Joined: 16 Jun 2004
Posts: 9481
Location: Where you least expect
Gyro setups and details
Hi all, for the first time in ages i finally finished my robot before the event and have just spent the day setting it up and practicing driving i think its also worth noting some details about the gyro as they apply to robots as there isnt much info on the subject.
first thing to get out of the way is that with most gyros after power up the robot must be still for about 5 seconds will the gyro sets itself up. if you dont do this the gyro will be more or less useless.
on my GY401 there are two main settings. Limit and delay.
Limit
the limit adjustment basically dictates how much correction the gyro will apply. i believe it goes between 80% and 140%. for low speed 80% is okay but you will find at a high speed turn for example it wont apply anywhere near enough correction, so you need quite a high limit.
on cobra its set a smidge off of the max setting. if it goes into a high speed spin and you let go of the stick it will usually spin the wheels the opposite direction momentarily and come to a stop in about 45 degrees.
Delay
this is a feature for helicopters only really (i should think) its just the amount of time the gyro will wait before applying correction. funnily enough the first few events i used this gyro it was all the way down and was pretty well no help at all.
disable the delay all together for robot use unless you have a drive train with alot of backlash.
there are two toggle switches as well. one sets it for digital servo mode. personally i have it OFF but im not sure what it does or what affect it implies. perhaps it uses feedback or something.. not sure..
theres also a direction switch that sets which way correction is applied. youll work out pretty quick if its in the wrong direction
Remote gain
some gyros have an remote gain feature which allows you to set how sensitive the gyro is. when wound up all the way the gyro will "hunt" alot if you have backlash in the drive system (it will just wobble left and right trying to find the place it things is center).
so you have to find the setting where the gyro will stop the robot from a high turn rate and stop dead straight away without wiggling back and forth.
you also need it in an ivertible robot to turn the gyro off completely as it will apply correction in the wrong direction when upside down so the robot will just spin non stop.. that is bad
Connection
To connect the gyro at first was a bit of a nightmare but its easy. on the gy type there is 3 wires. one is a signal wire (just has one wire in the plug) that goes into a 3rd channel. this controls remote gain.
the second goes into the steering channel of the reciever (female plug) and the male plug connects to the speed controller input (or IMX mixer if you use one).
Setting up with victors & IMX mixer
this is a hair puller everytime wiring it up is a bit of a prick and calibrating it all More so.. so this is how its done. step by step, not to worry if you dont understand it. this is probably more for my own reference
hook up is as follows
1) steering channel from IMX1 into steering output (female connector) to gyro.
2) steering input from gyro into steering channel of reciever
3) throttle channel to throttle channel on imx1 as per normal.
4) remote gain into 3rd channel on reciever.
to calibrate
5) default your radios settings (0% trim etc)
6) with the gyro, reciever, imx1 all turned on plug the steering input from the gyro only into the steering channel.
7) adjust the trim on the radio till the LED comes on.
plug the same servo lead into the throttle channel and do the same. dont worry if you have to trim the hell out of it to get it working.
9)plug the rest in as per the wiring instructions
10) turn power on and give the robot a test drive. should drive okay..
11) hold down the calibrate button on the victors and move the throttle and steering channels to their limits
12) release.. LED will flash green if it worked.
13) do the same with the other side
now your robot should work fine in in all directions and achieve 100% power in steering and throttle function. if you dont do this then you will probably not get the most out of your robot
any other info on gyros would be good. especially stuff pertaining to positioning within the robot etc..[/b] _________________ www.demon50s.com - Minimoto parts
http://www.youtube.com/user/HyzerGlen - Videoooozzz
Wed Jan 16, 2008 5:02 pm
Nick Experienced Roboteer
Joined: 16 Jun 2004
Posts: 11802
Location: Sydney, NSW
Thanks Glen, excellent work! I was just about up to that part with Scissorhands, so its much appreciated. The digital servo switch just doubles the pulse rate; for ESCs, it doesn't seem to make any difference. _________________ Australian 2015 Featherweight champion
UK 2016 Gladiator champion
Wed Jan 16, 2008 5:34 pm
kkeerroo Experienced Roboteer
Joined: 17 Jun 2004
Posts: 1459
Location: Brisbane
The digital servo signal can actually be a bad thing for most mixers. The standard servo signal is one 1-2ms pules every 20ms (ie 50Hz) while the digital signal is on pulse every 4ms (250 Hz). I checked this on a CRO. I have 3 different off the shelf mixers and they all glitch when mixing a digital signal and a standard sig (that is one signal from the gyro and the other straight from the receiver). Since my gyro doesn't have a standard output option I have had to build a little converter circuit to get a standard output. _________________ Get Some!!!
