How to build a prototype? And what 3D printer to use for an entry level designer?

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Building a prototype is one of the activities that being practiced by physical form designers. The process of building a prototype involve serious commitment of time, whether it is a simple product (phone casing) or a full-fledge quadcopter.

Depending on the purpose of the prototype, a designer can choose from several methods available. There exists some prototype such as ‘visual prototype’, ‘form study prototype’ or ‘proof of concept prototype’.

When focusing on designing physical objects, the most versatile method to come to the realization of the prototypes above is the 3D printing technology. One might argue that for visual and form study prototype, a low cost clay can be used. However since the visual and form study prototype are mostly can be done via computer-aided-design software. Through the use of 3D printing technology, one can instantly proof the concept of a new design could work via its physical movements and validating its use instantly.

Recommended 3D Printers.

I’d say from my experience, I would recommend Flashforge line of products. The one that I’m currently using is the FlashForge Creator. It’s inexpensive, sturdy and for this one and a half year I have been using them everyday to build my working quadrotor/tricopter vehicle without fail.

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General Tuning Advice for Arducopter

I’m going to pick some important points in terms of tuning the arducopter. At the time of writing, the current version is AC 3.1.

My two main problems with my tricopter are these two: maintaining Alt-Hold and wobbling oscillation while quickly descending.

So, here goes:

via [https://code.google.com/p/arducopter/wiki/AC2_Tweaks]

These two terms (Rate Control P, Throttle Rate P) go a long way to making your copter perform well, and are highly dependent on the thrust to weight ratio of your copter. More thrust = lower gains.

  • My copter oscillates quickly (smaller movements) when stabilized: Lower your gain in Rate Control P.
  • My copter oscillates slowly (larger movements) when stabilized: Lower your gain in Stabilize Control P.
  • My copter gets wobbly when descending quickly: Raise your gain in Rate Control P. You can tune most of this out, but it’s impossible to descend into your prop wash without some wobbles.
  • My copter is too sluggish : Raise your Stabilize Control P gain. These gains make ask the copter to respond faster to angle errors.
  • My copter yaws right or left 15° when I take off: Your Motors are not straight or your ESCs are not calibrated. Twist the motors until they are straight. Run the ESC calibration routine.
  • My copter angles back in the opposite direction I’m flying after forward flight: Raise your gain in Stabilize Control P.
  • After aggressive flying my copter leans to one side 10 – 30°: Do what ever you can to remove vibrations and isolate APM. You can even try and add a small weight to APM to keep it from vibrating. Also, just land for a few seconds, then continue flying, it will give APM a chance to correct without the vibration.
  • My copter won’t stay perfectly still in the air: Run the level command on a flat surface. (hold disarm for 15 seconds to invoke.) You can also fly in auto-trim mode in a windless (important!) environment. Any wind will cause the changes you make to work against you when the quad rotates 180°. You can use your radio pitch and roll trims, but remember to re-center them when you set up your radio with the config tools. Using the radio trims can have a negative effect in SIMPLE mode when yawing. Never Trim Yaw, Your copter may start spinning on it’s own. (Quads are also susceptible to drafts. They will need constant corrections unless you install an optical flow sensor. One day…)
  • My copter flies well, but then dips a motor arm in a fidgety manner while hovering: Your motor may be going bad or the bullets connectors between the motor and ESC may be at fault. Vibration from a bent shaft or unbalanced props can make bullet connections fail momentarily stopping the motor. A motor with bad bearings takes more power to spin. The ESC could be cutting out to protect itself. Or it maybe flying slow enough to stall the motor. Attach a current sensor between your battery and the motor and test the difference between a good motor and the bad one. If you are seeing higher draw in the bad one, replace or fix it.
  • In Loiter, my copter constantly overshoots: Try and increase your Nav_P term. You can also tune down your I terms because in some cases, the Nav_I or Loiter_I can causes overshoot. Making the Iterms 0 when in still wind is the best way to tune Nav_P.
  • My alt hold above 10 feet is only about 1-2m accurate: That’s actually the best you can achieve. The baro sensor is sensitive to light and wind. Use a felt cover to protect it from wind and make sure you don’t glue the hole and seal it up.
  • My copter increasingly swings up and down in alt hold. It eventually get’s down to the ground: Your THROTTLE_P is too high or low. You don’t need a lot of P to do alt hold. Think of how much you move the throttle to hold alt perfectly. Not much! That’s what you need P to do. I will ramp up as your battery goes lower to make up the difference.
  • I have a sonar installed but I can’t get it to work. Your sonar may be picking up electrical noise from the ESCs. Be sure to move it a few inches from any ESCs and try a shielded cable, if possible. If it’s cold outside, your sonar may stop working.
  • My quad loiters by rotating in a CW or CCW circle: Adjust your compass declination until it stops circling.

