# AOG without wheel angle sensor

**URL:** <https://discourse.agopengps.com/t/aog-without-wheel-angle-sensor/2929>\
**Category:** Autosteer\
**Created:** [4 October 2020 19:20 UTC](https://discourse.agopengps.com/t/aog-without-wheel-angle-sensor/2929 "2020-10-04T19:20:15Z")\
**Posts on this page:** 20\
**Page:** 15

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**Author:** ![Gianfranco](https://discourse.agopengps.com/letter_avatar_proxy/v4/letter/g/4af34b/32.png) [@Gianfranco](https://discourse.agopengps.com/u/Gianfranco)\
**Post date:** [2 January 2023 22:21 UTC](https://discourse.agopengps.com/t/aog-without-wheel-angle-sensor/2929/284 "2023-01-02T22:21:27Z")

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Have you considered orbitrol drift? It seems not to me looking at py code.

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**Author:** ![TomStein](https://discourse.agopengps.com/user_avatar/discourse.agopengps.com/tomstein/32/7833_2.png) [@TomStein](https://discourse.agopengps.com/u/TomStein)\
**Post date:** [2 January 2023 23:04 UTC](https://discourse.agopengps.com/t/aog-without-wheel-angle-sensor/2929/285 "2023-01-02T23:04:08Z")

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Not yet. This is something I will work on next. I want to go outside and have a test run first.  
I want to try out the ideas mentioned in this thread (e.g. zero point tracking using IMU, endpoint detection by resistance/amp measurement…).

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**Author:** ![Alan.Webb](https://discourse.agopengps.com/user_avatar/discourse.agopengps.com/alan.webb/32/11835_2.png) [@Alan.Webb](https://discourse.agopengps.com/u/Alan.Webb)\
**Post date:** [3 January 2023 00:19 UTC](https://discourse.agopengps.com/t/aog-without-wheel-angle-sensor/2929/286 "2023-01-03T00:19:25Z")

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Orbitol drift can be considerable and rather unpredictable. An encoder will need to be referenced to something pretty regularly to be reliable. On my old 716 this would need to be several times a minute as it drifts, especially when cold.

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**Author:** ![Munkhtamir](https://discourse.agopengps.com/letter_avatar_proxy/v4/letter/m/5f9b8f/32.png) [@Munkhtamir](https://discourse.agopengps.com/u/Munkhtamir)\
**Post date:** [3 January 2023 00:45 UTC](https://discourse.agopengps.com/t/aog-without-wheel-angle-sensor/2929/287 "2023-01-03T00:45:24Z")

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@TomStein Is it an absolute encoder or incremental encoder?

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**Author:** ![TomStein](https://discourse.agopengps.com/user_avatar/discourse.agopengps.com/tomstein/32/7833_2.png) [@TomStein](https://discourse.agopengps.com/u/TomStein)\
**Post date:** [3 January 2023 03:48 UTC](https://discourse.agopengps.com/t/aog-without-wheel-angle-sensor/2929/288 "2023-01-03T03:48:57Z")

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Good to know that. I will see if this is the case with the system I want to test on too. In that case, centering by IMU several times a minute might be challenging because of noise and the shaking cabin.

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**Author:** ![TomStein](https://discourse.agopengps.com/user_avatar/discourse.agopengps.com/tomstein/32/7833_2.png) [@TomStein](https://discourse.agopengps.com/u/TomStein)\
**Post date:** [3 January 2023 03:59 UTC](https://discourse.agopengps.com/t/aog-without-wheel-angle-sensor/2929/289 "2023-01-03T03:59:52Z")

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It is this HTK22 optical rotary encoder from Phidgets, which I am using: [Optical Rotary Encoder HKT22 - 3531\_0 at Phidgets](https://www.phidgets.com/?tier=3&catid=103&pcid=83&prodid=404)  
The [datasheet](https://www.phidgets.com/productfiles/3531/3531_0/Documentation/3531_0_Datasheet.pdf) doesn’t state directly if it is absolute or incremental. But from my understanding, I am pretty sure it’s incremental because of the price, connector and protocol. May I ask why you are interested in this?

