Method and device for weight compensation in a mechanism with closed kinematic chains
AssigneeSiemens Aktiengesellschaft
InventorsThomas Puchtler, Dirk Staimer
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Abstract
The aim of the invention is to compensate for the position-dependent length changes caused by the effect of weight in a variety of closed kinematic chains (K1 . . . Kn), for connecting a stationary first element (E1) to a movable second element (E2). Said aim is achieved, by using a back transformation (Λ−1), which determines a compensation value for each length change (dq1, dq2 . . . dqn), resulting from the application of the weight (Fg) impinging on the movable element (E2) in each kinematic chain.
Claims10
A method of compensating for position-dependent length changes (dq1, dq2 . . . dqn) caused by the effect of weight in a plurality (n) of closed kinematic chains (K1 . . . Kn) for connecting a stationary first element (E1) to a movable second element (E2), on which a weight (Fg) acts, respective actuators (A1 . . . An) being assigned to the kinematic chains (K1 . . . Kn), via which a relative movement between the first (E1) and the second element (E2) is predefined in a freely definable sequence of control instructions, by the respective positions (q) of the respective actuators (A1 . . . An) required for desired positions (x;
- E2A, E2B) of the movable element (E2) being determined via a back transformation (Λ−1), characterized in that
- by using these transformation rules, the weight (Fg) acting on the movable element (E2) is distributed to the respective kinematic chains (K1 . . . Kn) and in this way the forces (F1, F2 . . . Fn;
- τ1 . . . τn) caused therein are determined,
- in accordance with a respective compliance (G) of the kinematic chains (K1 . . . Kn), the resultant respective length changes (dq1, dq2 . . . dqn) are determined and
- the respective actuators (A1 . . . An) are acted on with a respective compensation value which compensates for the respective length change (dq1, dq2 . . . dqn) determined.
A three-dimensional coupling mechanism having a plurality (n) of closed kinematic chains (K1 . . . Kn) for connecting a stationary frame platform (P1) to a movable working platform (P2), each kinematic chain (K1 . . . Kn) being associated with at least one driven axis (A1 . . . An), for carrying out a relative movement between the stationary frame platform (P1) and the movable working platform (P2), having a control unit (S) which has computing means (R) for the back transformation (Λ−1) of the respective positions (q) of the respective axes (A1 . . . An) required for desired positions (x;
- E2A, E2B) of the movable working platform (P2), characterized in that the computing means (R) are configured in such a way that
- by using these transformation rules, the weight (Fg) acting on the moved element (E2) can be distributed to the respective kinematic chains (K . . . Kn) and in this way the forces (F1, F2 . . . Fn;
- τ1 . . . τn) caused therein can be determined,
- in accordance with a respective compliance (G) of the kinematic chains (K1 . . . Kn), the resultant respective length changes (dq1, dq2 . . . dqn) can be determined and
- the respective axes (A1 . . . An) can be acted on with a respective compensation value which compensates for the respective length change (dq1, dq2 . . . dqn) determined.
Dependencies are inferred from the claim text.