Avoiding contingent incidents by quadrotors due to one or two propellers failure

With the increasing impact of drones in our daily lives, safety issues have become a primary concern. In this study, a novel supervisor-based active fault-tolerant (FT) control system is presented for a rotary-wing quadrotor to maintain its pose in 3D space upon losing one or two propellers. Our approach allows the quadrotor to make controlled movements about a primary axis attached to the body-fixed frame. A multi-loop cascaded control architecture is designed to ensure robustness, stability, reference tracking, and safe landing. The altitude control is performed using a proportional-integral-derivative (PID) controller, whereas linear-quadratic-integral (LQI) and model-predictive-control (MPC) have been investigated for reduced attitude control and their performance is compared based on absolute and mean-squared error. The simulation results affirm that the quadrotor remains in a stable region, successfully performs the reference tracking, and ensures a safe landing while counteracting the effects of propeller(s) failures

A featureless approach for object detection and tracking in dynamic environments

One of the challenging problems in mobile robotics is mapping a dynamic environment for navigating robots. In order to disambiguate multiple moving obstacles, state-of-art techniques often solve some form of dynamic SLAM (Simultaneous Localization and Mapping) problem. Unfortunately, their higher computational complexity press the need for simpler and more efficient approaches suitable for real-time embedded systems. In this paper, we present a ROS-based efficient algorithm for constructing dynamic maps, which exploits the spatial-temporal locality for detecting and tracking moving objects without relying on prior knowledge of their geometrical features. A two-prong contribution of this work is as follows: first, an efficient scheme for decoding sensory data into an estimated time-varying object boundary that ultimately decides its orientation and trajectory based on the iteratively updated robot Field of View (FoV); second, lower time-complexity of updating the dynamic environment through manipulating spatial-temporal locality available in the object motion profile. Unlike existing approaches, the snapshots of the environment remain constant in the number of moving objects. We validate the efficacy of our algorithm on both V-Rep simulations and real-life experiments with a wide array of dynamic environments. We show that the algorithm accurately detects and tracks objects with a high probability as long as sensor noise is low and the speed of moving objects remains within acceptable limits

Control strategies for robotic manipulators

This survey is aimed at presenting the major robust control strategies for rigid robot manipulators. The techniques discussed are feedback linearization/Computed torque control, Variable structure compensator, Passivity based approach and Disturbance observer based control. The first one is based on complete dynamic model of a robot. It results in simple linear control which offers guaranteed stability. Variable structure compensator uses a switching/relay action to overcome dynamic uncertainties and disturbances. Passivity based controller make use of passive structure of a robot. If passivity of a feedback system is proved, nonlinearities and uncertainties will not affect the stability. Disturbance observer based controllers estimate disturbances, which can be cancelled out to achieve a nominal model, for which a simple controller can then be designed. This paper, after explaining each control strategy in detail, finally compares these strategies for their pros and cons. Possible solutions to cope with the drawbacks have also been presented in tabular form. © 2012 IEEE

Frequency of Post-Operative Fecal Incontinence and Healing Rate in Patients with Open and Closed Lateral Internal Anal Sphincterotomy

OBJECTIVES This study aims to compare the frequency of fecal incontinence and healing rate in patients treated with Open Internal Anal Sphincterotomy (OIAS) and Closed Lateral Internal Anal Sphincterotomy (CLIAS). METHODOLOGY This randomized control trial was carried out in the Department of Surgery Hayatabad Medical Complex, Peshawar Pakistan from Feb 2019 to Feb 2020. Eighty-four patients were assigned to the open method in Group B while eighty-four patients were allocated to the closed method in Group A (using blade 11) through the randomized control trial method. Fecal incontinence and healing rate were observed on the 7 th postoperative day. SPSS 23.0 software was used to analyse the data. RESULTS In group A out of a total of 84 patients, 96% of patients were in category A, 4% of patients were in category B, and no patients were in categories C and D. In group B out of 84 patients, 96% of patients were in category A while 4% patients were in category B and no patients were in category C and D. The total faecal incontinence in Group B (open method) was 21% while total fecal incontinence in Group A (closed method) was only 4% that is a clear dierence between the two groups. In group A (closed method) out of 84 patients, 2 patients (2.38 %) showed delayed healing while 82 patients (97.61 %) showed normal healing. In group B (open method) 7.4% of patients showed delayed healing with a signicance p level of 0.04 while 92.85 showed normal healing. CONCLUSION Fecal incontinence was less in closed Lateral Anal Sphincterotomy due to the use of blade 11 while it was higher in open internal anal sphincterotomy. Similarly, the healing rate was signicantly higher in the closed method while delayed healing was seen in the open method

