Journal of Engineering and Technology (JET)

TABLE OF CONTENTS VOL. 15 NO. 1 (2024)

2024-07-05T07:13:45+00:00

Table of Contents Vol. 15 No. 1 (2024)

THE STUDY OF KINEMATICS AND TRAJECTORY PLANNING OF A 9-DOF SERIAL REDUNDANT ROBOTIC MANIPULATOR

2024-02-07T07:36:53+00:00

A serial manipulator exhibits kinematic redundancy when the number of dimensions in its joint space exceeds that of its end-effector space. This paper proposes a solution to resolve the redundancy issue in a 9-Degree-of-Freedom (DOF) serial manipulator. The solution involves segmenting the robot's kinematic model into two sections: a 3-DOF base (axes 1-3) and a 6-DOF body (axes 4-9). Denavit-Hartenberg (D-H) parameters and homogeneous transformation matrices are used to formulate the forward kinematics equations for both sections. Subsequently, the inverse kinematics solutions for each section are derived using the Jacobian pseudo-inverse method. The proposed method's effectiveness is tested by commanding the base and body sections of the 9-DOF manipulator to follow two independent trajectories simultaneously, demonstrating its ability to generate dexterous motions. An experiment to assess the manipulator's capability to maneuver its end-effector along a specified path while its redundant links follow another, all while avoiding obstacles in a constrained environment is conducted. The results show that the end-effector and redundant links successfully track their respective trajectories with minimal position error and no collisions with the obstacle. In conclusion, the proposed method has been successfully demonstrated to effectively address the kinematic redundancy problem in a 9-DOF serial manipulator.

EFFECT OF COLEMANITE AND PVA FIBRE IN ULTRA HIGH PERFORMANCE CONCRETE (UHPC) FOR RADIATION SHIELD

2023-10-11T08:02:58+00:00

Nuclear energy provides cleaner energy and detail imaging but due to its highly penetrative nature, shielding is required for safe handling. Concrete has been widely used and studied as shielding material but there is dearth on utilizing ultra-high-performance concrete (UHPC) especially on neutron radiation. This research aimed to investigate the effect of incorporating colemanite and polyvinyl alcohol (PVA) fibre in UHPC on its mechanical strength and radiation shielding. Compressive strength results show sand UHPdC with the highest value at 131 MPa. Magnetite and barite UHPdC recorded compressive strength of 118.7 and 116 MPa respectively. In terms of flexural and splitting tensile strength, sand UHPdC also recorded the highest value at 20.0 and 17.6 MPa respectively. However, the highest value of gamma radiation shielding is recorded by magnetite UHPdC at 0.1972 and 0.139 cm^-1 based on exposure to Cs-137 and Co-60 respectively while sand UHPdC recorded the lowest value. This is also shown in neutron shielding value as magnetite recorded the highest value at 0.0307 cm^-1. Overall, presence of colemanite increase neutron shielding coefficient of UHPC but both colemanite and PVA fibre caused reduction in mechanical strength and gamma ray shielding of the concrete.

AUTOMATED SEED SOWING MACHINE FOR UNEVEN SURFACE

2024-02-21T09:09:50+00:00

Seed sowing is a crucial agricultural step as it marks the beginning of the plant's life cycle and establishes the foundation for healthy growth and successful cultivation. Traditional manual seeding process methods struggle with uneven surfaces, leading to inefficient seed distribution and reduced crop yields. The solution is by integrating sensors, actuators, and intelligent control systems to address these challenges. This study proposes an automated seed sowing machine designed specifically for uneven surfaces. The mechanism employs the combination of mechanical design and automation using microcontroller to assess real-time conditions. A central control unit processes this data to adjust seeding depth, spacing, and rate dynamically. It features a precision seeding unit with electric actuators for accurate seed placement, along with a robust chassis and adaptive systems to navigate rough surfaces. Based on the experiment conducted, it is concluded that the machine is capable to execute the seed sowing task properly.

CHARACTERIZATION OF PULVERIZED PALM KERNEL SHELLS BLOCKS

2024-03-14T08:37:08+00:00

The study focuses on addressing the environmental issue of palm kernel shell waste by exploring its potential use in improving conventional sandcrete blocks. Palm kernel shells are an abundant waste that contributes to environmental pollution when left untreated. The research aimed to substitute crushed palm kernel shells for sand in sandcrete blocks production. Palm kernel blocks with different proportions (2% to 30%) of crushed palm kernel shells were prepared with a standard mix ratio (1:6 cement to sand), and a fixed 0.5 water-to-cement ratio. After 28 days of curing, the blocks with palm kernel shells showed lower density, weaker compressive strength, and higher water absorption compared to the control. Palm kernel shell blocks were found to be lighter compared to conventional sandcrete blocks. Incorporating palm kernel shells in block formulations is a feasible and sustainable solution for addressing weight-related concerns in construction. Palm kernel shell blocks are suitable for building lightweight structures. Using palm kernel shells may offer potential benefits and contribute to sustainable construction.

PERFORMANCE INVESTIGATION OF A BOOST CONVERTER DRIVING A SEPARATELY EXCITED DC MOTOR USING RC FILTER

2024-02-26T07:41:36+00:00

Because boost converter circuits allow for precise speed regulation, frequent starting, flexible speed control, and support for stopping and reversing operations, they are becoming more and more common in industrial and electrical systems for powering DC motors. However, because these converters are made of non-linear devices, they introduced harmonic distortions that lowered the system's power quality and decreased the performance of the DC motor that was connected to them. This paper presents a low-cost and effective boost chopper circuit that drives a separately excited DC motor by combining it with an RC filter. Matlab/Simulink was used to simulate an RC filter model based on a boost converter that has a 120 V input DC voltage, a 50% duty ratio, and a 50 kHz switching frequency. The separately excited DC motor is powered by the boost converter's average output voltage and current. The RC filter significantly reduced total harmonic distortion (THD) from 37% to 11.8%. In addition to harmonic mitigation, this study investigated the efficiency of a separately excited DC motor, and a significant improvement in the motor’s efficiency from 74.42% without the filter to 91.42% with it was observed. This research underscores the effectiveness of integrating an RC filter with a boost chopper circuit to enhance power quality and optimize the performance of a DC motor system.

TAGUCHI OPTIMIZATION PREDICTION TO EVALUATE THE SYNERGETIC IMPACT OF COCONUT SHELL ASH PARTICLES ON THE TENSILE STRENGTH OF BANANA PSEUDO STEM FIBER COMPOSITES

2023-10-09T11:30:27+00:00

Bananas are a significant fruit crop cultivated around the world, with a substantial amount of biomass being neglected as a waste. This research aimed to investigate the effect of Coconut Shell Ash particle (CSA) on the Tensile strength of Banana Pseudo Stem (BPS) fiber reinforced epoxy composites. The composite was prepared by hand lay-up method by mixing epoxy and hardener in a ratio 2 to 1. Three processing parameters were considered, namely: Particle Percentage (PP), Particle Size (PS) and Curing Time (CT). Each this factor is varied thrice, i.e., PP (3, 6, 9%), PS (20, 35, 45 µm) and CT (12, 24, 36 hrs). The results indicated that the PP was the most influential factor, followed by the PS, while CT had the least impact. The experimental findings were comparable to the predictions obtained through Taguchi optimization The former was 68.1 MPa while the latter was 68.6 MPa, respectively. However, both methods revealed PP₉PS₃₅CT₁₂ as the optimum combination. This shows that 9% (PP), 35 µm (CT) and 12 hrs (CT) are the optimal levels. Percentage error between the experiment and optimisation modelling was less than 3% while the normal probability plot shows that the residual is well aligned to the linear graph. Thus, the model developed can be reliably utilised to predict the strength of CSA filler composites.

