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Öğe Application of Soft Actuation to Bilateral Control and Haptic Reproduction(Inst Control Robotics & Systems, Korean Inst Electrical Engineers, 2022) Sabanovic, Asif; Uzunovic, Tarik; Baran, Eray A.; Yokoyama, Minoru; Shimono, TomoyukiThe main research topic of this paper is to apply the sliding mode based soft actuation to smooth transition between position, force, and impedance control, and realize bilateral control and reproduction of the haptic motion. The proposed design rests on the sliding mode two steps procedure: in the first step, the generalized error - the sliding mode function - is selected in such a way that a closed loop system exhibits a desired dynamics. In the soft actuation method, the generalized error depends on the position and the force, thus allowing the modification of the position tracking if interaction with the environment appears. In the second step, the control is selected to enforce the desired convergence rate and the stability of the closed loop dynamics. The control allows natural - human-like behavior. The application to the bilateral control and reproduction of the haptic motion is discussed in detail and verified by experiments.Öğe Bilateral Control With Continuously Variable Scaling(IEEE, 2018) Oztoprak, Burak; Baran, Eray A.; Sabanovic, AsifThis paper proposes a method for the scaled bilateral teleoperation with continuously variable position and force scaling. In the proposed method, the controller is reformulated to synchronize the forces and velocities which provides the operator with the ability to change the scaling gains during operation. For the derivation of the controller, exponentially decaying error dynamics are preferred over the assumption of disturbance compensation with Disturbance Observers (DOB). Following the mathematical derivation, the algorithm is tested on a setup containing single DOF master and slave robots with the ability of giving force feedback to the operator. In order to provide a complete analysis, several different sets of experiments are made with sinusoidal velocity and force scales having different amplitudes and frequencies. Experiment results illustrate the successful tracking responses and stable operation of the proposed control scheme for the continuously varying velocity and force scales.Öğe Bilateral teleoperation with continuously variable scaling and PD force control(Sage Publications Ltd, 2021) Oztoprak, Burak; Baran, Eray A.; Sabanovic, AsifThis paper investigates the bilateral teleoperation with the possibility of continuously variable scaling during real-time operation. The algorithm proposed for this purpose provides the operator with the ability to change the scaling gains of force and velocity loops during operation. The controllers are derived to enforce exponentially decaying error dynamics on systems which have inner loop disturbance compensation. The proposed architecture assumes the scale factors as continuous functions of time which have continuous derivatives that are also included in the mathematical derivation. Unlike the existing studies, the presented framework allows real-time adaptation of scaling gains, which provides the user with the ability to conduct coarse and fine motion in the same operation. The Lyapunov stability proof of the proposed method is made and the margins of the controller gains are identified for practical operation. Furthermore, the operational accuracy is enhanced by the application of a PD force control loop which is also new for scaled bilateral teleoperation. The realization of PD loop is made using an alpha-beta-gamma filter to differentiate the force signal. The algorithm is validated on a setup consisted of two single DOF motion control systems. In order to provide a complete analysis, a wide range of experiments are made, velocity and force scales having sinusoidal patterns with different amplitudes and frequencies. Moreover, comparison with a classical bilateral control architecture is made to highlight the flexibility of the proposed control method. The efficacy of the proposed approach is solidified by the successful tracking responses obtained from these experiments.Öğe Comparative Analysis of a Selected DCT-Based Compression Scheme for Haptic Data Transmission(IEEE-Inst Electrical Electronics Engineers Inc, 2016) Baran, Eray A.; Kuzu, Ahmet; Bogosyan, Seta; Gokasan, Metin; Sabanovic, AsifIn this study, a novel compression and decompression algorithm, namely the selected discrete cosine transform (DCT), is presented for implementation in networked motion control systems. The proposed method relies on the utilization of a selection algorithm based on bubble sorting to choose the highest power coefficients of the signal obtained by using DCT. In order to better illustrate the effectiveness of the proposed method, comparisons are made with the methods existing in the literature. To this aim, the basics of the compression schemes used in the comparison, namely, the DCT, discrete Fourier transform, and wavelet packet transform, are also briefly discussed followed by the derivation of the proposed method. The algorithmic bases of all four schemes are given to provide further reference for practical applications. The proposed method is tested on an experimental platform consisting of a single-single-degree-of-freedom master and slave systems, and the results are comparatively analyzed based on relevant performance evaluation metrics. The obtained results demonstrate the improvement achieved by the proposed compression scheme over the existing compression methods used in network-based motion control applications, hence proving the feasibility of the approach in tele-operation systems.