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**Author:** ![Munkhtamir](https://discourse.agopengps.com/letter_avatar_proxy/v4/letter/m/5f9b8f/32.png) [@Munkhtamir](https://discourse.agopengps.com/u/Munkhtamir)\
**Post date:** [3 January 2023 07:00 UTC](https://discourse.agopengps.com/t/aog-without-wheel-angle-sensor/2929/290 "2023-01-03T07:00:34Z")

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Yes, I too didn’t find out whether it is absolute or incremental (I guess you made a home test already). If it was an absolute encoder, this method will be easily solved.

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**Author:** ![Gianfranco](https://discourse.agopengps.com/letter_avatar_proxy/v4/letter/g/4af34b/32.png) [@Gianfranco](https://discourse.agopengps.com/u/Gianfranco)\
**Post date:** [3 January 2023 07:58 UTC](https://discourse.agopengps.com/t/aog-without-wheel-angle-sensor/2929/291 "2023-01-03T07:58:52Z")

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HKT22 is clearly an incremental encoder and anyway Phidget Motor Control cant handle an absolute encoder.

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**Author:** ![BrianTee\_Admin](https://discourse.agopengps.com/user_avatar/discourse.agopengps.com/briantee_admin/32/7_2.png) [@BrianTee\_Admin](https://discourse.agopengps.com/u/BrianTee_Admin)\
**Post date:** [3 January 2023 15:03 UTC](https://discourse.agopengps.com/t/aog-without-wheel-angle-sensor/2929/292 "2023-01-03T15:03:52Z")

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Like a WAS perhaps on the kingpin… Then you would know the exact steering angle all the time 🙂

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**Author:** ![Alan.Webb](https://discourse.agopengps.com/user_avatar/discourse.agopengps.com/alan.webb/32/11835_2.png) [@Alan.Webb](https://discourse.agopengps.com/u/Alan.Webb)\
**Post date:** [3 January 2023 17:38 UTC](https://discourse.agopengps.com/t/aog-without-wheel-angle-sensor/2929/293 "2023-01-03T17:38:46Z")

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To me, a steer wheel (or motor) encoder coupled with a purely hydraulic steer is just adding massive vagueness to a fairly feedback critical system for little benefit. Orbitals are not consistent. The point of the WAS less thing to me was the total lack of a sensor, and more so the benefits of angular velocity over steer angle.

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**Author:** ![PotatoFarmer](https://discourse.agopengps.com/user_avatar/discourse.agopengps.com/potatofarmer/32/11865_2.png) [@PotatoFarmer](https://discourse.agopengps.com/u/PotatoFarmer)\
**Post date:** [3 January 2023 19:04 UTC](https://discourse.agopengps.com/t/aog-without-wheel-angle-sensor/2929/294 "2023-01-03T19:04:01Z")

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> [@Alan.Webb](#):
>
> Orbitals are not consistent.

Yup the Deere in the centre keeps going round and round, new random spot all the time.

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**Author:** ![BrianTee\_Admin](https://discourse.agopengps.com/user_avatar/discourse.agopengps.com/briantee_admin/32/7_2.png) [@BrianTee\_Admin](https://discourse.agopengps.com/u/BrianTee_Admin)\
**Post date:** [4 January 2023 05:31 UTC](https://discourse.agopengps.com/t/aog-without-wheel-angle-sensor/2929/295 "2023-01-04T05:31:33Z")

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One of the things lacking is a solid angular velocity. I think with the new use of the bno085 in uart-rvc at 100 hz may overcome that deficiency.

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**Author:** ![TomStein](https://discourse.agopengps.com/user_avatar/discourse.agopengps.com/tomstein/32/7833_2.png) [@TomStein](https://discourse.agopengps.com/u/TomStein)\
**Post date:** [4 January 2023 22:25 UTC](https://discourse.agopengps.com/t/aog-without-wheel-angle-sensor/2929/296 "2023-01-04T22:25:18Z")

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As the orbital drift seems to be a really big issue, I will get a Honeywell RTY090LVEAX WAS to have a good reference value. This can then also be used to capture quantitative data on how well the encoder solution is working.

