Well I’m making progress. The assembly giude / tutorial is coming along as well. The image below shows the real parts used for this. The sensor is nested in between the HUB-09 and the clear rubber “bumpers” so it’s pretty robust. The rubber end cap protects everything from lateral forces too. It’s adjusted to just not touch the sensor, so when the leg is up the sensor is highest resistance. The sensor with a 10k pull-up resistor gives the following output.
That really looks like a need solution for pressure sensors on the legs! Are they only gonne be for sale as a kit or also the seperate pressure sensors?
We made some progress on this today. The tutorial is completed, but we ran out of time to get the product added to the website. It’ll get done on Monday. Check out the guide.
Also, the other question I have, since I know nothing about FSRs… Is it the 90 degree bend that changes the resistance, or is it pressure on the pad at the end that changes resistance?
Just a note on these - they are analog sensors. One analog input is required for each sensor. This would require six analog inputs to put one of these on each foot of a hexapod.
This sounds like a job for the new SSC-NG board, an Atom PRO that is not using HSERVO, or something else with 8+ analog inputs.
Another simple solution would be using a Hex Schmitt-trigger inverter (ex. 40106), that gives you a digital 0/1 output for each leg. No need for a A/D converter if you just want to use the FSR sensor like a switch. Add a potmeter if you want to adjust the “trigger voltage”. I’ve not tried it yet, but I’m pretty sure it would work.
Of course the general I/O expander would do nicely as well. For now the sensors are very much do-it-yourself, but we will be making it easier as we go.
I’ve updated the guide. I added a bit more information at the top, fixed Figure 5, added an alternate schematic, and fixed the chart at the bottom. Hopefully everything is easier to understand now!
Do I detect a change in the design of the BRAT sensor foot? If so, it would be a good change, IMHO. Much more could be done with the ability to detect the actual force being applied to the terrain.
I have not changed my mind on the switch sensor board. But, yes I have already thought about using the FSR’s on the ARF-01 and ARF-02’s. I just haven’t been able to complete the assembly guide. It’s a simple matter of attaching a sensor in the corners, and then apply the rubber bumpers to all for corners. It should work very well. 8)
) it looked like the sensor was folded back on itself, due to the reflection.
