Friday, August 15, 2014

Building a Quadcopter Part 3



Previous post HERE





 We continue on development on the main frame of the quadcopter. The center frame will house some essential parts such as the control board, battery and the radio receiver.

The sketch above shows the placement of the Control Board and Battery which are placed center of the design. The board has an inboard gyroscope (tilt,shift,yaw) sensor which will help balanced the quadcopter by managing each individual motor. The battery is the heaviest component, so it will be better placed securely on the center of the body for optimum center of gravity,




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Above shows the CAD development on the quad's body, there are 6 points of contact to keep the battery sung inside. There are 4 pole extrudes for the Control board to be bolted on to. Make sure that the placements directions that are stated on the control board manual are follow, this particular one has its axis facing on the edges of the board thus having one point of the board face an arm.















After settling all the CAD data, we proceed to create a printed prototype for the proof of concept. Above shows the 3D printed parts that work flawlessly given a few tweaks on fitting tolerance.

Above shows a fully assembled quadcopter without blades

 Fully assembled and ready for test flight

Monday, August 4, 2014

Building a Quadcopter Part 2

Previous Post HERE



Designing the Arms 

A quad copter has 4 extended arms (logically). they all are connected to the main frame that houses the computing board and battery. Design a way to assemble the arm to the main body that would be sturdy and fixed in a axle while remaining easily detachable.

Our approach is to design an arm that is 180mm long point to point, with one end for the motor to be mounted on and the other end for the arm to mount onto the main body. The arm is attached via cylindrical mount joint that stays in position by a fix lock extrude. It will be sandwiched by two top and bottom bodies as shown on the concept sketch below.


Concept Sketch



The Three Variation


The above 3 design variation are to be compared together to see if the designs would be sturdy enough to withhold a 10N thrust force while  maintaining to be a light weight .

The Yellow design has a Tapered outward form that is biased to the motor mount. it has  triangle truss like pattern, with a leg stand on the bottom.

The Blue design has a honeycomb pattern for structural rigidity. its has a simple straight frame and needs a leg mount assembly.

The Red design has a very minimalistic approach mass wise, with a triangle truss pattern to withstand side impact. 


Simulation Analysis  

To make sure all the above designs are able to withstand real world conditions. All design will be manufactured using ABS plastic.


The bottom table shows the physical properti value of ABS. ABS has a tensile strength of 30 N/mm^2.   We can theoretically assume  that the yield strength of ABS is 24 N/mm^2(base on 80% tensile strength).  For our parts to pass, the parts cannot exceed a stress force of  24N/mm^2.


Using Solidworks Simulation workbench, we can select a fix geometrical point for the structure to remain a constant. In this case we've selected the inside and outside wall of the cylinder mount as our gemological fixtures as shown below.
We can apply force on the area where the motor is mounted. Select the face and direction of force, in this case a maximum load of 10 N to emulated maximum possible thrust force on each arm.



The Result

 
Yellow Mass = 44.5g 
Stress result = 20.5 N/mm^2


  Blue Mass = 43.5g 
Stress result = 14 N/mm^2
                                                                        
Red Mass = 26g
Stress result = 21.5 N/mm^2



All the result shows that the designs have pass the yield strength stress allowance of 24 N/mm^2

Base on the simulation results and looking at the total mass of the designs,  We've choose to go forward with the Red arm design, it has less then twice the mass then the rest thus we will be saving on weight and material cost.


We finish of the arm design with a stand assembly part so the quadcopter can take of and land on different terrain surfaces.



End of Part 2




Friday, August 1, 2014

Electrical Symbol Library



My fellow Electrical engineers, what is your current practice on doing your electrical schematic drawing? Are you still using the traditional way: drawing line by line?

Working in the CAD field, I’m impressed how easy it’s making our lives – we only need to draw the symbols once, and then save them into our own library so that we can reuse them. 

Few questions that I get asked a lot:  Where should the library being located?  How to manage and organize the symbols? How easy can you search for the symbols that you want to use? 

I normally categorize them into folders, and use a standard naming convention – this significantly reduces the time taken to search for the symbol. 

SolidWorks Electrical helps me complete my job much more effectively. There is a symbol library that has been pre-installed with the software, and by clicking on the “Insert Symbol, I can easily browse through the symbols library to choose the right one.  




I normally categorise the symbols based on their classifications. If that’s not fast enough for you, you can also use the filter that allows you to search for the symbols by their description. 



I’m so glad I could use this for my Schematic design – it made me much more productive and efficient! 

Electrical Workshop
If you would like to find out more about SolidWorks ElectricalRegister now to attend the 7th Aug class - seats are limited! 

To request for a trial, feel free to email marketing@cadcam.com.my