The Experts below are selected from a list of 4527 Experts worldwide ranked by ideXlab platform
Sung Jin Yoo - One of the best experts on this subject based on the ideXlab platform.
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adaptive leader follower formation control of mobile robots with unknown Skidding and slipping effects
International Journal of Control Automation and Systems, 2015Co-Authors: Bong Seok Park, Sung Jin YooAbstract:This paper investigates an adaptive leader-follower formation control problem of multiple mobile robots in the presence of unknown Skidding and slipping. First, we employ the concept of virtual robots to achieve the desired formation and derive the kinematics of the virtual leader and follower robots considering Skidding and slipping effects. Then, we design an adaptive formation controller based on a two-dimensional error surface where the adaptive technique is used for compensating the unknown Skidding and slipping effects that influence the follower robots. From Lyapunov stability theorem, we show that all errors of the closed-loop system are uniformly ultimately bounded, and thus the desired formation is successfully achieved regardless of the presence of unknown Skidding and slipping effects. Simulation results are provided to demonstrate the effectiveness of the proposed formation control scheme.
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adaptive neural tracking and obstacle avoidance of uncertain mobile robots with unknown Skidding and slipping
Information Sciences, 2013Co-Authors: Sung Jin YooAbstract:This paper presents a neural-network-based adaptive control approach for path tracking and obstacle avoidance of a class of mobile robots in the presence of unknown Skidding, slipping, and torque saturation. The model of mobile robots consists of kinematics and dynamics considering Skidding and slipping where all robot parameters as well as Skidding and slipping effects are unknown. The proposed adaptive controller is designed using systematic and recursive design methodologies, without the assumption of perfect velocity tracking, where the function approximation technique using neural networks is employed to compensate unknown nonlinear functions including the model uncertainties and bounds of the Skidding and slipping. From Lyapunov-stability analysis, it is shown that all signals of the controlled closed-loop system are semiglobally uniformly ultimately bounded, point tracking errors converge to an adjustable neighborhood of the origin outside the obstacle detection region, and the obstacle avoidance is guaranteed inside the region. The effectiveness of the proposed control system is demonstrated by simulation results.
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formation tracking control for a class of multiple mobile robots in the presence of unknown Skidding and slipping
Iet Control Theory and Applications, 2013Co-Authors: Sung Jin Yoo, Bong Seok ParkAbstract:This study investigates the formation control problem for a class of multiple mobile robots considering unknown Skidding and slipping, and torque saturation. The kinematics and dynamics of multiple mobile robots with Skidding and slipping effects are considered. The proposed formation control scheme is derived from the dynamic surface design and virtual structure approach where the reference trajectories consisting of path parameters are employed to satisfy both the tracking control and the formation maintenance. The adaptive technique is used to compensate the unknown Skidding and slipping effects. From Lyapunov-stability analysis, we prove regardless of unknown Skidding and slipping that all signals of the total closed-loop system are semiglobally uniformly ultimately bounded and the point-tracking errors and the synchronisation error for the desired formation converge to an adjustable neighbourhood of the origin. In addition, it is analysed that the orientation error for each robot is related to the speed of the reference trajectory and the Skidding effect. The performance and stability of the proposed approach are verified from simulation results.
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adaptive tracking control for a class of wheeled mobile robots with unknown Skidding and slipping
Iet Control Theory and Applications, 2010Co-Authors: Sung Jin YooAbstract:This study presents an adaptive tracking control approach for trajectory tracking of wheeled mobile robots with torque saturation in the presence of unknown Skidding and slipping. The robot kinematics and dynamics are induced from the perturbed non-holonomic constraints. The adaptive control system using the kinematics transformed in polar coordinates is developed to compensate unknown Skidding and slipping at the dynamic level of mobile robots with the input saturation. All signals of the controlled closed-loop system are uniformly bounded and the point tracking errors converge to an adjustable neighbourhood of the origin regardless of large initial tracking errors, input saturation and unknown Skidding and slipping. Simulation results are provided to demonstrate the performance and stability of the proposed control scheme.
Danwei Wang - One of the best experts on this subject based on the ideXlab platform.
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gps based tracking control for a car like wheeled mobile robot with Skidding and slipping
IEEE-ASME Transactions on Mechatronics, 2008Co-Authors: Chang Boon Low, Danwei WangAbstract:Many wheeled mobile robot (WMR) controllers are developed based on nonSkidding and nonslipping assumptions; however, these assumptions are usually violated due to wheel tire deformation. As a result, the performance of these controllers is not guaranteed. This paper presents a GPS-based tracking controller for a car-like WMR in the presence of wheel Skidding and slipping. The controller exploits real-time kinematic (RTK)-GPS and other aiding sensors to measure the WMR's posture, velocities, and perturbations due to wheel Skidding and slipping for control compensation. The reported experimental results validate the control scheme.
