Wavelet packet transform-based compression for teleoperation

This paper introduces a codec scheme for compressing the control and feedback signals in networked control and teleoperation systems. The method makes use of Wavelet Packet Transform (WPT) and Inverse Wavelet Packet Transform (IWPT) for coding and decoding operations, respectively. Data compression is carried out in low-pass filter output by reducing the sampling rate, and in high-pass filter output by truncating the wavelet coefficients. The proposed codec works on both directions of signal transmission between a master robot and a slave robot over a networked motion control architecture. Following the formulation of the compression/decompression methodology, experimental validation is conducted on a single-degree-of-freedom motion control system. In the experiments, responses from different Wavelet structures are analyzed and a comparative study is carried out considering the factors of compression rate, reconstruction power error and real-time computational complexity. It is confirmed that the controller using the proposed compression algorithm performs very close to the uncompressed one while enabling transmission of much less data over the network

Wavelet packet transform based compression for bilateral teleoperation

This paper introduces a codec scheme for compressing the control and feedback signals in bilateral control systems. The method makes use of Wavelet Packet Transform (WPT) and Inverse Wavelet Packet Transform (IWPT) for coding and decoding operations respectively. Data compression is carried out in low pass filter output by reducing the sampling rate; and in high pass filter output by truncating the wavelet coefficients. The proposed codec works on both directions of signal transmission between a master robot and a slave robot over a networked motion control architecture. Following the formulation of the compression/decompression methodology, experimental validation is conducted on a single degree of freedom (DOF) motion control system. In the experiments, responses from different Wavelet structures are analyzed and a comparative study is carried out considering the factors of compression rate, reconstruction power error and real time computational complexity. It is confirmed that the controller using the proposed compression algorithm performs very close to the uncompressed one while enabling transmission of much less data over network

Transparent and Shaped Stiffness Reflection for Telesurgery

status: publishe

Comparison of interaction modalities for mobile indoor robot guidance : direct physical interaction, person following, and pointing control

© 2015 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other worksThree advanced natural interaction modalities for mobile robot guidance in an indoor environment were developed and compared using two tasks and quantitative metrics to measure performance and workload. The first interaction modality is based on direct physical interaction requiring the human user to push the robot in order to displace it. The second and third interaction modalities exploit a 3-D vision-based human-skeleton tracking allowing the user to guide the robot by either walking in front of it or by pointing toward a desired location. In the first task, the participants were asked to guide the robot between different rooms in a simulated physical apartment requiring rough movement of the robot through designated areas. The second task evaluated robot guidance in the same environment through a set of waypoints, which required accurate movements. The three interaction modalities were implemented on a generic differential drive mobile platform equipped with a pan-tilt system and a Kinect camera. Task completion time and accuracy were used as metrics to assess the users’ performance, while the NASA-TLX questionnaire was used to evaluate the users’ workload. A study with 24 participants indicated that choice of interaction modality had significant effect on completion time (F(2,61)=84.874, p<0.001), accuracy (F(2,29)=4.937, p=0.016), and workload (F(2,68)=11.948, p<0.001). The direct physical interaction required less time, provided more accuracy and less workload than the two contactless interaction modalities. Between the two contactless interaction modalities, the person-following interaction mod- lity was systematically better than the pointing-control one: The participants completed the tasks faster with less workloadPeer ReviewedPostprint (author's final draft

Position / force control of systems subjected to communicaton delays and interruptions in bilateral teleoperation

Thesis (Master)--Izmir Institute of Technology, Mechanical Engineering, Izmir, 2012Includes bibliographical references (leaves: 65-68)Text in English; Abstract: Turkish and Englishix, 76 leavesTeleoperation technology allows to remotely operate robotic (slave) systems located in hazardous, risky and distant environments. The human operator sends commands through the controller (master) system to execute the tasks from a distance. The operator is provided with necessary (visual, audio or haptic) feedback to accomplish the mission remotely. In bilateral teleoperation, continuous feedback from the remote environment is generated. Thus, the operator can handle the task as if the operator is in the remote environment relying on the relevant feedback. Since teleoperation deals with systems controlled from a distance, time delays and package losses in transmission of information are present. These communication failures affect the human perception and system stability, and thus, the ability of operator to handle the task successfully. The objective of this thesis is to investigate and develop a control algorithm, which utilizes model mediated teleoperation integrating parallel position/force controllers, to compensate for the instability issues and excessive forcing applied to the environment arising from communication failures. Model mediation technique is extended for three-degrees-of-freedom teleoperation and a parallel position/force controller, impedance controller, is integrated in the control algorithm. The proposed control method is experimentally tested by using Matlab Simulink blocksets for real-time experimentation in which haptic desktop devices, Novint Falcon and Phantom Desktop are configured as master and slave subsystems of the bilateral teleoperation. The results of these tests indicate that the stability and passivity of proposed bilateral teleoperation systems are preserved during constant and variable time delays and data losses while the position and force tracking test results provide acceptable performance with bounded errors

