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E-bike data logger compatability

Posted: Nov 06 2017 3:25pm
by MechEng
Hello everyone,

I'm a first time poster on the forum but have been digging around here for information for a while now. I thought perhaps I could put out an open question to see if anybody has experience or knowledge regarding a challenge I am facing. I am a graduate student in mechanical engineering looking into some analysis regarding e-bikes.

What I am up to: I am working with a government organization through a federal research grant to deploy several e-bikes within their commercial fleet. Within this deployment I am hoping to set up data-loggers on the e-bikes so that I can record time varying speed, motor power (voltage and amperage), as well as GPS position. THis data will be used to perform some in-depth analysis of the performance of e-bikes within a commercial fleet as well as validating an e-bike drive train model that I am building.

My knowledge so far: I know of the cycle analyst and analogger combo from Grin Technologies but my partners at the government organization have strongly pushed towards a mid-drive style e-bike (such as a bosch, shimano, etc) and I am unsure of the compatability of the analogger+Cycle analyst with that technology. I have also been investigating the Bosch Nyon computer system which apparently records lots of user data but I can't find any definitive information regarding its ability to export raw data for me to analyse for my research.

My questions as I see it: Does anyone have experience connecting a cycle analyst and analogger to a closed system such as bosch and if so are you able to share what type of data can be recorded? Does anyone know of any other e-bike capable data loggers that might be able to give me what I need (motor power, time varying speed, GPS position) such that I can export it to a PC for later analysis? Has anyone used the Bosch nyon and could share their experience or if they are able to save+export data from a trip?

Thanks for any assistance you can offer me!

Re: E-bike data logger compatability

Posted: Nov 06 2017 5:04pm
by amberwolf
CA-SA model can be used to monitor voltage and current and ah (and thus watts/wh) on anything powered via DC. If you also have the wheel speed sensor mounted on a fork or stay, then it will also monitor speed and thus wh/mile. All you have to modify on the ebike system is to install the SA shunt between the battery and the controller.

The GPS-analogger will then log this data long wiht the GPS data.

If you want to log other data like human performance, on a closed system, you might have to add separate sensors and loggers for that information. There are systems available for regular pedal bikes that do this; not sure if they are all compatible with the middrives--anything that mounts at the rear wheel should be, though.

But if all you want is the electric and GPS data, the CA-SA + GPSanalogger will do it.

Re: E-bike data logger compatability

Posted: Nov 06 2017 5:45pm
by teklektik
CA3 can be used to log data from any controller by using an external shunt. If the motor has a freewheel in the drive, then you will need a wheel pickup for speed. It also supports simple PAS wheels with any number of magnets and can be configured to support a variety of torque sensors. For a mid-drive, you can typically borrow a signal from the built-in PAS wheel but a separate one can be added if drive modification is not desirable - this will give cadence information but without torque data the Human Power cannot be calculated. The CA can be set up to monitor and log cadence and torque data even if it does not control the pedal assist capability itself. Mid-drives generally drive via the bike chain and so torque sensing is not in the cards. A commercial mid-drive that contains a torque sensor could theoretically be modified to supply a 0-5V torque signal to the CA, but that is moving away from off-the-shelf solutions.

The CA3 data stream is shown below. The CA2 data stream in similar but lacks the columns relating to PAS, throttle, and other features unique to the CA3. This stream is in tab-separated CSV format and can be logged with a phone or other serial device. The Cycle Analogger is just a serial logger and can be had in a version that also logs GPS data in separate files that match each CA record with a record of GPS data.

Contact Justin at Grin for assistance in device selection and fitment (he is a big fan of instrumented testing) :D
CA3_SerialOutput.png (79.55 KiB) Viewed 579 times

Re: E-bike data logger compatability

Posted: Nov 06 2017 6:32pm
by amberwolf
teklektik wrote:tab-separated CSV format
Wouldn't that technically be "TSV format"? ;)

Re: E-bike data logger compatability

Posted: Nov 22 2017 1:02pm
by MechEng
Sorry it's taken me a while to respond. I appreciate all of the info you guys have given me. I've gotten my hands on a CA V3 and the analogger, and am now just waiting for more funding to come in for my research project so I can get a couple of e-bikes set up. I've now got a corporate partner funding some of my research as well as the government organization. The corporate partner wants to use the bionx system and that seems relativelyl straight forward to connect to the CA. As for the government partner since their e-bikes will be deployed in a fleet I'm thinking of recommendinig a front wheel hub motor so that the rear wheel can have an internal transmission for reduced maintenance and improved ease of use for the riders.

Thanks again for all your help!