Overall aim of the project

Figure 1: Illustration of the method to construct bioinspired foot and limb. (1) Biomechanical analysis of the limb for stable perching from living birds using pressure sensors and video acquisition in 3D with high-speed cameras (2) Construction of a bird-inspired limb and tactile pincer using artificial muscles, tendons and smart material for the active skin (Rakotondrabe, 2013), (Rakotondrabe et al., 2015), (Ivan et al., 2017), (Aljanaideh, 2018), (3) Test of stability of the robotic foot and limb using feedback control laws.

We want to understand how birds can dynamically maintain their stability on a branch using a tactile perception. We will model and construct a bird-inspired perching system for drones. The approach is interdisciplinary. The consortium is composed of :
(i) a morpho-functionalist at the Muséum National d’Histoire Naturelle in Paris (MNHN), Anick Abourachid and Thierry Decamps (Engineer at MNHN). We thank the staff and the caretakers of the Ménagerie of the Jardin des Plantes in Paris for giving us the possibility to make preliminary experiments with Kea parrots.
(ii) bio-roboticists at the Institute of Movement Sciences in Marseille (ISM Aix-Marseille Univ), Thibaut Raharijaona and Franck Ruffier.
(iii) a researcher in micro-mechatronic systems and materials at the national school of engineering in Tarbes (LGP – ENIT/INPT, University of Toulouse), Micky Rakotondrabe.

We will design a kinamtic model of the foot and the limb which takes into account the pressure applied by the foot on the substrate. We will collect data from experiments on living birds such as parrots, Harris buzzards and crows.
The perching system will be optimized in terms of energy consumption and space requirements. It will be equipped with a tactile perception using piezoelectric materials and artificial tendons.


Design a dynamic model of the bird’s leg including the pressure applied by the foot for perching drones (Figure 1).

Scientific issues

(i) We need to understand the biomechanical motion of the bird’s leg while perched on a branch,
(ii) We need to understand how the bird applies the pressure with its foot and fingers on the branch,
(iii) We need to understand the influence of the foot morphology on the perching performance.


(i) We will model the dynamics of the living bird’s leg while perched using video acquisition in 3D with high-speed cameras. For instance, in Backus et al. (2015), the authors model in 2D a grasping foot of a bird using full actuated and single tendon approaches (figure 2). They optimize the set of contact and actuator forces for a given force applied to the object. The model is limited in terms of degrees of freedom in order to make it numerically tractable.

Figure 2 : Diagram of how the digits wrap about an object, for a simulation of a single, distally inserted (red cross) tendon for digits I and III. For a given position of the object relative to the foot, the phalanges are sequentially wrapped about the object so that each link is tangent to the object and the talon tips make contact (Backus et al. 2015).

We will give a biomechanical model of the bird’s leg taking into account the muscles, the tendons and the articulations. For instance, in Abourachid (1991) the authors described the musculature of the pelvic limb in the turkey. In Baumel et al. (1993) and Raikow (1985), we can find the general anatomic description of the leg for avian species.
We will also use dissections of bird’s legs to observe the important elements such as tendons useful for finger bending (figure 3).

Figure 3 : Photo of dissection of a chicken’s leg (Gallus gallus) from the knee to the foot (lateral view); and highlighting of the flexor tendons of the fingers (picture taken by Damien Horsin).

(ii) We will measure the pressure applied by the foot and the fingers on the branch using an experimental setup equipped with pressure sensors. The results of research in Abourachid et al. (2017) and Tsang et al. (2019) describe bird’s foot configuration and its plantar structure (figure 4). These results based on measurements and the literature will stand for 2 complementary approaches. We will aim at describing the skin pattern of the foot using images provided by a computer-assisted tomography in 3D.

Figure 4 : Foot of a single comb White Leghorn chicken (Gallus gallus); plantar view (Baumel et al., 1993).

(iii) We will study the influence of the foot morphology on the perching performance using the results provided in Abourachid & Höfling (2012), Abourachid & Hugel (2016), Abourachid et al. (2016; 2017) and Raikow (1985) (figure 5). We aim at designing a 2D mechatronic prototype of the bird’s leg with joints and tendons.

Figure 5 : Lines of action of the principal muscles involved in the movements of the foot. EDL, m. extensor digitorum longus; FL, m. fibularis longus; G, m. gastrocnemius; TV, m. tibialis cranialis (Raikow, 1985).


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