How to control a manual robot with high precision

[vreg]

Hi,
I'm trying to build a robot manually controlled with PS2 controller. The robot has a square chassis with 4 omniwheels placed at the 4 corners, somewhat like the robot in this link: **broken link removed** (but much larger and with an aluminium chassis)...

However, while giving commands to the motors for moving in a particular direction, the robot does tend to move in an undesired way due to uneven contact by the wheels, difference in traction with the ground and various other reasons.

Is there any good way to sense the inconsistency in motion of the robot from the desired direction and automatically send specific commands to say, change motor speeds to bring it back on track?
Please suggest some ideas.

 

[BradtheRad]

Possibilities:

An electronic compass on board.

Optical sensor sights on an object directly ahead of the robot (or directly behind). Software sends commands to turn left or right to stay lined up on the object.

Spring suspension at two wheels (or all four) to maintain even contact with the ground.

Two caterpillar (tank) tracks, running the length of the robot, instead of wheels.

 

[vreg]

Possibilities:

An electronic compass on board.

Optical sensor sights on an object directly ahead of the robot (or directly behind). Software sends commands to turn left or right to stay lined up on the object.

Spring suspension at two wheels (or all four) to maintain even contact with the ground.

Two caterpillar (tank) tracks, running the length of the robot, instead of wheels.

Hi, thanks a lot for your reply...
I think an electronic compass or spring suspension might be feasible for my project. Could you please suggest a rough algorithm that could be implemented after getting the required values from the compass.

Would it be feasible to use an IMU or an optical mouse on similar lines?

P.S. The robot is manually controlled and doesnt move only in one direction, but either straight,backwards,left or right depending on the commands sent through the PS2 controller by the user.