We have made a quick final decision that we should lift at our coming event. However, our only problem at this point in time is that our wheelie bars are too long. We know that if we decrease the size of the wheelie bar that we will not catch a fall.
How are you guys using rubber band wheelie bars while lifting, are you retracting them?
Additionally, are people doing good without wheelie bars? How do you reduce tipping without them?
As a side note, I just wanted to make point that yes, I have seen posts alike this on the forum, but none of them will work for us.
We don’t tip backwards or forward, because our drive is similar to a drop center drive except we dont have one wheel in the center that is powered. We have a tank drive that is powered and the wheels are close together and we have 2 non powered wheels in the front and back of each side.
If you want to have an anti tip mechanism in the back which still allows you to hang, on our previous bot we had an anti yip mechanism which was a circular piece of legal plastic which we used so when we want to hang and we go far enough the robot just rolls off the circular edge and it allows our robot to successfully hang.
My sister team has an interesting mechanism for this. At the beginning of the match, a zip tie is connected to a polycarb hook, and this zip tie is loosely wrapped around their lift. When they lift at the start of the match, this zip tie is pulled up on, and the hook releases the anti-tip bar. The zip tie also releases from the lift. When they want to hang, they back into the field perimeter to push their anti-tip bar back into the hook.
NOTE: I am posting this because I am no longer using this method/procedure for my robot.
With my robot, my anti-tips are connected to the lift (It raises and lowers, not linearly slide out). Whenever my arm raises, the anti tips on the back of my robot lowers. When my arm lowers, the anti tips raise. To reduce clipping on the fence, the anti-tips are connected by one connection on the gear, and rubber bands hold the arm upwards. Whenever the arm lowers, standoffs on the gears push the anti tips down. When it raises, if the fence is clipping,the gear will turn, but the mechanism will stay down until the robots anti tips are out of the way. When time to lift, since the arm lowers when lifting, the anti-tips raise/retracts, making the anti-tips rotate into the robot, allowing the assurance of a reliable hang. The anti tips work something like this:
The first picture is no strain(lift in down position, no fence), the second one is strain (lift in dump position), and the third one is strain in down position(fence). This method is for anti-tips that have the capabilities to reach much farther than other anti-tips, as well as being able to retract upwards to do a high hang.
Key: Green = Gear, Silver = Standoff, Black = Anti-Tip, Yellow = Elastics, Orange = Fence
This mechanism is extremely useful, and has some pros and cons. The pros are that if there is too much velocity when tipping, then the anti-tips will also lower the lift as the force is being applied, which helps with prevention of falling. This is also useful because it is also very reliable too, and can save you if you are extensively light. The cons are that if there’s an object below you, it can cause some issues and you may have to push the object out of the way before you raise your lift.
