Design and control of a collision-resilient aerial vehicle with an icosahedron tensegrity structure

Abstract

We introduce collision-resilient aerial vehicles with icosahedron tensegrity structures, capable of surviving high-speed impacts and resuming operations post-collision. We present a model-based design approach, which guides the selection of the tensegrity components by predicting structural stresses through a dynamics simulation. Furthermore, we develop an autonomous re-orientation controller that facilitates post-collision flight resumption. The controller enables the vehicles to rotate from an arbitrary orientation on the ground for takeoff. With collision resilience and re-orientation ability, the tensegrity aerial vehicles can operate in cluttered environments without complex collision-avoidance strategies. These capabilities are validated by a test of an experimental vehicle operating autonomously in a previously-unknown forest environment.

Figures (12)

• Figure 1: The icosahedron tensegrity aerial vehicle created with the proposed model-based design approach. The length of each rod in the shell is 20cm. All electronics are directly mounted on the tensegrity rods.
• Figure 2: (a) The tensegrity vehicle is simplified as point masses in a stress network. Cyan spheres represent tensegrity nodes whereas orange spheres represent quadcopter nodes. (b) Strings and rods are modeled as massless spring-damper pairs. (c) Connections between two short rods are modeled as torsional spring-damper pairs.
• Figure 3: Left: illustration of the two collision-resilient aerial vehicles used for comparison. The top has a tensegrity shell whereas the bottom uses a propeller guard. Both vehicles have the smallest possible protection structure to host quadcopters with propellers of the same size. Right: we model both vehicles as point masses suspended in a stress network. We describe the vehicle's body-fixed frame with a set of three axes orthogonal to each other: $\boldsymbol{e}^B_x$, $\boldsymbol{e}^B_y$ and $\boldsymbol{e}^B_z$. Notice that for the tensegrity aerial vehicle, the quadcopter nodes are on the rods parallel to the $\boldsymbol{e}^B_x$ axis.
• Figure 4: Visualization of the Monte Carlo study result. The positions of the points correspond to the collision orientation. Top left: scatter plot of the maximum stress in propeller guard during collisions. Bottom left: scatter plot of the maximum stress in tensegrity. Right: the ratio of the maximum stress in propeller guard to that in tensegrity. Larger values indicate more tensegrity advantage. The color on the surface is interpolated from the scattered simulated experiment data points.
• Figure 5: This figure illustrates the structural advantage of tensegrity over propeller guard for aerial vehicles of varying scales. The horizontal axis represents the scaling factor, while the vertical axis indicates the relative advantage, measured as the ratio of maximum stress endured by propeller guard to tensegrity during collision simulations. The rising trend suggests the tensegrity's advantage becoming more prominent with larger vehicle sizes.