LeafLabs Garden » Topic: Interfacing with ESC's

LeafLabs Garden » Topic: Interfacing with ESC's http://forums.leaflabs.com/topic.php?id=1804 A place to share, learn, and grow... en-US Fri, 22 Jan 2016 00:19:22 +0000 http://bbpress.org/?v=1.0.2 <![CDATA[Search]]> q http://forums.leaflabs.com/search.php xchg.ca on "Interfacing with ESC's" http://forums.leaflabs.com/topic.php?id=1804#post-22152 Mon, 28 Jan 2013 23:15:31 +0000 xchg.ca 22152@http://forums.leaflabs.com/ <blockquote>I have done the above method before for several speed controllers</blockquote> Crenn, can you share some code which illustrates how to control ESC specifically on Maple (STM32) ? Thank you. Schillie on "Interfacing with ESC's" http://forums.leaflabs.com/topic.php?id=1804#post-11010 Thu, 31 May 2012 20:07:40 +0000 Schillie 11010@http://forums.leaflabs.com/ I believe I've collected a good list of parts, the motor I now plan on using is: NTM Prop Drive series 28 <a href="http://www.hobbyking.com/hobbyking/store/__17345__NTM_Prop_Drive_Series_28_26A_1200kv_250w.html" rel="nofollow">http://www.hobbyking.com/hobbyking/store/__17345__NTM_Prop_Drive_Series_28_26A_1200kv_250w.html</a> along with 9x4.7 GemFans <a href="http://www.innov8tivedesigns.com/product_info.php?cPath=46_132&products_id=975&osCsid=8e43faedf9e47719bb0eb6d513793787" rel="nofollow">http://www.innov8tivedesigns.com/product_info.php?cPath=46_132&products_id=975&osCsid=8e43faedf9e47719bb0eb6d513793787</a> I've only looked into the low-end ESC solution, namely: HobbyKing Red Brick 30A ESC <a href="http://www.hobbyking.com/hobbyking/store/__18004__HobbyKing_Red_Brick_30A_ESC.html#" rel="nofollow">http://www.hobbyking.com/hobbyking/store/__18004__HobbyKing_Red_Brick_30A_ESC.html#</a> The motor and the fans were both approved by the creator of the frame, so i feel set on those. However, the main issue is still the ESC. I feel like getting a basic, reliable one like I have listed above would be a good route, but i can see where greater update rates would help things out quite a bit. Has anyone used a ~200-400Hz ESC that they would recommend for this type of situation (ie, controlling it with a Maple)? Thanks! gbulmer on "Interfacing with ESC's" http://forums.leaflabs.com/topic.php?id=1804#post-11003 Thu, 31 May 2012 13:05:04 +0000 gbulmer 11003@http://forums.leaflabs.com/ My ESC guru tells me that many off-the-shelf brushless DC motor ESCs 'largely ignore the frame rate', 'mostly use the pulse width', and 'will run up to almost 400Hz'. I have no doubt that someone who understands the control problem could make a quadcopter with a 50Hz control rate, but ... A brushless DC motor could make more the a rev in 1/50th of a second, so there were several instants when motor speed could be adjusted. To put it in context, an object would free-fall about 2mm, and a powerful quadcopter could climb 10mm or more. Run at almost 400Hz and the free-fall is 1/64th that, and their are many more signals to control motor speed. I'd try to make it easier for myself by having an ESC that could run at several hundred Hz. crenn on "Interfacing with ESC's" http://forums.leaflabs.com/topic.php?id=1804#post-10935 Mon, 28 May 2012 08:42:52 +0000 crenn 10935@http://forums.leaflabs.com/ I disagree, while you can only update it at 50Hz, you can program to ensure the stability is available. In fact, a few hobby quadcopter controllers use off the shelf Hobby ESCs. blackswords on "Interfacing with ESC's" http://forums.leaflabs.com/topic.php?id=1804#post-10925 Mon, 28 May 2012 02:33:39 +0000 blackswords 10925@http://forums.leaflabs.com/ if you want to make a quad, you need special ESC. Standard ESCs accept a new command every 20ms (like servos) so 50 times per second but for stabilizing your quad, you need to update the outputs at least 200 times per second. So you have different possibilities. If you have some money, you can buy the ESCs from microkopter, they are especially made for this application. You can also seach for RapidESC and TuboPWM on google, you will find some interesting things. (I flashed some ESCs with the RapidESC firmware and it works fine) crenn on "Interfacing with ESC's" http://forums.leaflabs.com/topic.php?id=1804#post-10922 