Design of a Fuzzy Logic Controller for Skid Steer Mobile Robot

The control problem of four-wheeled skid steering mobile robots is quite challenging mainly because the skid steering system is an underactuated system and its mathematical model is highly uncertain. Skid steering configurations employ a differential-drive technique in which the wheels rotation is limited to around one axis and the lack of a steering wheel causes the navigation to be determined by the change of speed in either side of the robot for turning. Equal speed in both sides causes a straight-line motion. However, the implementation of the dead reckoning technique on skid-steer mobile robots will limit the precision of current robot’s position because skid-steer configuration intentionally relies on wheel slippage for normal operation and this possesses some difficulties when implementing motion control using the odometric system. The thesis describes the design of a fuzzy logic controller to compensate the dead reckoning limitation and implementation on a skid-steer mobile robot. The fuzzy controller has two inputs (angle error and distance), two outputs (translational and rotational speed) and 14 rules. These inputs are computed from the dead-reckoning method that is totally reliant on the odometry readings and data are fuzzified to be the inputs of the fuzzy controller. The outputs are the analogue voltages to the left and right motors, which drive the mobile robot. For simplicity, membership functions consisting of triangular and trapezoid shapes have been adopted. The membership functions of the fuzzy sets are chosen by trial-and-error based on experimentation. The heuristic rules control the orientation of the robot according to the information about the distances from the desired positions. The crisp output values from the fuzzy logic controller are decoded and fed into a decision module where the ratios of both sides motor voltage are determined for every smooth change in speed of the motors. To facilitate the implementation of control system, real-time execution is done in an indoor environment. Data acquisition is done in a LABVIEW and a MATLAB control algorithm is called in LABVIEW. A real mobile robot, PUTRABOT2 was used to conduct the experiment. Performance evaluation is observed from the accumulated error in orientation and its trajectory obtained after mapping the information gathered from the real world via odometry sensors. Few features such as the rise time, settling time and peak time of the output responses are analyzed. Comparisons are made between fuzzy logic and PD controllers. Comparative results among these two controllers indicate the superiority of the fuzzy approach with the ability to minimize the position and orientation errors. Moreover, the trajectory accuracy is very high and more reliable in the presence of unreliable odometry readings

Potential Field Based Motion Planning with Steering Control and DYC for ADAS

In this study, the development of motion planning and control for collision avoidance driver assistance systems is presented. A potential field approach has been used in formulating the collision avoidance algorithm based on predicted vehicle motion. Then, to realize the advanced driver assistance systems (ADAS) for collision avoidance, steering control system and direct yaw moment control (DYC) is designed to follow the desired vehicle motion. Performance evaluation is conducted in simulation environment in term of its performance in avoiding the obstacles. Simulation results show that the vehicle collision avoidance assistance systems can successfully complete the avoidance behavior without colliding

Walking gait event detection based on electromyography signals using artificial neural network

In many gait applications, the focal events are the stance and swing phases. Although detecting gait events using electromyography signals will help the development of assistive devices such as exoskeleton, orthoses, and prostheses, stance and swing phases have yet to be observed using electromyography signals. The core of this study is to propose a classification system for both stance and swing phases based on electromyography signals. This is to be done by extracting the patterns of electromyography signals from time domain features and feeding them into an artificial neural network classifier. In addition, a different number of input features and two prominent training algorithm of artificial neural network have been employed in this study. Eight subjects that participated in this study were divided into two categories namely, learned (first seven subjects) and unlearned data (the remaining one subject). It was observed that Levenberg-Marquardt algorithm with five time domain features performed better than other features with an average percentage of classification accuracy of 87.4%. This system was further tested with electromyography signals of learned and unlearned data to identify the stance and swing phases in order to detect the timing of heel strike and toe off. The mean absolute different values between artificial neural network and footswitch data for learned data were 16 ± 18 ms and 21 ± 18 ms for heel strike and toe off, respectively. For this case, no significant differences (p < 0.05) were observed in mean absolute different for heel strike and toe off detections. Besides, the mean absolute different values of unlearned data were shown to be acceptable, 35 ± 25 ms for heel strike and 49 ± 15 ms for toe off. By the end of this experiment, basing the examination of gait events with electromyography signals using artificial neural network is possible

An Analysis of Artists’ Practice in Hybrid Art and the Challenges Toward Malaysian Art Scene

Living in today's era, artists’ practice in creating artwork is different from those practiced 20 years ago.  With the existence of digital art followed by electronic art in the local art scene, the presentation, style and approach have evolved. Back in 2005 and 2007, some exhibitions brought hybrid art concept into an art exhibition. One of the shows was ‘Hybrid+ism’ which highlighted in various disciplines, media, applying unlimited processes and medium. The purpose of this paper is to study the artists’ practice in the hybrid art based on selected artworks. The artworks are selected based on some criteria ranging from experimental, mixed media, multi-disciplines, integration and technology as well as culture aspects. This paper is discussing the hybrid art practice among artists in the Malaysian art scene and the challenges to creating awareness on hybrid practice among audiences

