ASAP: adaptive transmission scheme for online processing of event-based algorithms

Abstract

Online event-based perception techniques on board robots navigating in complex, unstructured, and dynamic environments can suffer unpredictable changes in the incoming event rates and their processing times, which can cause computational overflow or loss of responsiveness. This paper presents ASAP: a novel event handling framework that dynamically adapts the transmission of events to the processing algorithm, keeping the system responsiveness and preventing overflows. ASAP is composed of two adaptive mechanisms. The first one prevents event processing overflows by discarding an adaptive percentage of the incoming events. The second mechanism dynamically adapts the size of the event packages to reduce the delay between event generation and processing. ASAP has guaranteed convergence and is flexible to the processing algorithm. It has been validated on board a quadrotor and an ornithopter robot in challenging conditions.

Hecatonquiros: Open-source hardware for aerial manipulation applications

This article presents Hecatonquiros, a complete open-source ecosystem for low cost and lightweight robotic manipulators. It has been released to focus on aerial manipulation applications but can be used in any other robotic application that requires the use of manipulators. The proposed framework provides the control system, a simulation environment, and a set of back ends to allow reusing the algorithms with different hardware setups. Additionally, it is released with a set of tools to ease its usage and various examples to teach the users. Several manipulators models and end-effectors are available for the users to adapt to their different requirements. All the hardware is designed to be three-dimensional printed and its components are low cost and available in common robotic stores, so anyone can reproduce and use them. The software is available in the GitHub repository https://github.com/Bardo91/hecatonquiros .

Backing-Up Maneuvers of Autonomous Tractor-Trailer Vehicles using the Qualitative Theory of Nonlinear Dynamical Systems

This paper presents an approach, based on the qualitative theory of nonlinear dynamical systems, for the analysis and design of control systems for autonomous articulated vehicles. In particular, backing-up maneuvers are considered. These maneuvers are dangerous because the vehicles tend to `jackknife' when the angle between the tractor and the trailer is greater than a certain value. This danger is increased when the actuators are saturated because they can cause a lack of controllability in the state space and control becomes complicated. The paper proposes a two-level control system with an orientation controller in the lower level and a look-ahead controller in the higher. In the paper, a general orientation feedback controller is presented. This control strategy represents a wide family of different nonlinear controllers and can be applied with different particular control laws. The paper applies the qualitative theory of nonlinear dynamical systems to study the stability of the control system. Thus, the stability of the system under some constraints is demonstrated. The paper includes both simulation and experimental results of the implementation on the Romeo 4R autonomous vehicle, which is a full-size autonomous electrical golf cart with a trailer.