Sesi Drone Briefing Bersama Unit Korporat (CITRA) UMT

Unit Korporat UMT sedang menimbangkan untuk membeli beberapa buah quadrotor drone. Oleh yang demikian, saya dengan berbesar hati meluangkan masa bersama dengan orang-orang kuat dari Unit Korporat iaitu En. Mokhtar (photographer), En. Amirul & En. Hadi untuk memberi penerangan ringkas sebelum pembelian dijalankan. Sesi turut dihadiri oleh ahli kumpulan penyelidikan saya, En Israr & Cik Hafidah.
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Event: Fundamentals and Building of Quadrotor Drone Bersama UMT-Petrosains

Pada 3 Julai yang lepas, saya telah menyampaikan sebuah bengkel latihan yang diberi nama Fundamentals and Building of Quadrotor Drone. Event ini telah dijalankan di Universiti Malaysia Terengganu, yang mana ia dihadiri oleh jemputan dari Petrosains dan ahli-ahli kumpulan penyelidikan saya iaitu Ocean Robotics & Optimization Group.

Bengkel Latihan ini dipecahkan kepada beberapa bahagian, iaitu; pengenalan asas elektronik & robotik, pengenalan kepada konsep quadrotor drone dan amali pemasangan quadrotor drone.

Bengkel amali ini adalah yang pertama seumpamanya diadakan di Universiti Malaysia Terengganu, dan mungkin pertama di Malaysia 🙂

Setiap peserta diberikan peluang untuk menerbangkan sendiri model drone dan juga diberikan sijil penyertaan.

Ucapan terima kasih saya sampaikan kepada para peserta, iaitu; Petrosains Outreach Programmes Department Director, En Kamaruddin Kassim (KK), Cik Nurhidayah Nordin (Hani), En. Johan Shah Arif (Joe), Cik Tengku Hafidah Tengku Hussian, En. Ahmad Israr Ihsan Mainong dan Dr. Syibrah di atas penglibatan mereka di dalam bengkel latihan ini.

InsyaAllah, bengkel ini akan diperluaskan lagi mengikut demand kepada peserta-peserta bermula dari peringkat lepasan SPM, universiti dan masyarakat umum.

Legal Issue: Can we use quadrotor for filming in Malaysia?

The answer is yes, you can use quadrotor for filming in Malaysia. At the time this write up is made, there are no specific regulation that deter you from using quadrotor for filming. However if you are in the US, there are some regulation applies.

The FAA (Federal Aviation Administration, America) outlined the below quote from this article:

Hobbyists are allowed to use small, radio-controlled crafts under specific guidelines, but “if you’re using it for any sort of commercial purposes, including journalism, that’s not allowed,”

But the FAA is only responsible to the US aviation. Their regulations can only be enforced in the US. The rules regarding the legality on such application should be based on the country where the quadrotor filming is practiced e.g. South Africa, Malaysia, Thailand and so on.

The user Peter Sachs commented:

FAA spokesperson Les Dorr is 100% wrong. ​Radio-controlled model aircraft are completely unregulated (at this writing). The FAA can send all the “cease and desist” letters it wants, but it has no legal authority whatsoever to force anyone to cease or desist. In fact, (at this writing), operators of those types of craft have an unfettered right to use them for pleasure or profit.​

There exists not a single FAA regulation concerning the use of radio-controlled model aircraft, (“drones”). I challenge ​Mr. Dorr (​or anyone else from the FAA​)​ to cite a single regulation that does.

