Physics Help Forum Position/Motion Vector Getting a future position
 Jan 26th 2011, 01:11 PM #1 Junior Member   Join Date: Jan 2011 Posts: 4 Position/Motion Vector Getting a future position Hi, I am currently reading a paper where it’s necessary to know the position of a node at a future time. A node will know its current (x,y) position, its previous (x,y) position one second ago and will know its current speed. Code: The paper says the following: v(I,T): motion vector of a node I at time T p(I,T): position vector of node I at time T It gives the following relationship: p(I,Tc)=p(I,Tr) + v(I,Tr).(Tc-Tr) where Tr is a past time, Tc is the current time  (This is basically the distance=speed*time formula from what I can see with the distance added to the (x,y) coordinates). Part of the algorithm says that a node should predict the position of another node at time Tc + Δt, where Δt is a small time like 1s, if it knows the nodes current position and motion vector. It says it relies on the accuracy of the motion vector and then says the following: Code: Let m denote the motion vector directly accessed from GPS. Mold and Mnew are the reported motion vectors at the last time and this time respectively. Mnew = alpha*Mold + (1 – alpha)*m, 0<=alpha<=1 Alpha=0.3 if the node is in the area of a junction, 0.7 otherwise  I am a programmer and don’t understand fully what information I should actually store in the motion vector and still don’t understand how given a node’s (x,y) position and speed at time Tc, I can work out its position at time Tc + 1 given that it could have moved in any direction? Can somebody please outline as simply as possible how I can get this future value? I am quite stuck so any help appreciated. Many thanks in advance.