Talk:CNC Torch Table Z Height Control

Sat Jul 22, 2017

Specific Steps for Signal Improving

1. Software level?

2. Hardware improvement? Ring size?

3. Filtering?

4. Averaging?

5. Calculation vs. observed - are we getting the expected capacitance? What is the current signal to noise ratio?

6. Improving amplitude of capacitance?

7. Better test-rig and -setup

8. Timing-strategies, adding delays between motor-movements and measuring may help against noise

Software

- First place for improvement, e.g. by applying filters for smoothening the signal and timing-related strategies

- hammer out default test-scenario (and test-rig setup)

- Visualization of sample data, e.g. by direct user interface or the host-monitor-tool. With help of the "processing"-IDE one can simulate the effects of any filters etc. based on the sample-data from the running process and have meanwhile a visual introspection. The algorithm-part then can be put modular into the firmware (via the arduino IDE) and tested directly on the board.

- other kinds of signal-processing algorithms and techniques, like frequency distribution (gaussian, variance, chi-square) up to patter-recognition (ANNs), etc.

- doing something with the registers of the AD7747 chip according to its datasheet. Maybe there are still unused option, e.g. for calibration, or influence sampling-rate, gain etc.

- algorithm in the firmware could still contain bugs to eliminate

- there are some "Adjusting Screws" in the firmware, e.g. width of window for sliding average that can/should be fine-tuned

Hardware

- Sensor: bigger ring-version

- Better grounding and shielding, has huge influence on signal-quality. I tried to connect the case of the stepper-motor to the shield-potential, but that made the signal much more worse, maybe because GND and SHield-GND are two different potentials

- other kind of shields / EMF-countermeasures, like cages

- add end-stop, implement push-button functionality of the KY-040, for improving the flow and control of the experimental setup. E.G.: A testrun may start with its calibration loop from a manually adjusted home-position and then goes into balancing-loop. But if you start the Serial Monitor from the Arduino IDE, it regularly resets the board and starts again the calibration-loop on a wrong position. Steering this by the jogwheel pushbutton could be helpful in this case. Also Host-monitoring could be replaced by a direct-user-interface (like OLED-display).