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modeling and analysis of Skidding and slipping in wheeled mobile robots control design perspective
IEEE Transactions on Robotics, 2008Co-Authors: Danwei WangAbstract:This paper aims to give a general and unifying presentation on modeling of wheel mobile robots (WMRs) in the presence of wheel Skidding and slipping from the perspective of control design. We present kinematic models that explicitly relate perturbations to the vehicle Skidding and slipping. Four configurations of mobile robots are considered, and perturbations due to Skidding and slipping are categorically classified as input-additive, input multiplicative, and/or matched/unmatched perturbations. Furthermore, we relate the WMR's maneuverability with the vehicle controllability that provides a measure on the WMR ability to track a trajectory in the presence of wheel Skidding and slipping. These classifications and formulations lay a base for the deployments of various control design techniques to overcome the addressed perturbations.
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gps based path following control for a car like wheeled mobile robot with Skidding and slipping
IEEE Transactions on Control Systems and Technology, 2008Co-Authors: Chang Boon Low, Danwei WangAbstract:Most wheeled mobile robot (WMR) controllers have been developed based on nonSkidding and nonslipping assumptions. Unfortunately, wheel Skidding and slipping are inevitable due to wheel tire-deformation; consequently, the stability and performance of these controllers are not guaranteed. This brief aims to develop a global positioning system (GPS)-based path following a controller for a car-like wheeled mobile robot in the presence of wheel Skidding and slipping. The proposed control scheme uses real-time kinematic (RTK)-GPS and other aiding sensors to measure the WMR's posture, velocities, and perturbations due to wheel Skidding and slipping. These measurements are applied to compensate the path following errors based on a backstepping controller. The reported experimental results validate the control scheme. With this solution, the WMR is able to maneuver with better precision in outdoor environments in the presence of wheel Skidding and slipping.
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integrated estimation for wheeled mobile robot posture velocities and wheel Skidding perturbations
International Conference on Robotics and Automation, 2007Co-Authors: Chang Boon Low, Danwei WangAbstract:This paper presents a scheme for high-update rate wheel mobile robot (WMR) posture, velocities, and perturbation estimation using real-time kinematic global positioning system (RTK-GPS) and inertial sensors for WMR control in the presence of wheel Skidding and slipping. An outdoor estimation system based on Kalman filtering combines the inertial measurements with centimeter accuracy RTK-GPS measurements to provide essential posture, velocities, and perturbation information. The particular contribution of this paper is in designing an estimation system to be able to deal with WMR control problems in the presence of wheel Skidding and slipping. The experimental results suggest that with careful modelling of WMR, the estimation scheme is able to provide reliable and high update rate information for WMR control applications in the presence of wheel Skidding and slipping.
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modeling Skidding and slipping in wheeled mobile robots control design perspective
Intelligent Robots and Systems, 2006Co-Authors: Danwei Wang, Chang LowAbstract:This present paper aims to give a general and unifying presentation on modeling of WMRs in the presence of wheel Skidding and slipping from the perspective of control design. We present kinematic models that explicitly relate the perturbations to the vehicle Skidding and slipping. Four configurations of mobile robots are considered and the perturbations due to Skidding and slipping are categorically classified as input additive, input multiplicative, and/or matched/unmatched perturbations. These classifications and formulations lay a base for the deployments of various control design techniques to overcome the addressed perturbations.
Zi Qiang Zhao - One of the best experts on this subject based on the ideXlab platform.
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Investigation of Skidding in angular contact ball bearings under high speed
Tribology International, 2015Co-Authors: Yunlong Wang, Wen Zhong Wang, Sheng Guang Zhang, Zi Qiang ZhaoAbstract:Abstract This paper proposes a dynamic model to investigate Skidding in angular contact ball-bearings with considering the interaction between balls and raceways, cage and lubricant. The differential equations governing the motions of bearing elements are established and solved using a fourth-order Runge-Kutta algorithm; traction forces between balls and raceways are evaluated based on elastohydrodynamic lubrication theory. The results show that the applied axial load significantly influences the behavior of Skidding due to the changes of internal load, orbital and rotation speeds of ball under different operating conditions; appropriate axial load can be determined to avoid severe Skidding.
Eric K. Zenner - One of the best experts on this subject based on the ideXlab platform.
