Claudio Rosales

Trajectory tracking of a mini four-rotor helicopter in dynamic environments - a linear algebra approach

This paper presents the design of a controller that allows a four-rotor helicopter to track a desired trajectory in 3D space. To this aim, a dynamic model obtained from Euler-Lagrange equations describes the robot. This model is represented by numerical methods, with which the control actions for the operation of the system are obtained. The proposed controller is simple and presents good performance in face of uncertainties in the model of the system to be controlled. Zeroconvergence proof is included, and simulation results show a good performance of the control system.

3D Formation Control of Autonomous Vehicles Based on Null-Space

This paper proposes a new algorithm for controlling a formation of multiple autonomous aerial vehicles based on multiple control objectives. The strategy includes using the null space of a Jacobian matrix to achieve the different control objectives in a non-conflicting way. The mission is split into two elementary tasks, with suitable command references generated for each robot. The commands for each task are combined through a hierarchical method by using the projection of commands onto the null space. The incorporation of ground vehicles in the control scheme is also considered, thus extending the proposed scheme for controlling heterogeneous formations. The stability analysis of the control system shows that such a system is asymptotically stable, and experimental results validate the proposed control system.

Formation control of unmanned aerial vehicles based on the null-space

In this paper a new algorithm for formation control of autonomous flight vehicles is presented based on multiple control objectives. The strategy includes using the null space of a Jacobian matrix to achieve different control objectives. The mission is decomposed in elementary tasks and, for each one of them, command references are generated for each robot. The different commands obtained for each task are combined through a hierarchical method using the projection in the null space, to cater multiple tasks. The proposed system is scalable, whereby the control system can be easily expanded. Finally, the stability analysis of the proposed controllers is performed and simulation results are shown, to confirm the good performance of the controllers.

An Adaptive Dynamic Controller for Quadrotor to Perform Trajectory Tracking Tasks

This work proposes an adaptive dynamic controller to guide an unmanned aerial vehicle (UAV) when accomplishing trajectory tracking tasks. The controller structure consists of a kinematic controller that generates reference commands to a dynamic compensator in charge of changing the reference commands according to the system dynamics. The final control actions thus generated are then sent to the UAV to make it to track an arbitrary trajectory in the 3D space. The parameters of the dynamic compensator are directly updated during navigation, configuring a directly updated self-tuning regulator with input error, aiming at reducing the tracking errors, thus improving the system performance in task accomplishment. After describing the control system thus designed, its stability is proved using the Lyapunov theory. To validate the proposed system simulations and real experiments were run, some of them are reported here, whose results demonstrate the effectiveness of the proposed control system and its good performance, even when the initial values of the parameters associated to the dynamic model of the UAV are completely unknown. One of the conclusions, regarding the results obtained, is that the proposed system can be used as if it were an on-line identification subsystem, since the parameters converge to values that effectively represent the UAV dynamics.

Multi-objective control for cooperative payload transport with rotorcraft UAVs

A novel kinematic formation controller based on null-space theory is proposed to transport a cable-suspended payload with two rotorcraft UAVs considering collision avoidance, wind perturbations, and properly distribution of the load weight. An accurate 6-DoF nonlinear dynamic model of a helicopter and models for flexible cables and payload are included to test the proposal in a realistic scenario. System stability is demonstrated using Lyapunov theory and several simulation results show the good performance of the approach.

Adaptive dynamic control for trajectory tracking with a quadrotor

This work proposes an adaptive dynamic controller for an unmanned aerial vehicle (UAV) to track a desired trajectory. Initially, reference velocities are generated by a controller that is based only on the kinematic model of the UAV. Subsequently, new control actions are calculated to compensate for the internal dynamics of the robot. Then the model parameters that characterize the robot dynamics are updated during navigation, chareacterizing an adaptive controller. In this way, the performance of the flight application with the quadrotor is improved, since the control errors are minimized. The stability of the proposed control system is proven, based on the Lyapunov theory. Finally, simulated results are presented, demonstrating the good performance of the controller even without any previous knowledge of the values of the parameters of the UAV dynamics.

Adaptive dynamic control of a quadrotor for trajectory tracking

This work presents an adaptive trajectory tracking controller for an unmanned aerial vehicle (UAV) which combines a feedback linearization controller based on a nominal model of a quadrotor and a Neuro Adaptive Compensation (NAC). The NAC is introduced in order to minimize the control errors caused by uncertainties in the nominal parameters. The uncertain parameters of the nominal model are balanced by a Neuro Adaptive Compensator. The proposed adaptive control scheme is robust and efficient to achieve a good trajectory following performance for outdoor and indoor applications. The analysis of the neural approximation error on the control errors is included. Finally, the effectiveness of the control system is proved through numerical simulation.

Control of a heterogeneous aerial-terrestrial formation using null space approach

This paper proposes a multi-objective strategy, based on the null space control theory in order to guide formation composed by aerial and terrestrial robots. A mathematical representation for a triangular heterogeneous formation is presented considering the constraints imposed by the UGVs into the formation variables. The stability of the controller is analysed using Lyapunov theory and simulation results validate the proposal.

Port-hamiltonian modelling of a differential drive mobile robot with reference velocities as inputs

In this paper it is proposed a dynamic model of a differential drive mobile robot based on the port-Hamiltonian approach. The model inputs are reference velocities, as in most commercial robots. The model arises from a positioning controller at desired velocities, which is asymptotically stable.

3-D positioning tasks for RUAS using switched PVTOL controllers

In this work a switching strategy associated to three PVTOL controllers is proposed to guide a rotorcraft during 3D navigation. The proposal is to orientate the rotorcraft to the desired point (using a Z-PVTOL controller) and then to move it ahead (using a XZ-PVTOL controller), considering the body reference frame. In such goal search, if a lateral displacement error greater than a threshold value is observed an YZ-PVTOL controller is run to minimize it. The stability proof for each of such sub-systems is also included, as well as a strategy to switch between them without affecting the stability of the whole system. Finally, experimental results are presented to validate the proposed approach and its performance during a flight mission is compared to the performance of a controller based on partial nonlinear feedback, proposed to control all degrees of freedom simultaneously.