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USA
Asked — Edited
Resolved Resolved by DJ Sures!

Questions With Robot. Lost And Need Support!

Greetings EZ-Robot Team. We are currently having some issues with servo and movement pathing.

Our robot is currently an old child's toy from the 60s outfitted with a basic kit. We have dubbed him OkraBot.

Currently, the robot is spinning around in a circle when it is indicated in the UI that it is moving forward. Another issue is that one of the arms is currently wanting to move upward, as it is attached to a servo. Amusingly, it looks like it's trying to fist-pump the world.

We have attached a YouTube video for reference. We are entering a time crunch as the robot is due to be shown to our student body and staff at the end of the month.

Thank you for any assistance you are able to provide!


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PRO
Canada
#1  
Hello jfew,

In ARC I would recommend playing with the center value on the continuous rotation servo on the foot. Not all continuous rotation servos are calibrated the same so the center value (the non-moving position) is a bit different from servo to servo.

If you are using a Movement Panel and don't want to adjust your values (or can't) you should be able to use a small phillips screwdriver and adjust the potentiometer on the servo. There should be a small circular hole on one side of the servo that allows you to adjust the center position. I wouldn't recommend this as your first option but I figured I'd let you know that the option (should be) is there for you.

The other servo twitch might be due to the weight of the Arm or just the position that it's in, try changing the position of the arm and see what happens. If it's still quivering try to mount the arm a little differently (change the angle) or try to shed some weight off of the arm. It also could be a low battery issue but it doesn't seem likely as the other servos seem to be operating ok.
PRO
USA
#2  
@Jfew , Welcome to the community

Skater is right , first make sure your batteries are fresh , second remount about 5 degrees off what it's mounted now to ensure it's not sitting in the deadband. I imagine the arm doesn't weight much but there's always the high torque servo option too.
USA
#3  
the arms appear to be working correctly for the most part. current problem is when the object avoidance mode the robot spins in a circle and on the user interface shows that it is moving forward, or turning left. the wheel servos are connected to D2 & D3 and the arms are on D5 & D6. In placing both wheel servos to them max (10) the robot only goes forward and the UI shows turning and backing. I reset the center on the arms and that appears to have solved the issue with the fist pump (I thought is cool for it to to do it without programming).
PRO
Canada
#4  
Ok I think I may know what's happening, the two feet servos are oriented in opposite directions so you will have to send a value of 10 to one and 90 to the other in order for the robot to go straight, and then both the same value in order for it to turn. I hope that makes sense.
PRO
Synthiam
#5  
Might want to set the values to 100 and 1 instead of 90 and 10:)
USA
#6  
made the suggested changed and uploaded the results
PRO
USA
#7  
Are you wanting it to backup like that? Was this the intended result? It appears the robot is using the obstacle avoidance and is backing up and turning when the minimum set distance is sensed. You may want to reduce the min distance before it turns.
USA
#8  
min distance is set to 30. the UI shows it is going forward the whole time it is running, turning when paused. It is running the obstacle avoidance function. what would you suggest I change the min distance to?
PRO
USA
#9  
Try changing the min distance to 10 and see if that allows it to move forward. Most of these ping sensors don't have a standard for measurement. Also it may be a good idea to just try driving it with the Movement Panel without the obstacle avoidance on to check your servos are performing the way you wanted to.
USA
#10  
changing the distance did not change its issue. it still goes in a circle and now keeps the arms locked behind it. Thinking it may need a larger place to roam.
PRO
Synthiam
#11  
It might be power related because those arm servos look like they're locked last the threshold. If servos are set to move to a position behind their limit, they will draw major current. Then when the modified servos are turned on, the distance sensor might not have enough power to work correctly. So what you're getting is that behavior.

Try disabling the arms and use only the modified servos.

It's common practice when trouble shooting to eliminate part by part to identify the problem source.
USA
#12  
we made the changes as suggested and the robot still spins in a circle. With the arms disabled and in a outdoor setting the robot did move forward more often but kept turning to the right and would fall forward when stopped to change direction (we corrected this by adding counter-weights to the back). As the term is closing, we were told to take the robot apart and turn in the kits so we'll have to wait until next term to try again else.
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