Center for Robotics Research
Center for Robotics Research
van der Wijk V.,Center for Robotics Research
Mechanisms and Machine Science | Year: 2017
Force balance is an important feature in high-speed machinery to move fast without base vibrations and in large moving structures to move safely and with minimal effort. Advantageous balanced linkages can be synthesized from inherently balanced linkage architectures, i.e. linkages with solely the essential kinematic relations for balance. The center of mass of such a linkage is in a stationary point in one of the links for all motion. In this paper it is shown that the known 4R four-bar based inherently balanced linkage architecture is only part of the complete or grand 4R four-bar based inherently balanced linkage architecture, which is presented here. It is shown that this architecture comprises all related theories and that they all depend on principal vectors. Also various new balanced linkages are derived. © Springer International Publishing Switzerland 2017.
van der Wijk V.,Center for Robotics Research
Mechanisms and Machine Science | Year: 2018
A shaking force balanced mechanism is a mechanism that does not exert dynamic reaction forces to its base and to its surrounding for any motion. For mobile mechanisms such as exoskeletons, humanoid robots, drones, and anthropomorphic hands force balance is an important property for, among others, their dynamic behavior, stability, safety, control, and low energy consumption. For the design of force balanced mechanisms with multiple closed loops it can be a significant challenge to obtain the balance conditions, especially when the mechanism consists of closed loops that depend on other closed loops. In this paper it is shown how with mass equivalent modeling the force balance conditions can be derived of a complex multi-degree-of-freedom parallel mechanism with multiple closed loops of which one or more depend on other closed loops. It is shown how such a mechanism can be divided in mass equivalent linkages such as mass equivalent dyads and mass equivalent triads for which each can be analyzed individually with principal vectors and linear momentum equations. © Springer International Publishing AG 2018.
Friston K.,University College London |
Rigoli F.,University College London |
Ognibene D.,Center for Robotics Research |
Mathys C.,University College London |
And 4 more authors.
Cognitive Neuroscience | Year: 2015
We offer a formal treatment of choice behavior based on the premise that agents minimize the expected free energy of future outcomes. Crucially, the negative free energy or quality of a policy can be decomposed into extrinsic and epistemic (or intrinsic) value. Minimizing expected free energy is therefore equivalent to maximizing extrinsic value or expected utility (defined in terms of prior preferences or goals), while maximizing information gain or intrinsic value (or reducing uncertainty about the causes of valuable outcomes). The resulting scheme resolves the exploration-exploitation dilemma: Epistemic value is maximized until there is no further information gain, after which exploitation is assured through maximization of extrinsic value. This is formally consistent with the Infomax principle, generalizing formulations of active vision based upon salience (Bayesian surprise) and optimal decisions based on expected utility and risk-sensitive (Kullback-Leibler) control. Furthermore, as with previous active inference formulations of discrete (Markovian) problems, ad hoc softmax parameters become the expected (Bayes-optimal) precision of beliefs about, or confidence in, policies. This article focuses on the basic theory, illustrating the ideas with simulations. A key aspect of these simulations is the similarity between precision updates and dopaminergic discharges observed in conditioning paradigms. © 2015 Taylor & Francis.
Lee K.,Hanyang University |
Uhm T.,Center for Robotics Research |
Park J.-I.,Hanyang University
2017 IEEE International Conference on Consumer Electronics, ICCE 2017 | Year: 2017
In this paper, we propose a contactless touch interface using thermal imaging camera is, for users who are not capable of using their fingers and hands. In this way, an interaction where a user does not need to directly touch with his/her finger is made possible. For the interaction method, user's breath touches the surface of a screen, transmitting the heat to the surface; then the thermal residue is detected as a touched spot, enabling to operate in the same way which touch by finger works. The proposed method is highly useful in the sense that many users who cannot use their fingers and hands can interact under a system that is quasi-identical to normal touch system, along with the sense that it can enlarge available ranges of touch interface. © 2017 IEEE.
Hwang D.,Korea Institute of Science and Technology |
Ihn Y.S.,Korea Institute of Science and Technology |
Hwang S.,Center for Robotics Research |
Hwang S.,Hoseo University |
And 2 more authors.
Proceedings of the IEEE RAS and EMBS International Conference on Biomedical Robotics and Biomechatronics | Year: 2016
This paper presents a preliminary study on the method for stable and reliable implantation of neural interfaces into peripheral nervous system (PNS). The implantation of the neural interfaces such as a microelectrode array would be regarded as the most important first step in carrying out diverse neuroscientific studies accompanying the experiment for electrical-stimulation of PNS and/or direct recording of neural signal. Because the result of surgical implantation significantly influences on the overall performance of the study, we focus on investigating a more effective implantation method which facilitates achieving the successful implantation result such as: reliable penetration of nerve membranes, avoidance of neurological damage to the peripheral nerve, prevention of microelectrode fracture in inserting, and long-Term stability. One of key reasons of difficulty for implantation is that the PNS is encircled with pliable but tough internal and external membranes obstructing the straightforward insertion of the microelectrodes. In this preliminary study, with consideration for this elemental property of the PNS, we attempt to utilize high-frequency mechanical vibration in inserting the microelectrode into the nerve. The result on pilot experiment for feasibility assessment demonstrates helpfulness and potential applicability of the proposed method. © 2016 IEEE.
