Towards reconfigurable and flexible multirotors

Abstract

Reconfigurable multirotors (RMs) with flexible frames and integrated mechanical compliance are increasingly explored to develop multifunctional aerial robots with high power-to-weight ratios. In this paper, we review the state-of-the-art research on RMs and classify them into three broad categories as tiltrotors, multimodal and foldable RMs. The RMs with the ability to arbitrarily orient their thrust by employing tilting rotors are classified as tiltrotors, the multirotors with multi modal locomotion capabilities by transforming the chassis into land/water propulsion systems are classified as multimodal RMs, and those which can alter the size of the chassis are labelled as foldable RMs. Existing platforms are analyzed from three different perspectives-mechanical design, challenges of low-level control and high level motion planning techniques. Finally, we identify the critical parameters for design optimization, and discuss the issues associated with developing a common control and motion planning algorithm that can leverage any RM's features to demonstrate successful autonomous missions.in body frame i i th Rotor's spin velocity N ∈ ℝ n Vector of squared rotor spin velocities k i ∈ ℝ Constant to calculate torque generated by ith motor ∈ ℝ Event trigger i ∈ 1 i th Rotor tilt angle i ∈ 1 i th Arm folding angle A ∈ ℝ 3×3 Control allocation matrix A g ∈ ℝ 3×3 Control allocation matrix in ground mode Abbreviations LLFC Low-level flight controller HLMP High-level motion plannning MoCap Indoor motion capture system * Karishma Patnaik

Adopting Physical Artificial Intelligence in Soft Aerial Robots

“…In the bottom-right quadrant, aerial robots with a limited DOF and requires high precision control is representative of classical rigid multicopters or fixedwing robots. In the top right quadrant, with an increasing number of DOFs that require high precision control, the design space shifts to highly adaptable, active, reconfigurable and foldable multi-rotors [19,20]. On the other end of the spectrum, the bottom-right quadrant, a lower DOF and less requirement for active control, leads to design of drones with PAI embodied adaptable bodies, such as soft bodied drones and passive foldable multi-rotors [3,[21][22][23].…”

“…As we will see throughout this paper, metamorphosis augments the functionalities of soft aerial platforms. From the capabilities of adapting their size to go through apertures, or to absorb impact, or to manipulate objects [3,19,33]. Metamorphosis is also highlighted in multi-modal transitions, from aerial to terrestrial environments [34,35] and aerial to aquatic environments [36,37].…”

Adaptive Attitude Control for Foldable Quadrotors

“…Proof: To analyze this case, consider a switched system generated by two dynamical systems such that P = [1,2]. Let t i < t j be two switching times when σ = 1.…”

“…Foldable quadrotors (FQrs) have created a paradigm shift in the design of multirotor aerial vehicles for widening the scope of applications such as flying through small openings and cluttered spaces [1]. While there is ample research demonstrating the mechanical feasibility of the foldable designs [2], [3], limited literature exists on the analysis of the low-level flight controller and the effects of inflight configuration switching.…”

Adaptive integral backstepping control of a reconfigurable quadrotor with variable parameters’ estimation

“…According to recent studies, 1–3 the reconfigurable multirotors can be divided as shown in Figure 1. In the paper, 4 a new reconfigurable quadcopter, which can change its mechanical structure, was presented.…”