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**Author:** ![Alan.Webb](https://discourse.agopengps.com/user_avatar/discourse.agopengps.com/alan.webb/32/11835_2.png) [@Alan.Webb](https://discourse.agopengps.com/u/Alan.Webb)\
**Post date:** [5 January 2023 13:15 UTC](https://discourse.agopengps.com/t/aog-without-wheel-angle-sensor/2929/297 "2023-01-05T13:15:08Z")

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It will be drifting and it won’t be consistent. Beyond that I can’t see the encoder being overly useful.

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<div class="post-metadata">

**Author:** ![Alan.Webb](https://discourse.agopengps.com/user_avatar/discourse.agopengps.com/alan.webb/32/11835_2.png) [@Alan.Webb](https://discourse.agopengps.com/u/Alan.Webb)\
**Post date:** [5 January 2023 13:17 UTC](https://discourse.agopengps.com/t/aog-without-wheel-angle-sensor/2929/298 "2023-01-05T13:17:05Z")

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I agree. This neatly bypasses all the side draft, slip and WAS zeroing issues.

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**Author:** ![Erik](https://discourse.agopengps.com/letter_avatar_proxy/v4/letter/e/b5ac83/32.png) [@Erik](https://discourse.agopengps.com/u/Erik)\
**Post date:** [5 March 2024 00:52 UTC](https://discourse.agopengps.com/t/aog-without-wheel-angle-sensor/2929/299 "2024-03-05T00:52:12Z")

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@BrianTee_Admin Could we copyright strike [Farmtek.fr](http://Farmtek.fr)? Farmtek developed a WASless compatible version of AOG including automatic calibration.

AOG is licensed under GNU GPL which states: Any modifications to or software including GPL-licensed code must also be made available under the GPL along with build & install instructions.

The goal of the copyright strike would not be to bring down this company, but to force it to upstream the code to AOG so we can enjoy it as well.

[![](https://discourse.agopengps.com/uploads/default/original/3X/6/c/6cbd11b15ff5c7a4e51c0db23f6cb963b7c80abf.jpeg "AUTOGUIDAGE RTK 3990€ www.farmtek.fr") ](https://www.youtube.com/watch?v=EGj3ibvf8EA)

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**Author:** ![nikolaos](https://discourse.agopengps.com/letter_avatar_proxy/v4/letter/n/d6d6ee/32.png) [@nikolaos](https://discourse.agopengps.com/u/nikolaos)\
**Post date:** [30 March 2024 19:32 UTC](https://discourse.agopengps.com/t/aog-without-wheel-angle-sensor/2929/300 "2024-03-30T19:32:31Z")

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I have not a working-install system of AOG yet, but isn’ t possible to use an absolute encoder with multiturn possibilities and remember the location? I think that will use continuous power supply to the sensor in order to keep track of the position of the steering wheel (low power with sleep mode). I will check soon a solution for this.

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**Author:** ![Davidwedel](https://discourse.agopengps.com/letter_avatar_proxy/v4/letter/d/e9a140/32.png) [@Davidwedel](https://discourse.agopengps.com/u/Davidwedel)\
**Post date:** [30 March 2024 20:17 UTC](https://discourse.agopengps.com/t/aog-without-wheel-angle-sensor/2929/301 "2024-03-30T20:17:21Z")

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That would theoretically work if your steering wheel is always in the same position when the wheels are forward (like a car). I know the farm equipment that I run the wheels and the steering wheel relative position change continually.

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**Author:** ![nikolaos](https://discourse.agopengps.com/letter_avatar_proxy/v4/letter/n/d6d6ee/32.png) [@nikolaos](https://discourse.agopengps.com/u/nikolaos)\
**Post date:** [31 March 2024 02:55 UTC](https://discourse.agopengps.com/t/aog-without-wheel-angle-sensor/2929/302 "2024-03-31T02:55:51Z")

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Thank you for this info. I do not have that knowledge.

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**Author:** ![m\_elias](https://discourse.agopengps.com/letter_avatar_proxy/v4/letter/m/94ad74/32.png) [@m\_elias](https://discourse.agopengps.com/u/m_elias)\
**Post date:** [31 March 2024 03:12 UTC](https://discourse.agopengps.com/t/aog-without-wheel-angle-sensor/2929/303 "2024-03-31T03:12:09Z")

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There’s always some hydraulic slippage

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