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The robotic welding processes have been highly widespread in manufacturing industries due to large-scale production. An area where these processes are widely applied are shipyards, where there are necessary hundreds to thousands of kilograms of weld by hour. However, systems that operate in open-air environments are vulnerable to sundry disturbances, noises in measures, as well as possible unavailability...
This paper proposes an adaptive control for a rigidlink, flexible-joint robot using the Cerebellar Model Articulation Controller (CMAC) and the backstepping method, which is a suitable method when joints are underdamped and exhibit a large amount of flexibility. A previously proposed robust weight update method, deemed the introspective method, is placed into a Lyapunov-stable framework. In the introspective...
This work proposes a modification to the Cerebellar Model Articulation Controller (CMAC) for use in a direct adaptive control scheme. With the original CMAC, when an oscillation in the input occurs between two CMAC cells and across the origin, the weights in the adjacent cells drift in opposite directions — resulting in control signal chatter. When the chatter is severe it can cause a sudden increase...
Reconstructing a 3D model of an unknown object via incremental registration of multiple appearance models is a challenging task. With availability of low cost sensors and robust algorithms, the field of visual scene reconstruction has advanced considerably. While these advances has enabled robust reconstructions of cluttered and unstructured scenes, an active 3D reconstruction of a generic handheld...
Corobotics involves humans and robots working collaboratively as a team. This requires physical human–robot interaction (pHRI) systems that can adapt to the preferences of different humans and have good robustness and stability properties. In this brief, a new inner-loop/outer-loop robot controller formulation is developed that makes pHRI robust to changes in both corobot and human user. First, an...
In this paper, a novel robust adaptive controller is proposed to simultaneously cope with the unknown nonlinear backlash, friction and dynamic uncertainties in the 3-DOF robotic head system. Inverse backlash compensation with on-line backlash parameter estimation and model-based friction compensation with off-line Stribeck friction identification are incorporated into this robust adaptive scheme....
This paper presents an adaptive sliding mode controller for quadrotor trajectory tracking in presence of uncertainties and disturbances. An exponential reaching law is implemented using the gain adaptation control, which has the advantage of not requiring the knowledge of the upper bound of the lumped uncertainties and external disturbances. Numerical simulation results are provided to illustrate...
Autonomous robots enjoy a wide popularity nowadays and have been applied in many applications, such as home security, entertainment, delivery, navigation and guidance. It is vital for robots to track objects accurately in real time in these applications, so it is necessary to focus on tracking algorithms to improve the robustness, speed and accuracy. In this paper, we propose a real-time robust object...
In this paper, a novel robust adaptive control scheme is proposed for a lower limb rehabilitation robot designed by our laboratory. The proposed control strategy is based on the radial basis function (RBF) neural networks and the parameters of the system dynamics are unknown. The weights of the RBF neural networks are updated by an adaptive law according to the Lyapunov stability analysis. The robustness...
Acoustic perturbation due to reverberation and the changes in speaker position are detrimental to seamless human-robot speech-based communication. These cause a mismatch between the speech features at runtime condition and the acoustic model (training condition). Then the degradation of the Automatic Speech Recognition (ASR) and the Spoken Language Understanding (SLU) performances is imminent. As...
This paper presents a new adaptive sliding mode control (ASMC) scheme using time-delay estimation (TDE) technique and then applies it to robot manipulators. The proposed ASMC employs a new adaptive law to achieve good tracking performance with small chattering effect. The new adaptive law considers an arbitrarily small vicinity of the sliding manifold, where the derivatives of its adaptive gains are...
Two time-scale model based adaptive control method is proposed for a helicopter to overcome wind disturbances in this paper. Wind disturbances are considered as a mixture of four sinusoidal signals with unknown frequencies, amplitudes and phases. The controller is designed based on the concept of time-scale separation, which has the advantage of decoupling of the rotational and translational dynamics...
Iterative learning control(ILC) is used to track the trajectory of repetitive motion, especially for industrial robot. The proposed control scheme is based upon the feedback of tracking error and corresponding change rate, which construct a switching surface, with the use of a proportional structure, for which it is called sliding mode-like P-type ILC. In addition, an adaptive item was added to not...
Recently, adaptive fuzzy observers have been introduced that are capable of estimating uncertainties along with the states of a nonlinear system represented by an uncertain Takagi-Sugeno (TS) model. In this paper, we use such an adaptive observer to estimate the uncertainties in the state matrices of a two-degrees-of-freedom robot arm model. The TS model of the robot arm is constructed using the sector...
Tracking control for Euler — Lagrange (EL) systems is a very important problem. Current control methods have achieved a lot of success in solving the problem with the accurate and stable kinetic model as well as no disturbance. Facts have shown that there were many EL systems working in unstable environment, or carrying different masses, which is conducive to significant modeling errors, disturbances...
This paper presents a novel formation control technique of a group of differentially driven wheeled mobile robots employing artificial potential field based navigation and leader-follower formation control scheme. In the proposed method, the leader robot of the group determines its path of navigation by an artificial potential field and the other robots in the group follow the leader maintaining a...
We propose a general adaptive procedure to select the appropriate degree of assistance based on a Bayesian mechanism used to estimate psychophysical thresholds. This technique does not need an accurate model of learning and recovery processes. This procedure is validated in the context of a motor skill learning problem (control of a virtual object), in which the controller is used to gradually increase...
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