In: Advances in Aerospace Guidance, Navigation and Control. Springer, Berlin, pp. 3–14 (2011)
Fraichard, T., Scheuer, A.: From Reeds and Shepp’s to continuous-curvature paths. IEEE Trans. Rob. 20(6), 1025–1035 (2004)
Jung, D., Tsiotras, P.: On-line path generation for unmanned aerial vehicles using B-spline path templates. J. Guid. Control Dyn. 36(6), 1642–1653 (2013)
Pachikara, A.J., Kehoe, J.J., Lind, R.: A path-parameterization approach using trajectory primitives for three-dimensional motion planning. J. Aerosp. Eng. 26(3), 571–585 (2011)
Yang, K., Sukkarieh, S.: 3D smooth path planning for a UAV in cluttered natural environments. In: Intelligent Robots and Systems, IROS 2008. IEEE/RSJ International Conference on. IEEE 2008, pp. 794–800 (2008).
Yang, K., Sukkarieh, S.: An analytical continuous-curvature path-smoothing algorithm. IEEE Trans. Robot. 26(3), 561–568 (2010)
Jung, D.: Hierarchical Path Planning and Control of a Small Fixed-Wing UAV: Theory and Experimental Validation. Ph.D. dissertation, Georgia Institute of Technology (2007)
Dubins, L.E.: On curves of minimal length with a constraint on average curvature, and with prescribed initial and terminal positions and tangents. Am. J. Math. 79(3), 497–516 (1957)
Zolotukhin, Y.N., Nesterov, A., et al.: Aircraft path planning with the use of smooth trajectories. Optoelectron. Instrum. Data Proces. 53(1), 1–8 (2017)
Wang, H., Kearney, J., Atkinson, K.: Robust and efficient computation of the closest point on a spline curve. In: Proceedings of the 5th International Conference on Curves and Surfaces, pp. 397–406 (2002).
Stevens, B.L., Lewis, F.L.: Aircraft Control and Simulation. Wiley, Oxford (2003)
Barsky, B.A., DeRose, T.D.: Geometric continuity of parametric curves: three equivalent characterizations. IEEE Comput. Graphics Appl. 9(6), 60–69 (1989)
Farouki, R.T.: Construction of G2 rounded corners with pythagorean-hodograph curves. Comput. Aided Geometr. Des. 31(2), 127–139 (2014)
Manning, J.: Continuity conditions for spline curves. Comput. J. 17(2), 181–186 (1974)
Rida, A., et al.: Pythagorean-Hodograph Curves: Algebra and Geometry Inseparable. Springer, Berlin (2008)
Pinchetti, F., Stephan, J., Joos, Fichter, W.: Flysmart—automatic take-off and landing of an EASA CS-23 aircraft. In: Deutscher Luft- und Raumfahrtkongress 2016 (2016)
Acknowledgements
Part of the work executed for this paper has been funded by the FlySmart project, conducted under the LuFo program, and financed by the German Bundesministeriums für Wirtschaft und Technologie. The authors would like to thank the partners in this project, namely Airbus Defence and Space for the management, the Institute for Aircraft Systems of the University of Stuttgart for providing the FBW platform, and Diamond Aircraft for conducting the flight tests.
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Pinchetti, F., Joos, A. & Fichter, W. Efficient continuous curvature path generation with pseudo-parametrized algebraic splines. CEAS Aeronaut J 9, 557–570 (2018). https://doi.org/10.1007/s13272-018-0306-3
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DOI: https://doi.org/10.1007/s13272-018-0306-3