Radio Control Servos with UR5

aneehall 2019-11-20

Hello,

I am working on a project that requires an actuator or solenoid to operate a small device. Due to cost, I would rather use a hobby (Radio Contol) grade servo, as an industrial actuator would be overkill for this application. The problem is I am totally stumped on how to control the servo using an output from the UR5. I found a topic on this forum that references using an Actuonix control board and actuator, which is close but not quite what I was looking for.

My understanding is that RC servos use a PWM signal between 1.0 to 2.0 microseconds to set the servo position. I am looking for way to achieve this with the UR5, whether it can do it directly, or if an external servo control circuit is required.

Any ideas?

bcastets 2019-11-21

I found an article about servo control on the web:
https://learn.sparkfun.com/tutorials/hobby-servo-tutorial/all

Voltage is 5.5 VDC and UR is 24V.
Maybe you could use an analog output and try to make a program to generate the PWM pulse ?

aneehall 2019-11-21

Thank you for the reply! I had considered trying that, I will have to look into the capabilities of the analog output further.

I found another thread (https://dof.robotiq.com/discussion/comment/5479#Comment_5479) where you commented on using an actuator controller that can accept a 4-20 mA control signal. I am still hoping to find a hardware controller that will work for servos. I could use an Arduino to process a signal from the robot and send this to a servo controller but that doesn't seem like an elegant solution.

bcastets 2019-11-22

The post https://dof.robotiq.com/discussion/comment/5479#Comment_5479 is not related. It was a specific request.
You could use a rasberry pi with a hat to control the servolike this one:
https://www.adafruit.com/product/2327

Then you can make on the raspberry pi a python program which control the servo. It could interface with the robot using Ethernet connection.

aneehall 2019-11-22

Interesting, I hadn't though of using the ethernet connection like that. I will have to look more into the raspberry pi or arduino (which I believe has a similar servo hat), as I do not have much expereience with these devices.

Thanks for the reply!

henradrie 2019-12-16

Raspberry Pi's have horrible pulse timing. I wouldn't use them for anything motion related.

Instead I would suggest using an arduino. Use an RC pulse library to control the servo and use the analog output from the bot to control the arduino. Use a voltage divider to step down the voltage to a suitable level if needed. A servo hat is nice but as long as the signal pin is connected to a digital out, grounds are connected, and power isn't run through the arduino (good way to smoke one) you should be fine.