TECHNICAL FIELD

The present invention relates to a method for controlling propulsion of a drilling rig. The invention also relates to a computer program product comprising program code for a computer for implementing a method according to the invention. The invention also relates to a system for controlling propulsion of a drilling rig and a drilling rig being equipped with such a system.

BACKGROUND

Today there are various platforms having tracks, said platforms being available for various applications. A drilling rig may be an example of such a platform having tracks. Said drilling rig may for an example be arranged for operation on a ground surface. Hereby the drilling rig may be arranged for performing various kinds of construction works.

Said platforms may be controlled by an operator, i.e. a driver may control propulsion and operation of for example tools or machines of the platform from a cabin. Alternatively said platforms may be radio controlled/remote controlled.

Said platform may be arranged for being controlled by means of so called track control. These platforms may be propelled by means of tracks or wheels. Hereby a speed of a track on a first side and speed of a second track on a second side may be controlled manually by means of suitable electronic or mechanical actuator means, for example a steering wheel and an accelerator pedal. The platform may thus be made to turn by applying different speeds of said first track and said second track.

At propulsion of the platform involving making turns various disadvantages may occur. In particular these disadvantages may occur when changing propulsion direction when propulsion is performed on a wet, muddy or sandy surface where relatively large forces are applied by means of the tracks for turning the platform about a rotational axel of the same.

These disadvantages may partly relate to tricky operation of the platform where an operator has to perform gear shifts of a transmission of a platform at same time as he must keep watch for safe propulsion. Further, the driver in some cases also has to consider carried equipment, such as for example drilling devices, during propulsion of said platform. Propulsion of a platform with two tracks may be perceived as complex by an operator, in particular when turning, because a number of work tasks needs to be carried out simultaneously or substantially simultaneously.

These disadvantages may relate to non-desired changes of operation conditions of the platform. These changes of operational conditions may relate to non-desired reduction of a current engine speed of an engine of the platform due to increased load of the platform arising during said changes of propulsion direction. Hereby non-desired stalling of the engine may occur. In certain situations said tracks hereby stop if an increased load of the platform becomes too large.

U.S. Pat. No. 7,290,390 B2 depicts a control device for a hydraulic excavator of crawler type where a slow start is provided during manual operation thereof.

SUMMARY OF THE INVENTION

There is thus a need to in a reliable, user friendly and robust way manage controlling of a platform having two tracks for propulsion of the platform.

One object of the present invention is to provide a new and advantageous method for controlling propulsion of a drilling rig.

Another object of the invention is to provide a novel and advantageous system for controlling propulsion of a drilling rig and a new and advantageous computer program for controlling propulsion of a drilling rig.

Yet another object of the invention is to provide an alternative method, an alternative system and an alternative computer program for controlling propulsion of a drilling rig.

Yet another object of the invention is to provide a user friendly method for achieving reliable propulsion of a drilling rig, where hazard for stalling and/or interruption of tracks during propulsion is reduced.

Yet another object of the invention is to provide a method, a system and a computer program for improving performance of a so called crawler type drilling rig.

Some of said objects are achieved by a method for controlling propulsion of a drilling rig according to claim 1. Other objects are achieved by a system for controlling propulsion of a drilling rig according to claim 9. Advantageous embodiments are depicted in the dependent claims.

According to an aspect of the invention there is provided a method for controlling propulsion of the drilling rig, said drilling rig comprising right propulsion means and left propulsion means and mutually independent speed control and a transmission for driving said right propulsion means and left propulsion means, said transmission providing at least two gear states, comprising the steps of:

- requesting propulsion speed for said right propulsion means and for said left propulsion means;
- determining a difference between requested propulsion speed of said right propulsion means and said left propulsion means;
- determining a suitable gear state on the basis of the thus determined difference.

Said at least two gear states is according to an example provided at a gearbox.

Hereby is achieved a reliable and user friendly method for controlling propulsion of a drilling rig. During turning of said drilling rig a suitable, lower, gear state may be determined for allowing automatic downshifting of a transmission of the drilling rig. In this way an operator may be relieved and hereby gain better possibilities for identifying movable or fixed objects or persons in a surrounding of the drilling rig. Hereby the drilling rig may be propelled in a safer way.

Advantageously the number of work tasks is reduced for an operator of the drilling rig, which provides a better working environment and less stress.