AbstractThis paper presents a control strategy for indus-trial robot manipulators which consists of the combination of a calibration-free, vision-based control method with an impedance control approach. The vision-based, robot control... more
AbstractThis paper presents a control strategy for indus-trial robot manipulators which consists of the combination of a calibration-free, vision-based control method with an impedance control approach. The vision-based, robot control method known as camera-space manipulation ...
Engineers have for some time known that singularities play a significant role in the design and control of robot manipulators. Singularities of the kinematic mapping, which determines the position of the end-eector in terms of the manipu-... more
Engineers have for some time known that singularities play a significant role in the design and control of robot manipulators. Singularities of the kinematic mapping, which determines the position of the end-eector in terms of the manipu- lator's joint variables, may impede control algorithms, lead to large joint velocities, forces and torques and reduce instantaneous mobility. However they can also
ABSTRACT This paper presents a control strategy for improving the performance of force-based foot motion trajectory generation with optimal impedance control for a hydraulically driven hexapod robot known as COMET-IV. This technique... more
ABSTRACT This paper presents a control strategy for improving the performance of force-based foot motion trajectory generation with optimal impedance control for a hydraulically driven hexapod robot known as COMET-IV. This technique facilitates walking/operating on extremely uneven and unstructured terrain. The trajectory module is stabilized using the derived impedance control with optimal force input. The robot’s body moment of inertia is calculated (instead of employing environmental modeling) and adapted as an impedance control input with improvement of TSK-FLC that is locally optimized via the solution of the algebraic Riccati equation of virtual robot dynamic itself. The proposed control strategy aims to generate a smooth dynamic signal in order to reduce the shaking of the robot’s foot while placing it on the ground during a walking session. The proposed control strategy is verified using an actual robot system while walking/operating on a setup consisting of an unstructured terrain and on actual extremely uneven terrain.
This work is focused on impedance control of robot manipulators performing six-degree-of-freedom interaction tasks. An energy-based formulation leads to formally deriving the dynamic equation characterizing a mechanical impedance at the... more
This work is focused on impedance control of robot manipulators performing six-degree-of-freedom interaction tasks. An energy-based formulation leads to formally deriving the dynamic equation characterizing a mechanical impedance at the end effector. An inverse dynamics strategy with contact force and moment measurement is adopted to obtain a configuration-independent desired impedance. For given contact force and moment, an impedance control scheme is proposed acting on both translational displacement and rotational displacement where end-effector orientation is described using a singularity-free representation in terms of a unitary quaternion. Experimental results on an industrial robot with open control architecture are presented
Variable impedance actuators provide the ability to robustly alter interaction impedances mechanically, without bandwidth, power, and stability limitations. They can achieve the physical benefits of an elastic transmission and also... more
Variable impedance actuators provide the ability to robustly alter interaction impedances mechanically, without bandwidth, power, and stability limitations. They can achieve the physical benefits of an elastic transmission and also recover characteristics of traditionally controlled, inelastic motors. We review previously explored benefits of variable impedance actuators for energetic tasks and impact safety. We then focus on benefits in low frequency force interactions. We examine impedance and force dynamic ranges and illustrate how they are significantly increased by physical impedance variation. Theoretical analysis is confirmed by experiments on a 1-DOF testbed with three impedance settings.
An outstanding question in research of central pattern generators is whether CPGs can be used for whole body control of a robot. Given the spine's important role in walking, including a robotic spine may be a prerequisite for answering... more
An outstanding question in research of central pattern generators is whether CPGs can be used for whole body control of a robot. Given the spine's important role in walking, including a robotic spine may be a prerequisite for answering this question, but most current robots use rigid torsos. Tensegrity offers exciting possibilities for future robotic structures, as their continuous tension networks automatically distribute forces. This property creates robust structures and shows the potential to improve torsos of legged robots, and may also provide mechanisms for distributed coordination of motor patterns and entrainment with oscillatory controllers such as CPGs. Our prior work with CPGs on tensegrity structures allowed for some adaptations in rough terrain, but without feedback success was limited with larger perturbations. This work demonstrates a CPG controlled tensegrity spine with locomotor capability on additional terrains by providing feedback to the CPG.