Teleoperación [de robots]: técnicas, aplicaciones, entorno sensorial y teleoperación inteligente

En este trabajo centraremos la atención en los sistemas robóticos teleoperados, especialmente analizaremos los sistemas teleoperados desde internet, veremos una clasificación de las metodologías de teleoperación, los diferentes sistemas de control y daremos una visión del estado del arte en este ámbito de conocimiento

Force reflecting teleoperation with adaptive impedance control

©2004 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.DOI: 10.1109/TSMCB.2003.811756Experimentation and a survey of the literature clearly show that contact stability in a force reflecting teleoperation system requires high levels of damping on the master robot. However, excessive damping increases the energy required by an operator for commanding motion. The objective of this paper is to describe a new force reflecting teleoperation methodology that reduces operator energy requirements without sacrificing stability. We begin by describing a new approach to modeling and identifying the remote environment bf the teleoperation system. We combine a conventional Multi-Input, Multi-Output Recursive Least Squares (MIMO-RLS) system identification, identifying in real-time the remote environment impedance, with a discretized representation 'of the remote environment. This methodology generates a time-varying, position dependent representation of the remote environment dynamics. Next, we adapt the target impedance of the master robot with respect to the dynamic model of the remote environment. The environment estimation and impedance adaptation are execute simultaneously and in real time. We demonstrate, through experimentation, that this approach significantly reduces the energy required by an operator to execute remote tasks while simultaneously providing sufficient damping to ensure contact stability

Commande des systèmes sous frottement utilisant le formalisme LMI : application aux systèmes robotiques avec contact et aux actionneurs pneumatiques

Le frottement présente systématiquement un risque accablant dans l'altération des performances de mouvement des systèmes mécaniques. La mise-en-place d'un système de contrôle efficace pour dissiper ce genre d'anomalie constitue encore un sujet d'actualité dans les domaines de la recherche et de l'ingénierie. Les mécaniciens, les tribologues, spécialistes de la théorie de frottement, et les automaticiens oeuvrent pour l'étude de ce phénomène des points de vue: caractérisation, modélisation et compensation. Une revue assez exhaustive de ces travaux est présentée dans le chapitre 1. Dans le présent travail de thèse, nous proposons un schéma général de contrôle des systèmes sous frottement que nous pouvons utiliser dans plusieurs applications. En respectant les paradigmes standards de stabilité, de robustesse et d'optimisation (de types H2, H∞ , etc.), ce shéma est basé sur l'estimation en boucle fermée du frottement dynamique, selon le modèle de LuGre, et la structure dynamique de contrôle linéaire par retour de sortie. La synthèse de cette commande repose sur les outils numériques des inégalités matricielles linéaires. En plus, pour tenir compte de la variété des structures dynamiques de mouvement et aussi de force dans les différents dispositifs en question, le schéma de la commande que nous proposons peut comprendre des termes d'actions statiques (ou) dynamiques, linéaires (ou) non linéaires et éventuellement robustes. Une illustration simple de la commande de mouvement d'une masse, sur une surface sous frottement, est exposée dans le chapitre 2. Il s'agit d'une généralisation du principe de commande stabilisante par rétroaction statique introduit par Canudas et al.(1995). Ensuite, nous appliquons notre schéma dans des cas plus complexes (non linéarités, incertitudes et couplages de force/position non négligeables). Pour ce faire, nous proposons dans le chapitre 3 l'étude de la commande hybride de position/force du robot manipulateur dont l'élément final est en contact sous frottement avec une surface donnée. Dans le chapitre 4, nous développons le schéma de contrôle de force (i.e. de pression) de l'actionneur pneumatique. Et dans le chapitre 5, nous présentons le schéma détaillé de contrôle de position de ce type d'installation qui renferme plusieurs points de contact avec frottement. Des résultats expérimentaux sont présentés pour valider notre approche de commande et aussi la comparer à d'autres schémas de commande et/ou de compensation de frottement. Pour conclure ce travail, nous recommandons, en particulier, l'extension de l'approche proposée en utilisant un modèle de frottement encore plus générale comme celui de glissement généralisé de Maxwell (GMS) dans une suite logique et aussi ambitieuse de ce travail