Nutritive Value and Digestion Kinetics of Manure Ensiled Wheat Straw Treated with Varying Levels of Urea and Corn Grains

The aim of this was to study the nutritive value of urea and corn grain treated wheat straw ensiled with cattle manure. The different levels of urea (0, 2 and 4%) and corn grain (2 and 4%) were used to treat wheat straw. The urea-corn grain treated wheat straw was mixed with cattle manure in the ratio of 70:30. The silages were fermented in laboratory silos for 20, 30 and 40 days. After the completion of ensilation period, the samples of ensiled wheat straw were analyzed for pH, dry matter (DM), crude protein (CP), true protein (TP), ammonia nitrogen (NH3- N), neutral detergent fiber (NDF) and acid detergent fiber (ADF). The result showed that pH, NDF and ADF were decreased at 40 days ensilation period, 4% corn grains (CG) and urea levels each. Dry matter, CP, TP and NH3-N were increased at 40 days of ensilation period, 4% CG and urea level each. On the findings of this result, wheat straw was ensiled with manure for 40 days and 4% level of CG and urea each. Then in situ digestion kinetics of untreated and ensiled wheat straw was determined by using fistulated buffalo bulls. The results of the present study showed that dry matter digestibility (DMD) of manure ensiled wheat straw (EWS) were higher than untreated wheat straw (UWS) that was 15.43 and 13.71 respectively. Similarly, neutral detergent fiber digestibility of EWS was higher than UWS that was 57.60 and 41.43 respectively

Factors affecting wool quality and quantity in sheep

There are varieties of factors which can affect wool (macro and micro elements of wool) in sheep directly or indirectly. Genetic and environmental factors are major factors influencing wool quality and quantity. There are some bacterial, viral, fungal and espically parasitic diseases which also affect the wool. Other factors are exogenous chemicals, hormones, weather and photo period. In the present study, existing knowledge on the factors affecting wool were reviewed but there are gaps to conduct research on fundamental aspects of wool growth, which could have relevance to other areas of biology.Keywords: Wool quality, staple length, ultra high-sulphur proteins, fleec

Increasing Performance through Assessed Training (A Human Recourse Management Strategy)

This research finds out the way of increasing employee’s performance through training. There are many organizations which give their workers training but do not get any enhancement in their performance. Performances of a worker are directly correlated with his/her capabilities and know how to do the job. This study develops a strategy for improving the capabilities of workers which leads to increase their performance. The research proposes that just after an organization want to increase the performance of its workers, it must find out the area where they have weaknesses. After finding out the weaknesses, organizations have to assess how that weakness should be made solved. In the third stage they have to give specific training their weaknesses. This will enhance the capabilities of workers and their performance will be increased. Keywords: Weakness, Weakness needs Assessments, Training and Performanc

Modelling, Simulation, and Control of a Flexible Space Launch Vehicle

Modern Space Launch Vehicles (SLVs), being slender in shape and due to the use of lightweight materials, are generally flexible in nature. This structural flexibility, when coupled with sensor and actuator dynamics, can adversely affect the control of SLV, which may lead to vehicle instability and, in the worst-case scenario, to structural failure. This work focuses on modelling and simulation of rigid and flexible dynamics of an SLV and its interactions with the control system. SpaceX's Falcon 9 has been selected for this study. The flexible modes are calculated using modal analysis in Ansys. High-fidelity nonlinear simulation is developed which incorporates the flexible modes and their interactions with rigid degrees of freedom. Moreover, linearized models are developed for flexible body dynamics, over the complete trajectory until the first stage's separation. Using classical control methods, attitude controllers, that keep the SLV on its desired trajectory, are developed, and multiple filters are designed to suppress the interactions of flexible dynamics. The designed controllers along with filters are implemented in the nonlinear simulation. Furthermore, to demonstrate the robustness of designed controllers, Monte-Carlo simulations are carried out and results are presented.Comment: Presented at 20th International Bhurban Conference on Applied Sciences and Technology (IBCAST), 202