Hello,
I have a project where I want to use a linear actuator with a hook to pull a rod rearward, this rod is spring loaded and after a certain distance, the hook is to release the rod and let it spring forward. The linear actuator would then push forward and hook the rod again and repeat. I want to be able to set the cycle count as well as display what the current count is at. I believe I can use some kind of proximity sensor and a trigger mechanism to keep count as well trigger the hook. I took an electromechanical class a few years ago where we used Arduino to program a robot to navigate a maze so I can somewhat familiar with using arduino. Does anyone have any suggestions on how to move forward with this project?
Hello @gregkeez and welcome to the RobotShop forum,
You have a good general idea of how to execute the project, however I have some doubts. What exactly would the proximity sensor be for? Also, how would the hook be “activated”?
Linear actuators commonly use limit switches to implement a trigger at the end of the travel, so if you choose a linear actuator with a stroke that meets your requirement that should be enough. If you need to program the cycle count and display the current count you will need a programmable motor controller, or a motor controller and a microcontroller.
If the distance between the actuator and the spring-loaded mechanism can vary then it is better to use a linear actuator with feedback. In that case, I get why you would need the proximity sensor but it would be pretty much the same idea, you would also need a motor controller (to control the actuator) and a microcontroller (to program the cycle, check the proximity sensor status, trigger the “hook”, and display the current count). Again, I’m not sure how you could trigger the “hook”, maybe with some sort of magnetic mechanism.
I hope that helps!
Thanks for the response! You’re right, I don’t think the proximity sensor would be needed as I could just have the hook triggered to release at the end of the linear actuator pull and then re-engage at the end of the actuator’s push? Could I attach some sort of actuator with the hook at the end of the linear actuator to engage/disengage? Would it be possible to keep count of how many times the linear actuator has retracted and stop at a certain count? Would it be possible to be able to set the count outside of the program?
I could just have the hook triggered to release at the end of the linear actuator pull and then re-engage at the end of the actuator’s push?
Again, I’m not sure on how you are planning to trigger the hook to achieve that, maybe if you share more details of what you have in mind I could give you my thought on it.
Could I attach some sort of actuator with the hook at the end of the linear actuator to engage/disengage?
I am not sure what you are referring to, could you elaborate?
What I can think of would be to use an electromagnet so that you can “activate/deactivate” the grip. However, this would depend on how much force is needed to stretch the spring. I don’t know if this is the best option but it was the only thing that came to my mind.
Would it be possible to keep count of how many times the linear actuator has retracted and stop at a certain count?
For sure, you can easily program this with a microcontroller.
Would it be possible to be able to set the count outside of the program?
Do you mean setting the count manually? In other words, not having to change the code to change the cycle count? If that’s the case, then yes you could do that, maybe with two buttons (to increase/decrease the count), maybe add a 7-segment display to easily check the cycle count and the current count. But you would have to program all of this, although I’m sure you will find many tutorials on similar projects, for example:
