A control system comprising a remote-controlled working machine equipped with a manoeuvrable arm, carrying at its free end a tool (14, 16), the remote-controlled working machine being further equipped with a control computer and a hydraulic control circuit, the control system further comprising a control unit for remote control of the working machine, whereby an operator walks next to the working machine and is in connection, either by cable or wirelessly, with the control computer, the control unit including a pair of control sticks (4a, 4b) and associated buttons (4d, 4e) and knobs that through their influence allow the working machine to be switched between different functional or working modes, whereby the manoeuvrable arm can be caused to carry out desired motions through a number of operating means (31, 32, 33, 34) that are driven hydraulically, that are arranged at the manoeuvrable arm, and that can be influenced by means of the said control sticks (4a, 4b), characterised in that the working machine can be switched through the control unit between two different working modes, comprising: a first mode for manual operation in which the operator controls the motion of the manoeuvrable arm through direct influence of the relevant control sticks (4a, 4b) of the control unit, and a second mode for semi-automatic or fully automatic operation in which the operator, on influence at least one of said relevant control sticks (4a, 4b), causes the manoeuvrable arm to move under parallel guidance along a determined linear course in the horizontal or vertical direction through synchronised control of at least two of the operating means (31, 32) of the manoeuvrable arm following a valve control curve (26a, 26b) for each one of these that is stored in the control computer as software whereby the hydraulic control circuit is provided with means for the adjustment of the parameters of the valve control curves (26a, 26b) during the said operation through the influence of correction factor curves (27a, 27b) that, stored as software in the control computer are selected depending on the weight of the tool (14, 16) that is supported by the working machine. a first mode for manual operation in which the operator controls the motion of the manoeuvrable arm through direct influence of the relevant control sticks (4a, 4b) of the control unit, and a second mode for semi-automatic or fully automatic operation in which the operator, on influence at least one of said relevant control sticks (4a, 4b), causes the manoeuvrable arm to move under parallel guidance along a determined linear course in the horizontal or vertical direction through synchronised control of at least two of the operating means (31, 32) of the manoeuvrable arm following a valve control curve (26a, 26b) for each one of these that is stored in the control computer as software whereby the hydraulic control circuit is provided with means for the adjustment of the parameters of the valve control curves (26a, 26b) during the said operation through the influence of correction factor curves (27a, 27b) that, stored as software in the control computer are selected depending on the weight of the tool (14, 16) that is supported by the working machine.