SUMMARY OF PROJECTS
| ORGANIZATION | John F. Welch Technology Centre, | |
| PROJECT | Development of a weld free contactor. | |
| DURATION | May 16, 2005 to July 5, 2005 |
This project was focused to improve the device performance of contactors being manufactured by General Electric(GE). The team was facing problems dealing with estimation and effects of electrodynamic forces produced due to current interactions in the device. This electrodynamic effect varies with current path in the device. We developed a digital tool to determine the magnitude of the force produced due to this effect by studying the current paths in the system. Further, I suggested a few innovative design changes to improve the contactor performance which were implemented and analysed for incorporation.
| | PROJECT TITLE | Design, analysis and control of a Variable voltage variable frequency (VVVF) controller using power electronic devices. |
| | DURATION | December, 2004 to May, 2005 |
| | SUPERVISOR | Dr. A. K. Kapoor, Professsor, Deptt. of Electrical Engg, IT-BHU. |
The project dealt with the development of a Variable voltage variable frequency (VVVF) drive for a 3 phase, 5kW Induction motor. The project work included the designing of the VVVF drive from the basic power electronics devices its simulation and verification of the obtained results. Main design considerations were harmonics elimination, wide speed and torque range, switching timing calculations, heat dissipation and sink calculations. Further it was required to design the control circuit for the VVVF drive for the control of the power electronic devices used in the drive for accurate switching timings and desired output.
| | PROJECT TITLE | Simulation of 8085 Microprocessor for a virtual development kit. |
| | DURATION | January to May, 2005. |
| | SUPERVISOR | Dr. S.C. Gupta, Prof and Head, Deptt. of Electrical Engg, IT-BHU. |
This project was aimed towards the development of a software interface for the simulation of 8085 microprocessor. We studied the techniques to generate 8085 assembly code corresponding to various user defined functions and procedures in the input language (a new language for embedded programming with 8085), using C++ for parsing and code generation. We suggested suitable modifications required in the syntax of functions so that processing in C++ is convenient and yet the input language is not too cryptic for the user. We wrote C++ program for reading simple procedure calls and generating 8085 assembly language instructions for them. We proposed suitable predefined functions in the input language so that users can easily write code for reading and writing various ports on the 8251 and 8255 ICs.
| | PROJECT TITLE | Reconstruction of electric car made in the Deptt. of Electrical Engg.. |
| | DURATION | July to December, 2004. |
| | SUPERVISOR | Dr. S. K. Sharma, Professor and Head, Deptt. of Mechanical Engg, IT-BHU. |
Major project work included the reconstruction of a dilapidated Electric car developed by the Electrical Engg. Department in 1990’s. This included the fault diagnosis of the electric circuit and motor used for driving the vehicle. Also many other mechanical changes were done by the team. The project further extended to construct an Autonomous guided vehicle using the base structure of the electric car. This part included image extraction, image processing, decision making and control system of the vehicle. This part was only partially completed as the image processing algorithms were working fine for straight roads but were not able to handle successfully the complexity of turnings and traffic.
VARIABLE CHAIN DRIVEN SYSTEM
(July-September 2003)
Team Members: Rajat Kashyap, Sachin Aggarwal and Vibhav Agrawal
Under: Dr. S. K. Sharma, Professor IT-BHU, Varanasi, INDIA.
General Details:
The idea of the project was initiated when I was in B. Tech. 1st year in Mechanical
Engg. This was a very novice idea and was our first project in the institute. Aim was to provide a cheap and affordable gear mechanism for the poor cycle-rickshaw pullers, which used only one gear wheel. Motivation for this came after watching cycle-rickshaw pullers of our Institute. Many possible designs and there flaws were discussed, at last we worked out a design that was somewhat very different from the gear wheel so we named it as the "Variable Chain Driven System".
The model got selected for interview at the "Kishore Vagyanik Protsahan Yogna" held at IIT- Bombay and was also selected at 5th place for summer camp invite at IISc., Bangalore in the final list
Mechanical Details:
As seen in picture the main body of the system was made of Mild Steel (MS) and fabricated in Institute’s Workshop. The teeth used in the prototype were the brake hoes of bicycle. The hollow pipes used to hold brake shoes were of gunmetal, which were available in automobile market. The whole assembly was designed to move in radial direction to change the radius of the wheel (gear). We used a spring-rod mechanism to move the teeth of the wheel as shown in the fig. These springs and the rods were supported by an annular ring which was also made of MS. A belt was driven by this whole variable wheel. A third gear supported with spring was also incorporated for the varying tension of the belt due to varying length.
Experience and Result:
Many problems were faced in fabrication of the prototype in Institute’s workshop.