FLOW ANALYSIS IN SUDDEN AND GRADUAL CONTRACTION AND EXPANSION PIPES

2024-04-26T06:18:20+00:00

This project aims to study the fluid flow characteristics of sudden and gradual contraction and expansion pipes. Recent study has revealed that the flow behavior in sudden contraction and expansion pipes can be quite complicated with vortices, eddies, and other flow phenomena affecting the pressure and velocity distribution. This understanding is important to design more efficient and reliable piping systems that can reduce energy consumption, improve system performance, and minimize failure risk. In this study, the length of larger diameter for sudden and gradual contraction and expansion pipes is 0.040 m. Next, the length of the smaller diameter for gradual is 0.050 m and 0.060 m for sudden. The sudden and gradual contraction and expansion pipes are designed using the SolidWorks software and ANSYS Fluent simulation software was used to plot the contour of velocity magnitude and static pressure of the pipes in which water is a media. In a sudden contraction pipe, the velocity flow shows a large separation at the edge of the upstream region before entering the contraction region which creates vortices and eddies. In a sudden expansion pipe, the pressure is unstable and fluctuates in the wider section. In a gradual expansion, the pressure pattern near the wall of the upstream section increases gradually and steadily. It proves that the flow pattern in the gradual expansion and gradual contraction creates less separation and disturbance of flow compared to the sudden expansion and sudden contraction pipes.

DESIGN, TOPOLOGY OPTIMISATION AND ANALYSIS OF THREE-DIMENSIONAL PRINTED STINGLESS BEEHIVE BOX

2023-09-13T06:39:46+00:00

Using a traditional wooden compartment to house a hive for stingless bees presents numerous challenges. Among these issues, one significant concern arises from the gradual decay of the enclosure structure due to temperature fluctuations, forming holes. The wooden compartment is vulnerable to pests that risking potential failure and producing mouldy beehives. Besides, beekeepers face challenges in harvesting honey due to the heavy weight of the compartment and inadequate cover used. The objective of the study was to design a new stingless beehive box using three-dimensional printing method with topologically optimised features to solve the aforesaid problems. This involved the collection of primary and secondary data through methods such as observation, interviews, and the examination of journal articles. The study then progressed through a series of stages, including the conceptualisation of design ideas, the creation of three-dimensional models, prototype fabrication, numerical analysis, and thorough usability testing. Our results indicated that the proposed stingless hive box design is considered satisfactory, given the incorporation of attributes such as materials with minimal deterioration and increased resistance to pests, a lightweight and low-cost design, user-friendliness, and efficiency in the harvesting process of the honey due to its two-layer structure and improved cover, and appealing aesthetic design. To further enhance the functionality of the box for accommodating the stingless beehive, additional refinements may be warranted.

THE DERIVATION OF A DESIGN MATRIX FOR A FOOT-MOUNTED INERTIAL PEDESTRIAN NAVIGATION USING INVARIANT OBSERVER APPROACH

2023-08-15T07:54:07+00:00

This paper describes a derivation of a design matrix for a foot-mounted inertial pedestrian navigation. The design matrix sometimes known as state space propagation matrix, or transition matrix, that propagate the modelled states over time. An inertial sensor is assumed to be strapped tightly on the foot of a pedestrian, and therefore the measurements obtained are assumed to be highly correlated with the movement of a foot. This permit the use of velocity update whenever the foot is on the ground. The design matrix is then derived using the Invariant Extended Kalman Filter (IEKF) framework. The navigation state is represented as an element of the matrix Lie group of double direct isometries, which is a mathematical description of the space in which the pedestrian moves, including position, velocity, and attitude. The model also incorporates accelerometers and rate-gyros biases, which are common in inertial sensors. A comparison with the design matrix derived from the standard Extended Kalman Filter (EKF) are made, and will be shown unvarying with attitude estimates, which is an improvement over the standard EKF.