Öğe Drift compensation of a holonomic mobile robot using recurrent neural networks(Springer Heidelberg, 2022) Canbek, Kansu Oguz; Yalcin, Hulya; Baran, Eray A.Mecanum wheeled robots can exhibit serious slippage problems because of the discontinuous contact between the wheels and the ground which negatively influences the overall navigation quality. Addressing this problem, the aim of this paper is to demonstrate how a learning-based method can be used for the estimation of the drifting error from multiple sensors with distinct measurement types. Here, a recurrent neural network (RNN)-based drift compensation algorithm is proposed for the estimation of the positioning drift. In order to improve the positioning performance in dead reckoning the estimated drift is used within the real-time control loop for proper modification of the motion trajectory. During the training phase, the data acquired from the acceleration sensors attached to the robot chassis and the encoders of the wheels of the robot are used as the main features to train a gated recurrent unit-based RNN. The drift estimator is trained using the computer-generated reference position data, and the response position data which is measured using an optoelectronic motion tracking device. The performance of the proposed learning-based drift estimation and control algorithm is validated through a series of experiments. The responses obtained from the experiments are graphically illustrated and the improvements in the positioning performances are numerically evaluated. The results obtained from the experiments illustrate the effective performance of the proposed algorithm by considerably decreasing the positioning errors.Öğe Flexible Linear Absolute Encoder System for Force Localization in Soft Environments(IEEE, 2020) Erdil, Kuter; Korkut, Dogukan; Akcan, O. Gokalp; Muslu, Batin; Gokdel, Y. Daghan; Baran, Eray A.This paper proposes a novel disposable linear absolute encoder system and its peripheral electronic readout circuitry to be used for the localization of force in a continuum media such as a flexible robotic arm. The proposed structure relies on the design of graphite layers on a flexible surface that shows varying resistance based on the applied strain. The proposed topology can localize the force applied on a continuous paper based sensor having the geometry of an absolute encoder system. The successful results obtained from the experiments prove the efficacy of the proposed system while opening new paradigms for the possibility of contact force localization in flexible structures like soft robots.Öğe Improved bilateral teleoperation with proactive haptic sensing and transmission(Sage Publications Ltd, 2018) Kuzu, Ahmet; Baran, Eray A.; Bogosyan, Seta; Gokasan, Metin; Sabanovic, AsifThis article presents a novel master-slave control configuration that is experimentally demonstrated to improve teleoperation performance under random network delay. This is achieved via the design of a proactive haptic sensing system based on a laser range sensor on the slave side, which in turn allows for the proactive transmission of force control from the master to the slave, thus compensating for Internet-based network delays. The proposed configuration introduces three main contributions to the literature of bilateral control systems: (1) fully decoupled position and force control systems, which allow for the controller gains of each loop to be tuned independently, eliminating the trade-off common to most previous literature; (2) a novel approach that exploits the slow variation nature of the environment parameters, resulting in a lower bandwidth requirement in comparison to previous force control methods; (3) capability to measure the slave environment location and the prediction of the contact force as a result, which provides the human operator with the capability to generate the reaction force proactively on the master side. The conducted experiments demonstrated a significantly improved performance in terms of synchronized forces and positions despite the random network delay between the master and slave systems.Öğe Modular and reconfigurable desktop microfactory for high precision manufacturing(Springer London Ltd, 2017) Zhakypov, Zhenishbek; Uzunovic, Tarik; Nergiz, Ahmet Ozcan; Baran, Eray A.; Golubovic, Edin; Sabanovic, AsifSub-millimeter scale devices are developing rapidly taking smaller, smarter, and more precise forms. This is achieved thanks to advancements in micro-manufacturing tools and techniques. For micro-production, a miniaturization of the machinery is a prominent idea that has numerous benefits in terms of material usage, precision, transportation, modularity, and reconfigurability. In this paper, a modular and reconfigurable desktop microfactory for high precision machining and assembly of sub-millimeter scale mechanical parts is presented and experimentally validated. The proposed system is built based on important functional and performance requirements, including miniaturization, high precision operation, modular and reconfigurable design, parallel processing capability, ease of installation, and transportation. The miniature factory consists of five mini