​- ​Advisory Circular 91-57 is merely a list of ​common sense ​”suggestions,” and ​is not legally enforceable.

​- ​The FAA Modernization and Reform Act of 2012 is merely a set of “​directives​”​ to the FAA to develop regulations concerning unmanned aircraft. By definition, that means none currently exist. Moreover, ​language found within ​”directives​” ​​to ​an agency​ ​are not ​themselves regulations, and are not legally enforceable.

​- ​The FAA 2007 “​Clarification” ​merely ​clarifies the FAA’s current ​”​policy​”​ concerning operations of unmanned aircraft in the National Airspace System. ​Agency “policies​”​ are not
​regulations, and are not legally enforceable.

Attorney Brendan Schulman, (who has also commented here), has argued quite correctly and eloquently on behalf of his client in the first test case regarding commercial drone use— Administrator v. Raphael Pirker, NTSB Docket CP-217.​ ​It will be interesting to see the outcome of that case given the points I’ve included above and the far more expansive arguments Attorney Schulman set forth in his motions and memoranda of law.

At the moment this writing were made, there were no regulation exists yet (please drop an update in the comment area if you are able to find any for other’s information as well). However safety, ethical and common sense applies.

  1. Don’t fly your drone in public area, but if public area were to be used, make sure you are can be easily seen so the public will be aware, or set the time when people are not in the zone
  2. Observe the local property and people when flying.
  3. Safety first. If your drone should crash, let it be. Make the public safety paramount.

Fly safely, fly responsibly and enjoy.

————————-Updates below———————–

Update: One of the commenter outlined below regarding the legal aspects of flying in Malaysia. He said (name redacted for privacy) –

DCA and JUPEM ( west Malaysia only ) have policy to control the flight of UAV or Drone in Malaysia. No matter is hobby or commercial, we need approval from them. I copy paste this term from the DCA policy : “2.2 UAVs shall not be flown without obtaining prior relevant DCA approval” This mean what we are flying now consider illegal flight. I have a meeting with DCA officially, what I can said is they just close 1 of their eye. However this doesn’t mean you wont receive saman from them. In Sarawak, DCA did give saman to flyer few months ago.

3D printing stuff: I built a working drone in 24 hours

Last week I manage to get some time off from markings, teaching classes and meetings. As a designer, I found that the more stressed I am, the more drive I got to build things.

So armed with a caliper and an old ProEngineer CAD software, I manage to design from scratch a simple quadcopter frame. It is basically consist of a centerbase (I printed it twice), and an arm (I printed it 4 times).

You can download the the STL files here:

Scidrones 3D Printed Quad

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Pic above: the built drone, fresh from the 3D printer

The motivation comes from my DJI F330 frame that broke due to a crash last few months ago as shown below. So I was thinking, well this is a good reason to custom-design my own simple frame. If it crash and broken, I’ll just print it again. So it makes the downtime shorter.

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Pic above: My broken quad

So once my frame were printed, which took about 6 hours to complete (ABS material, 50% infill, on a FlashForge Replicator printer), I installed the control board (APM 2.5), the 20 amp electronic speed control (ESC), a 2200mah battery, four Gemfan 8×4.5 SF prop and four brushlesh motor (Prodrive 1200kV) on the frame.

It took me another half an hour to upload the PIDs, checking the balance, trimming the cable-ties and whatnot before I test-fly it in my office.

And it fly great! No wobblings, very light and fairly strong!

Some flyers concern about the motors being hot due to enclosure, but this is a tough decision that I have to make. In my defense,
1. I’ve tested the hover to the maximum battery-time capacity of 7 minutes and the motors only heated up to 63 celcius and the 7-minute ride is more than enough to cover UMT’s shoreline at the altitude of 600 metres.
2. The battery and esc’s are cool and happy!

Now the to-do’s!
1. Design and build a simple camera-gimbal to stabilize my GoPro camera.
2. Design and build a water- and sand-resistant enclosure for the motor and electronics.

Next up, if I’m not in the office, I’m probably at the UMT coastal line to run aerial coastal monitoring. See you there!