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Methods

2. Methods


The Lift Shaft
2.1 The design of the shaft
2.2 Considerations of the use of materials
2.3 Consideration of suggestions
2.4 From concept to reality
2.5 Equipment List
2.6 Risk and Safety


2.1 The design of the shaft




To begin with the development on The Smart Lift, Our group had to decide on the design of the shaft. Many questions were asked, leading to many problems. Some of these problems included how to maximise the use of space in the lift to have a larger capacity and the prevention of the the lift and counter-weight crashing onto the walls of the shaft. Lastly and most importantly, we also needed to ensure that we could do maintenance on the lift easily should there be any problem. And these were probably the smallest problems out of the many questions we asked ourselves in search of the perfect design. After thinking of possible ways the shaft should look like, we started on our initial sketches and modelling.Here is the first version of our lift shaft.


Figure 2.1a: Overview of shaft
Figure 2.1b: Side view of shaft


Figure 2.1c : Top view of shaft



2.2 Considerations of the use of materials


Our initial idea was to make a the shaft out of a combination of acrylic and plywood, but soon we decided that it was too time consuming and it will cost a lot more than just wood itself. One more problem was structural integrity. Afraid that the shaft would collapse under the load of the lift and counterweight, we devised a brand new idea. Our Team redesigned the whole shaft.

2.3 Suggestions and considerations

Some of our ideas include having a pulley system to give the lift a mechanical advantage. Another suggestion was to have doors at the side as an alternative to a windowed shaft. Thinking about it, having doors really will lighten our load. It will be easier for us to install and/or replace parts easily without having to take the whole shaft apart. Having the doors will also allow people to take a look at the interior of our lift.

2.4 From concept to reality

2.4.1 Making sure that the shaft will work properly with the lift unit



After the lift unit had been designed, our team did some minor adjustments to both the shaft and lift unit to fit them together. The result would be A Smart Lift that will work in coordination and there will be no big problems as long as the parts fit properly without any errors. To ensure that, the lift shaft has been design at all sides to have a little leeway of about 10mm to 20mm for us to make minor adjustments.


2.4.2 Finalised version of sketch

As mentioned, here are our sketches.The whole lift will be around 264(mm) by 264(mm) by 74(mm).

Figure 2.4.2a: Sketch of the front panel of shaft.
Figure 2.4.2b : Sketch of the rest of the panels of shaft.





2.4.3  3D Modelling

After we had completed the dimensions, we made a 3D model using Google Sketch-Up.
Figure 2.4.3a  Overview of the 3D model.
Figure 2.4.3b  View From Top

Figure 2.4.3c  Bottom and Side View


To download 3D model, please click here .

2.5 Equipment List
  1. Cotton string(5m)
  2. Hinges x 4
  3. Handle x 2
  4. Wood(Dimensions shown in Section 2.4.2)

2.6 Risk and safety



Risk
Safety Precautions
We might piece the pieces together incorrectly or the dimensions might be wrong
We have to double check all dimensions and refer to the dimensions before piecing the pieces together
We might hurt ourselves when  handling sharp equipment such as penknives or saws or drills.
We must be careful and not be distracted when using saws,penknives and drills so as not to hurt ourselves.
We might get hurt when handling the shaft as the edges of the wood might be sharp or there might be splinters of wood of the shaft
Use sandpaper to make the wood smooth and free of rough edges/splinters




















The Lift Unit

3.1 Equipment

3.1.1 The Type of Lift

3.1.2 Considerations for Types of Materials to be Used
3.1.3 Equipment List

3.2 Procedures

3.2.1 Dimensions of the lift unit

3.2.2 Overcoming Internal Structural Problems

3.2.3 From Paper and Pen to Digital Modelling

3.2.4 Overcoming Modelling errors
3.2.5 Concept to Reality
3.2.6 Fitting of parts
3.3 Risk and safety
3.3.1 Risk and safety precautions
3.4    Analysing Data
3.4.1 Brainstorming and Organising Data
3.4.2 Getting Suggestions


3.1 Equipment

3.1.1 The Type of Lift


To start off, our group had to start decide on what type of lift to make. We had to decide on the type of lift to use, and in the end, our group decided to just design and build a conventional lift. Due to time constraints, we decided to make a conventional lift with a counter-weight. Now, we had to decide what software to use. We decided to use Arduino although it is rarely used to control a lift.Learning to program an Arduino would be much easier than programming Java. Next, we also had to think of other complications that would affect the lift and its design.

3.1.2 Considerations for Types of Materials to be Used

Next, there are other things that needs consideration as well. The type of material used had to be strong and light. Acrylic and plywood were good choices. Plywood and acrylic are both very strong. The average weight of a 3mm piece of acrylic with an area of a square meter would weigh 7.5kg(usplastic.com,2010) and 2.3kg per square meter for 3mm plywood. Acrylic can also be translucent or transparent, depending on the type of acrylic used, which means that we can see whatever is going inside the lift although it is enclosed. Also, we can get to see the wiring behind the scenes from the outside.

