Offshore assembly comprising a motion compensation platform carrying an object with a height of 30-50 meters or more, motion compensation platform, as well as use of the assembly

An assembly comprising:

• a vessel,
• an object with a vertical height of at least 30 metres, such as 30-50 metres or higher,
• a motion compensation platform, comprising:
• a base which is attachable to a vessel, and
• a bearing frame on which the object is placeable or has been placed,
• wherein the platform furthermore comprises:
• an x-y actuator system configured to rotate the bearing frame with respect to the base about an x-axis and a y-axis, wherein the x-axis, the y-axis and a vertical z-axis together define an imaginary system of orthogonal axes;
• a sensor system configured to i) detect:
• an x-axis rotating movement, and
• a y-axis rotating movement,
• and to ii) generate a sensor signal which is representative of an x-axis rotating movement and a y-axis rotating movement which the base is subjected to due to water movement;
• and
• an x-y control system configured to generate an x-y control signal in response to the received sensor signal in order to actuate the x-y actuator system in such a way that the position of the bearing frame with respect to the base is adjusted;
• wherein the platform is mounted on the vessel and the object is situated on the bearing frame with its vertical height extending in the z-direction,
• wherein the bearing frame is supported at a vertical distance above the base by means of a three-point support, which three-point support consists of a first support, a second support and a third support;
• wherein the first support of the three-point support is a hinged, fixed support, which first, fixed support comprises a first hinge and is configured to:
• during the movement-compensating operation of the platform, define a predetermined fixed distance between the bearing frame and the base at the location of the first, fixed support, and
• by means of the first hinge, allow an x-axis rotating movement and a y-axis rotating movement of the bearing frame with respect to the base;
• wherein the second and the third support of the three-point support each comprise a hinged support which is telescopic in the longitudinal direction of the z-axis, which telescopic supports form part of the x-y actuator system and are configured to be able to adjust the vertical distance between the bearing frame and the base at the location of the respective telescopic support, actuated by the x-y control signal, in such a way that the angular position of the bearing frame with respect to the base changes in order to be able to counteract changes in the angular position of the bearing frame with respect to the x-y plane;
• wherein, at the top side of the object, the object is provided with a load engagement point;
• wherein the assembly furthermore comprises:
• a crane which is fixed with respect to the fixed world and is provided with a gripper configured for picking up the object at the load engagement point, and
• a heave compensator comprising:
• a z-actuator configured to:
• move the gripper with respect to the fixed world, or
• move the load engagement point with respect to the object;
• a z-sensor configured for detecting a z-axis movement of the gripper with respect to the load engagement point in the direction of the z-axis and for generating a z-sensor signal which is representative of the detected z-axis movement;
• a z-control system which is configured to generate, when the gripper is within a predetermined distance of the load engagement point and/or of the vessel, a z-control signal in response to the z-sensor signal which actuates the z-actuator in such a way that the object is prevented from hitting the gripper, due to the z-axis movement.