Lucio Rafael Salinas

Quantitative Absolute Transparency for Bilateral Teleoperation of Mobile Robots

This paper proposes a new criterion, called absolute transparency, to design control schemes applied to bilateral teleoperation of mobile robots with time-varying delay. The absolute transparency measures how and how fast the human operator and the remote system interact with each other through a teleoperation system. The absolute transparency of different control schemes is analyzed and tested through teleoperation experiments where a human operator drives a mobile robot and receives both visual and force feedback.

Teleoperation of a mobile robot with time-varying delay and force feedback

This paper proposes a prediction system and a command fusion to help the human operator in a teleoperation system of a mobile robot with time-varying delay and force feedback. The command fusion is used to join a remote controller and the delayed users commands. Besides, a predictor is proposed since the future trajectory of the mobile robot is not known a priori being it decided online by the user. The command fusion and predictor are designed based on the time delay and the current context measured through the crash probability. Finally, the proposed scheme is tested from teleoperation experiments considering time-varying delay as well as force feedback.

PD-like controller with impedance for delayed bilateral teleoperation of mobile robots

Fil: Slawinski, Emanuel. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico San Juan. Instituto de Automatica; Argentina

Complete Bilateral Teleoperation System for a Rotorcraft UAV with Time-Varying Delay

This paper proposes the use of simple proportional plus damping injection (P+d) controllers for delayed bilateral teleoperation of a rotorcraft UAV. The proposed control scheme involves P+d remote and local controllers, considers master and slave dynamics, and takes into account asymmetric time-varying delays. The stability of the proposed teleoperation system is analyzed using Lyapunov-Krasovskii functionals and delay-dependent stability criteria are obtained under linear-matrix-inequalities conditions. The performance of the teleoperation scheme is tested driving a virtual nonlinear 6DOF dynamic model of a minihelicopter in a human-in-the-loop simulation.

Switching control signal for bilateral tele-operation of a mobile manipulator

This paper presents both the design and the implementation of a bilateral teleoperation system for a mobile manipulator, allowing a human operator to perform complex tasks in remote environments. Two teleoperation operation modes are proposed: the locomotion mode (mobile manipulator) and the manipulation mode (robotic arm). The human operator can select the modes through the switch located on a haptic device. The user receives visual and force feedback from the remote site, and it sends velocity or position commands to the slave, according to the operation mode. Furthermore, the redundancy control of the system for obstacle avoidance is considered by the mobile platform, and the singular configuration prevention through the systems manipulability control. Finally, experimental results are reported to verify the performance of the proposed system.

Human-centered control scheme for delayed bilateral teleoperation of mobile robots

Teleoperation task performance strongly depends on how well the human operator’s commands are executed. In this paper, we propose a control scheme for delayed bilateral teleoperation of mobile robots that considers user’s commands execution in order to achieve a high-performance teleoperation system in some important aspects like time to complete the task, safety, and operator dependence. We describe some evaluation metrics that allow us to address these aspects and a quantitative metric is proposed and incorporated in the control scheme to compensate wrong commands. A force feedback is applied to the master at the local site as a haptic cue. In addition, the system stability is analyzed taking into consideration the master and remote robot dynamic models and the asymmetric time-varying delays of the communication channel. Multiple human-in-the-loop simulations were carried out and the results of the evaluation metrics were discussed. Additionally, we present experiments where a user teleoperates a mobile robot via the Internet connection between Argentina and Italy. Graphical Abstract

Stable Path-Following Control for a Quadrotor Helicopter Considering Energy Consumption

A substantial interest in aerial robots has grown in recent years. However, the energetic cost of flying is one of the key challenges nowadays. Rotorcrafts are heavier-than-air flying machines that use lift generated by one or several rotors (vertically oriented propellers), and because of this, they spend a large proportion of their available energy to maintain their own weight in the air. In this brief, this concept is used to evaluate the relationship between navigation speed and energy consumption in a miniature quadrotor helicopter, which travels over a desired path. A novel path-following controller is proposed in which the speed of the rotorcraft is a dynamic profile that varies with the geometric requirements of the desired path. The stability of the control law is proved using the Lyapunov theory. The experimental results using a real quadrotor show the good performance of the proposed controller, and the percentages of involved energy are quantified using a model of a lithium polymer battery that was previously identified.

Path Following for Unmanned Helicopter: An Approach on Energy Autonomy Improvement

In the last decades, the research efforts related to Unmanned Aerial Vehicles (UAV) has grown substantially in terms of control stabilization and navigation strategies. However, the energy available on board is finite and this is a limiting factor that prevents engineers from coming up with the best aerial solution in many situations. In this paper the path following control of a helicopter UAV based on the kinematic model is proposed, using a feedback linearization technique. The helicopter speed is adjusted according to direction changes of the desired path. Thus, the aircraft should holds its own weight in the air for the shortest possible time, aiming to save energy without neglecting the position control errors which can accumulate when its velocity increases and path direction changes. The proposed controller output is coupled to a dynamic model of a helicopter in order to evaluate the dynamic effects and to adjust the controller parameters. The stability of the controller is demonstrated in the sense of Lyapunov theory and validated by simulation results. DOI: http://dx.doi.org/10.5755/j01.itc.45.1.12413

Energy evaluation of low-level control in UAVs powered by lithium polymer battery

Nowadays, the energetic cost of flying in electric-powered UAVs is one of the key challenges. The continuous evolution of electrical energy storage sources is overcome by the great amount of energy required by the propulsion system. Therefore, the on-board energy is a crucial factor that needs to be further analyzed. In this work, different control strategies applied to a generic UAV propulsion system are considered and a lithium polymer battery dynamic model is included as the propulsion system energy source. Several simulations are carried out for each control strategy, and a quantitative evaluation of the influence of each control law over the actual energy consumed by the propulsion system is reported. This energy, which is delivery by the battery, is next compared against a well-known control-effort-based index. The results and analysis suggest that conclusions regarding energy savings based on control effort signals should be drawn carefully, because they do not directly represent the actual consumed energy.

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.