Due to fabrication delays the model finished only in my II year. The whole design due to fabrication limitations was not at all compact. Due to large dimensions and use of Mild Steel prototype was too heavy and the mechanism was partly working. Also the springs used to push the teeth in forward direction were not able to provide strength to the whole structure under stretched state due to tension of the belt. The whole system was tested without the inclusion of the third spring gear and the results were supportive, stopped work on it till more facilities for fabrication were available.
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AUTONOMOUS UNDERWATER VEHICLE:
(September-December 2003 and March-April 2004)
Team Members: Rajat Kashyap and Vibhav Agrawal
Under: Dr. S. K. Sharma, Professor, IT-BHU, Varanasi, INDIA.
General Details:
A senior guided us to world of Underwater Vehicles and we decided to make the first AUV of our institute. This project was started in my II year and was the most time consuming project. The first aim was to build an Underwater Vehicle that would be imply able to stay inside water without any leaks. The next thing was to build its driving system. A new innovative mechanism had to be worked up to avoid the design of water tight shaft seals. We worked on the use of water pumps as the source of propulsion force for the vehicle. The mechanical designing was done and the complexity of placement of CG (Centre of gravity) and CB (Centre of Buoyancy) were solved by proper placing of the components. After the mechanical design, control system was designed to make it truly autonomous. Model fabricated was shown at the National Institute of Oceanography, GOA during summer project work of 2004.
Mechanical Considerations:
During design the most essential requirement was to keep CG and CB in same vertical line with CG below CB for stability. The core body was a pressure hull and was made of a plastic pipe which was very light weight so our model was becoming positive buoyant. Next the components were to be such placed that the CG remain exactly at he centre so that there is no initial pitch or roll in the vehicle. Calculations for the position of all the components were done. Movement of CG was used to provide pitch motion to the vehicle. A nut-screw mechanism prior fitted with a gear box with a reduction ratio of 117:1 was used to move the battery placed just at the CG to move the CG. To make the hull watertight was the most difficult part and we never completely succeeded in it. We used tubes of bicycle to make them water tight but they were effective only for a day or two, during which we did our testing and then again replaced the tubes.
Electronics and Control System Design:
The next step after the development of the mechanical model was to make it autonomous or at least remotely operable. For this we needed to control the witching of two motor pumps and the switching and the direction of the DC motor used for the movement of the battery by nut-screw mechanism. For this we had to design a circuit and only basic electronic components such as timer IC’s, flip-flops were available. We used a wireless microphone for communication between the operator and the AUV. Pulses at receiver were generated by switching transmitter of the microphone on or off. We counted these pulses and used them to switch on or off our devices with the use of solid-state relays. The system was working fine for about half a meter depth of water. The final assembly of the electronic circuitry in the AUV was not done due to last time leakage and breakage of hull and time constraints for remaking another hull. The whole circuit was then made on a single layered PCB.
Performance:
The AUV as such without electronic equipments was around 0.7 kg positive buoyant. It had approximately 20-30 degrees roll under neutral conditions. The water pumps used by us were able to drive it but at slow speed and were not sufficient for it, ut we couldn’t find better pumps at our place. The electronic circuitry designed to control and navigate the AUV had no sensors and any sort of feedback so it was just a "see and control" or remotely operated type of mechanism. We planned for an autonomous model as soon as sensors were available to us.
Result:
The project was time consuming and tiring for me but had a very big contribution in my experience in every field of engineering. On its basis we got an opportunity to o our summer project work at National Institute of Oceanography, where the first funded project of India on AUV "Maya" was going on. There we showed our model got appreciation for its simplicity and innovativeness.
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PROGRAMMING OF A HMT CNC T-70 MACHINE:
(March 2004)
General Details:
We had a CNC Machine in our Institute which was not being worked upon due to inability of any qualified working operator. In fact nobody in the institute knew ow to operate that machine at that time and was not also willing to learn. I took the task and studied how to program the machine and within a month I was able to work on it. Later I taught how to work on it to the working staff and was partially succeeded in my effort. This work was done during my B. Tech. 2nd year and was the last project in my second year.
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SUMMER PROJECT AT NATIONAL INSTITUTE OF OCEANOGRAPHY (NIO)
(May-June 2004)
Team Members: Rajat Kashyap and Rohit Kumar.
