Assistive trajectories for human-in-the-loop mobile robotic platforms

Autonomous and semi-autonomous smoothly interruptible trajectories are developed which are highly suitable for application in tele-operated mobile robots, operator on-board military mobile ground platforms, and other mobility assistance platforms. These trajectories will allow a navigational system to provide assistance to the operator in the loop, for purpose built robots or remotely operated platforms. This will allow the platform to function well beyond the line-of-sight of the operator, enabling remote operation inside a building, surveillance, or advanced observations whilst keeping the operator in a safe location. In addition, on-board operators can be assisted to navigate without collision when distracted, or under-fire, or when physically disabled by injury

Differential evolution method for mobile robot optimal trajectory planning

Bu yayında önerilen yöntemle, mobil robotlarda, çevreden gelen kısıtlamalar (engeller) ve robotun hız ve ivme gibi fiziksel kısıtlamaları dikkate alınarak, önceden görünebilirlik grafik metoduyla (VGM) planlanmış yol üzerinde zaman-optimal yörünge bulunmuştur. Yörüngeler, düz kısımlardan (dönme ivmesi as=0 ve dönme hızı vs=0) ve eğri kısımlardan (öteleme ivmesi at=0 ve öteleme hızı vt= sabit ) oluşturulmuşlardır. Eğri kısımları oluşturmak için sadece q  (dönüş açısı) ve vt (eğri kısım öteleme hızı) parametrelerinin bilinmesi yeterli olmaktadır. Olası tüm eğri kısımlar kümesi (qÎ(0,p]° ve vt [0,40] inç) içerisinden evrimsel bir global optimizasyon metodu olan diferansiyel evrim (DE) ile, engellerle çakışmayan zaman-optimal amaç ölçütünü sağlayan yörüngenin seçilmesi gerçeklenmiştir. Anahtar Kelimeler: Mobil robot, optimizasyon, yörünge planlama, diferansiyel evrim.A method is proposed to find the time optimal trajectory on predefined path of mobile robots, which is found by using visibility graph method. Constraints from environment (obstacles) and physical constraints (i.e. steering and translational accelerations/velocities) are taken into consideration in the method. The planned trajectories are composed of line segments (steering accaleration/deceleration as=0 and velocity vs0=0) and curve segments (translational acceleration/deceleration at=0 and velocity vt= vt0). The structures of the curves are determined by only two parameters: q, turn angles, these are produced by visibility graph method and vt, translational velocities on the curve segments, these are the elements of the parameter vector. A curves set is formed by all possible curves in parameters range qÎ(0,p]° and vt [0,40] inch. Then diferrential evolution (DE), that is an evolutionary optimizastion method is used to find time optimal trajectory from this set. The curve segments are formed in two ways: a) serial expansion of the robot?s equations (Mclauren series) and b) artificial neural networks (YSA). YSA model is used to form the curves instead of serial expansion of the robot?s equations. Thus, the optimization time is decreased to approximately 1/7. There is no need to a controller for tracking the planned trajectory. Keywords: Mobile robot, optimisation, trajectory planning, differential evolution

Path following hybrid control for vehicle stability applied to industrial forklifts

The paper focuses on a closed-loop hybrid controller (kinematic and dynamic) for path following approaches with industrial forklifts carrying heavy loads at high speeds, where aspects such as vehicle stability, safety, slippage and comfort are considered. The paper first describes a method for generating Double Continuous Curvature (DCC) paths for non-holonomic wheeled mobile robots, which is the basis of the proposed kinematic controller. The kinematic controller generates a speed profile, based on slow-in and fast-out policy, and a curvature profile recomputing DCC paths in closed-loop. The dynamic controller determines maximum values for decelerations and curvatures, as well as bounded sharpness so that instantaneous vehicle stability conditions can be guaranteed against lateral and frontal tip-overs. One of the advantages of the proposed method, with respect to full dynamic controllers, is that it does not require dynamic parameters to be estimated for modelling, which in general can be a difficult task. The proposed kinematic dynamic controller is afterwards compared with a classic kinematic controller like Pure-Pursuit. For that purpose, in our hybrid control structure we have just replaced the proposed kinematic controller with Pure-Pursuit. Several metrics, such as settling time, overshoot, safety and comfort have been analysed.This work was supported by VALi+d and PROMETEO Programs (Conselleria d'Educacio, Generalitat Valenciana), DIVISAMOS (DPI-2009-14744-C03-01) and SAFEBUS (IPT-2011-1165-370000): Ministry of Economy and Competitivity.Girbés, V.; Armesto Ángel, L.; Tornero Montserrat, J. (2014). Path following hybrid control for vehicle stability applied to industrial forklifts. Robotics and Autonomous Systems. 62(6):910-922. https://doi.org/10.1016/j.robot.2014.01.004S91092262

Generación de Trayectorias de Curvatura Continua para el Seguimiento de Líneas basado en Visión Artificial

Desarrollo matemático y análisis de nuevas técnicas para la generación de trayectorias de curvatura continua aplicado al problema del seguimiento de línea con curvatura y brusquedad acotadas.Girbés Juan, V. (2010). Generación de Trayectorias de Curvatura Continua para el Seguimiento de Líneas basado en Visión Artificial. http://hdl.handle.net/10251/12881Archivo delegad