# Why use GraphSLAM?

I am doing some project on Slam. I have a data set of a moving Robot which can give me the value of forward velocity(m/s) and angular velocity(rad/s) and time(s). Now if this data are provided I can find out the x,y,theta value of a Robot which I can plot and find the Robot path.

Now I am working on Graph Slam and little bit confused in this aspect. I know Graph slam also gives us path and map, but I can already determine the path using forward velocity and angular velocity then what is the need for Graph Slam?

• Do you mean path or pose? – koverman47 Jul 25 '18 at 20:11

If you simply fuse your onboard sensor data to obtain an $(X, Y, \theta)$ estimate of your poses, it is extremely likely that this estimate will drift from the actual ground truth over time. Observing additional information (landmarks) and performing sensor fusion will help in reducing this drift. At the same time, while using SLAM, you can keep track of if/when you're observing the same landmarks you've seen before and use that information to adjust your pose estimates, commonly known as loop closure.