A versatile biomimetic controller for contact tooling and haptic exploration

International audienceThis article presents a versatile controller that enables various contact tooling tasks with minimal prior knowledge of the tooled surface. The controller is derived from results of neuroscience studies that investigated the neural mechanisms utilized by humans to control and learn complex interactions with the environment. We demonstrate here the versatility of this controller in simulations of cutting, drilling and surface exploration tasks, which would normally require different control paradigms. We also present results on the exploration of an unknown surface with a 7-DOF manipulator, where the robot builds a 3D surface map of the surface profile and texture while applying constant force during motion. Our controller provides a unified control framework encompassing behaviors expected from the different specialized control paradigms like position control, force control and impedance control

Eksplicitna regulacija sile robotskog manipulatora aktivnim prigušenjem brzine

This paper presents a new interaction control structure that generates a family of explicit force regulators for robot manipulators. The proposed structure includes a term of a class of proportional-type functions in terms of force error; the force error is defined as the difference between a desired force and the actual force measured with a force sensor located at the end-effector. Also, the structure includes a generalized active velocity damping term in order to have a control of the energy dissipation, and a term used to compensate the gravity forces of the links. The stability analysis is performed in Lyapunov sense. An experimental comparison of two new explicit force regulators and the linear proportional structure, on a three degree-of-freedom, direct-drive robot, is presented. Also, proofs of the most important properties of the Cartesian dynamic model, are presented.Ovaj rad predstavlja novu interakcijsku kontrolnu strukturu koja predstavlja skupinu exsplicitnih regulatora sile za robotske manipulatore. Predložena struktura uključuje član klase funkcija proporcionalnog tipa u smilsu pogreške sile; pogreška sile se definira kao razlika između željene sile i stvarne sile koju mjere senzori postavljeni na kraju manipulatora. Također, struktura uključuje član za generalizirano aktvino prigušenje brzine kako bi se omogućila kontrola disipacije energije i član kojim se kompenzira utjecaj sile gravitacije na članke manipulatora. Analiza stabilnosti je napravljena u smislu Lyapunova. Prikazana je eksperimentalna usporedba dva nova eksplicitna regulatora sile i linearno-proporcionalne strukture na robotu s direktnim pogonom i tri stupnja slobode. Također su prikazani dokazi najvažnijih svojstava kartezijskog dinamičnog modela

Automatic Electromechanical Perturbator for Postural Control Analysis Based on Model Predictive Control

Objective clinical analyses are required to evaluate balance control performance. To this outcome, it is relevant to study experimental protocols and to develop devices that can provide reliable information about the ability of a subject to maintain balance. Whereas most of the applications available in the literature and on the market involve shifting and tilting of the base of support, the system presented in this paper is based on the direct application of an impulsive (short-lasting) force by means of an electromechanical device (named automatic perturbator). The control of such stimulation is rather complex since it requires high dynamics and accuracy. Moreover, the occurrence of several non-linearities, mainly related to the human–machine interaction, signals the necessity for robust control in order to achieve the essential repeatability and reliability. A linear electric motor, in combination with Model Predictive Control, was used to develop an automatic perturbator prototype. A test bench, supported by model simulations, was developed to test the architecture of the perturbation device. The performance of the control logic has been optimized by iterative tuning of the controller parameters, and the resulting behavior of the automatic perturbator is presented

The Next-Generation Surgical Robots

The chronicle of surgical robots is short but remarkable. Within 20 years since the regulatory approval of the first surgical robot, more than 3,000 units were installed worldwide, and more than half a million robotic surgical procedures were carried out in the past year alone. The exceptionally high speeds of market penetration and expansion to new surgical areas had raised technical, clinical, and ethical concerns. However, from a technological perspective, surgical robots today are far from perfect, with a list of improvements expected for the next-generation systems. On the other hand, robotic technologies are flourishing at ever-faster paces. Without the inherent conservation and safety requirements in medicine, general robotic research could be substantially more agile and explorative. As a result, various technical innovations in robotics developed in recent years could potentially be grafted into surgical applications and ignite the next major advancement in robotic surgery. In this article, the current generation of surgical robots is reviewed from a technological point of view, including three of possibly the most debated technical topics in surgical robotics: vision, haptics, and accessibility. Further to that, several emerging robotic technologies are highlighted for their potential applications in next-generation robotic surgery

Efficient tele-operation of a robot manipulator by means of a motion capture interface

One of the core challenges of developing an autonomous robotic system is that of establishing appropriate channels for imparting commands to the robotic system. A successful communication infrastructure is an important component not only for a robotic system at the final deployment state, where it would allow the users to specify tasks, but also during the development stages where the robotic system still has to learn desired behaviours and appropriate responses to the environment's events and other external stimuli. In the framework of Learning by Demonstration, positive (and sometimes negative) examples are provided to the system by means of direct execution. Kinesthetic teaching consists in providing such demonstrations by physically moving the robot's body -- alas, it is known to be a cumbersome and time-consuming procedure. Another approach is that of controlling the robotic system more indirectly through tele-operation. We would like to build the appropriate infrastructure to control our PR2 robot using tele-operation, such that a human executer can perform a variety of tasks with minimal effort. We aim at achieving this using our high-precision Polhemus G4 motiontracking system to keep track of human poses and gestures, and interpret these as appropriate commands for the PR2. The ability of switching between various modalities of control is highly desired (e.g in one modality the user controls the position of the robot in the room; in another he controls the arms to perform manipulation; etc). This project touches upon the subjects of task-space control, collision avoidance and compliance, and gesture recognition.Das zuverlässige Senden von Befehlen zu einem Robotersystem ist eine kern Herausforderung für die Entwicklung solcher Systeme. Nicht nur im finalen Entwicklungszustand zum Steuern, sondern auch schon während der Entwicklung werden gut funktionierende Kommunikationsinfrastrukturen benötigt. Besonders während der Entwicklung, bei dem das System Bewegungsabläufe und Reaktionen auf die Umgebung noch zu erlernen hat. Aus dem Kontext von "Leaning by Demonstration", bei dem durch physisches bewegen des Roboters, posistive sowohl als auch negative Beispiele generiert werden. Solche physische Demonstrationen sind bekannt dafür eine zeitaufwendige Prozedur zu sein. Ein weiterer Ansatz wäre ein Robotersystem indirekt über Teleoperation zu steuern. Das Ziel dieser Arbeit ist es eine Infrastruktur zu errichten um den PR2 Roboter mittels Teleoperation zu steuern. Der Mensch soll die Möglichkeit erlangen eine Vielzahl von Aufgaben mit möglichst geringem Aufwand durchzuführen. Dafür benutzen wir unser hochpräzises G4 Motiontracking-System um Bewegungen des Menschen in Steuerbefehle für unseren Roboter zu übersetzen. Zusätzlich soll der Benutzer zwischen verschieden Moden wechseln können (z.B von Positioniersteuerung des Greifers zu Positioniersteuerung des Roboters im Raum). Dieses Projekt umfasst die Themen "Task-space control", Kollisionsvermeidung, "Compliance" sowie Gestenerkennung

Hierarchical Control of End-Point Impedance and Joint Impedance for Redundant Manipulators

This paper proposes an impedance control methodfor redundant manipulators, which can control not only the endpointimpedance using one of the conventional impedance controlmethods, but the joint impedance which has no effects on theend-point impedance. First, a sufficient condition for the jointimpedance controller is derived. Then, the optimal controller fora given desired joint impedance is designed using the least squaresmethod. Finally, computer simulations and experiments using aplanar direct-drive robot are performed in order to confirm thevalidity of the proposed method