Flapping-wing flight: actuation & control - 5 Flashcards
What is the respective role of the wings and tailplane in tailed FWMAVs?
Wings are mainly responsible for lift and thrust, and the tail is for maneuvering and active control by handling pitch and yaw,
What effect does varying the flapping frequency have on tailed FWMAVs?
Higher flapping frequency leads to an increased force generation which allows for slower flight.
What are the advantages and disadvantages, respectively, of (i) tailplane-based actuation, and (ii) wingbased
actuation?
(i) Adds passive stability, allows for a simple flapping mechanism, and leads to lower complexity. However, it offers less maneuverability, higher sensitivity to perturbations, and reduces steering capabilities.
(ii) High maneuverability, smaller and lighter designs, and more resilience to wind gusts. However, with its more complex flapping mechanisms, more complex control needs active stabilization.
What parameters can be adjusted to enable wing-based actuation?
Flapping frequency f, stroke amplitude 2\phi, stroke offset \phi_off, stroke plane angle beta, geometric angle of attack \alpha, wing rotation angle \theta and wing rotation timing, t_rot
What effect do the (i) wing angle of attack, (ii) flapping frequency, and (iii) stroke amplitude have on
wing force production?
They all lead to a higher force production
What two high-level approaches can be used to implement actuation on tailless FWMAVs?
Flapping kinematics modulation by changing the flapping parameters during the flap cycle or wing deformation by deforming the wings during the flap cycle
Explain two different ways to generate, respectively, rolling, pitching and yawing moments on FWMAVs.
Roll: Stroke offset asymmetric left right and amplitude or varying flapping frequency asymmetrically
Pitch: Stroke offset symmetrically on both sides and amplitude or tilt stroke plane
Yaw: Stroke offset asymmetric left-right opposed and amplitude or tilt-wing planes differently or vary flapping speed opposed on each side’s strokes
What are some of the requirements for effective wing actuation?
Low cross-coupling between axes (separate actuators should not influence each other)
Minimal time lag (get the minimum time it takes to respond to a command)
Low weight
Fast control moment generation
Spectrum-wide moment generation
What are the major challenges for FWMAV control?
Time-varying dynamics, nonlinear dynamics, wide flight envelope, real-life implementation, limiting modeling capability, limited system knowledge
What sensors can be used for FWMAV control?
Gyroscope, accelerometer, vision sensors, magnetometer, pressure sensor, gps, motion tracking system
What are the difficulties of fully on-board control?
FWMAVs have mass restrictions so the number of sensors is limited. Another challenge is obtaining the required measurements on board with sufficient accuracy (there is noise, drift, etc).
Explain the concept of sensor fusion.
Combine data from different sensors to get the best of different sensors. The estimation of a variable will be a combination of different sensor data.
