Towards Efficient Full Pose Omnidirectionality with Overactuated MAVs

Abstract

Omnidirectional MAVs are a growing field, with demonstrated advantages for aerial interaction and uninhibited observation. While systems with complete pose omnidirectionality and high hover efficiency have been developed independently, a robust system that combines the two has not been demonstrated to date. This paper presents VoliroX: a novel omnidirectional vehicle that can exert a wrench in any orientation while maintaining efficient flight configurations. The system design is presented, and a 6 DOF geometric control that is robust to singularities. Flight experiments further demonstrate and verify its capabilities.

Design and optimal control of a tiltrotor micro-aerial vehicle for efficient omnidirectional flight

“…The second type, which we refer to as a kinematic singularity, occurs when rotor thrusts cannot contribute to the desired body wrench w B , which leads to tilt angles not being uniquely defined. This condition has been described by Bodie et al (2018).…”

“…As previously identified by Bodie et al (2018), an OMAV can encounter two types of singularity cases that result from the allocation model. The first type occurs when the tilt angles a i are aligned in a way that leads to a rank reduction of the instantaneous allocation matrix A a .…”

“…This article extends upon the work presented at the 2018 International Symposium on Experimental Robotics (ISER 2018) (Bodie et al, 2019(Bodie et al, , 2018, and is structured as follows. Section 2 states assumptions and notation, and derives a general model of the tiltrotor OMAV.…”

“…In this section we present a PID controller that yields-rigid body jerk commands. The jerk commands are computed by numerically differentiating acceleration commands that are computed from a PID controller as in Bodie et al (2018) and Kamel et al (2018). Using the current as well as the reference state of the system, reference accelerations are obtained as follows:…”

“…The LQRI and PID controllers presented above return jerk commands that need to be executed by the platform. Extending the work from Bodie et al (2018) and based on work by Ryll et al (2015), we present a weighted differential allocation of actuator commands according to Figure 7, and include task prioritization in the null space.…”