processing units; two parallel kinematic robots for manipulation, the laser micro-machining system, the camera system for detection and inspection, and the rotational conveyor system for micro-part delivery. Different configurations of the system layout are proposed taking advantage of their modular design. Experiments are conducted to evaluate the system performance within a single process, like pick-place of a metallic ball with 3 mm diameter, laser machining of a half-millimeter size contour on the surface of the ball, and inspection and verification of the machined contour by means of microscopic camera. The results presented in this work demonstrate micrometer precision operation of the microfactory, showing high potential for manufacturing electro-mechanical devices with ease of readjustment of the microfactory layout.Öğe A multiple sensor fusion based drift compensation algorithm for mecanum wheeled mobile robots(Tubitak Scientific & Technological Research Council Turkey, 2021) Alhalabi, Abdulrahman; Ezim, Mert; Canbek, Kansu Oguz; Baran, Eray A.This paper investigates a multiple sensor fusion based drift compensation technique for a mecanum wheeled mobile robot platform. The mobile robot is equipped with high-precision encoders integrated to the wheels and four accelerometers placed on its chassis. The proposed algorithm combines the information from the encoders and the acceleration sensors to estimate the total drift in the acceleration dimension. The inner loop controller is designed utilizing a disturbance-observer-based acceleration control structure which is blind against the slipping motion of the wheels. The estimated drift acceleration from the sensor fusion is then mapped back to the joint space of the robot and used as additional compensation over the existing controllers. The proposed algorithm is tested on a series of experiments. The results of the experiments are also compared with those of a recent study in order to provide a benchmark evaluation. The enhanced tracking performance yielding towards smaller error magnitudes in the experiments illustrate the efficacy and success of the proposed control architecture in attenuating the positioning drift of mecanum wheeled robots.Öğe A novel hybrid contouring control method for 3-DOF robotic manipulators(Pergamon-Elsevier Science Ltd, 2016) Uzunovic, Tarik; Baran, Eray A.; Golubovic, Edin; Sabanovic, AsifA novel controller for three-dimensional contouring control of three-degrees-of-freedom (3-DOF) robotic manipulators is presented in this paper. The proposed controller comprises of an independent joint controller, designed in the configuration space, and a sliding mode controller that enforces desired dynamics for the tracking error projections to the Frenet-Serret frame. Therefore, the presented controller has a hybrid structure and it is named as hybrid contouring controller. In this paper, contour tracking with constant magnitude tangential velocity is discussed. Reference trajectory is generated using the time based spline approximation in order to provide a smooth reference path. The proposed hybrid contouring controller was experimentally compared with the independent joint controller that is designed in the acceleration control framework with disturbance observer. Experimental results, undertaken on a delta robot, showed that hybrid contouring controller outperforms independent joint control architecture. (C) 2016 Elsevier Ltd. All rights reserved.Öğe Paper-Based Piezoresistive Force Encoder for Soft Robotic Applications(IEEE-Inst Electrical Electronics Engineers Inc, 2022) Akcan, Omer Gokalp; Erdil, Kuter; Korkut, Dogukan; Baran, Eray A.; Gokdel, Y. DaghanThis work demonstrates the design, implementation, and experimental results of a low-cost disposable flexible sensor system capable of both impact localization and measurement. The proposed flexible sensor structure utilizes a special series of Bristol paper as the main fabrication material, which is coated with electric paint graphite paste and silver paste. The implemented sensor system uses a planar absolute encoder-like sensing topology to locate the impact and has a low-cost and quick manufacturing process. The size of the structure is 210 x 18.56 mm with a thickness of approximately 340 mu m. It has an electronic read-out consisting of three identical Wheatstone bridge circuits and instrumentation amplifiers for each bit. It can detect the external forces in the range of 0.6N to 12N with a spatial resolution of 2.4 cm and 0.55 cm in horizontal and vertical axes, respectively. The proposed sensor structure is tested in a series of experiments using a robotic setup consisted of a pantograph mechanism and a direct drive linear motor. The experiments illustrate the results with measurement sensitivity as small as 1N and proper fatigue resilience against repetitive loads.