Difference between revisions of "Trackstanding"
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Track standing is a method used by bicycle riders to balance their bike while only moving a minimal distance. The idea behind track standing is that if you keep the front steering wheel at a constant angle, you can move forwards and backwards slightly forward and backwards to stay upright. When you have the angled steering wheel, moving forwards or backwards creates torques, due to the turning motion. Imagine that you are on a bike and the steering wheel is angled 30 degrees to the right. Moving forwards will apply torque CCW, while moving backwards will apply torque CW. | Track standing is a method used by bicycle riders to balance their bike while only moving a minimal distance. The idea behind track standing is that if you keep the front steering wheel at a constant angle, you can move forwards and backwards slightly forward and backwards to stay upright. When you have the angled steering wheel, moving forwards or backwards creates torques, due to the turning motion. Imagine that you are on a bike and the steering wheel is angled 30 degrees to the right. Moving forwards will apply torque CCW, while moving backwards will apply torque CW. | ||
| − | For our control system for balance, the control variable was the steer angle rate. But here the steer angle will be held at a constant rate and the speed needs to be updated, so the acceleration becomes the control variable. The cost variables lean angle and lean angle rate still apply, however instead of steer angle we use velocity. We want to minimize velocity, because the basis of track standing is moving very little to stay upright. The equation of motion of the track standing bicycle used for the LQR becomes: | + | ==Track Standing Controller== |
| + | For our control system for balance, the control variable was the steer angle rate. But here the steer angle will be held at a constant rate and the speed needs to be updated, so the acceleration becomes the control variable. The cost variables lean angle and lean angle rate still apply, however instead of steer angle we use velocity as the third cost variable. We want to minimize velocity, because the basis of track standing is moving very little to stay upright. The equation of motion of the track standing bicycle used for the LQR becomes: | ||
[[File:EOMtrackstand.PNG|500px|left]] | [[File:EOMtrackstand.PNG|500px|left]] | ||
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| − | In our track standing development, we set the steer angle to be pi/ | + | ==Testing== |
| + | In our track standing development, we set the steer angle to be pi/6 radians. In our initial tests the bike would change velocity but would not go backwards. After doing some long term tests we noticed that the bike was slowing down to a single velocity value and continuing at that velocity. It was in a steady state solution where it would drive infinitely around in a circle since we fixed the steer angle. | ||
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| + | We then edited the balance score equation, adding a distance formula term to check that the bike did not move far from the initial position. This term was scaled to 1/10 as to not be massive in magnitude compared to the other balance score terms such as lean angle. This worked much better and the bike had three different responses based on different LQR trained gains. | ||
| + | *1 - Go to a track standing state where it would switch between positive and negative velocities | ||
| + | *2 - Attempt to track stand, go backwards very fast and fall over | ||
| + | *3 - Negative velocity steady state | ||
Revision as of 15:55, 17 May 2020
What is track standing?
Track standing is a method used by bicycle riders to balance their bike while only moving a minimal distance. The idea behind track standing is that if you keep the front steering wheel at a constant angle, you can move forwards and backwards slightly forward and backwards to stay upright. When you have the angled steering wheel, moving forwards or backwards creates torques, due to the turning motion. Imagine that you are on a bike and the steering wheel is angled 30 degrees to the right. Moving forwards will apply torque CCW, while moving backwards will apply torque CW.
Track Standing Controller
For our control system for balance, the control variable was the steer angle rate. But here the steer angle will be held at a constant rate and the speed needs to be updated, so the acceleration becomes the control variable. The cost variables lean angle and lean angle rate still apply, however instead of steer angle we use velocity as the third cost variable. We want to minimize velocity, because the basis of track standing is moving very little to stay upright. The equation of motion of the track standing bicycle used for the LQR becomes:
Testing
In our track standing development, we set the steer angle to be pi/6 radians. In our initial tests the bike would change velocity but would not go backwards. After doing some long term tests we noticed that the bike was slowing down to a single velocity value and continuing at that velocity. It was in a steady state solution where it would drive infinitely around in a circle since we fixed the steer angle.
We then edited the balance score equation, adding a distance formula term to check that the bike did not move far from the initial position. This term was scaled to 1/10 as to not be massive in magnitude compared to the other balance score terms such as lean angle. This worked much better and the bike had three different responses based on different LQR trained gains.
- 1 - Go to a track standing state where it would switch between positive and negative velocities
- 2 - Attempt to track stand, go backwards very fast and fall over
- 3 - Negative velocity steady state
