Remote controlled operation requires a lot of information about the working environment. Cameras and proximity sensors cannot give all the information being considered as necessary for working in a narrow and hardly observable environment. If the environment is geometrically more or less defined, computer support can give the missing information. The handling task in this case is the cutting of the old mortar in brick sewers and the replacing of a new one. The sewers have an elliptic cross-section which is exactly mathematically described. Therefore, the handling task can be pre planned by a computer algorithm. During the cutting operation the operator has the possibility to correct the cutter path with a joystick which works in a coordinate frame fitting to the sewer surface. In the first working step the longitudinal gaps are cut and the end points of the transverse gaps are taught. In this way we get a number of path points which have to be combined by a special computer algorithm to an extended gap-program. The operator has the ability to change the path velocity between 0% and 100%; therefore, it can react on unpredictable events. In case of emergency, like breaking of a cutter, the operator can start a interruption routine. After repairing of the damaged part the automatic program can be restarted at the beginning of a gap. The real manipulator movement will be shown on three video terminals. Additionally, a synthetical two-dimensional representation on a personal computer is available which does not only show the manipulator in the sewers but also the working process and the state of the machine.