Öğe Performance improvement of bilateral control systems using derivative of force(Cambridge Univ Press, 2018) Baran, Eray A.; Uzunovic, Tarik; Sabanovic, AsifThis paper proposes a bilateral control structure with a realization of the force derivative in the control loop. Due to the inherent noisy nature of the force signal, most teleoperation schemes can make use of only a proportional (P) control structure in the force channel of the bilateral controllers. In the proposed scheme, an alpha-beta-gamma filter is designed to smoothly differentiate the force signal obtained from a reaction force observer integrated to both of the master and slave plants. The differentiated force signal is then used in a proportional-derivative (PD) force controller working together with a disturbance observer. In order to design the overall bilateral controller, an environment model based on pure spring structure is assumed. The controller is designed to enforce an exponentially decaying tracking error for both position and force signals. With the presented controller design approach, one can independently tune the controller gains of the force and the position control channels. The proposed approach is experimentally tested in a platform consisted of direct drive linear motors. As illustrated by the experiment results, the contribution of the PD control in the force channel improves the teleoperation performance especially under hard-contact motion scenarios by attenuating the oscillations, hence, improving the transparency when compared to the structures using only a P force control.Öğe Robust Motion Modification for Robot Manipulators in Constrained Environments(IEEE, 2018) Muslu, Batin; Oztoprak, Burak; Baran, Eray A.; Sabanovic, AsifThis paper presents a controller structure for the continuous and robust modification of motion for multi body systems encountering contact with an environment during free motion. The presented algorithm relies on the reformulation of the position tracking error with a term proportional to the reaction force. With the proposed method, fusion of the position and the force controllers can be achieved which provide the robot with certain level of compliance. The derivation of the proposed method is followed by experiments made on a pantograph mechanism actuated by direct drive linear motors. The results obtained from the experiments illustrate the success of the proposed control architecture in providing a natural behavior for the robotic systems working in constrained environments.Öğe Silicone Mold Implementation for High-Sensitive Detection of Strain Sensing using Paper-Based Piezoresistive System(IEEE, 2020) Korkut, Dogukan; Erdi, Kuter; Akcan, O. Gokalp; Muslu, Batin; Baran, Eray A.; Gokdel, Y. DaghanThis paper presents the design, fabrication, experimental results and related discussion of a portable bending enhancing silicone mold structure for biomedical applications in which a high-sensitive but low-cost force measurement structure with a large-dynamic range is required. Proposed system is composed of a replaceable parts like graphite coated Strathmore (R) 400 series Bristol paper and cheap RTV-2 silicone molds. The results shows that low-cost, portable and high-sensitive force and strain sensor systems can be realized for point-of-care biomedical applications in the future.Öğe Toward a Smart Actuating System for Service Robots(IEEE, 2023-10-05) Uzunoviç, Tarık; Baran, Eray A.; Özçelik, İlkay TuraçOwing to the increasing engagement of service robots in everyday life, significant requirements are imposed on their control systems to ensure safe interaction between robots and humans. The stiffness of the motion executed by the service robots is not high, as with industrial robots, but has to be variable depending on the defined task. Therefore, a service robot needs to have soft actuation, delivering “humanlike” motion dependant on the interaction force between the robot and its environment. Such an operation requires switching from the trajectory tracking (position control) mode to the interaction (force control) mode, and vice versa. Conventional control methods, based on hybrid position/force control, or switching between a position and force controller, may fail short in these cases. Thus, we have previously proposed a new control method, denoted as universal motion controller, that merges the position and force control into a single control structure. The control method is elaborated in this article, and its experimental validation is presented for the first time for multi-degree-of-freedom systems.Öğe Unified Kinematics of Prismatically Actuated Parallel Delta Robots(Cambridge Univ Press, 2019) Baran, Eray A.; Ozen, Ozhan; Bilgili, Dogacan; Sabanovic, AsifThis paper presents a unified formulation for the kinematics, singularity and workspace analyses of parallel delta robots with prismatic actuation. Unlike the existing studies, the derivations presented in this paper are made by assuming variable angles and variable link lengths. Thus, the presented scheme can be used for all of the possible linear delta robot configurations including the ones with asymmetric kinematic chains. Referring to a geometry-based derivation, the paper first formulates the position and the velocity kinematics of linear delta robots with non-iterative exact solutions. Then, all of the singular configurations are identified assuming a parametric content for the Jacobian matrix derived in the velocity kinematics section. Furthermore, a benchmark study is carried out to determine the linear delta robot configuration with the maximum cubic workspace among symmetric and semi-symmetric kinematic chains. In order to show the validity of the proposed approach, two sets of experiments are made, respectively, on the horizontal and the Keops type of linear delta robots. The experiment results for the confirmation of the presented kinematic analysis and the simulation results for the determination of the maximum cubic workspace illustrate the efficacy and the flexible applicability of the proposed framework.