Sun, 27 May 2012 20:56:33 +0000 crenn 10922@http://forums.leaflabs.com/ It's not so much a motor/esc recommendation but a motor/esc/propeller recommendation that you want. They recommend 2 prop sizes, and some motors, so take a look at that. It's possibly a good idea to look into a program called MotoCalc to calculate the draw of the motor versus the thrust of it. You want to balance the weight of the quad with the thrust produced, it's not going to be very good if you need to have all the engines at full to get off the ground and for it to only last a short time. Look at a getting the props at full thrust to be doing 2-3 times the weight of the quad if you can. This way the engines will not be working hard and it will also help with moving around rapidly. As for ESCs, just go for one of the hobby king ESCs which aren't card programmable. That should allow for easy interfacing. Schillie on "Interfacing with ESC's" http://forums.leaflabs.com/topic.php?id=1804#post-10915 Sun, 27 May 2012 17:31:27 +0000 Schillie 10915@http://forums.leaflabs.com/ Im planning on putting together a quadcopter using the following frame: <a href="http://www.hoverthings.com/frame-sets/ht450bk.html" rel="nofollow">http://www.hoverthings.com/frame-sets/ht450bk.html</a>. It lists a recommended motor in the 750-1050kv range; i put the motor above within the post as an example. If you had a motor + esc recommendation, that would be great. blackswords on "Interfacing with ESC's" http://forums.leaflabs.com/topic.php?id=1804#post-10909 Sun, 27 May 2012 14:41:59 +0000 blackswords 10909@http://forums.leaflabs.com/ What is the application for this motor? It's a good start to choose the right ESC. Schillie on "Interfacing with ESC's" http://forums.leaflabs.com/topic.php?id=1804#post-10908 Sun, 27 May 2012 14:32:42 +0000 Schillie 10908@http://forums.leaflabs.com/ Thanks for the responses! Since I'm doing this project on the side, I don't think I'll have the time required to build a custom brush-less controller from scratch (however, it definitely will be something to keep in mind as another project to pursue, so thanks for the links). That being said, I think I'll go with buying a market ESC. Has anyone found a good "bare-bones" ESC for controlling ~20A motors that works reliably but doesn't include all the various RF communication features? Thanks for the arming tips crenn, I'll probably go that route as well; using I2C sounds like a bit too much work for me at the moment. Thanks again! crenn on "Interfacing with ESC's" http://forums.leaflabs.com/topic.php?id=1804#post-10898 Sat, 26 May 2012 22:22:08 +0000 crenn 10898@http://forums.leaflabs.com/ For that speed controller, set the period of the timer to be 20-22ms, and the channel values should be between 1.0ms-2.0ms. If the controller doesn't like that, look at using a values between 1.25ms and 1.75ms. Usually for ESCs you need to start at a value other than your lowest point, stay there for about 500ms and then set the signal to have the lowest value (so either 1.0ms or 1.25ms depending on the speed controller) for about 1-2 seconds to allow the speed controller to 'arm'. I have done the above method before for several speed controllers (unfortunately, I don't have any speed controllers and motors that aren't in aircraft, so I can't give you a demonstration via youtube) and it's worked well. There is also another method for controlling the ESCs, but it requires a bit of work to do. Usually you need to rewire the internals of the speed controller (cutting traces and also removing the BEC) to free up the TWI/I2C interface pins on the microcontroller (majority of the speed controllers are based around the Atmel ATMEGA8 or ATMEGA88, there are a few other non-atmel microcontroller based ones floating around) to allow you to interface with the ESC via I2C. I personally haven't done the conversions myself, however the person I was working with on my final year project did the conversions (and only broke 2 pins out of about 10 speed controllers, it's quite fiddly work) which allowed us to communicate 'faster' with the speed controllers (we had some other problems which I believe was the speed controllers crashing