1.1 BACKGROUND OF THE STUDY
The problem our thesis work will solve is to reduce backlash in induction motor. Backlash is described as a mechanical form of dead band that can lead to error on hole location, if the motion required to machine the holes causes a reversal in axis direction it also lead to loses of motion between input and output shafts, making it difficult to achieve accurate positioning in equipment such as instruments, machines tools etc. The main problem electrically are vibrations from motor as a result of high ripple torque in the induction motor.
An induction motor is a kind of an AC machine in which alternating current is supplied to the stator directly and to the rotor by induction from the stator. Induction motor can appear in a single phase or a poly phase. (Toufouti, et al, 2013).
In construction, the motor has a stator which is the stationary portion consisting of a frame that houses the magnetically active angular cylindrical structure called the stator lamination. It stack punched from electrical steel sheet with a three phase winding sets embedded in evenly spaced internal slots.
The rotor which is the rotatory parts of a motor is made up of a shaft and cylindrical structure called the rotor lamination. It stack punched from electrical steel sheet with evenly spaced slots located around the periphery to accept the conductors of the rotor winding (Ndubisi, 2006).
The rotor can be a wound type or squirrel cage type.
in a poly phase motor, the three phase windings are displaced from each other by 120 electrical degrees in space around the air-gap circumference when excited from a balanced poly phase source, those windings (stator winding) will produce a magnetic field in the air-gap rotating at synchronous speed as determine by the number of stator poles and the applied stator frequency (Bimal, 2011).
In the controlling of electrical motor; the introduction of micro-controllers and high switching frequency semiconductor devices, variable speed actuators where dominated by DC motors.
Today, using modern high switching frequency power converters controlled by micro-controllers, the frequency phase and magnitude of the input to an AC motor can be changed and hence the motor’s speed and torque can be controlled. AC motors combined with their drives have replaced DC motors in industrial applications because they are cheaper, better reliability, less in weight, and lower maintenance requirement. Squirrel cage induction motors are most generally used than all the rest of the electric motors as they have all the advantages of AC motors and they are easy to build.
The main advantage is that motors do not require an electrical connection between stationary and rotating portion of the motor. Therefore, they do not need any mechanical commutators to the fact that they are maintenance free motors. The motors also have lesser weight and inertia, high efficiency and high over load capability. Therefore, they are cheaper and more robust, and less proves to any failure at high speeds.
Furthermore, the motor can be used to work in explosive environments because no sparks are produced.
Taking into account all the advantages outlined above, induction motors must be considered as the perfect electrical to mechanical energy converter. However, mechanical energy is more than often required at variable speeds, where the speed control system is not a trivial matter. The effective way of producing an infinitely variable motor speed drive is to supply the motor with three phase voltage of variable amplitude.
A variable frequency is required because the rotor speed depends on the speed of the rotating magnetic field provided by the stator. A variable voltage is required because the motor impedance reduces at low frequencies and the current has to be limited by means of reducing the supply voltage. (Schauder, 2013).
Before the days of power electronics, a limited speed control of the motors was achieved by switching the three stator windings from delta connection to star connection, allowing the voltage at the motor windings to be reduced. Induction motors also available with more than three stator windings to allow a change of the number of pole pairs.
However, a motor with several windings is very costly because more than three connections to the motor are needed and only certain discrete speeds are available. Another method of speed control can be realized by means of a wound rotor induction motor, where the rotor winding ends are brought out to slip rings (Malik, 2013). However, this method obviously removes the main aim of induction motors and it also introduces additional losses by connecting resistor or reactance in series with the stator windings of the motors, poor performance is achieved.
With the enormous advances in converters technology and the development of complex and robust control algorithms, considerable research effort is devoted for developing optimal techniques of speed control for the machines. The motor control has traditionally been achieved using field oriented control (FOC). This method involves the transformation of stator currents in a such manner that is in line with one of the stator fluxes. The torque and flux producing components of the stator currents are decoupled, such that the component of the stator current controlling the rotor flux magnitude and the component controls the output torque will differ (Kazmier and Giuseppe, 2013).
The implementation of this system however is complicated. The FOC is also well known to be highly sensitive to parameter variations. It also based on accurate parameter identification to obtain the needed performance.
Another motor control techniques is the sensor less vector control. This control method is only for both high and low speed range. Using the method, the stator terminal voltages and currents estimate the rotor angular speed, slip angular speed and the rotor flux. In this case, around zero speed, the slip angular velocity estimation becomes very difficult.
Motivation for the work
When we were on training in machine in our office, we are told gave us a drawing to produce a machine shaft. During the process, when we feed in a cut of 10mm to the machine, it would cut 9.5mm and when we wanted to drill a hole at the center of the job, it would drilled it off centered, we called on our supervisor after we have wasted much time, power and materials. Surprisingly, after his supervision, he told us that backlash in the machine is responsible for that and he instructed us to use another machine which we did and got what we need immediately. Therefore, that ugly experience motivated us to research on how to reduce high ripple torque in induction motor which is the main causes of vibrations that lead to the backlash in the industrial machine.

