Electricity: motive power systems – Positional servo systems – Digital or numerical systems
Reexamination Certificate
1999-12-01
2001-10-30
Ro, Bentsu (Department: 2837)
Electricity: motive power systems
Positional servo systems
Digital or numerical systems
C318S461000, C324S160000, C324S166000
Reexamination Certificate
active
06310458
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to motion control systems. More particularly, the present invention relates to a method and system for estimating a speed of a moving member in the motion control system.
In many motion control systems (rotary or linear), it is necessary to know the speed or velocity of a moving member in order to properly control the moving member. Typically, speed or velocity is determined as a function of displacement of the moving member. For instance, a position sensor, such as an encoder, provides a periodic output signal as a function of displacement. A first method of determining speed of the moving member includes counting the number of occurrences (e.g., edges of a square wave) in a selected time period. This technique can provide accurate estimates of the speed of the moving member particularly when higher speeds are present. However, when the moving member is traveling at a slow rate of speed, less accurate estimates are obtained.
A second technique of speed estimation includes measuring the time between successive occurrences of the periodic output signal. This technique provides accurate estimates of the velocity of the moving member when the moving member is traveling slowly. However, at higher rates of speed, less accurate results are obtained.
Accordingly, there is an ongoing need to provide an accurate system and method for estimating the speed of a moving member at slow and high rates of speed.
SUMMARY OF THE INVENTION
A system and method for calculating the speed of a moving member having an output device providing an output periodic signal as a function of displacement of the moving member includes measuring a time duration for a plurality of first periodic occurrences of the output periodic signal to occur. A number of second periodic occurrences of the output periodic signal is also counted in a selected time period. A speed of the moving member is calculated as a function of the time duration for the plurality of first periodic occurrences to occur and the number of second periodic occurrences to occur in the selected time period.
REFERENCES:
patent: 4503374 (1985-03-01), Sakano
patent: 4689539 (1987-08-01), Unno et al.
patent: 5073746 (1991-12-01), Sakamoto et al.
patent: 5168220 (1992-12-01), Min
patent: 5231597 (1993-07-01), Komatsu
patent: 5533166 (1996-07-01), Yoshida et al.
Koehler S.
MTS Systems Corporation
Ro Bentsu
Westman Champlin & Kelly P.A.
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