Motorized Height Gauge retrofit
03 Jun 2015 23:10 #59382
by gernoff
Replied by gernoff on topic Motorized Height Gauge retrofit
True. What would be nice is if I could watch the lvdt (or a strain gauge) in hardware for a set point. The chosen point would be set for a specific gauging force. Then I could write the various measurement routines to command the servo driver to drive the carriage in a required direction (up or down) and the hardware would stop the motor once it had settled at the calibrated position of the lvdt. I guess a better would be linuxcnc on the new raspberry pi. Would the Pi2 have the horsepower to run this.
Here is what I see as requirements:
Able to read quadrature signal from 20 micron scale at sufficient speed to be usable (tbd).
Read a analog signal from the lvdt or strain gauge for gauge force set point. I already have suitable lvdt's but suspect a strain gauge may be easier to implement.
Drive the DC motor that positions the probe carriage.
The height gauge has a battery compartment and if I can make a Raspberry Pi work, my new system can still be completely self contained.
Here is what I see as requirements:
Able to read quadrature signal from 20 micron scale at sufficient speed to be usable (tbd).
Read a analog signal from the lvdt or strain gauge for gauge force set point. I already have suitable lvdt's but suspect a strain gauge may be easier to implement.
Drive the DC motor that positions the probe carriage.
The height gauge has a battery compartment and if I can make a Raspberry Pi work, my new system can still be completely self contained.
Please Log in or Create an account to join the conversation.
03 Jun 2015 23:44 #59390
by andypugh
I think that an Arduino can read encoders and there are SPI force sensor things: (HX711 for example)
www.ebay.co.uk/itm/New-Weighing-Sensor-A...p2141725.m3641.l6368
Where does the data go?
I don't know how fast an Arduino can count encoder pulses (they are pretty weak computationally) but a standalone one with an LCD display might be an option.
I haven't tried compiling linuxCNC on RPi recently (I don't think, I might have forgotten).
Other possible platforms are things like: www.kickstarter.com/projects/udoo/udoo-n...t-40-sensors/?src=i1
It all depends on how much you want to make-happen yourself.
x86 PC + LinuxCNC + Mesa encoder card in PCI slot = no software to write, but significant cost and bulk and tied to mains.
Replied by andypugh on topic Motorized Height Gauge retrofit
In some ways, but maybe not others. I tried a Pi2 + preempt-rt kernel and the latency was rather poor.Would the Pi2 have the horsepower to run this.
I think that an Arduino can read encoders and there are SPI force sensor things: (HX711 for example)
www.ebay.co.uk/itm/New-Weighing-Sensor-A...p2141725.m3641.l6368
Where does the data go?
I don't know how fast an Arduino can count encoder pulses (they are pretty weak computationally) but a standalone one with an LCD display might be an option.
I haven't tried compiling linuxCNC on RPi recently (I don't think, I might have forgotten).
Other possible platforms are things like: www.kickstarter.com/projects/udoo/udoo-n...t-40-sensors/?src=i1
It all depends on how much you want to make-happen yourself.
x86 PC + LinuxCNC + Mesa encoder card in PCI slot = no software to write, but significant cost and bulk and tied to mains.
Please Log in or Create an account to join the conversation.
04 Jun 2015 00:20 #59396
by gernoff
Replied by gernoff on topic Motorized Height Gauge retrofit
I only want to display the measurement data. No data stream to other devices etc.
It'd be nice to make a Rasp Pi2 work with a cheap touchscreen tablet as the interface.
It'd be nice to make a Rasp Pi2 work with a cheap touchscreen tablet as the interface.
Please Log in or Create an account to join the conversation.
Moderators: cncbasher
Time to create page: 0.095 seconds