1.2 STATEMENT OF THE PROBLEM
• The statement of the human problem our research work will solve is to reduce backlash in industrial machine.
• Explanation of the problem

We Will Write a Custom Essay Specifically
For You For Only $13.90/page!


order now

BACKLASH
Backlash can be defined as the maximum distance or angle through which any part of a mechanical system may be moved in one direction without applying appreciable force or motion to the next part in mechanical sequence and is a mechanical form of dead band. More so, it is any non-movement that occurs during axis reversals. For instance, when x – axis is commanded to move one inch in the positive direction, immediately, after this x – axis movement, these x-axis is also commanded to move one inch in the negative direction if any backlash exists in the x-axis, then it will not immediately start moving in the negative direction and the motion departure will not be precisely one inch.
So, it can cause positioning error on holes location, if the motion required to drill the holes causes a reversal in axis direction, it also causes loses ofmotion between reducer input and output shafts, making it difficult to achieve accurate positioning in equipment such as machines tools etc.
The main cause of this problem electrically is vibrations from electric motor as a result of high ripple torque in the induction motor.

• Benefits of solving the problem
1. High quality products will be produce.
2. Productivity will increase because adjustment and readjustment of machine feeding handle or feeding screw to eliminate backlash have been reduced.
3. Operational cost will reduced.
4. Greater efficiency will be guaranteed.
5. Greater accuracy and precision of product will be guaranteed.
6. Wasting of materials will be highly reduced.
1.3 RESEARCH OBJECTIVES
1. To develop a model that will control the error to achieve stability using DTC and fuzzy logic with duty ratio.
2. To determine the error in the torque of the machine that causes vibration which lead to backlash that result in production of less standard products.
3. To determine the position of the stator flux linkage space vector in the poles of the induction motor.
4. To determine the stator linkage flux error in the induction motor that also causes vibration.
5. To simulate the model above in the Simulink environment and validate the result.

1.4 SCOPE AND LIMITATION OF THE WORK
This project work is limited to the use of fuzzy logic controller with duty ratio to replace the torque and stator flux hysteresis controllers in the conventional DTC techniques. The controllers have three variable inputs, the stator flux error, electromagnetic torque error and position of stator flux linkage vector. The inference method used was the Mamdam fuzzy logic inference system. The deffuzzification method adopted in this work is the maximum criteria method.

