Suggestions for a new encoder

[Richard_Parsons]

Hey everyone

I am thinking about upgrading the included rotary encoder that comes with odrive. The current encoder has the following specs:

• Encoder resolution at 2400 counts per revolution
• A realistic top speed of around 5,000 RPM
• No support for an index pulse.

For me the lack of an index pulse is the issue. I believe the current firmware road map means we can look forward to index support some time soon and then integration of this into the anti-cogging feature soon after. The idea being then that the anti-cogging calibration need only be conducted once for a given mechanical setup, rather than at every power on.

So does anyone have a suggestion for alternative encoders?

So far I have seen the following mentioned both on the forums and on discord:

AMT10X Series

Cost: $24 USD
Encoder resolution: Configurable, 2048 Max
Index Pulse: Yes
Size: On shaft
Maximum Speed: Depends on configured encoder resolution, 7500 RPM at 2048 ppr and 15,000 RPM at 1024 ppr.

TRD-MX1024AD

Cost: $74 USD
Encoder resolution: 1024 ppr
Index Pulse: Yes
Size: Separate can, with a 4mm shaft
Maximum Speed: 5859rpm

Cheers,

Richard

[madcowswe]

Thanks for the recommendations.
I just ordered some inventory of the CUI AMT-102 encoders to be available along with the current no-brand Chinese one as an option when buying from the ODrive shop.

[Richard_Parsons]

Don’t thank me, thank @Bauerslab who recommended them in one of his posts!

[youngiif]

AMT10X Series

Cost: $24 USD

I’ve said this elsewhere, but arrow.com is best place I’ve found to buy these encoders. I believe they’re cheaper than digikey and they offer next day shipping free and have 10% off coupons available pretty often.

I’ve been using these encoders for a while and can’t recommend them enough.

[Richard_Parsons]

AMT-102

Thanks for the link. I would pick one up from arrow but they have no stock of the AMT102 in their Australian warehouse.

Do you mind if I ask how you mounted the encoder? Did you go for the wide base or the standard?

Cheers.

[youngiif]

Here’s a quick and dirty mount a colleague modeled/printed. It works, but there are a few tweaks he’s got in his next revision that move the mounting holes out for easier mounting.

Before that, I just used the non-ear version of the encoder base plate and it screwed onto the Turnigy motor, I just had to enlarge the plate’s holes a bit if I remember correctly.

If anyone is interested in the 3d model I can get it from him.

[Richard_Parsons]

Thanks for the photos. They gives me a much better sense of how it goes together than just looking at the data sheet. I don’t have a 3d printer myself but i’m sure others would appreciate the 3d model.

My mounting solution currently consists of angled aluminium extrusion so perhaps I can get away with drilling and tapping that directly and mounting the encoder with some standoffs.

[FCam1]

Few month ago I ordered an AMT113V, very interesting :

• 4096 PPR (programmable)
• Channels A,B,Z
• mounting kit, etc…

I had big problems with the connector because on AMT11xx models the pitch is 1.27mm.

You can buy the official wire (expensive). If you want to make your own connectors you can buy the official SAMTEC parts detailled here with the Straight Action Hand Tool (CAT-HT-203-2832-11 very expensive).

I decided to make my connectors without the clamp but with officials SAMTEC parts. I barely succeeded to weld the wires to the crimp pins and after I mont this in the connector.
Result : I have play between the connector and the slot. Currently it works but sometimes I have big noise on A,B due to the bad connection slot/connector. (Ok ok if you look right I did a mistake and I didn’t ordered exactly the good connector, maybe is the cause of the play).

My home made connector :

My assembly :

I ordered a new AMT102V that allow to have 2048 PPR, standart connector (2.54mm) and a wide base for fixation.

If you are looking for 3D models AMT provides them on their catalog.

[madcowswe]

I just ordered 200 pcs of this cable spec (please enjoy the output of the engineering CAD package “Photoshop”):

This is for the CUI AMT-102 (and I think maybe also the AMT-103). The other side is the correct pinout for the ODrive. It may be several weeks before this cable is ready. When it is, the CUI encoder option when ordering the motor from the ODrive shop will come with this cable.

I could also make an “acessories” collection in the ODrive shop and make this available separately. Who thinks this is a good idea?

• Yes offer various useful accessories (including CUI encoder cable)
• No it’s not important

[Richard_Parsons]

Here is another option: Omron E6B2CWZ6C.

Cost: ~$25 to 35 USD (resolution depending)
Encoder resolution:Fixed, but a wide range available (20 to 2500 ppr [80 to 10,000 counts per rotation)
Index Pulse: Yes
Size: 40mm dia. can
Maximum Speed: 6,000 RPM.

Note: After talking with @madcowswe about this encoder he pointed out that it has a maximum frequency response of 100kHz. This means that if you go with a high ppr encoder version then you will have a limited maximum speed. ie: 2400 RPM (100,000 Hz / 2500 ppr * 60 sec) for the 2500 ppr version. This may suit some people and not others. This is also the case for the AMT10x.

This encoder may be of interest to people who have a shaft diameter or length that is not compatible with the AMT10x series. However I would still recommend the AMT10x if it fits your setup since its resolution is configurable and its more compact.

[Richard_Parsons]

A length of L channel aluminium extrusion with the CUI encoders makes for a compact mounting option. There is just enough shaft left over to connect a shaft coupler or pulley.

[Tony_Penoyer]

Hi Richard,
I’m thinking about mounting a motor and encoder using this technique and I’m wondering how you mounted the motor to the aluminum channel? Did you use the turnigy sk3 motor mount included with each motor? Are there machine screws flush with the aluminum under the encoder?

Thank you,

Tony