Wall Computers
One of R2-D2's abilities is his power to interface with various wall computers throughout the levels. These computers can open doors or unlock other important pieces that allow you to proceed through the level. You must first play as R2-D2 if you are not already by positioning your current character next to him and pressing the "Triangle" button on PlayStation, the "1" or "2" button on the Wii or the "Y" on the Xbox 360. Move R2-D2 in front of the wall computer and press and hold the "Circle" button on the PlayStation, the "Z" button on the Wii, or the "X" button on the Xbox 360.
Hovering
R2-D2 is also helpful when trying to reach a certain location that is too far for other characters to jump. His hovering ability allows him to fire rockets on his base, allowing him to hover or fly for a few seconds. By holding down the "X" button on the PlayStation, the "A" button on the Wii or the "A" button on the Xbox 360, then moving with the joystick on the controller, you can make R2-D2 fly a certain distance, usually several yards.
Chancellor in Peril
In this chapter, you are making your way through General Grievous' flagship. On your way through, you battle and defeat Count Dooku. Just after the battle, you rescue Chancellor Palpatine and make your way through the ship on your way to the main bridge to take control of the ship. At one point, you encounter two sets of steam vents that you must pass to continue your way to the bridge.
Getting Around the Last Vent
Pass the first vent by using Anakin or Obi-Wan's force ability to turn the wheel and shut off the vent. The second vent is trickier, since there is no wheel to force the steam off. Instead, you must become R2-D2 and hover your way around the outside of the vents, then land on to the other side. But the other characters must also be able to proceed. Use R2-D2 to access the wall computer. He shuts off the final vent and allows everyone to continue.