1.5 SIGNIFICANCE OF THE WORK
The importance of this work in industry where induction motor drives are mainly in application cannot be over emphasis.
As earlier noted, induction motors because of their ruggedness simple mechanical structure and easy maintenance; electrical drives in industries are mostly based on them.
Also, a wide range of induction motor applications require variable speed, therefore induction motor speed, if not accurately estimated will affect the efficiency of the overall industrial processes. Equally, the harmonic losses if not put in check will shorten the life span and efficiency of the motor inverter.
Based on the above, it is aimed at reducing the principle causes of the inefficiency in the DTC induction motor and improves the performance of the system.
1.6 ORGANIZATION OF THE WORK
The work is organized into five chapters. Various control techniques were discussed in chapter two, in chapter three, we discusses the methodology, design and implementation of the direct torque control of induction motor using fuzzy logic with duty ratio controller.
Chapter four discusses data collection, analysis and the simulated results showing the system using conventional method of control and the proposed fuzzy logic with duty ratio method of control under applied load torque conditions.
Conclusion, recommendations and suggestion for further work are mentioned in chapter five.

1. Introduction.

AHF is stand for Aviation Human Factors is the courses of study about understanding human conduct and execution. At the point when connected to flight tasks, Human Factors information is utilized to upgrade the fit amongst individuals and the frameworks in which they work with a specific end goal to enhance wellbeing and execution. A man has a limit on doing something.
This is evidenced by the percentage in the study. 70% is caused by humans example Pilot, maintenance, air traffic controller and Airline Management.
At that point 30% is because of ecological variables and cases of broken hardware or gadgets, poor support, plan defective, climate condition, medicinal status and air terminal task.
The first factor is the sample decision made by the manufacturer. Unless you plan and build your own aircraft, it’s far from your control.

We Will Write a Custom Essay Specifically
For You For Only $13.90/page!


order now

However, other factors are examples of things you can control to a certain extent. This is all about the weak Aeronautical Decision Making (ADM), these intended to help you understand the psychological factors that affect ADM, and what you can do to improve your results.

