Scaled bilateral teleoperation using discrete-time sliding mode controller

In this paper, the design of a discrete-time slidingmode controller based on Lyapunov theory is presented along with a robust disturbance observer and is applied to a piezostage for high-precision motion. A linear model of a piezostage was used with nominal parameters to compensate the disturbance acting on the system in order to achieve nanometer accuracy. The effectiveness of the controller and disturbance observer is validated in terms of closed-loop position performance for nanometer references. The control structure has been applied to a scaled bilateral structure for the custom-built telemicromanipulation setup. A piezoresistive atomic force microscope cantilever with a built-in Wheatstone bridge is utilized to achieve the nanonewtonlevel interaction forces between the piezoresistive probe tip and the environment. Experimental results are provided for the nanonewton-range force sensing, and good agreement between the experimental data and the theoretical estimates has been demonstrated. Force/position tracking and transparency between the master and the slave has been clearly demonstrated after necessary scalin

Observer based dynamic control model for bilaterally controlled MU-lapa robot: Surgical tool force limiting

During laparoscopic surgeries, primary surgical tool insertion is the demanding and strenuous task. As the surgeon is unaware of the type of the tissue and associated parameters to conduct the insertion, therefore, to ease the procedure, the movement of the surgical tool needs to be controlled. It’s the operational capabilities that are to be manipulated to perform a smooth surgery even from a distant location. In this study, a robot system is being introduced for laparoscopic primary surgical tool insertion. It will incorporate a novel observer based dynamic control along with robot assisted bilateral control. Moreover, a virtual spring damper force lock system is introduced through which the slave system will notify the master regarding the target achieved and excessive force. The validation of the proposed control system is experimented with bilaterally controlled MU-LapaRobot. The experiment is comprising 3 cases of bilateral control criteria which are non-contact motion, contact motion, and limit force locking. The results defined the same value for contact and non-contact motion by 0.3N. The results depicted a force error of 3.6% and a position error of 5.8% which validated the proposed algorithm

Visual Servoing in Robotics

Visual servoing is a well-known approach to guide robots using visual information. Image processing, robotics, and control theory are combined in order to control the motion of a robot depending on the visual information extracted from the images captured by one or several cameras. With respect to vision issues, a number of issues are currently being addressed by ongoing research, such as the use of different types of image features (or different types of cameras such as RGBD cameras), image processing at high velocity, and convergence properties. As shown in this book, the use of new control schemes allows the system to behave more robustly, efficiently, or compliantly, with fewer delays. Related issues such as optimal and robust approaches, direct control, path tracking, or sensor fusion are also addressed. Additionally, we can currently find visual servoing systems being applied in a number of different domains. This book considers various aspects of visual servoing systems, such as the design of new strategies for their application to parallel robots, mobile manipulators, teleoperation, and the application of this type of control system in new areas

Passivity-Based adaptive bilateral teleoperation control for uncertain manipulators without jerk measurements