Secretary of the Queensland Robotics Sports Club inc.
Wed Jan 16, 2008 5:46 pm
iluvmatools
Joined: 02 Jan 2008
Posts: 18
Location: blacktown syd
lol wot exactly is a gyro ?? a way of turning the bot?? or for a weapons system????
Wed Jan 16, 2008 5:54 pm
Philip Experienced Roboteer
Joined: 18 Jun 2004
Posts: 3842
Location: Queensland near Brisbane
The gyro make the robot easier to control. It looks at what you are telling the robot and what the robot is doing then applies a correction when needed.
For example, your robot might be damaged and dragging one corner. The gyro would tell the speed controller on that side to give that motor more power.
There is probably a better explanation on line somewhere. _________________ So even the rain that falls isn't actually going to fill our dams and our river systems
Wed Jan 16, 2008 8:02 pm
Glen Experienced Roboteer
Joined: 16 Jun 2004
Posts: 9481
Location: Where you least expect
i have to play with my remote gain setup as the gyro still wasnt 100% in melbourne. its always a struggle between hunting and not correcting properly (it will always not apply enough correction)
so i think im having issues between normal mode and heading lock mode.
Joined: 16 Jun 2004
Posts: 9481
Location: Where you least expect
got the gyro working in cobra offset to the side finally (chugging through the archaic setup procedure a few times with the trims offset got it working great)
i dont want to have to loose the inverted steering function or gyro remote gain, so i was wondering i could just wire the signal wire for the gain channel into the flip channel so there in parrallel with each other, so that when its upside down (when i beat it back into shape so it can ) itll turn the gyro off and flip the steering channel.
Joined: 16 Jun 2004
Posts: 11802
Location: Sydney, NSW
IT sounds plausible, worth testing at least. How did Cobra drive with the offset gyro?
Sat Jan 31, 2009 8:05 pm
Glen Experienced Roboteer
Joined: 16 Jun 2004
Posts: 9481
Location: Where you least expect
its always hard to tell because theres so much slop in the drive system but its much better then without it. and it doesnt seem to over correct to one side like it used to.
definitely put one in scissor hands though if you have any spare space. it would make all the difference in the world (youd have to go back to in bot mixing though)
Sat Jan 31, 2009 8:09 pm
Nick Experienced Roboteer
Joined: 16 Jun 2004
Posts: 11802
Location: Sydney, NSW
I am thinking more about using a gyro in the flame-thrower bot - I can mount it on-axis.
Sat Jan 31, 2009 8:39 pm
shreddy
Joined: 09 Jan 2009
Posts: 518
Location: Wantirna, Melbourne
The day I stop giving 100%, is the day I stop competing
Mon Jul 06, 2009 9:09 pm
Glen Experienced Roboteer
Joined: 16 Jun 2004
Posts: 9481
Location: Where you least expect
the gyro just goes in line with the steering channel between the radio and the sabretooth. youll have to use the sabretooths mixing. wont work if you mix in the radio.
I know SFA about gyro, but I'm looking at experimenting with one in my next version of the melty brain. I'm in need of a head locking unit, but have no idea what's good, bad or are they all the same. So far I'm just looking at hobbycity since they are cheap
Joined: 09 Jan 2009
Posts: 518
Location: Wantirna, Melbourne
hey i just ordered the mks 292 headlock gyro so wen i get that ill be sure to update you on it. it seemed like the best balance for price and options i rekon. _________________ http://au.youtube.com/user/crustydemonsully
The day I stop giving 100%, is the day I stop competing
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