2017-10-08, 07:02
Made good progress with the code and measuring cadence from the strain gauges is working amazingly well.
![[Image: W4CjtV.jpg]](http://imageshack.com/a/img924/7820/W4CjtV.jpg)
First thing I did was lift the zero force value up off 0V. I then had to rethink how I measured the min value for everything to be calculated from. Constantly recalculating the min value from the dead spot on my pedal stroke just wasn’t going to work for accuracy as it doesn’t represent 0 force. In the end I moved the min value, or should now be called zero force value, code into the setup. It takes 3 reading 1 sec apart and obtains an average before the loop starts to run.
It seems to be capable of returning to this zero value with minimal drift over a decent length of time. If it does start to drift I’ve added an external reset for the Arduino. Better than switching off and on as it maintains the Bluetooth connection.
The following data is recorded at 0.5 second intervals, the amount of data gets a bit much otherwise. Where the gauge value stays below 0 is when my foot is resting on the pedal while behind the bottom bracket.
![[Image: DtBZTF.jpg]](http://imageshack.com/a/img924/6030/DtBZTF.jpg)
I’ve started to increase the speed at which the code is running from a very slow 25Hz to 100Hz. This gets the cadence resolution to about 1 rpm, will experiment with how much I can push the speed. The output of the amplifier is disappointing noisy which I find odd because it was very smooth when I had everything temporarily wired with 30cm lengths of wire. To improve this I have the other timer running a 1kHz interrupt with a running average of 50 values.
Next challenge is to do a proper job of wiring the strain gauges to the amp. Until I get that reliable I can’t go any further with the project.
First thing I did was lift the zero force value up off 0V. I then had to rethink how I measured the min value for everything to be calculated from. Constantly recalculating the min value from the dead spot on my pedal stroke just wasn’t going to work for accuracy as it doesn’t represent 0 force. In the end I moved the min value, or should now be called zero force value, code into the setup. It takes 3 reading 1 sec apart and obtains an average before the loop starts to run.
It seems to be capable of returning to this zero value with minimal drift over a decent length of time. If it does start to drift I’ve added an external reset for the Arduino. Better than switching off and on as it maintains the Bluetooth connection.
The following data is recorded at 0.5 second intervals, the amount of data gets a bit much otherwise. Where the gauge value stays below 0 is when my foot is resting on the pedal while behind the bottom bracket.
I’ve started to increase the speed at which the code is running from a very slow 25Hz to 100Hz. This gets the cadence resolution to about 1 rpm, will experiment with how much I can push the speed. The output of the amplifier is disappointing noisy which I find odd because it was very smooth when I had everything temporarily wired with 30cm lengths of wire. To improve this I have the other timer running a 1kHz interrupt with a running average of 50 values.
Next challenge is to do a proper job of wiring the strain gauges to the amp. Until I get that reliable I can’t go any further with the project.
- Oran