Profile of Parkia speciosa hassk metabolites extracted with SFE using FTIR- PCA method

A rapid identification, classification and discrimination tool, using Fourier Transform Infrared (FTIR) spectroscopy combined with Principal Component Analysis (PCA), was developed and applied to determine the profile of the Supercritical Fluid Extraction (SFE) of Parkia speciosa seeds under various temperature and pressure conditions (313, 323, 333, 343, 353 and 363 K and 20.68, 27.58, 34.47, 41.37, 48.26, and 55.16MPa). The separation and identification of the compounds was carried out by Gas Chromatography coupled with Time of Flight Mass Spectrometry (GC/TOF-MS). This technique has made it possible to detect the variability obtained under different SFE conditions and the separation of different chemical compounds in P. speciosa seeds. The FTIR-PCA results were verified by GC/TOF-MS, and the FTIR-PCA method successfully identified the unsaturated carboxylic acids with the highest percentage area under the different conditions

A Safe-Distance Based Threat Assessment with Geometrical Based Steering Control for Vehicle Collision Avoidance

This work proposes a vehicle collision avoidance strategy based on the usage of Geometrical Based Steering Controller. The algorithm is composed of these features : 1) Collision Detection strategy using safe distance threshold, 2) predicts the future trajectory of the vehicle in the occurrence of obstacle, 3) decision making prior to avoiding collision, 4) avoiding obstacles while ensuring the vehicle to return to its original path. The strategy used a nonlinear vehicle model with steering and braking input as the actuators that will react and avoid collisions. Simulation results depict the ability of the methods to avoid the potential collision while returning to its original path. The inclusion of the Threat Assessment Strategy ensures the hindrance of the vehicle from colliding with the obstacle's edg

Artistic Knowledge and Practices of Hybrid Art based on the Analysis of Malaysian Artists’ Artworks

The objective of this paper is to identify the artistic knowledge and practices of hybrid art among Malaysian artist’s artworks. The purpose is to analyze the artistic knowledge through Malaysian artist’s artworks. Ten selected artworks from the multidisciplinary artists had been choose. The researchers applied observation method to select the artworks that have the element of hybrid art and Kawakita Jiro method for the purpose of clustering the attributes for the artistic knowledge and practices of hybrid art. The finding shows that the advancement of technology, and freedom in exploring the material have affected the creation of hybrid artworks production.    Keywords: Artists’ practices, Hybrid art practice, integration, cross disciplines.    eISSN: 2398-4287 © 2020. The Authors. Published for AMER ABRA cE-Bs by e-International Publishing House, Ltd., UK. This is an open access article under the CC BYNC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer–review under responsibility of AMER (Association of Malaysian Environment-Behaviour Researchers), ABRA (Association of Behavioural Researchers on Asians) and cE-Bs (Centre for Environment-Behaviour Studies), Faculty of Architecture, Planning &amp; Surveying, Universiti Teknologi MARA, Malaysia.   DOI: https://doi.org/10.21834/ebpj.v5iSI1.230

Resolution of asthmatic symptoms following successful endoscopic resection of tracheal mucoepidermoid carcinoma

Mucoepidermoid carcinoma (MEC) is a rare tumour of the trachea accounting for up to 0.2% of reported primary lung malignancy. We report a case of a 54-year-old man, ex-smoker, whose presentation mimicked adult onset asthma with cough and wheezing, which did not respond to conventional treatment. He had occasional haemoptysis and weight loss in which CT scan performed for malignancy screening showed a protruding mass in the distal trachea causing endobronchial obstruction. Bronchoscopic intervention was performed to relieve the obstruction that resulted in resolution of asthmatic symptoms. Histological diagnosis confirmed MEC. This case emphasised the importance of a high index of suspicion in an unusual presentation of a common disease and the pivotal role of bronchoscopic intervention in malignant central airway obstruction

An Analysis of Artistic Diversity in Hybrid Art Practice among Malaysian Artists

This research objective is to analyze the artistic diversity in hybrid art practice among selected Malaysian artists. The paper examines the process of making hybrid artworks where focusing on media diversity and experiment activity. The researchers had used cluster sampling and twenty artists involved to answer the questionnaires. The researchers used bar graph and Principal Component Analysis to analyze the artistic diversity in Hybrid Art. The finding of media diversity shows that Malaysian artists are focusing on mixed media, strength and equipment. Besides, the artists are focusing on subject matter, experiment, influence and research for the finding of experiment activity.    Keywords: Collaboration, experiment activity, media diversity, hybrid approach.    eISSN: 2398-4287 © 2020. The Authors. Published for AMER ABRA cE-Bs by e-International Publishing House, Ltd., UK. This is an open access article under the CC BYNC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer–review under responsibility of AMER (Association of Malaysian Environment-Behaviour Researchers), ABRA (Association of Behavioural Researchers on Asians) and cE-Bs (Centre for Environment-Behaviour Studies), Faculty of Architecture, Planning &amp; Surveying, Universiti Teknologi MARA, Malaysia.   DOI: https://doi.org/10.21834/ebpj.v5iSI1.230