Bosch Drivetrain - 1000 measurements PER second???

[Howard A]

I'm researching e bikes and discovered a claim from Bosch that their Activeline drivetrain has 3 sensors that conduct 1000 measurements per second.
What exactly are they measuring?

As far as I know there are really only 2 primary inputs into a typical bicycle drivetrain and those are torque on the crank arms and cadence.

I'm wondering what the other 998 are.

I'm sure I'm missing something, but on the surface this is a confusing claim.

Feedback and thoughts appreciated.

Thanks in advance, still learning!

Howard A.

 

[Ravi Kempaiah]

Admins: @Angela M. and @mitchhackleman

Could we please move this post to the Bosch forum?

@Howard A

The sensors in the motor are not measuring 1000 different parameters but they are measuring 3 different parameters (see below) 1000 times per second. It is like the microprocessor is taking 1000 pulses of these parameters every second and adjusting the power delivery quite quickly to respond to those changes observed in 1000 measurements.

1. Torque on pedal spindle
2. Cadence of crank arms
3. Speed of the bike as measured by the spoke-sensor

Hope this helps.

 

[Howard A]

Great help Angela, thanks!

 

[webcurl]

1. Torque on pedal spindle
2. Cadence of crank arms
3. Speed of the bike as measured by the spoke-sensor

And probably along with those 3 sensors being sampled at 1khz (1000 cycles per second) would be:
Power delivery to Motor (Volts & Amps) - which it already knows but would come into the calculations - to know how much extra/less power to apply to the motor going forward and also for shift detection calculations.
Also battery level readings (maybe less than 1khz) - for Range calculations & determining whether to shut the motor off or not (flat battery).
Maybe (guessing) an accelerometer for walk mode & other calculations.

 

[Ravi Kempaiah]

probably along with those 3 sensors being sampled at 1khz (1000 cycles per second) would be:

Do you know of any publicly available links that talk about sampling frequency in these sensors?
I can't find a single document from Bosch or Yamaha or Shimano or Bafang that talks about this in technicality.

Specifically,

What sensor is used for sampling and how the sampling is done (magnetically, optically, hall-sensor based, electromagnetically ...).
Because of this lack of reliable test data from verified sources, it is hard to understand how one motor behaves from another and what can be done to improve it.

1kHz is a very decent sampling frequency but it only makes sense if we understand what's the mechanism behind it.

My subjective experience is Brose uses a different kind of sensor compared to Bosch and combined with the fact that they use belt drive, makes for a very smooth power delivery.

Bosch Gen 4 and Yamaha comes pretty close.

 

[Johnny]

Do you know of any publicly available links that talk about sampling frequency in these sensors?
I can't find a single document from Bosch or Yamaha or Shimano or Bafang that talks about this in technicality.

Specifically,

What sensor is used for sampling and how the sampling is done (magnetically, optically, hall-sensor based, electromagnetically ...).
Because of this lack of reliable test data from verified sources, it is hard to understand how one motor behaves from another and what can be done to improve it.

1kHz is a very decent sampling frequency but it only makes sense if we understand what's the mechanism behind it.

My subjective experience is Brose uses a different kind of sensor compared to Bosch and combined with the fact that they use belt drive, makes for a very smooth power delivery.

Bosch Gen 4 and Yamaha comes pretty close.

Yeah 1khz probably only corresponds to torque and cadence sensors(sampling of rider input in general).

 

[webcurl]

In the vehicle electronics world 1khz sampling is quite slow. The microcontroller does this.
Not sure about the Bosch sensors but they also produce them for motor vehicles.
Accelerometers are made by several semiconductor companies and now i'm almost dead certain Bosch must use one in their ebikes, how else would walk assist be able to work so quickly without a revolution from the rear wheel or any input from the crank?
The sampling speed would also apply to the algorithm's applied to the electrical input to the motor i think.
As for smoothness of Bosch vs Brose, etc. i guess it somewhat depends on the speed/accuracy of the sensors but more to do with the algorithm's in the software.

 

[webcurl]

I can't find a single document from Bosch or Yamaha or Shimano or Bafang that talks about this in technicality.

Trade secrets!