Distance Sensors

Instead of using discrete sensors to sense the distance to a wall, you can consider using an analog distance sensor like the Sharp GP2D12. An obvious advantage is that the distance measurement is no longer discrete, the resolution is limited only by electrical noise and the ADC (10-bit ADCs are built-in to the ATMega128).

Another advantage that has nothing to do with error detection is that you don't need sensor banks hanging in front of the robot if you use these distance sensors.

A disadvantage is that you cannot see beyond a wall. With look-down sensors hanging from wings that look over walls, a robot can map immediate walls on the other side of walls surrounding the robot.