2. Altitude and Hypoxia.

2.1 Altidude.

There are many type of altitude such as true altitude, indicated altitude, pressure altitude, absolute altitude and density altitude.
True altitude is your stature above “mean ocean level”, a generally discretionary reference point. By “signify” we signify “normal”, since ocean levels do differ with the tides, and the breeze causes waves, so mean ocean level midpoints out every one of these impacts to a solitary “signify” ocean level. You’re fundamentally intrigued by this since territory and snags are outlined with reference to MSL heights, and you need to ensure you’re well over these when flying over them. In the event that we were on the ground, we’d call this “height”. Lamentably, nothing in your plane is probably going to quantify this, an extremely precise GPS would come the nearest, so we rather depend on something that is a truly decent estimation.
Indicated altitude is nothing in your plane estimates genuine elevation, we utilize “indicated altitude” as the following best thing. This is the thing that your altimeter gives you when you have the present “altimeter setting” connected to. We utilize indicated altitude for 2 things, looking after landscape/impediment freedom and keeping up vertical detachment between planes that ignore each other. For landscape/deterrent leeway, we’re utilizing demonstrated altitude as a substitute for genuine elevation, which we’re typically not prepared to quantify in our plane. In case you’re close, both along the side and vertically, to the climate observing site from which you got your altimeter setting, at that point this is a quite decent estimation of genuine altitude, which is the thing that you truly need. An altimeter takes the weight estimated at an adjacent ground station (the altimeter setting), measures the weight it’s inclination noticeable all around the plane, takes the distinction, and by making a suspicion of about how rapidly pneumatic stress drops as you get higher, it makes a gauge of what your actual height may be. Be that as it may, the rate at which gaseous tension drops as you get higher is variable, and the higher you get from the climate station the more prominent this mistake can be, and the more regrettable your gauge gets. Likewise, as you increase parallel separation from the revealing station, the surrounding weight can change marginally, with the end goal that a closer announcing station would report an alternate number. Our leeway from landscape is most basic while doing instrument approaches, as should be obvious the territory in IMC to know in case we’re clear of it. Luckily, coming in low and near a climate revealing station gives us the most exact estimate of genuine elevation. A most pessimistic scenario case may fly around evening time over mountains. Our altimeter setting may be from a ground station both horizontally numerous miles away, yet additionally from a rise much lower than our elevation. This could prompt a huge altimeter mistake, and perhaps we’re nearer to the highest point of that tall tree on the highest point of that tall mountain than we might suspect we are. Beneath 18000 ft. we additionally utilize showed height to guarantee 2 planes flying over each other have “vertical detachment”; at the end of the day, two planes may head specifically towards each other, however as long as one is flying higher than the other, there’s no danger of crash. The planes might be a long way from the closest climate revealing station, and high above it, so we might get a poor estimate to genuine altitude, however for this situation all we think about is that the two planes are a specific vertical separation from each other. So while each might have an expansive mistake with respect to genuine elevation, they each fundamentally have a similar blunder, expecting they’re both utilizing a similar altimeter setting (as they ought to be), thus vertical partition can be guaranteed.
Pressure altitude is Consider the “vertical partition” contention above and keep running with it. Up over 18000 feet planes are flying quick and high, getting cutting-edge altimeter settings isn’t extremely handy, and the blunder with respect to genuine elevation is high because of the stature over the revealing stations. In any case, up here we don’t have landscape to battle (with just a couple of special cases), so we’re just keen on vertical partition, and not especially about flying a specific tallness over the ground. So up here we fly “weight heights”. Everyone places 29.92 into their altimeters, and flies whatever height ATC allocates. At the point when our altimeter peruses 34000, we know we’re most likely not especially near 34000 feet MSL, but rather we couldn’t care less, all we think about is that the other person coming the other way whose altimeter peruses 33000 is extremely around a 1000ft underneath us. A plane flying at FL180 is riding along whatever level in the air yields a specific barometrical weight, to be specific the weight that we hope to see at 18000MSL under states of standard temperature and weight. It will fly higher over the ground on a high pressure or high temperature of day, and closer to the ground on a low pressure or low temperature of day. On multi day with especially low pressure, it’s feasible for the genuine height related with FL180 to be low to the point that it can struggle with pilots flying a demonstrated elevation of 17500. At the point when this happens, ATC won’t dole out FL180.
Obsolute altitude is outright elevation is your stature over the ground. On the off chance that you fly a steady height for each your altimeter, your supreme elevation could be shifting significantly. In the event that you fly over a major mountain, your tallness over the ground drops; on the off chance that you at that point fly over a major valley, your stature over the ground rises. You might fly a steady showed elevation, however since the stature of the ground differs quickly, your tallness over the ground changes also. You’re exceptionally intrigued by your stature over the ground when you’re flying low and risking really running into something down there. You’d get a kick out of the chance to know how clear you are of landscape and hindrances. While completing an instrument approach, you’d extremely get a kick out of the chance to know with exactness your tallness over the ground, in light of the fact that in IMC you can’t perceive what may ascend to destroy thee. A gadget to quantify total height is a radar altimeter. Note that your supreme elevation can vary drastically as the territory rises and falls, despite the fact that your “normal” barometric altimeter is shake enduring. Most little planes don’t have radar altimeters, and most non military personnel little planes just fly IMC along all around diagrammed ways, so supreme elevation doesn’t become possibly the most important factor much in minimal plane flying. Rather we utilize demonstrated elevation as a guess to genuine height, and reference our showed elevation against outlines that rundown MSL esteems.

1.1 Describe how to establish respectful, professional relationships with children and young people

Establishing respectful and professional relationships with children and young people is essential and involves being able to change the way in which you express yourself in relation to the environment you are in, in terms of both your behavior, and the way in which you communicate. For both children and young people, you need to ensure that when building relationships, you make them feel secure and valued and show respect.

We Will Write a Custom Essay Specifically
For You For Only $13.90/page!


order now

In order to achieve this, it is vital to establish ground rules from the start. If both the practitioner and children or young people are aware of what is expected from them from the beginning respectful and professional relationships can develop as boundaries have been set from which to work from.

The practitioner needs to be supportive and approachable at all times in order to gain trust from the child or young person. They need to be a positive communicator in terms of both giving and receiving information. Children and young people will gain confidence from being able to carry out instructions correctly and a large part of this comes down to receiving clear, positive instruction through the communication skills of the practitioner. It is important also to show good listening skills, a child or young person is more likely to want to talk to you and express any worries or questions they may have if they feel that you are actively going to listen to them.

