Optimal mapping of joint faults into healthy joint velocity space for fault-tolerant redundant manipulators

redundant manipulator

Optimal actuator fault tolerance for static nonlinear systems based on minimum output velocity jump

Fault tolerance for a class of non linear systems is addressed based on the velocity of their output variables. This paper presents a mapping to minimize the possible jump of the velocity of the output, due to the actuator failure. The failure of the actuator is assumed as actuator lock. The mapping is derived and it provides the proper input commands for the healthy actuators of the system to tolerate the effect of the faulty actuator on the output of the system. The introduced mapping works as an optimal input reconfiguration for fault recovery, which provides a minimum velocity jump suitable for static nonlinear systems. The proposed mapping is validated through different case studies and a complementary simulation. In the case studies and the simulation, the mapping provides the commands to compensate the effect of different faults within the joints of a robotic manipulator. The new commands and the compare between the velocity of the output variables for the health and faulty system are presented

Joint velocity redistribution for fault tolerant manipulators

If the end-effector of a robotic manipulator moves on a specified trajectory, then for the fault tolerant operation, it is required that the end-effector continues the trajectory with a minimum velocity jump when a fault occurs within a joint. This problem is addressed in the paper. A way to tolerate the fault is to find new joint velocities for the faulty manipulator in which results into the same end-effector velocity provided by the healthy manipulator. The aim of this study is to find a strategy which optimally redistributes the joint velocities for the remained healthy joints of the manipulators. The optimality is defined by the minimum end-effector velocity jump. A solution of the problem is presented and it is applied to a robotics manipulator. Then through a case study and a simulation study it is validated. The paper shows that if would be possible the joint velocity redistribution results into a zero velocity jump

Fault tolerance force for redundant manipulators

Fault tolerant manipulators maintain their trajectory even if their joint/s fails. Assuming that the manipulator is fault tolerant on its trajectory, fault tolerant compliance manipulators provide required force at their end-effector even when a joint fails. To achieve this, the contributions of the faulty joints for the force of the end-effector are required to be mapped into the proper compensating joint torques of the healthy joints to maintain the force. This paper addresses the optimal mapping to minimize the force jump due to a fault, which is the maximum effort to maintain the force when a fault occurs. The paper studies the locked joint fault/s of the redundant manipulators and it relates the force jump at the end-effector to the faults within the joints. Adding on a previous study to maintain the trajectory, in here the objective is to providing fault tolerant force at the end-effector of the redundant manipulators. This optimal mapping with minimum force jump is presented using matrix perturbation model. And the force jump is calculated through this model for single and multiple joints fault. The proposed optimal mapping is used in different fault scenarios for a 5-DOF manipulator; also it is deployed to compensate the force at the end-effector for the 5-DOF manipulator through simulation study and the results are presented

Internal Controls and Problems in Governmental Segment: Evidence from Iran

ABSTRACT In order to gain assurance of achieving the anticipating aims, successful accomplishment of activities in all areas, preventing any embezzlement, fraud, or misuse of resources and assets, and also fulfill the responsibilities of accountability for activities carried out, managers of state and private sectors design and implement the internal control systems. Regarding to the high volume use of the public resources in state sectors and the government's responsibilities in utilizing and conservation of such resources and its accountability, designing and implementation of internal control systems in state sector proves significant. Current paper is one applied kind researches, and has been carried out as a case study in state organizations of Zanjan province. The purpose of the research is not to apply the limitation theory in state organizations, but to discuss topics related to that and get acquaintance with significance of identifying the limitation and barriers of a system, and implements the limitation theory though in the system as the following step. Methodology, from the point of nature and content, is of descriptive and conductive type. Findings suggest that effective practical training of the financial staff, internal control regularities, and expert labor force prove as the trial conditions to accomplish the internal control effectively

On the effort of task completion for partially-failed manipulators

Adding to a previous work of the authors for task completion for partially failed manipulator, other aspects of the effort are discussed. The paper aims to investigate on the strategies of maximum effort for maintaining the availability of partially failed manipulators. The failures are assumed as the joint lock failures of the manipulators. The main objective is to facilitate the existing manipulators to continue their tasks even if a non catastrophic fault occurs into their joints. The tasks includes motion tasks and force tasks. For each group of tasks a constrained optimality problem is introduced. Then in a case study a required force profile on a desired trajectory using a 3DOF planar manipulator is indicated. Through this study the joint angles and joint torques for a healthy manipulator and a faulty manipulator are shown. It is illustrated that a failure in the second joint is tolerated on the trajectory of end-effector