In this work, we consider the bilateral teleoperation problem of cooperative robotic systems in a Single-Master Multi-Slave (SM/MS) configuration, which is able to perform load transportation tasks in the presence of parametric uncertainty in the robot kinematic and dynamic models. The teleoperation architecture is based on the two-layer approach placed in a hierarchical structure, whose top and bottom layers are responsible for ensuring the transparency and stability properties respectively. The load transportation problem is tackled by using the formation control approach wherein the desired translational velocity and interaction force are provided to the master robot by the user, while the object is manipulated with a bounded constant force by the slave robots. Firstly, we develop an adaptive kinematic-based control scheme based on a composite adaptation law to solve the cooperative control problem for robots with uncertain kinematics. Secondly, the dynamic adaptive control for cooperative robots is implemented by means of a cascade control strategy, which does not require the measurement of the time derivative of force (which requires jerk measurements). The combination of the Lyapunov stability theory and the passivity formalism are used to establish the stability and convergence property of the closed-loop control system. Simulations and experimental results illustrate the performance and feasibility of the proposed control scheme.No presente trabalho, considera-se o problema de teleoperação bilateral de um sistema robótico cooperativo do tipo single-master e multiple-slaves (SM/MS) capaz de realizar tarefas de transporte de carga na presença de incertezas paramétricas no modelo cinemático e dinâmico dos robôs. A arquitetura de teleoperação está baseada na abordagem de duas camadas em estrutura hierárquica, onde as camadas superior e inferior são responsáveis por assegurar as propriedades de transparência e estabilidade respectivamente. O problema de transporte de carga é formulado usando a abordagem de controle de formação onde a velocidade de translação desejada e a força de interação são fornecidas ao robô mestre pelo operador, enquanto o objeto é manipulado pelos robôs escravos com uma força constante limitada. Primeiramente, desenvolve-se um esquema de controle adaptativo cinemático baseado em uma lei de adaptação composta para solucionar o problema de controle cooperativo de robôs com cinemática incerta. Em seguida, o controle adaptativo dinâmico de robôs cooperativos é implementado por meio de uma estratégia de controle em cascata, que não requer a medição da derivada da força (o qual requer a derivada da aceleração ou jerk). A teoria de estabilidade de Lyapunov e o formalismo de passividade são usados para estabelecer as propriedades de estabilidade e a convergência do sistema de controle em malha-fechada. Resultados de simulações numéricas ilustram o desempenho e viabilidade da estratégia de controle proposta

Ukupno harmoničko izobličenje i brzina prostorne modalne informacije za analizu haptičkog paralelnog gibanja

In this paper, two kinds of evaluation index for the haptic motion analysis in parallel multiple degrees–of–freedom (MDOF) system are proposed. At first, the spatial modal decomposition method based on discrete Fourier series expansion (DFS) is presented. Spatial modal information expresses a motion element that corresponds to a specific physical action. The spatial modal information can mathematically be defined by the Fourier coefficients. Then, this paper proposes the total harmonic distortion (THD) and the content rate of the haptic modal information as motion evaluation indexes. THD of the spatial modal information can evaluate the complexity of the human motion and/or the deformability of the contact environment. Content rate of the spatial modal information can evaluate the priority of motion element. Some experimental results on the bilateral motion control of a parallel five DOF haptic system are shown, in order to confirm the utility of the proposed indexes.U ovom radu predložena su dva indikatora vrednovanja haptičkog gibanja u paralelnom sustavu s više stupnjeva slobode. Prikazana je metoda prostorne modalne dekompozicije zasnovana na proširenom diskretnom Fourierovom redu. Prostorna modalna informacija predstavlja element koji odgovara specifičnoj fizikalnoj radnji. Prostorna modalna informacija matematički se može opisati koristeći Fourierove koeficijente. U ovom se radu kao indikatori za evaluaciju gibanja predlažu ukupno harmoničko izobličenje i brzina haptičke modalne informacije. Ukupnim harmoničkim izobličenjem prostorne modalne informacije može se ocijeniti kompleksnost ljudskog gibanja i/ili deformabilnost kontaktne okoline. Przina prostorne modalne informacije ocjenjuje prioritet elementa u gibanju. Kako bi se potvrdila korisnost predloženih indikatora vrednovanja prikazani su eksperimentalni rezultati dobiveni dvoosnim prostornim upravljanjem paralelnim haptičkim sustavom s pet stupnjeva slobode

External force estimation for telerobotics without force sensor

This paper establishes an approach to external force estimation through the use of a mathematical model and current sensing, without employing a force/torque sensor. The advantages and need for force feedback have been well established in the field of telerobotics. This paper presents the requirement for sensorless force estimation and comparative results between a force sensor and the presented approach using an industrial robot. The approach presents not only a cost effective solution but also a solution for force sensing in hazardous environments, especially ionizing radiation prone environments where the dose rates limit the use of sensing equipment. The paper also discusses the applications and advantages presented by this work in various fields

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