An arrangement for determining the calibration position of a robot joint where the joint has a moveable joint element and a stationary joint element, where one of the joint elements has a holding structure and the other a force providing protrusion, a robot controller, a motor connected between the robot controller and the moveable joint element and a force receiving element adapted to form a kinematic coupling with the holding structure and the force providing protrusion, where the kinematic coupling has at least two areas of contact between the structure and the force receiving element and one area of contact between the force providing protrusion and the force receiving element, the force receiving element being fastenable to the holding structure for stretching out across a gap between the two robot joint elements for receiving a force from the force providing protrusion.

A method of calibrating a delta robot, the method including executing an arm movement by moving one driving link relative to other two driving links; measuring a movement of a point in fixed relationship with a tilting body during the arm movement as an arm measurement; executing a tilting movement by tilting the tilting body about a fifth axis; measuring a movement of the point during the tilting movement as a tilting measurement; and calibrating a fourth axis based on a comparison of the arm measurement and the tilting measurement. A method of calibrating the fifth axis, a control system, and a robot system are also provided.

An arrangement for determining the calibration position of a robot joint where the joint has a moveable joint element and a stationary joint element, where one of the joint elements has a holding structure and the other a force providing protrusion, a robot controller, a motor connected between the robot controller and the moveable joint element and a force receiving element adapted to form a kinematic coupling with the holding structure and the force providing protrusion, where the kinematic coupling has at least two areas of contact between the structure and the force receiving element and one area of contact between the force providing protrusion and the force receiving element, the force receiving element being fastenable to the holding structure for stretching out across a gap between the two robot joint elements for receiving a force from the force providing protrusion.

A robot includes an actuator that changes an angle of a second member relative to a first member in accordance with a command value. In a first step of an angle calibration method, a measurement object distance is obtained by measuring a distance between wall surfaces of the two measurement object portions, the measurement being made while the actuator is given an arbitrary command value. In a second step, an angular difference is obtained by calculation, the angular difference corresponding to a difference in distance between two measurement object portions, the calculation being made based on a reference measurement object distance obtained in the past and the measurement object distance obtained in the first step, the reference measurement object distance having been obtained by measuring the measurement object distance while the actuator was given an arbitrary command value.