I am sorry if it is not the right Stack Exchange website i should ask this question on, but it seems to me that this is closely related to software programming more than electrican engineering ! If it should be elsewhere, please tell me.
Let’s assume we want to control a 2 motorized wheels robot to go from point A to point B. Let’s assume i want to control my robot by providing it the distance and angle.
I could first do the control on my angle, and then on the distance, so the robot first turns around its center (by providing positive order to one wheel, negative to the other one), and then travel until the point B is reached (by providing two positive oders to the wheels).
However, if i want the robot to do it in one move, i want the two different control values to be controlled at the same time. This way the robot does have a nice curve until it reaches the destination. Doing this, i provide two positive orders to the wheels, and i add on one side a positive order, and a negative one to the other side.
With this last solution, i have some troubles to understand how to reach the right direction.
If, for example, i want to go 1meter backward. I will set my order as point B : (1m,180°). With the first solution, no problem, the angle is done first, and when it is done, the 1m are done.
With the second solution, i move WHILE i turn, therefore, the curve is way bigger than the ordered 1m, and it stops after 1m, not at the point B.
How should i address this concern ? Do you have any advice, or maybe did i not understand well this technique ? I tried to simulate a control system with a little XNA game to try out solutions even without any robot, so feel free to give any advices you may think interesting !
Al_th
I’m not fully qualified to answer this myself, but there is some great material about this on Udacity: http://www.udacity.com/view#Course/cs373/CourseRev/apr2012/Unit/510040/Nugget/515042. Sebastian Thrun (who runs Google’s autonomous car project) will explain this much better than I ever could.
Edit: the example in the video assumes a bicycle model (two wheels only), so it’s not directly applicable to your case. However, you might get some valueable info that you can utilize.