3.1.3 Equipment List


Acrylic and wood(Dimensions shown in Section 3.2)

3.2 Procedures
3.2.1 Dimensions of the lift unit
Figure 3.2.1a
Figure 3.2.1b




Figure 3.2.1c








3.2.2 Overcoming Internal Structural Problems

In the interior of the lift where the buttons are, there must be a motherboard and wires connecting them to the Arduino. Therefore, 2 panels were placed in the lift with a spacing of 2mm in between them. This will allow wires to be able to fit through easily and should have enough space for the buttons and LED wiring.To keep the lift upright and not shake while moving up and down, we also can put a rod in 2 corners so that the lift can be guided along it and not be out of alignment.

3.2.3 From Paper and Pen to Digital Modelling
Figure 3.2.3a
Front view of lift. The door frame which is made of acrylic(Translucent/Transparent)






Figure 3.2.3b
Screen Shot 2015-02-25 at 1.10.30 pm.pngScreen Shot 2015-02-25 at 1.17.35 pm.png


90 Degree and L-brackets are also used in the lift to secure the acrylic to the wood planks as the acrylic cannot be glued easily. Thus, we have used nuts and bolts to secure them together.

3.2.4 Overcoming errors in modelling

After all the modelling, we went through the tedious procedure of making sure every piece of the 3D model was of the correct size. Whenever we discovered an error, we redid the various designs, modules and parts such that everything would fit into the size limit of 230mm. This included the pulley at the top as well.

3.2.5 Concept to Reality

Next, we have to go to the carpenter to get the wood with the correct dimensions. For the rest of parts, we would then get the hardware online or at Sim Lim Towers or Fook Hai building.


3.2.6 Fitting of parts

After the wood is ready,we would have to glue(epoxy/Cyanoacrylates glue) and piece everything together. Then, we would put the lift in the shaft. Wiring and programming will then take place.

3.3 Risk and safety

3.3.1 Risk and safety precautions


Risk
Safety precaution
The friction between the stepper motor and cotton string hoisting the lift unit is not enough to hoist the lift unit upward
Use materials such as rubber on the axle of the motor to increase friction or decrease the weight of the lift by using lighter materials such as styrofoam
Positioning of stepper motor is wrong and the lift door is unaligned with the door to the lift
Ensure that the stepper motor is placed in the right position and the programming brings the lift unit to be aligned with the lift door on the shaft
Lift unit banks to one side as the centre of gravity is not in the centre
Make sure the centre of gravity is such that the lift unit is stable and does not tilt to any side at all before building the lift unit

3.4 Analysing data

3.4.1 Brainstorming and Organising Data

Ideas and procedures are important to ensure the smooth running of this part of the project. Therefore, we need to organise all the data we currently have and compile them together so no errors would happen throughout the course of this project. We have already compiled our current plans to prevent any errors.

3.4.2 Getting Suggestions

After that, we had to get suggestions to improve our current design. We needed more innovations in our lift thus got Mr Tan to give us some ideas. These included an overload sensor,sound sensor, and the replacement of the lift buttons with infrared sensors.
The sound sensor would function by having a person in the lift state the floor he needs to go to verbally.The infrared sensors would work when someone puts an object or hand over it. These ideas would work well when the passenger’s hand is full and he cannot press the buttons. This would help him as he would not need to put everything down to press the buttons.




This is all for the part 2(Lift) and will be continued in Part 3(Electronics).















Electronics
4.1 Equipment
4.1.1 Finding the right materials
4.1.2 List of materials
4.2 Procedures
4.3 Risk and safety
4.3.1 Risks and safety precautions











4.1 Equipment

4.1.1 Finding the right materials

  With consideration of the type of lift we are about to build,the wires of the lift would have to move up and down together with the lift unit.This alone would pose many problems with the wiring of the lift.

Problem 1.We need to find the right wire that fits our needs to wire the lift unit.

Problem 2.We need to find the right replacement for the buttons and see if it is feasible.
Figure 4.1.1a-General layout of lift(From top)

Resolving Problem 1.
For the power cable to enter the lift shaft and connect to the lift unit,it has to be light and flexible.Such properties would allow the wire to bend as the lift unit makes its way upward and downward.This will ensure that the wire would not resist and motion of the lift unit.To solve this problem,we decided to use jumper wires as that is both light and flexible and therefore suitable for us to use.

Resolving Problem 2.
Our original plan was to drill the wire hole at the first floor(refer to figure 4.1.1b),but we decided to shift it up to the second floor(refer to figure 4.1.1c) for fear that the wire might be damaged as the lift unit rose higher and the wire had to pay out, or might obstruct the lift unit as it descended back to the first floor.The wire might not be able to fit back into the wire hole and out of the lift shaft as the lift unit reached the first floor.
Figure 4.1.1b

In order not to damage the wire or the lift unit as the lift moves up and down,the wire will be inserted via a hole drilled into the side of the lift shaft at the second floor.






