Cao Z.,Beijing University of Chemical Technology |
Yin L.,Beijing University of Chemical Technology |
Fu Y.,Harbin Institute of Technology |
Dai J.S.,Center for Robotics Research
International Journal of Humanoid Robotics | Year: 2016
A significant amount of work has been reported in the area of vision-based stabilization of wheeled robots during the last decade. However, almost all the contributions have not considered the actuator dynamics in the controller design. Considering the unknown parameters of the robot kinematics and dynamics incorporating the actuator dynamics, this paper presents a vision-based robust adaptive controller for the stabilization of a wheeled humanoid robot by using the adaptive backstepping approach. For the controller design, the idea of backstepping is used and the adaptive control technique is applied to treat all parametric uncertainties. Moreover, to attenuate the effect of the external disturbances on control performance, smooth robust compensators are employed. The stability of the proposed control system is analyzed by using Lyapunov theory. Finally, simulation results are given to verify the effectiveness of the proposed controller. © 2016 World Scientific Publishing Company
Liu H.,Center for Robotics Research |
Nguyen K.C.,University Pierre and Marie Curie |
Perdereau V.,University Pierre and Marie Curie |
Bimbo J.,Center for Robotics Research |
And 5 more authors.
Autonomous Robots | Year: 2015
In this paper we introduce a novel contact-sensing algorithm for a robotic fingertip which is equipped with a 6-axis force/torque sensor and covered with a deformable rubber skin. The design and the sensing algorithm of the fingertip for effective contact information identification are introduced. Validation tests show that the contact sensing fingertip can estimate contact information, including the contact location on the fingertip, the direction and the magnitude of the friction and normal forces, the local torque generated at the surface, at high speed (158–242 Hz) and with high precision. Experiments show that the proposed algorithm is robust and accurate when the friction coefficient $$\le $$≤1. Obtaining such contact information in real-time are essential for fine object manipulation. Using the contact sensing fingertip for surface exploration has been demonstrated, indicating the advantage gained by using the identified contact information from the proposed contact-sensing method. © 2015, Springer Science+Business Media New York.
Sadati S.M.H.,Center for Robotics Research |
Noh Y.,Center for Robotics Research |
Naghibi S.E.,Queen Mary, University of London |
Kaspar A.,Center for Robotics Research |
Nanayakkara T.,Center for Robotics Research
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2015
Continuum and soft robotics showed many applications in medicine from surgery to health care where their compliant nature is advantageous in minimal invasive interaction with organs. Stiffness control is necessary for challenges with soft robots such as minimalistic actuation, less invasive interaction, and precise control and sensing. This paper presents an idea of scale jamming inspired by fish and snake scales to control the stiffness of continuum manipulators by controlling the Coulomb friction force between rigid scales. A low stiffness spring is used as the backbone for a set of round curved scales to maintain an initial helix formation while two thin fishing steel wires are used to control the friction force by tensioning. The effectiveness of the design is showed for simple elongation and bending through mathematical modelling, experiments and in comparison to similar research. The model is tested to control the bending stiffness of a STIFF-FLOP continuum manipulator module designed for surgery. © Springer International Publishing Switzerland 2015.
Wei G.,Center for Robotics Research |
Stephan F.,French Institute for Advanced Mechanics |
Aminzadeh V.,Center for Robotics Research |
Dai J.S.,Center for Robotics Research |
Gogu G.,French Institute for Advanced Mechanics
Springer Tracts in Advanced Robotics | Year: 2014
This paper presents for the first time an application study of using dexterous robotic hands for deboning operation so as to establish a human-robot co-working platform for cutting, deboning and muscle extraction operation in meat industry. By setting up a test rig consisting of a support and a customized knife integrated with force sensors and utilizing a modified data glove, manual ham deboning operations are carried out providing essential information and background for the robotic hand design, appropriate force/torque and position sensors identification, and human-robot co-working platform trajectory planning. Principle component analysis method is then employed for trajectory mapping and planning associated with the knife peak coordinates, and concept of force cone is introduced leading to an efficient algorithm for trajectory planning. Further, design and kinematics of a metamorphic hand are investigated laying a background for measuring manipulation and grasp quality of the proposed robotic hand. The above experimental, theoretical, hardware and software preparations finally lead to the applications of using two dexterous robotic hands, i.e. one Shadow C6M left hand and one KCL G4 metamorphic hand to replace human left hand in deboning operation. The experiment thus laid background work for the robotization of meat industry and gave insight into the benchmarking of utilizing dexterous hand in deboning operation constructing a human-robot co-working hyper-flexible cell. © Springer International Publishing Switzerland 2014.
Deters C.,Center for Robotics Research |
Wurdemann H.A.,Center for Robotics Research |
Dai J.S.,Center for Robotics Research |
Seneviratne L.D.,Center for Robotics Research |
Althoefer K.,Center for Robotics Research
Advances in Reconfigurable Mechanisms and Robots I | Year: 2012
This paper investigates the use of an agent based assembly strategy for a wind turbine hub. The manual assembly procedure for a wind turbine is presented. The hub parts are constantly optimised and therefore a fully automated assembly line requires continously reprogramming. Thus, a new reconfigurable assembly system is introduced which is flexible and self-adaptive. The methodology of implementing an intelligent agent for designing the assembly strategy for the wind generator hub and the algorithm for the optimal task sequence are described. This reconfigurable automation runs a Partial Order Planning algorithm in real-time using Beckhoff TwinCAT® 3. © Springer-Verlag 2012.