Perhaps you should try some spelling variations:
estimation algorithms » estimation algorithm, optimization algorithms, optimisation algorithm
passive estimation » pose estimation
modified control » mode control
method algorithm » mom algorithm
modified passive » modified adaptive
control method » control methods

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (( modified control method algorithm ) OR ( modified passive estimation algorithms ))~.
• Adding a wildcard symbol may retrieve word variants: (( modified control method algorithm ) or ( modified passive estimation algorithms ))*.