Figure 4.1.1c

List of materials


  1. AC to DC adapter x 1
  2. Jumper wires


  1. Packs of 80 Female to Female wire x 2
  2. Packs of 80 Male to Male wire x 2
  3. Stepper motor x 1
  4. LED Display x 3
  5. LED Colour buttons x 8

4.2  Procedures

4.2.1 Connection of Lift unit to Arduino

     First,button holes of diameter 30mm would be needed to be drilled into the side of the lift shaft and also the lift unit.This would enable the buttons to be fitted outside the shaft and inside the lift unit.These buttons will then be wired to the Arduino,which will control the lift according to which buttons are pressed.We will need 7 buttons,1 on the second floor,2 on the third floor,and 1 on the fourth floor,and 3 in the lift unit. There will also be a safety button in the lift unit to ensure safety of the user.The motor will only start after a  5 second delay,allowing the user to have time to take his hand out of the lift unit so as to prevent injury or damage.

 The Arduino will be programmed to start the motor after the safety button has been pressed and allow the motor to reach the designated floor.In order for the lift unit to reach the designated floor,the motor that is controlled by the Arduino will be programmed to coil the wire up or down a fixed number of times.These calculations have to be very precise because we have to ensure that the lift unit is not out of place.That is the main reason why we decided to purchase a stepper motor,in which one step is 1.8 degrees.This would help with the programming.


Figure 4.2.1



4.2.2 Connection of Arduino to Motor

  Another problem that we encountered was that the motor could only rotate in one direction.We had to find a solution to allow the motor to be able to rotate both clockwise and anticlockwise.The construction of the lift would be impossible if the motor could only perform one function.There would not be enough space in the shaft to place two engines.To solve this problem,we have come up with a solution on how to allow the motor to rotate both clockwise and anticlockwise.
Figure 4.2.2

This system circuit will comprise of 4 switches.We will connect each switch to 1 pin on the Arduino.The Arduino will be programmed such that when switches 1 and 3 in the diagram is closed ,the motor will turn clockwise.When switches 2 and 4 are closed,the motor will turn anti-clockwise.


4.2.3 Connection of Arduino to LED Display

   For a single digit LED display,the minimum number of pins that have to be connected to the Arduino is 9.The Arduino will be programmed to display which floor the lift unit is currently at.

4.3 Risk and Safety

4.3.1 Risk and Safety Precautions


Risk
Safety Precaution
Electrocution when handling electrical cables
Wear rubber gloves when coming in contact with wires/electric current.
If all switches are open at the same time in Figure 4.2.2,the motor might become overloaded and break down.

We have to take precaution and label the
switches of prevent the wires being connected wrongly and the  motor failing.

Too many wires inside the shaft might result in short circuits
Use heat string(a shrinkable plastic tube used to insulate wires) to cover any exposed metal parts of wires
Wires might be connected to the wrongly and due to confusion as there are too many wires
Label the wires so that confusion can be avoided


The metal tips of the jumper wires might break off
Handle the wires with care




































Arduino

5.1 Equipment
5.1.1 Finding the right materials
5.1.2 List of materials
5.2 Procedures
5.3 Risk and safety
5.3.1 Risks and safety precautions

5.1 Equipment list:

Arduino Uno x 1
Arduino Mega x 1
Mega Breadboard x 2
Annikken Andee x 1

5.2 Coding

Figure 5.2.1a

This shows a LED lighting up. This is the most basic thing when coding Arduino.

Figure 5.2.1b
shows the coding which makes the LED switch on and off.
Figure 5.2.1c
Figure 5.2.1c  shows the circuit such that when you push the pushbutton, the LED lights up.
Figure 5.2.1d
Figure 5.2.1d  shows the LED light lighting up when the pushbutton is pushed.
Figure 5.2.1e shows the program for the the actions in  
Figure 4.2.1c and Figure 4.2.1d .
We were asked to program 12 pushbuttons and 4 LEDs such as in the diagram below. He want me to program such that when PB1, 2 or 3 is pressed LED 1 lights up. When PB4, 5, 6 is pressed LED 2 lights up. When PB7, 8 or 9 is pressed LED 3 lights up. When PB10, 11 or 12 lights up, LED 4 lights up.
Figure 5.2.1f
The diagram below shows the program for the task.
Figure 5.2.1g
Figure 5.2.1h
Figure 5.2.1i
Figure 5.2.1
There are a lot of problems with the programming since there are many situations that the lift should work. If there are only exterior buttons, the program is much simpler. But since, there are interior and exterior buttons, the program must be coded in way such that when someone press the first floor, the lift should go to the first floor.
After research and help from my parents and uncle, I managed to program it. Below shows the code.
5.3 Risk and safety

5.3.1 Risks and safety precautions


Risk
Safety Precaution
There is a possibility of the person handling the parts to bleed as the end tips of the parts are sharp and scratch us.
We should wear gloves when handling Arduino or wires to prevent ourselves from getting scratched.
There is a possibility of the Arduino to break easily as it is fragile
Always handle Arduino and Arduino shields with care

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stanley yeo 杨志艺

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