Encoder Vs Potentiometer

Has anyone tried an encoder on the end of the phidget Dc motor instead of using a WAS? I’m not sure if I understand the concept all that well, but couldn’t we potentially use a 16-bit encoder which would eliminate the need for a WAS and ADS ?? Also not sure if the Arduino code would need to be altered since it is already setup to receive a 16 bit digital input from the ADS. Just a thought…

Trouble with using an encoder at the steering wheel is that AGopengps needs to know where straight ahead is.
If you could engage the motor at the straight ahead point every time, it would probably kind of work.

Another problem is slipping in the power steering system and motor to steering wheel.

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Very True never really thought of that I’m hoping to use a gear driven setup rather than a rubber wheel…Has anyone come up with a solution to do away with WAS ? Do the commercial systems use Steering Sensors ?

Quite a few folks have done the gear driven set up. Some have also put encoders on their steering columns. The problem is that we still need to know when the wheels are pointing straight ahead. Most commercial systems JD, CNH etc. use a Wheel Angle Sensor.

Thanks for the info! Looks like I will have to quit being lazy and mount a WAS !!!


…and to complicate matters, orbital steering units can and do creep so there is no direct correlation between wheel angle and stering wheel position.

Very Understandable…So can someone explain in simple terms what Heading would be used for then such as an IMU or Dual antenna setup…This doesn’t eliminate the need for a WAS correct ? Basically I’m taking it as Heading is just a more precise way of driving in a straight line and can be used if GPS signal is lost momentarily?

Heading is used in the algorithms that steer the tractor along the line. Information of heading supplements the position and steer angle which are essential. I don’t know if it compensates if GPS signal is lost, but that must never be the case. Heading is important for example when there’s some slide of the wheels on a hill. Probably all systems with a steering axle use a WAS, it’s easy to measure steer angle correctly and continuously.

Heading is used to help compute where you need to go from where you are (course error). Steering angle sensor is needed to have a closed feedback loop controlling the steering hydraulics. In other words if your heading is to the left of where you really want to go, you need to steer to the right. The question is, how much steering? It might need just a little correction, which can be done with a small input to the steering. Without the WAS, AOG has no idea how much steering to command. Stable course following would be impossible. Also there’s the issue of knowing where straight is.

I’ve seen servo systems work without a steering angle sensor. But they are making guesses based on how much the steering wheel has moved. They can learn where the neutral position is, but there’s always going to be some oscillation and error without a WAS.

I would hazard a guess that any and all autosteers that work directly with the hydraulic block require a WAS.

Talking about dual receivers brings up an interesting question. With a single receiver, the heading is based on what direction the tractor is actually moving. with two receivers, it’s now a very accurate direction that the tractor is facing. That can be very different. If the implement is side drafting quite heavily, causing the tractor to slide (say in the mud), how will the auto steer react? The heading could be quite wrong.


We work on some quite steep ground and regularly have to drive off the mark to maintain implement position. Your dual antenna point is interesting.