The practitioner needs to be kind and considerate towards all children and young people regardless of the situation. This opens up a relationship where the practitioner is approachable and also demonstrates to the child or young person good behavior of which to model on. If a child or young person approaches you with a situation and you respond in a kind and considerate manner they learn that this way of dealing with situations leads to positive outcomes regardless to the initial situation.

To have patience and understanding is a very important skill for the practitioner. Children and young people can often take their time in conveying information or completing a task, and not always put across the correct information, in taking your time with the child or young people in order to understand what it is they are doing or communicating gives them the trust in the practitioner to come to them again with them knowing that they will be given the time they need to fully explain themselves. The practitioner does though need to be aware that at what times it is appropriate to change the way in which they are dealing with a child or young person as sometimes they can use a practitioners patience in order to seek attention away from a task in hand for example a communication that starts with a child or young person needing a piece of work explained to them develops into the child discussing what they watched on tv last night at times like this it is important to remind the child or young person of what is expected of them as a member of the school and this is also a point at which it shows importance to have set up the initial ground rules with the child or young person as these too can be referred back to.

The practitioner should at all times lead by example, children and young people learn by example, they model what the behavior they see. The practitioner should not gossip about anyone, as this is a very negative behavior that has no positive outcomes. They should at all times be polite and courteous to other members of the school (adults, children and young people) as well as the wider, school linked, community. To set this positive behavioral role model for them is vital to their overall learning. The practitioner also needs to lead by example as to how to deal with something if they accidently do something wrong. If the practitioner is to do something wrong, then this needs to be explained to the child or young person in order for them to realise and therefore learn that everyone gets things wrong and that it is ok to get things wrong. If the practitioner shows that with the mistake that they have made that they can positively rectify it or learn from their mistake, it shows the child or young person that it is ok for them to make mistakes and positive ways in which they can deal with the mistakes. It also builds trust in the practitioner and confidence in the child or young person as they are more likely to give things a go knowing that if they make a mistake it is not an issue.

1. What are the main duties of the different team members that Mr. Spencer should put together to ensure the success of the “Post-It” project?
– Of the duties required of the team of scientists to the success of this project. Is to make a team of scientist’s great efforts to promote ideas and the necessary things in their environment and provide them with innovators who take these ideas and think of ways to improve or develop. The manager must have a passion for providing all that is new and innovative to the team to encourage them to achieve work.
2. What kind of ethical concerns could arise when working on the “Post-It” project?
– It is unethical to make people pay for something which is may be had cheap quality and when promoting the product somebody lie and may tell more than what the product is really advantages for.

3. What are the different pros and cons of putting together a team that will handle the “Post-It” project? Based on these pros and cons what would be your recommendations for Mr. Spencer?
– Pros: The presence of a project management team is a knowledge of dealing with each case and there are ways to solve problems. They will have a common direction to follow and more ideas to share different views to find a solution to a particular situation. When a large group works on an idea, work is done faster and more efficiently.
– Cons: The group wastes more time thinking about an idea that may be delayed at the start of the project.
– Sometimes the group members are less focused because they do not know each other and do not adapt to each other. 
– The Mr. Spencer shouldn’t say “no” for an idea, that will lead the team accept the new ideas and face any difficulties to achieve the project.

We Will Write a Custom Essay Specifically
For You For Only $13.90/page!


order now

4. Each team has always a leader who will oversee the progress of a project. What are these duties in the specific context of the “Post-It” project?
– The leader makes sure that each member of the team completes his work on time.
–  The commander must ensure that all teams work together accurately and correctly.
– Great leadership invest in the project from their own money. Leaders are the link between different teams and CEO.

– In the project “Post it” the development of long-term strategies was the real challenge of the leader. It tracks the numbers and instant outputs, they must make sure to get the benefit of the product.