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Influence of ground-based Skidding on physical and chemical properties of forest soils and their effects on maple seedling growth
European Journal of Forest Research, 2016Co-Authors: Ramin Naghdi, Ahmad Solgi, Eric R. Labelle, Eric K. ZennerAbstract:The main purpose of this study was to evaluate the effects of Skidding operations on the physical and chemical properties of soil as well as root and height growth of maple seedlings. Treatment plots with three replications included combinations of three levels of traffic frequency (three, eight, and 16 passes of a rubber-tired skidder Timberjack 450C) and two levels of trail gradient (≤20 and >20 %) to quantify soil disturbance and corresponding seedling growth. Significant differences between undisturbed areas and machine trail areas of bulk density (0.75 vs. 1.26 g cm^−3), total porosity (70.6 vs. 50.4 %), macroporosity (44.5 vs. 18.5 %), microporosity (26.1 vs. 31.8 %), moisture content (50.0 vs. 31.3 %), and forest floor biomass (3498 vs. 1271 kg ha^−1) were strongly related to the level of traffic frequency and the trail gradient. Similarly, Skidding caused significant reductions in the amount of soil OC (by 41 %), concentrations of nitrogen (53 %), phosphorous (28 %), potassium (31 %), and soil acidity (40 %) compared to undisturbed areas. Finally, germination rate, root length, and stem height of seedlings were inversely related to compaction. Physical and chemical soil properties are often significantly impacted by Skidding operations, depending on trail gradient and traffic frequency, which resulted in restrictions to seedling growth.
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recovery of soil bulk density porosity and rutting from ground Skidding over a 20 year period after timber harvesting in iran
Silva Fennica, 2012Co-Authors: Sattar Ezzati, Akbar Najafi, Eric K. ZennerAbstract:Ground-based Skidding can have detrimental effects on soil properties trough soil profile disturbance and compaction that can persist for decades. We investigated the recovery of physical properties of disturbed brown soils on four abandoned downhill skid trails in a deciduous mountain forest in northern Iran. The most recent Skidding operations had taken place 1–5 yrs, 6–10 yrs, 11–15 yrs, and 16–20 yrs ago, providing a 20-year chronosequence with four 5-year recovery periods. For each recovery period, mean values for soil bulk density (BD), total porosity (TP), macroporosity (MP), soil moisture content (SM), and rut depth (RD) were assessed for three levels of traffic intensity (Primary (PS), Secondary (SS) and Tertiary (TS) skid trails) and two levels of slope gradients (Gentle (G) and Steep (S)) and compared to those in undisturbed (control) areas. Over the 20-year recovery period, PS trails on gentle slopes exhibited mean values that were 35–42% (BD), 3–7% (SM), and 13–19 cm (RD) greater and 18–24% (TP) and 19–28% (MP) lower compared to undisturbed areas; on steep PS trails, values were 40–46% (BD), 2–13% (SM), and 13–21 cm (RD) greater and 23–27% (TP) and 28–35% (MP) lower, respectively. While RD and SM recovered, 20 years was not long enough for the other physical soil properties, particularly on steep slopes. To minimize soil disturbance, Skidding should be confined to areas with gentle slopes and alternative harvesting methods such as cable yarding should be used where slope gradients exceed 20%.
Paolo Pennacchi - One of the best experts on this subject based on the ideXlab platform.
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Ball bearing Skidding and over-Skidding in large-scale angular contact ball bearings: Nonlinear dynamic model with thermal effects and experimental results
Mechanical Systems and Signal Processing, 2021Co-Authors: Shuai Gao, Steven Chatterton, Lorenzo Naldi, Paolo PennacchiAbstract:Abstract From a kinematic point of view, rolling elements should continuously roll on the raceways of rolling element bearings. When the dynamic behaviour is also considered, pure rolling occurs if the bearing is properly loaded and the system is correctly lubricated. In the absence of these conditions, the rolling elements may slide, or skid, from time to time. In the literature, this behaviour is well documented and occurs generally for low-load roller bearings. During a long-lasting experimental test on a large-scale industrial angular contact ball bearing (ACBB), not only Skidding behaviour but also so-called over-Skidding behaviour was observed on the rolling elements of the bearing. The term over-Skidding, or negative-Skidding, means that the cage/rotor speed ratio exceeds the value calculated under pure rolling kinematic conditions. To the best of authors’ knowledge, this phenomenon has not been fully described or analysed before. Therefore, a comprehensive model considering the kinematics of the bearing components, the Hertzian contact between the rolling elements and raceways, the interaction between the rolling elements and cage, the hydro-dynamic lubrication, and the thermal effects is introduced in this paper to study and forecast the over-Skidding and Skidding mechanisms. The model acronym is KH-THD, that is the kinematic-Hertzian-thermo-hydro-dynamic model. The empirical existence of over-Skidding indicates that the use of the theoretical value for the cage/rotor speed ratio is inaccurate for determining whether the bearing rolling elements are slipping or not on the raceways, especially for large-scale industrial bearings. The results of the experimental tests on such kinds of bearings obtained by varying the load and under three different operating rotational speeds and two lubricant supply conditions suggest that the KH-THD model is more accurate than existing models, which neglect the thermal effects due to friction. The analysis of the friction thermal effects due to Skidding shows that a considerable temperature gradient forms in the bearing. The increase in the lubricant flow rate can somehow mitigate the increase in temperature even though it can worsen the Skidding. The proposed model is useful for determining this trade-off for a given load.
