Position encoder

1. Position encoder ( 1 ) for measuring a position containing:

a position sensor ( 2 ) configured to provide electrical signals representing angular position,

a measuring device for measuring the electrical signals and configured to output at least one electrical position signal representing the position, and

signal processing means ( 3 ) configured to process the position signal,

wherein the signal processing means ( 3 ) comprise at least a speed estimator ( 5 ) configured to output an estimated speed and a dynamic speed limiter ( 7 ) configured to limit a change in the position signal depending on the estimated speed by calculating a range of position values possible at a current speed, the dynamic speed limiter connected in parallel to the speed estimator ( 5 ),

and wherein the position signal is processed in parallel by the speed estimator ( 5 ) and the dynamic speed limiter ( 7 ).

2. The encoder ( 1 ) according to claim 1 , wherein the speed estimator ( 5 ) comprises a first differentiator ( 51 ) configured to calculate the current speed from the position signal.

3. The encoder ( 1 ) according to claim 2 , wherein the speed estimator ( 5 ) comprises a dynamic slope filter ( 53 ) connected in series to the first differentiator ( 51 ) and is configured to provide a noise reduced speed signal.

4. The encoder ( 1 ) according to claim 1 , wherein the speed limiter ( 7 ) comprises a dynamic clamping means ( 71 ), having clamping limits determined from the output of the speed estimator ( 5 ), and configured to limit changes in the position signal depending on the estimated speed.

5. The encoder ( 1 ) according to claim 4 , wherein the speed limiter ( 7 ) comprises a second differentiator ( 73 ) configured to receive the position signal and directly connected to an input of the dynamic clamping means ( 71 ).

6. The encoder ( 1 ) according to claim 5 , wherein the speed limiter ( 7 ) further comprises an integrator ( 75 ), connected in series to the dynamic clamping means ( 71 ), and configured to output a noise reduced position signal.

7. The encoder ( 1 ) according to claim 1 , wherein the signal processing means ( 3 ) further comprises correction means ( 9 ) configured to compensate for errors occurring within the speed limiter ( 7 ).

8. The encoder ( 1 ) according to claim 7 , wherein the correction means ( 9 ) is a closed loop comprising at least a proportional plus integral controller ( 91 ).

9. The encoder ( 1 ) according to claim 3 , wherein the dynamic slope filter ( 53 ) has a transfer function depending on an error occurring in the speed limiter ( 7 ).

10. The encoder ( 1 ) according to claim 1 , wherein the signal processing means ( 3 ) further comprises a lag compensator ( 11 ) configured to compensate for a signal delay occurring within the dynamic clamping means.

11. The encoder ( 1 ) according to claim 10 , wherein the lag compensator ( 11 ) is configured to calculate a sum of a noise reduced, error compensated position signal and a noise reduced speed signal multiplied by a first predefined factor Kc.

12. The encoder ( 1 ) according to claim 3 , wherein the dynamic slope filter ( 53 ) is a dynamic low pass filter having a time constant depending on an error occurring in the speed limiter ( 7 ).

13. The encoder ( 1 ) according to claim 12 , further comprising an absolute value means ( 55 ) configured to process the error signal including multiplying the error signal by a predefined second factor Ks and feed the processed error signal to the dynamic low pass filter ( 53 ).

14. The encoder ( 1 ) according to claim 1 , further comprising a dynamic position filter ( 13 ), configured to receive the noise reduced position signal, and having a time constant depending on an output of squaring means ( 133 ) configured to receive the current speed, and wherein an output of the dynamic position filter is multiplied by a predefined third factor Kq.