DEVELOPMENT OF AN EMBEDDED WIRELESS PYRANOMETER USING NODEMCU

2023-08-18T09:56:28+00:00

Solar radiation monitoring is a crucial step in estimating the size of solar modules, as well as their best position and inclination angle for maximum power generation. Standard large-scale solar radiation measurement tools are prohibitively expensive, need specialist skills to operate, and are unavailable in emerging economies. As a result, this inquiry recommends the use of a NodeMCU development board as the processing unit for a low-cost wireless pyranometer. A solar module and an ACS712-05B current sensor as the sensory unit and a 16x2 LCD screen as the display unit make up the proposed instrument. By closely monitoring the short circuit current of the module and deducing the output voltage of the current sensor, the proposed meter determines the instantaneous solar radiation. In this study, the measurements are communicated to the ThingSpeak (an Internet of Things analytics platform that sends sensor data privately to the cloud) so that the measured data could be accessed remotely. Two daystar DC-05 pyranometers geo-located for solar irradiation measurements were used to compare the proposed meter's field performance. The pyranometers' performances were found to be equivalent, each exhibiting a Root Mean Squared Error of 0.0946705 and 0.064885 respectively.

A HOUSEHOLD ELECTRICITY CONSUMPTION PREDICTION AND ANOMALY DETECTION BASED ON FEATURES USING TWO-STEP UNSUPERVISED DEEP LEARNING APPROACH

2023-12-28T08:38:29+00:00

Accurate prediction of household electricity consumption is significant as it serves as a building block for effective energy management and operational decisions, essential for curtailing non-technical losses. A range of machine learning techniques have been implemented for detecting abnormal electricity consumption and have achieved significant results. However, with the evolution of anomalous electricity consumption coupled with the rapid growth in electricity consumption data, new challenges confronting anomalous electricity consumption are emerging. This current study proposes a two-step unsupervised machine learning approach, including a gated recurrent unit (GRU) regular network and a gated recurrent unit (GRU-autencoder) autoencoder, to detect consumption anomalies. The analysis was based on data collected from 450 households over a three-month period within the Tamale municipal assembly. The performance of the proposed model (the GRU autoencoder) was estimated using the MSE value, f-score, precision, and accuracy. The GRU autoencoder outperforms state-of-the-art methods in detecting anomalous electricity consumption, achieving an accuracy of 90.97% on the trained dataset.

OPTIMIZING TASK EFFICIENCY: PATH PLANNING FOR MOBILE ROBOTS

2024-02-21T08:45:37+00:00

In an ideal scenario, a smart mobile robot should have precise and reliable movements to navigate paths efficiently while performing tasks swiftly, accurately, and seamlessly. However, mobile robots often encounter manoeuvrability constraints, resulting in incorrect movements with a significant margin of error. This project aims to develop a mobile robot capable in planning its path based on path generation time. The examination begins with an assessment of various path planning algorithms in MATLAB. Results show that the Dijkstra path planning algorithm is chosen for implementation, providing the shortest path with the fastest completion time in simulations compared to RRT*. Future projects may explore implementing the Dijkstra algorithm as the path planner on a real robot to analyse system performance in terms of speed, stability, and reliability.

ENHANCING SAFETY AND RELIABILITY IN RAILWAY SIGNALLING SYSTEMS: A COMPREHENSIVE FMEA-BASED APPROACH

2024-03-21T05:22:45+00:00

Railway signalling systems, classified as safety-critical systems, must adhere to specific safety principles outlined in CENELEC standards to ensure the desired levels of safety and reliability. The Interlocking system serves as the central intelligence behind railway signalling, authorizing trains to navigate safe routes under predefined conditions, eliminating collision risks. Object controllers (OCs), a crucial component of the interlocking subsystem, are responsible for overseeing and managing field elements such as signals, points, track circuits, and other vital controllable objects. Object controller boards encompass both hardware and software components, necessitating compliance with relevant railway safety standards such as EN50129 and EN50126. This paper focuses on a developed test platform designed to streamline the design and development life cycle of Object controllers. Within this tool, the importation of system architecture facilitates risk identification and assessment using the Failure Modes and Effects Analysis (FMEA) method. Ultimately, the paper calculates the reliability of both subsystems and the entire system.