The paper deals with the application of model reference adaptive control to robot impedance control, which is actually a technique of steering the end-effector on a prescribed path and satisfying a prescribed dynamic relationship between... more
The paper deals with the application of model reference adaptive control to robot impedance control, which is actually a technique of steering the end-effector on a prescribed path and satisfying a prescribed dynamic relationship between the force and the end-effector position. Due to unknown parameters of the environment (stiffness, exact position), a model reference algorithm is proposed which differs from classical algorithms in its method of excitation. The results of the proposed procedure are illustrated by implementation on the ASEA IRb 6 industrial robot.
In this work, the internal impedance of the lithium-ion battery pack (important measure of the degradation level of the batteries) is estimated by means of machine learning systems based on supervised learning techniques MLP-Multi Layer... more
In this work, the internal impedance of the lithium-ion battery pack (important measure of the degradation level of the batteries) is estimated by means of machine learning systems based on supervised learning techniques MLP-Multi Layer Perceptron-neural network and xg-Boost-Gradient Tree Boosting. Therefore, characteristics of the electric power system, in which the battery pack is inserted, are extracted and used in the construction of supervised models through the application of two different techniques based on Gradient Tree Boosting and Multi Layer Perceptron neural network. Finally, with the application of statistical validation techniques, the accuracy of both models are calculated and used for the comparison between them and the feasibility analysis regarding the use of such models in real systems.
Özetçe Bu çalışmada 6 serbestlik dereceli insansı robot kolu konum ve kuvvet kontrolüne yer verilmiştir. Robotik alanında kullanılan kontrol yöntemleri incelenmiş, insansı robot kolu için yapılması istenebilecek görevler göz önünde... more
Özetçe Bu çalışmada 6 serbestlik dereceli insansı robot kolu konum ve kuvvet kontrolüne yer verilmiştir. Robotik alanında kullanılan kontrol yöntemleri incelenmiş, insansı robot kolu için yapılması istenebilecek görevler göz önünde bulundurularak en uygun görülen Empedans Kontrol yöntemi seçilmiştir. Bu yöntem, belirlenen senaryo ile benzetim çalışmaları üzerinde analiz edilmiştir. Robot kol modeli Solidworks programında yapılan çizimi, SimMechanics araç çubuğu ile Matlab Simulink ortamına aktarılmış, benzetim çalışmaları bu arayüzden yürütülmüştür. Görev olarak çember çizimi tanımlanmış ve robot kolunun hareketli bir levha üzerine çizim yapması istenmiştir. Gerçekleştirilme açısından değerlendirilip, konum ve kuvvet kontrolü için en uygun görülen Temel Empedans Kontrol Yöntemi seçilmiştir. Bu yöntemde hassas olarak belirlenmesi gereken katılık, sönüm, konum ve hız modifikasyon matrisleri bulunmaktadir. Bunlar kontrolcü katsayılardır. Katsayıların belirlenmesinde öncelikle deneme-yanılma yöntemi kullanılmış ve kabul edilebilir konum hatalarıyla uç eyleyici konum-kuvvet kontrolü gerçekleştirilmiştir. Abstract One of the most important parameters is that the robot can be controlled to perform a desired task. It is essential that position or force control or both should be provided. In this study, the position and force control of a robot arm with 6 degrees of freedom are given. Different methods in the literature are examined to select the controller and the "Impedance Control Method" which may be suitable for a desired task is selected and the simulation works are done. Robot arm has been modelled using Solidworks® program and the model transferred to the MATLAB® Simulink interface through with SimMechanics toolbox. Simulation studies have been carried out on the Simulink model and the results have been evaluated.
Active control of the acoustic impedance of walls in rooms allows fine control of the reverberation in auditoria. Such active materials may use locally reacting cells comprising a transducer connected to an electronic control circuit. In... more
Active control of the acoustic impedance of walls in rooms allows fine control of the reverberation in auditoria. Such active materials may use locally reacting cells comprising a transducer connected to an electronic control circuit. In this paper, a simple feedback circuit based on a linear combination of the pressure at the transducer diaphragm and the velocity of the diaphragm is presented. We then discuss the desired characteristics of a transducer dedicated to our application, and show that the isodynamic technology is an interesting candidate, especially if using rubber magnet bars. We present results from simulations involving a finite element model of such transducer, which predict a good control over two frequency decades. Preliminary experimental results obtained with a basic prototype of isodynamic transducer are encouraging, yielding an absorption coefficient approaching 1 (> 0.7) from 30 up to 500 Hz. We think that far better results can be obtained (specially in the "super-reflecting" case) with closer control over the various mechanical parameters. Future work will also address the optimisation of the magnet geometry.
