Im4X
Posts: 2
Joined: Thu Apr 25, 2019 9:13 am

Controlling the generated force of a voice coil actuator

Tue May 07, 2019 1:49 pm

Hey guys!

I am currently working on a project containing Hall-Sensors (measurment of magnetic fields) and voice coil actuators (high frequency linear motors, which have a force proportional to current output).

I don't know how to describe my knowlege better than "non-existent":

My task is to measure a magnetic field using a Hall-Sensor and generating a force proportional to that magnetic field. In order to do so, I've thought about this:
1. Measuring the magnetic field ( https://docs-emea.rs-online.com/webdocs ... 06a158.pdf)
2. Transforming that signal with an ADC (https://learn.adafruit.com/raspberry-pi ... sh-ads1115)
3. feeding the RaspPi with that information
3. using PWM to stimulate the gatevoltage of H-bridged motor driver (https://docs-emea.rs-online.com/webdocs ... 620d96.pdf)
4. using a current-power-supply for the motor driver

My goal is to control the current's amplitude, that is running through the motor and my questions are: is the idea above realizable, or is there a even better way?

Thank you!

Greetings
Im4X

User avatar
omegaman477
Posts: 148
Joined: Tue Feb 28, 2017 1:13 pm
Location: Sydney, Australia

Re: Controlling the generated force of a voice coil actuator

Thu May 09, 2019 10:37 pm

Im4X wrote:
Tue May 07, 2019 1:49 pm
Hey guys!

I am currently working on a project containing Hall-Sensors (measurment of magnetic fields) and voice coil actuators (high frequency linear motors, which have a force proportional to current output).

I don't know how to describe my knowlege better than "non-existent":

My task is to measure a magnetic field using a Hall-Sensor and generating a force proportional to that magnetic field. In order to do so, I've thought about this:
1. Measuring the magnetic field ( https://docs-emea.rs-online.com/webdocs ... 06a158.pdf)
2. Transforming that signal with an ADC (https://learn.adafruit.com/raspberry-pi ... sh-ads1115)
3. feeding the RaspPi with that information
3. using PWM to stimulate the gatevoltage of H-bridged motor driver (https://docs-emea.rs-online.com/webdocs ... 620d96.pdf)
4. using a current-power-supply for the motor driver

My goal is to control the current's amplitude, that is running through the motor and my questions are: is the idea above realizable, or is there a even better way?

Thank you!

Greetings
Im4X
A valid approach to design. Generally speaking, measuring magnetic fields is tricky, and usually requires several sensors depending on the field orientation(s), as is screening/rejection of environmental fields. Also depending on your sample, compute, control timing and sample rates, do ensure that the RPI is capable of handling the workload real time. But using dedicated ADC and PWM chips will assist greatly.Sounds an interesting project.
..the only thing worse than a stupid question is a question not asked.

User avatar
Gavinmc42
Posts: 3927
Joined: Wed Aug 28, 2013 3:31 am

Re: Controlling the generated force of a voice coil actuator

Fri May 10, 2019 2:17 am

I have used light as the position feedback from voice coils.
It removes the magnetic field influences.
Voice coils are simple linear devices so if you measure/control current the rest is simple maths, which I have forgotten :oops:
I'm dancing on Rainbows.
Raspberries are not Apples or Oranges

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