Re: Motor_Controller_Design
A USB-A cable is rated 5 ampere at 5 volt over a short distance and is not decently shielded.
Re: Motor_Controller_Design
Quote:
Originally Posted by
klaas123
A USB-A cable is rated 5 ampere at 5 volt over a short distance and is not decently shielded.
I thank you for your time write a reply!
The dielectric of a standard USB-A cable is rated at 20V. I am guessing that a 20V dielectric will endure up to 50V. In general amperage is the conductor killer, not voltage. So say that the power supply is 48V, the current is 5A.
The maximum continuous power applied to a NEMA 23 motor would be:
P= V * I = (48V)*(5A)=240W
I am guessing that a 240W power supply is enough for a NEMA 23 motor. (someone please correct me)
Mechanical engineers use strange units (oz-in) (N-m). A better unit would be (Joules)/(cycle). "(Joules)/(cycle)" would allow direct translation of a motor's power requirement for a given rotation rate(Hz).
Also the digital signals inside of a USB cable are differential. A "differential" digital signal design is specifically used to eliminate the corrosive effects from noise from adjacent unshielded power conductors. The low frequency AC transients from power supply are not a problem worth losing sleep.
I again thank you for your reply!
PS. Holland should declare the "Stroop Waffel" the national cookie! "Stroop Waffel" => YUM!:)
Re: Motor_Controller_Design
I really don't see the advantage?
setting up remote controllers for each motor, you will still need interpolation commands sent from some source or another.
Also, NEMA is not a motor power rating, it is a mounting plate standard.
You can obtain commercial stepper motors where one is double the length of another, i,e, power x2 but still have identical NEMA mountings.
Al.
Re: Motor_Controller_Design
Al ( Boomhauer?),
I thank you for your reply!
What I would like to develop is >90% hardware. Any modifications interpolation software(and firmware) from existing application software will as small as possible. For example, I do not want to develop a new “g-code” interpreter.
Ideally, I want to deliver to the end user a product that has:
- Other than motor itself use universally available off the self parts E.G. USB-A cables, cheap ubiquitous 48V power supplies, HVAC cables, USB to RS485 dongles.
- Chimp simple “Product commissioning” . “Product commissioning” are the steps between connecting cables and power to your product and when the software communicates to hardware.
- Eliminate the central box and separate motor controllers (IE Gecko controllers)
- Vastly simplified product connections
I will grant you challenges exist!
The biggest challenge is motor synchronization to less than say 0.1 millisecond. The synchronization challenge has been solved for Ethernet, so I do not foresee and “deal killers” in terms of firmware development with a RS485 interface.
Basic product commissioning would the same as has been done in the HVAC industry for the last 25 years.
STEP 1: RS485 interface initialization.
STEP 2: Control node initialization.
Explanation STEP:1
An RS485 interface mimics the RS232 firmware/software interface that already exists on your computer’s operating system. Some RS485 devices are “plug and play”. You only need to transfer the COM port number (EG 2,6,12,31) to your application software.
Example RS485 device:
https://www.ftdichip.com/Products/Cables/USBRS485.htm
Explanation STEP:2
By “control node” I mean something like a end stop detector, motor, coolant sprayer, fan, end mill dust vacuum. In the HVAC industry, control nodes have “DIP_switches”. A small jeweler’s screw driver adjusts the switches. Control node commissioning is done by generating a 7 bit number with the DIP_switch for up to 128 control nodes. The bus then recognizes each control node by unique ID number. No additional hardware initialization necessary.
(Please see attached image “DIP_switch.PNG”)
As far as the definitions of NEMA 23 and NEMA 34, please forgive me. I am an EE not ME. Please forgive me!
Please look at the two data sheet snippets for NEMA 23 and NEMA34 motors. Do the performance numbers suggest a stout motor suitable for say a NEMA 23 or a NEMA 34 3-axis gantry mill?
Please see attached image “Example_NEMA_23_specifications”
Please see attached image “Example_NEMA_34_specifications”