Under: Dr Elgar de Sa, (Scientist F),
Marine Instrumentation and Computer Division (MICD),
National Institute of Oceanography (NIO), Dona Paula, GOA, INDIA
The "MAYA" is the first Indian attempt to build world class shallow water Autonomous Under Water Vehicle (AUV) for civilian scientific purposes. Mainly our work was to prepare a dc motor for testing purposes of the AUV’s different parts and hull and also to suggest all possible safety considerations and other mechanisms of the AUV which were supposed to make it operable underwater. Some of the tasks we did there are:
A) VOLTAGE AND CURRENT FEEDBACK:
General Details:
It is very important to monitor to motor parameters in any of Underwater Missions, so during our summer training at NIO we were asked to get various feedbacks from a 24V, 1.2 Amp. DC Motor using Microcontroller and then implement the same thing on a bigger motor of 48V and 2Amp. Major parameters are the voltage fed to the motor and the current drawn by it. We used a mixed Microcontroller Cygnal 8051F007 for the purpose.
Technical Details:
The normal operating range for operation of the motor was from -0.9 Amp to +0.9 Amp and 15-30 Volts but we designed the circuit for the operating range of -5.0 Amp to +5.0 Amp and 0-48 Volts so that the similar circuit can be implemented on the bigger motor without any modifications. We used op-amps for giving the feedback to the ADC channel of the Microcontroller. The voltage feedback was provided directly using a potential divider and an op-amp to check loading of Microcontroller and the feedback for current was taken across a 0.5.-50 Watt resistor. This was then manipulated to give feedback for both direction of the current using op-amp.
Calibration curves for both the voltage and current were obtained and the Calibration equation for them was also calculated. Using this equation when we nalyzed the motor it was found to be giving precise value with only slight error of about 0.4% in operating conditions which was a very good result.
B) RPM FEEDBACK:
General Details:
For RPM feedback of the dc motor we first thought of generating an equivalent voltage signal similar as in voltage and current but then we thought of why not recisely calculating the RPM of the motor and storing it in the memory to gAve the exact value of the operating speed.
Technical Details:
We used an photo coupler for calculating the precise value of the RPM and this idea came from an experiment we did in our 1st year by opening a computer mouse and exploring the photo coupler mechanism used in it to detect the motion of mouse. Thus we assembled this photo coupler on the shaft of the motor and the output obtained from the photo coupler was sent to a comparator which was then fed to the Microcontroller’s ADC for counting of the pulses. Falling edges of the pulses were recognized by the interrupts generated by the program. Initial and final time was aken by reading the timer value. 60 divided by this value gives the rpm. 10 samples were taken just to remove any undesired value or fluctuation.
Performance and Result:
This RPM feedback device gave excellent results. It gave exact RPM from a range of 4 to 6500, which was far beyond than what we expected from it. Even the scientists present there praised it. At lower RPM result was exact and at higher RPM there was maximum error of 4 RPM which was within the permissible limits. Also after getting all the feedbacks of voltage, current and RPM we implemented all of them on a single PIC 16F876 IC. Thus a single chip was required to get all the feedbacks of the motor. We also later implemented speed control of the motor using PWM with the same IC.
C) PWM FOR SPEED CONTROL OF DC MOTOR:
General Details:
After the successful completion of getting feedbacks from the dc motor we were asked to also control it’s RPM in a large range and it’s direction of rotation so hat a compact motor could be assembled with all the feedbacks and also with speed control capability. So we tried to implement PWM for the speed control of the motor. This meant lesser losses due to absence of any resistance and thus a larger battery life in the AUV.
Technical Details:
We used the same PIC16F876 that was earlier used for the rpm feedback of the motor and using this PIC pulses were generated of constant frequency with varying duty cycle. The duty cycle was varied from 98 to 2 percent due to which rpm of the motor varied from its rated value to zero. An interfacing circuit was implemented to avoid loading of the PIC. This circuit consisted of a power MOSFET IRF510, two diodes, a relay (2 C/O 5 D) and a NPN transistor (SL100). Power MOSFET supplies the required voltage to the motor and relay along with the SL100 decides the direction of rotation of the motor. The input to SL100 comes from PIC whenever direction change is required. The diodes are used to clip the reverse voltage.
Performance and result:
The assembly worked fine and was able to control both the RPM and the rotation direction of the motor. It faced little problem while switching from one direction o other at speed, i.e. it was not able to make the rotating motor change its direction immediately and rotate in other direction with same speed. It had to go to zero speed first and then its speed could be increased in other direction. This was due to the power MOSFET which was unable to handle the requirement of high current due to sudden direction change of motor.
D) REPORT ON VARIOUS SAFETY AND BUOYANCY ASPECTS OF THE AUV "MAYA"
We were also asked to prepare a report on the following fields after analysis and study of various papers and journals on AUV
i) Safety considerations of the AUV.
ii) Dead Weight considerations and its working mechanism for the AUV.
iii) Buoyancy trimming devices for the AUV.
