Method for modelling an external object (14, 17) with a hand-guided robot having a jointed arm with at least one joint, and an end effector connected to one end of the arm, comprising the following steps: - measuring a total moment at each joint of the arm affecting the robot while the robot is being hand-guided and subjected to a mechanical tension due to contact with an external object (14, 17), the mechanical tension influencing a motion of the jointed arm or the end effector, - based on the measured at least one moment determining at least one external moment caused by the mechanical tension and/or a force exerted by a user for hand-guiding the robot and affecting the robot, - computing a positional correction factor for a position of the end effector based on the at least one external moment and a simplified model of the robot, wherein the simplified model assumes that the robot can move freely and unhindered, - while the robot is still in contact with the external object (14, 17) computing a current position of the end effector based on a correction model in dependence on the positional correction factor, wherein the correction model uses the positional correction factor to specify a difference between the objective current position of the end effector and a calculated position of the end effector, characterized by the following steps: - determining the position of the external object based on the computed current position of the end effector, - moving the end effector sequentially into contact with the external object (14, 17) in multiple different contact points (15, 16), - computing the respective current position of the end effector in each of the multiple different contact points, and - virtually modelling the external object (14, 17) based on the multiple computed respective current positions. - measuring a total moment at each joint of the arm affecting the robot while the robot is being hand-guided and subjected to a mechanical tension due to contact with an external object (14, 17), the mechanical tension influencing a motion of the jointed arm or the end effector, - based on the measured at least one moment determining at least one external moment caused by the mechanical tension and/or a force exerted by a user for hand-guiding the robot and affecting the robot, - computing a positional correction factor for a position of the end effector based on the at least one external moment and a simplified model of the robot, wherein the simplified model assumes that the robot can move freely and unhindered, - while the robot is still in contact with the external object (14, 17) computing a current position of the end effector based on a correction model in dependence on the positional correction factor, wherein the correction model uses the positional correction factor to specify a difference between the objective current position of the end effector and a calculated position of the end effector, - determining the position of the external object based on the computed current position of the end effector, - moving the end effector sequentially into contact with the external object (14, 17) in multiple different contact points (15, 16), - computing the respective current position of the end effector in each of the multiple different contact points, and - virtually modelling the external object (14, 17) based on the multiple computed respective current positions.