Anyone have any good tricks to minimize the vibration the camera picks up from the shooter ?
Can you post a picture of your robot and the camera as to where you want to place it?
Not with robot right now. No pics with me. We have a typical turret with the shooter wheels / motor turning on it. Above the wheels, at the top of the back frame the balls roll up the camera is currently mounted to get it as high as possible. Its as far from the motor and wheels as we can make it on the shooter but the high speed rotating wheels are not balanced so some buzzing vibration is going through the shooter frame. In my mind, not extreme, not avoidable without serious dynamic balancing equipment etc. The actual shooting of a ball is not an issue as the camera will already have a lock.
Start by minimizing the vibration produced by the shooter.
Once you have it running as smooth as possible, try to make the camera mount and supporting frame as stiff as possible. Do not leave any portion of the mounting frame unsupported. In other words, try not to mount the camera on a big moment arm that can start oscillating.
Take a close look at this video and you can see how the camera frame is supported. (The camera is the high point on the robot.) We have very little vibration and can track targets even with the wheels up to speed.https://www.facebook.com/photo.php?v=3314964842956
Nice Robot!
Our camera frame is similar to yours and VERY stiff and is very effective in transmitting higher frequency wheel vibration to the camera unfortunately.
Will work on wheel vibration. I suppose we could rubber mount things
Dave,
Much of the vibration that is transmitted is likely moving the frame for your turret so I am guessing that the camera is mounted somewhere on the turret frame. If you are using something that solidly attaches to the robot frame like a lazy susan bearing or some other low vibration mounting, getting the camera mounted as close to that point would eliminate much of the vibration in the camera. You would likely have more luck if you were to isolate the shooter from the turret as the camera does not contain enough mass to easily isolate it.
I’ll also throw my advice towards eliminating the source of the vibration rather than trying to isolate the camera from a vibrating frame. If nothing else, try with other wheels of the same model to see which introduce the least vibration. Another stiffener you may try is guy wires to anchor it to the corners of the robot.
To modify the frequency of the vibration transmitted to the camera, you may try some different density of rubber, polystyrene, urethane, etc. If you can extend the bolt, add a rubber bushing to hold the bolt away from the edges of the mounting hold, and add the right density of material on each side, you can certainly improve things, and of course adding some mass to the mounted camera will modify the period too.
Keep in mind that the camera exposure is probably between 5 and 50ms, depending on the lighting – faster on the field, slower in the dim shop/classroom.
Greg McKaskle
Thanks all good ideas. Clearly our shooter direct had excessive vibration. This morning it would hit a resonance point say at 3/4 full power and the whole assembly would become a blur due to vibration, then it would smooth out at faster speeds. We have since completely redone the drive train and improved the wheel hubs to try to solve this (will know tomorrow).
Made the first step to flex mount the camera but as someone said it is so light. May not be necessary we hope.
Some guy was talking about using a “mass balance” system of counter weights to isolate the camera (I am guessing the counter weights vibrate out of phase to the frame vibration to net it out. Anyone know anything about this.
if your losing the target use a feedback node to save the information last time your camera saw the target, we use the same thing
IF, and it is a big IF. If you measure your system very well – knew the driving frequency and mass distribution, you could indeed identify where to add or subtract mass so that the camera happens to be at a node with little or no vibration. This link shows examples of a simple system. They don’t change the mass, but change the frequency to cause standing waves where some portions of the spring are in a quiet place while other portions of the spring are bouncing all about.
Again, I’d try to get rid of the source. Strong vibration will do more than cause bad images. Before long, you’ll see that the bolts are loose, welds break, cables loosen or break, not to mention shaking the chips off of the camera’s circuit board.
Greg McKaskle
Dave,
The mass balance is a technique where mass is added to the mechanism that is vibrating and then the mechanism is isolated from the source through very flexible material. This is a technique that has been long used for acoustic isolation for things like turntables up to entire rooms. Radio, TV and Film studio design regularly will isolate the floor with springs and dampers and then build the entire studio on the floating floor. Mason Industries makes some pretty good isolation and has interesting discussions on their website.
You can try using some really spongy material to hold the camera and mount on the robot and that might quell some of the vibration. Be advised that the 3/4 throttle vibration you observed could be the sum of several different vibrational sources that all contribute at the frequency. Is it possible to isolate the wheel and motor assembly from the rest of the robot using rubber isolation?
Our revised power train for the shooter has no material vibration so the camera appears to be working okay. Lesson learned: we need a machinist mentor 