Head-body coupling for pitch stability and aerodynamic braking
A colugo-inspired morphing platform that coordinates its head, body, and posterior surfaces to restore pitch stability and execute terminal braking for perching.
Key contributions
- Showed that scheduled head motion reshapes the anterior membrane and changes the pitching response from destabilizing to restoring.
- Used posterior actuation to set zero-pitch-moment equilibria across angles from 0 to 50 degrees.
- Demonstrated terminal braking in free flight, reducing translational mechanical energy by 77% within 0.43 s.
Liming's role: Co-conceived the study; designed and built LemurGlider; performed the wind-tunnel and free-flight experiments; analyzed the data; and drafted the manuscript.
Manuscript: Liming Zheng et al. “Head-body coupling inspired by gliding mammals restores pitch stability and enables aerodynamic braking for perching.” Under review, 2026.
LemurGlider studies the transition from steady gliding to the rapid pitch-up required before perching. The robot separates the problem into three coordinated functions: the head regulates anterior flow and pitch stability, the posterior surface sets pitch equilibrium, and whole-body rotation generates lift and drag for braking.
The research challenge
Perching over a short distance creates an aerodynamic conflict. The vehicle must increase lift and drag to lose energy, but a steep pitch-up also drives the flow toward separation and can remove the restoring pitch response needed for control. A fixed geometry cannot satisfy the same stability requirement throughout both gliding and braking.
Morphing strategy
The platform draws inspiration from the head and anterior membrane of colugos and other gliding mammals. The head follows the local freestream during pitch-up, reshaping the anterior membrane and moving flow separation downstream. A separate posterior actuator changes the pitching moment without removing the stabilizing contribution of the head-body coupling.
Experimental programme
Liming Zheng designed and built LemurGlider, then tested it under steady angles of attack and prescribed pitch-up motions in the wind tunnel. Force and moment measurements were paired with aerodynamic modelling and flow diagnostics. Free-flight experiments tested whether the measured mechanisms could produce terminal braking toward targets at different heights.
Main findings
- Head scheduling moved the maximum-lift angle from 27° to 42° and changed the effective pitching response from destabilizing to restoring.
- Posterior actuation created zero-pitch-moment equilibria from 0° to 50° angle of attack across attached and separated flow.
- Faster pitch-up increased maximum lift by 41% and raised the drag coefficient at maximum lift from 0.63 to 1.29.
- During free-flight terminal braking, translational mechanical energy fell by 77% within 0.43 s.
Why it matters
The project shows how different body regions can take complementary aerodynamic roles during a demanding manoeuvre. Morphology changes the stability, equilibrium, and braking response in sequence, allowing the airframe to adapt as the flight condition changes.
This manuscript is currently under review. The website presents the research summary and video but does not distribute the manuscript PDF.
Supplementary media
Full experimental videos associated with this project. The selected clip above provides a quick introduction; the videos below document the individual experiments and demonstrations.
Movie S1 · Head articulation and anterior-membrane morphing
Head pitch reshapes the neck membrane at the anterior edge of the continuous lifting surface.
Movie S2 · PIV at static angle of attack
Particle image velocimetry acquisition for fixed-angle measurements at three head configurations.
Movie S3 · Real-time flow visualization
PIV visualization shows how head deflection moves the separated region downstream.
Movie S4 · Closed-loop pitch-equilibrium tracking
Scheduled head and posterior-membrane actuation track commanded equilibria from 0° to 50°.
Movie S5 · Recovery from a pitch disturbance
The model returns toward a 40° equilibrium after an impulse increases its angle of attack to about 55°.
Movie S6 · Dynamic perching PIV
PIV acquisition during prescribed pitch-up manoeuvres from 15° to 80° angle of attack.
Movie S7 · Free-flight terminal braking
Slow-motion flights toward terminal target distances of 3.2 m and 4.2 m.