Waypoint based online trajectory generation and following control for the ACT/FHS

New research activities on DLR’s EC135 ACT/FHS research helicopter, has led to new challenges for the automatic flight control software of this testbed. Noise abatement flights, innovative automatic approach trajectories and other topics all require the helicopter to follow a set of waypoints as precisely as possible. This paper presents a new algorithm which is capable of generating curvature-continuous trajectories. A modification of the natural cubic spline algorithm is presented, which allows to incrementally fit cubic splines with defined boundary conditions through subsets of the waypoint list. By joining several of these splines with matching boundary condition, a continuous trajectory is obtained. This approach allows to distribute the computational load of the cubic spline calculation over several execution cycles of the real-time system. Based on these results, two controllers to follow the generated trajectories are developed and compared in terms of their ability to reduce and stabilize the distance between the trajectory and the vehicle. The approach is verified in DLRs Air Vehicle Simulator (AVES)

HID-1 is required for sensing CO₂ level in the pharynx.

<p>(<b>A</b>) One-day-old adult <i>hid-1(yg316)</i> and N2 worms were exposed to 5%, 10%, or 20% CO₂ balanced with 21% O₂ and N₂. The pumping rate was measured under a dissecting microscope while the animals were exposed to the different gas mixtures. A gas mixture of 21% O₂ and 79% N₂ was used as a normal air control. (<b>B</b>) The inhibition of the pumping rate of the pharynx after exposure to high CO₂ level in <i>hid-1(yg316)</i> allele mutants is significantly reduced. Similarly, the inhibition of the pumping rate of the pharynx after exposure to high CO₂ level is reduced in other <i>hid-1</i> allele mutants (<i>sa772</i> and <i>sa1058</i>). Transgenic expression of HID-1 fused to eGFP in the <i>sa722</i> or <i>yg316</i> background (<i>hid-1(sa722</i>);HID-1::GFP or <i>hid-1(yg316)</i>;HID-1::GFP) is sufficient to restore the effect of high CO₂ level on the pumping rate back to the wild-type phenotype. In all experiments <i>N</i>≥30 animals. Different groups were compared by one-way ANOVA followed by <i>t</i> test. ***<i>P</i><.001. Error bars indicate SEM.</p