Mapping scalp to intracranial eeg using generative adversarial networks for automatically detecting interictal epileptiform discharges

Both scalp and intracranial electroencephalograms (EEGs) are of great importance for diagnosing brain disorders. However, the scalp EEG (sEEG) is attenuated by the skull and contaminated with artifacts. At the same time, intracranial EEG (iEEG) is almost free of artifacts and can capture all brain activities without any attenuation due to being close to the brain sources. In this study, the aim is to enhance the performance of sEEG by mapping the sEEG to the iEEG. To do so, we here develop a deep neural network using a generative adversarial network to estimate the sEEG from the iEEG. The proposed method is applied to sEEG and iEEG recorded simultaneously from epileptics to detect interictal epileptiform discharges (IEDs). The proposed method detects IEDs with 76% accuracy outperforming the state-of-the-art methods. Furthermore, it is at least twelve times less complex than the compared methods

Generation of 3D sparse feature models using multiple stereo views

Augmented Reality (AR) renders virtual information onto objects in the real world. This new user interface paradigm presents a seamless blend of the virtual and real, where the convergence of the two is difficult to discern. However, errors in the registration of the real and virtual worlds are common and often destroy the AR illusion. To achieve accurate and efficient registration, the pose of real objects must be resolved in a quick and precise manner.<br /

The Effect of Contact Lens Induced Myopia and Hyperopia on Retinal Thickness and Volume Measured by Optical Coherence Tomography

Purpose:To determine the effect of induced myopia and hyperopia in emmetropic eyes using soft contact lenses on retinal parameters, measured by optical coherence tomography.Patients and Methods: In this quasi-experimental self-controlled study 57 emmetropic participants, 18 - 42 years of age, were studied. Each subject underwent a complete ophthalmic examinations including, measurement of best corrected visual acuity, intraocular pressure, dry and cycloplegic refractions, and axial length. Optical coherence tomography scans to measure foveal thickness, parafoveal thickness and perifoveal thickness were performed while different refraction powers were induced in each eye by wearing soft contact lenses of five different diopter (- 10.00, - 5.00, plano, + 5.00, + 10.00).Results: Fifty seven normal emmetropic participants with a mean age of 25.78 ± 6.50 years participated in the present study. Average foveal thickness was 246.02 ± 22.03 μm, 245.47 ± 22.78 μm, 246.47 ± 24.38 μm, 246.42 ± 22.96 μm, and 246.18 ± 22.46 μm in high-induced- myopic (CL: + 10.00 D), mild-induced-myopic (CL: + 5.00 D), emmetropic (CL: Plano), mild-induced-hyperopic (CL: - 5.00 D), and high-induced-hyperopic (CL: - 10.00 D) groups, respectively. Average parafoveal thickness was 329.21 ± 16.31 μm, 329.24 ± 16.36 μm, 328.86 ± 16.46 μm, 328.92 ± 16.57 μm, and 328.80 ± 16.76 μm in high-induced-myopic, mild-induced-myopic, emmetropic, mild-induced-hyperopic, and high-induced-hyperopic groups, respectively. Corresponding numbers for perifoveal thickness was 312.25 ± 14.39 μm, 311.84 ± 14.91 μm, 312.46 ± 16.55 μm, 311.57 ± 14.88 μm, and 311.77 ± 14.96 μm. Conclusion: Contact lens induced myopia and hyperopia had no significant effect on foveal thickness,parafovealthickness and perifoveal thickness readings in Fourier domain optical coherence tomography.Keywords: Optical coherence tomography; myopia; hyperopia; retinal parameters; contact lens.

Segmentation and Feature Extraction of Human Gait Motion

This paper presents segmentation and feature extraction of human gait motion. The methodology of this paper focuses on segmenting ‘XYZ’ position curves, in reference to time of gait motion based on the velocity or acceleration of the movement. The extracted features include amplitude, time, and equally spaced sample data, maximum and minimum for each segment. The results can be used for reconstruction of a viable dataset that is critical for simulation and validation of human gaits. We propose a method to enables the fitting of the same curve with limited data. Such data sets may prove valuable for studying impairments and improving simulations of rehabilitation tools, and statistical classification for researchers worldwide