the I2C interface by holding it low. The problem was never verified.) with either an Arduino or a Maple/Maple Mini. We also used level converters with the speed controllers to protect the Maple/Maple Mini from the higher voltages on the I2C bus. As for which ones you can use, I'd recommend searching around the rcgroups forum for conversion threads, but here are a couple: The TowerPro 25A ESC (HobbyKing no longer sells these last I checked) <a href="http://www.rcgroups.com/forums/showthread.php?t=766589" rel="nofollow">http://www.rcgroups.com/forums/showthread.php?t=766589</a> <a href="http://ng.uavp.ch/moin/Documentation/HOWTO/BL-Ctrl/HK-TypeH-rev1.1" rel="nofollow">http://ng.uavp.ch/moin/Documentation/HOWTO/BL-Ctrl/HK-TypeH-rev1.1</a> <a href="http://www.mikrokopter.de/ucwiki/en/TowerPro25A2Regler" rel="nofollow">http://www.mikrokopter.de/ucwiki/en/TowerPro25A2Regler</a> The HobbyKing BlueSeries 30A ESC <a href="http://www.hobbyking.com/hobbyking/store/uh_viewitem.asp?idproduct=13429" rel="nofollow">http://www.hobbyking.com/hobbyking/store/uh_viewitem.asp?idproduct=13429</a> <a href="http://www.rcgroups.com/forums/showthread.php?t=1401408" rel="nofollow">http://www.rcgroups.com/forums/showthread.php?t=1401408</a> Those should get you started. gbulmer on "Interfacing with ESC's" http://forums.leaflabs.com/topic.php?id=1804#post-10894 Sat, 26 May 2012 19:13:16 +0000 gbulmer 10894@http://forums.leaflabs.com/ you might get some inspiration from: <a href="http://www.robotpower.com/products/osmc_info.html" rel="nofollow">http://www.robotpower.com/products/osmc_info.html</a> That is a 160A design. Toshiba do quite a lot of motor control, and have specific Cortex-M3 parts for motor control: <a href="http://www.toshiba-components.com/microcontroller/TMPM370.html" rel="nofollow">http://www.toshiba-components.com/microcontroller/TMPM370.html</a> so they may have some application notes (I thought I saw an application note a few weeks ago, but can't see it now) How smart do you need it? How small do you need it? How cheap do you need it? How much time and effort can you afford? Do you have test equipment (oscilloscope, storage scope)? You should be able to measure the motor-current using a high-side current shunt, so you can have feedback from the motor without external (e.g. Hall) sensors. blackswords on "Interfacing with ESC's" http://forums.leaflabs.com/topic.php?id=1804#post-10892 Sat, 26 May 2012 13:19:00 +0000 blackswords 10892@http://forums.leaflabs.com/ It's quite complicated to build such ESCs, especially the sensorless ones. The code is complicate for having good results. I'm not saying that's impossible, I saw some realizations on the web but none with Maple or an STM32. Most of them are written in assembly because they use small MCU but still need some performance. If you can find anything helpful, post it, I am very interested in that subject too Schillie on "Interfacing with ESC's" http://forums.leaflabs.com/topic.php?id=1804#post-10891 Sat, 26 May 2012 11:18:32 +0000 Schillie 10891@http://forums.leaflabs.com/ I need to control motors: <a href="http://www.hobbyking.com/hobbyking/store/uh_viewitem.asp?idproduct=2105&aff=588847" rel="nofollow">http://www.hobbyking.com/hobbyking/store/uh_viewitem.asp?idproduct=2105&aff=588847</a> KD A22-15M Brushless Outrunner Motor Kv (rpm/v) 1050 Max Current (A) 20 Max Voltage (V) 11 using my Maple for a project I'm currently working on. Most of the RC community uses ESCs such as the following: <a href="http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=4312" rel="nofollow">http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=4312</a> TURNIGY Plush 18amp Speed Controller Cont Current: 18A Burst Current: 22A BEC Mode: Linear BEC : 5v / 2A Lipo Cells: 2-4 however, these units are built to be used with a standard RF controller and have a number of built in features that I don't need (since I can easily implement them using the Maple). They are also (from what I've heard) a bit finniky to control via a micro controller. Sadly, I cannot find a solution for controlling ~20A motors that doesn't involve one of these ESCs. I was curious if anyone had done this before/has any ideas? Thanks