A. Rodriguez-Castano

Closed-Loop Behavior of an Autonomous Helicopter Equipped with a Robotic Arm for Aerial Manipulation Tasks

This paper is devoted to the control of aerial robots interacting physically with objects in the environment and with other aerial robots. The paper presents a controller for the particular case of a small-scaled autonomous helicopter equipped with a robotic arm for aerial manipulation. Two types of influences are imposed on the helicopter from a manipulator: coherent and non-coherent influence. In the former case, the forces and torques imposed on the helicopter by the manipulator change with frequencies close to those of the helicopter movement. The paper shows that even small interaction forces imposed on the fuselage periodically in proper phase could yield to low frequency instabilities and oscillations, so-called phase circles.

Fractional controller for guidance of autonomous ground vehicles

Abstract This paper investigates the use of Fractional Order Control (FOC) in path tracking problems. A fractional controller has been simulated to analyze the performance for changes in navigation speed. This controller is compared to a typical Pure-Pursuit technique. Experiments with the ROMEO 4R autonomous vehicle have been carried out using the fractional controller.

Lightweight and human-size dual arm aerial manipulator

This paper presents the design of a dual-arm aerial manipulator consisting of a multi-rotor platform with an ultra-lightweight (1.8 Kg) human-size dual arm prototype and its control system. Each arm provides three degrees of freedom (DOF) for positioning the end- effector, and two DOF for orientation. As most model-based controllers assume that joint torque feedback is available, a torque estimator for the arms is developed. Note that low cost servos used for building low weight manipulators do not provide any torque feedback or control capability. The redundant DOFs in the dual arm prototype are exploited for generating coordinated motions during contact-less phases in such a way that reaction torques can be partially canceled. Preliminary flight tests have been conducted in outdoors, evaluating the torque compensation capability in test-bench. The influence of the reaction torques exerted by the arms over the UAV controller is also analyzed in simulation.

High-speed autonomous navigation system for heavy vehicles

The paper presents techniques for autonomous path tracking of heavy vehicles at high speeds.Vehicle state estimation is based on fuzzy logic, and a Takagi-Sugeno type controller is used for vehicle lateral control.The paper describes the real implementation and testing of the controllers in a real truck.The implementation of high speed robot controllers for heavy vehicles is more difficult in practice than for small mobile robots.The paper also describes experiments with the soft controller at high speeds, up to 100km/h. This paper presents techniques for GPS based autonomous navigation of heavy vehicles at high speed. The control system has two main functions: vehicle position estimation and generation of the steering commands for the vehicle to follow a given path autonomously. Position estimation is based on fusion of measurements from a carrier-phase differential GPS system and odometric sensors using fuzzy logic. A Takagi-Sugeno fuzzy controller is used for steering commands generation, to cope with different road geometry and vehicle velocity. The presented system has been implemented in a 13tons truck, and fully tested in very demanding conditions, i.e. high velocity and large curvature variations in paved and unpaved roads.

Analysis of a GPS-Based Fuzzy Supervised Path Tracking System for Large Unmanned Vehicles

Abstract This paper studies a fuzzy-supervised path tracking system designed and implemented for driving large unmanned vehicles at high speed. Thus, reliability and high performance are very important issues. The control system has two main functions: vehicle position estimation and generation of the steering commands for the vehicle to follow a given path autonomously. Position estimation is based on a differential OPS system with additional functions to improve the reliability. In fact, the highly demanding navigation conditions impose strict requirements on the dynamic behavior. This paper presents a frequency response analysis of the control loop. The results of this analysis correspond to the obtained experimentally with a truck circulating by testing tracks.

Motion planning with dynamics awareness for long reach manipulation in aerial robotic systems with two arms

Human activities in maintenance of industrial plants pose elevated risks as well as significant costs due to the required shutdowns of the facility. An aerial robotic system with two arms for long reach manipulation in cluttered environments is presented to alleviate these constraints. The system consists of a multirotor with a long bar extension that incorporates a lightweight dual arm in the tip. This configuration allows aerial manipulation tasks even in hard-to-reach places. The objective of this work is the development of planning strategies to move the aerial robotic system with two arms for long reach manipulation in a safe and efficient way for both navigation and manipulation tasks. The motion planning problem is addressed considering jointly the aerial platform and the dual arm in order to achieve wider operating conditions. Since there exists a strong dynamical coupling between the multirotor and the dual arm, safety in obstacle avoidance will be assured by introducing dynamics awareness in the operation of the planner. On the other hand, the limited maneuverability of the system emphasizes the importance of energy and time efficiency in the generated trajectories. Accordingly, an adapted version of the optimal Rapidly-exploring Random Tree algorithm has been employed to guarantee their optimality. The resulting motion planning strategy has been evaluated through simulation in two realistic industrial scenarios, a riveting application and a chimney repairing task. To this end, the dynamics of the aerial robotic system with two arms for long reach manipulation has been properly modeled, and a distributed control scheme has been derived to complete the test bed. The satisfactory results of the simulations are presented as a first validation of the proposed approach.

Motion planning for long reach manipulation in aerial robotic systems with two arms

In this paper an aerial robotic system with two arms for long reach manipulation (ARS-LRM) while flying is presented. The system consists of a multirotor with a long bar extension that incorporates a lightweight dual arm in the tip. This configuration allows aerial manipulation tasks increasing considerably the safety distance between rotors and manipulated objects. The objective of this work is the development of planning strategies to move the ARS-LRM system for both navigation and manipulation tasks. With this purpose, a simulation environment to evaluate the algorithms under consideration is required. Consequently, the ARS-LRM dynamics has been properly modeled with specific methodologies for multi-body systems. Then, a distributed control scheme that makes use of nonlinear control strategies based on model inversion has been derived to complete the testbed. The motion planning problem is addressed considering jointly the aerial platform and the dual arm in order to achieve wider and safer operating conditions. The operation of the planner is given by an RRT∗-based algorithm that optimizes energy and time performance in cluttered environments for both navigation and manipulation tasks. This motion planning strategy has been tested in a realistic industrial scenario given by a riveting task. The satisfactory results of the simulations are presented as a first validation of the proposed approach.

Design of a High Performance Dual Arm Aerial Manipulator

This paper presents the design of a dual arm aerial manipulation robot consisting of a customized hexarotor platform equipped with a lightweight dual arm manipulator. The proposed design is intended to integrate multiple devices required for building a complete aerial manipulation system, including vision and range sensors, on-board computers, communication devices, navigation systems, along with the manipulator. The developed platform will provide optimum performance in terms of flight time and payload taking into account the current technology available for building these kind of aircrafts. The design of the platform also considers vibration isolation, control and stability, and extended workspace for the manipulator. A lightweight (1.8 kg) and human-size dual arm manipulator has been integrated in the developed platform. Each arm provides 5 degrees of freedom (DOF) for end effector positioning and orientation. The arms are built using smart servo actuators and a frame structure manufactured in anodized aluminum. The design is validated through rigidity and modal analysis using finite element methods (FEM). The developed platform has been tested in outdoor flights, evaluating the influence of arms motion over the stability of the platform.