This invention relates inter alia to a motion generator which comprises: an end effector; a stationary support having a base; at least one first tensile member, and at least six second tensile members, wherein each of the at least one first tensile member and the at least six second tensile members comprises a elastic element and each of which tensile members being attached at one end thereof to the end effector and being attached at the other end thereof to the stationary support; in which each tensile member applies a tensile force between the end effector and the stationary support, and in which each one of the at least six tensile members is independently adjustably tensioned by an actuator fixed to the stationary support which acts on the tensile member at a point along its length between the end effector and the elastic element, wherein the actuator acts to change the tension in the part of the tensile member between the end effector and the actuator in order to affect the forces and moments applied to the end effector by the system, wherein the actuator reacts the tensile force it applies to the tensile member against the stationary support, and wherein the tensile force applied by each tensile member to the end effector reacts against the tensile forces applied by the other tensile members via the end effector such that the end effector is maintained in suspension and out of contact with the stationary support by the tensile forces in the tensile members and any other forces applied to the end effector.