Nacer ABBAS

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8 years, 8 months ago.

RC Servo

Hi, After i have modified my RC servo (HS 645MG) to continous rot, i want to command it for directions(left, right and middle ) with set in a numbr of steps, is there any proposition?

2 Answers

Steffen Wehner
8 years, 8 months ago.

Hi, there is a very good explanation to this here: https://www.arduino.cc/en/Reference/ServoWrite Overwise just try this Program

Repository: Servo_HelloWorld

It will start to accelerate the servo in one direction and than into the over. I would expect the servo to be driving one direction full speed at p = 0.0 and at p = 1.0 into the other. At p = 0.5 it should be still but I would expect you have to tune that.

thank you

posted by Nacer ABBAS 14 Apr 2016

hi, i tried this prog but that wasn't the case you described here. my servo took just one direction and didn't stop at 0.5 nor reversed sens at 1.0 !!!!!!!!

posted by Nacer ABBAS 16 Apr 2016

well it won't change direction till 2.0 ms (most likely) you modified it for continuous rotation - it's a motor not a servo anymore [I am refering to standard servo commands - I am NOT familiar with the Arduino code]

posted by Gary Z 16 Apr 2016
Gary Z
8 years, 8 months ago.

you mentioned that you modified the servo for continuous operation. That used to mean that the physical stop was taken out AS WELL AS the feedback resistor input to the drive circuitry. ' If that is the case - you won't be able to get a 'middle' position [without an external feedback of some sort - you could solder a wire from the internal feedback resistor and bring it outside the case to be hooked up to an A/D input, but there will most likely be a 'dead zone' OR use an optical encoder wheel of some sort] ' with a modified servo - it runs forward or reverse - depending on the pulse you send - 1ms for one direction, 2 ms for the opposite direction ' HTH

thanks a lot, i'd like to get explanation about your proposition, is there any link to any vidéo or some thing like this?

posted by Nacer ABBAS 14 Apr 2016

mini-sumo robot builders (google it) may have some links. You can have a white (or metal) wheel with black spokes, then use an ir-detector pair to sense the black & white regions ( or just the 'middle' point!. a disk with a hole in it could also be used for a middle point. the wire for the A/D input is a more involved process. no specific links or videos - but the mini-sumo bots have lots of info on them.

posted by Gary Z 15 Apr 2016