Control and Configuration Planning of an Aerial Cable Towed System

Abstract

This paper investigates the effect of the robot configuration on the performance of an aerial cable towed system (ACTS) composed of three quadrotors manipulating a point mass payload. The kinematic and dynamic models of the ACTS are derived in a minimal set of geometric coordinates, and a centralized feedback linearization controller is developed. Independent to the payload trajectory, the configuration of the ACTS is controlled and is evaluated using a robustness index named the capacity margin. Experimental validation is performed with optimal, suboptimal, and wrench infeasible configurations. It is shown that configurations near the point of zero capacity margin allow the ACTS to hover but not to follow dynamic trajectories, and that the ACTS cannot fly with a negative capacity margin. Dynamic tests are performed on the ACTS, showing the effects of the configuration on the achievable accelerations.

Design and Control of a Variable Aerial Cable Towed System

“…Therefrom the cable lengths and the unit vectors along cable directions are computed. The hardware and software platform and their working frequencies are detailed in [13]. The winch servo motor is controlled via ROS messages over Pixhawk AUX outputs.…”

“…8. The VACTS prototype with 3 quadrotors, winches and a point-mass The motion planning for a VACTS can be divided into several parts based on the task space state vector: the motion of payload, the system configuration of cable directions, and the cable lengths: (i) The motion of payload can be designed under the knowledge of environment; (ii) The design methodology for system configuration [13], [21] varies from quasi-static to dynamic case. In short, it is designed under capacity margin and cost optimization; (iii) The cable lengths are determined on the basis of limited volume space.…”

“…In [12] an ACTS prototype for 3-dimensional manipulation and a decentralized linear quadratic control law are proposed and [6] develops a general feedback linearization control scheme for over-actuated ACTS with a 6-DOF payload. An ACTS prototype with three quadrotors and a point mass is implemented in [13] and the performance was evaluated using capacity margin, a wrench-based robustness index adapted from the CDPR in [14].…”

Shared Control of an Aerial Cooperative Transportation System with a Cable-suspended Payload

“…The authors of [7,9] analyze the wrench capability of an ACTS, expanding previous studies on wrench feasible workspaces for CDPRs by accounting also for the thrust limits of the MAVs propellers. This wrench analysis is combined in [8] with a modified version of a controller developed for discretely reconfigurable CDPRs. The parallelism between ACTS and CDPR is even more pronounced in [30], where the MAVs of the transportation system are equipped with actuated winches.…”

“…a frame of reference attached that is oriented as F P , but placed on the center of mass of the payload. 8 Using this notation, the dynamics of the rigid payload pulled by the cables, as shown in [24,25,45], is (16) where -B P (x ν ) ẍ is dependent on the acceleration and represents the inertia of the system, with…”