Sampled data servo positioning system
First Claim
1. A sampled data servo positioning system for moving a member between a current and a target position comprising:
- an actuator responsive to applied drive signals to move such a member;
a position transducer movable with the member for producing signals in response to motion thereof;
position signal generating means responsive to the position transducer signals to produce at least one incremental position signal representative of the position of the member at sampling times;
a model responsive to an input signal to produce at least one continually available model incremental position signal;
profile signal generating means for generating a profile signal, corresponding to a predetermined velocity profile, as an input signal for the model;
phase comparing means for comparing and indicating the phase difference between the sampled and model position signals at the sampling times;
actuator feedforward signal generating means for generating a feedforward control signal for the actuator corresponding to the predetermined velocity profile;
and stage indicating means for indicating various stages of the motion in accordance with predetermined conditions;
the system being characterized by switching means responsive to the stage indicating means to switch the system between first and second operational configurations, by a source of saturation control signals of opposite polarity for application to the actuator to cause maximum acceleration or deceleration thereof,and by means for deriving a continuous performance signal representative of actuator motion; and
wherein, in the first operational configuration, the switching means connects the saturation control signal source to the actuator and connects a combination of the actuator performance signal as a feedforward input and the position phase difference signal as a feedback input to the model so that the model tracks the actuator system,and wherein, in the second operational configuration, the switching means connects the model input profile signal to the model, and connects a combination of the actuator feedforward control signal as a feedforward input and the position phase difference signal as a feedback input to the actuator so that the actuator tracks the model.
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Abstract
A sampled data servo positioning system employs an actuator to move a member between a current and a target position. Incremental position feedback is provided only at sampling times. The system employs a model responsive to a velocity related input signal to produce a continually available model incremental position signal. Phase comparing means indicates phase differences between the model and sampled position signals at the sampling times.
The system has two operational configurations in the first of which a source of saturation control signals is connected to the actuator to cause maximum acceleration or deceleration thereof. In this first configuration, the model is forced to track the actuator motion by means of feedforward plus feedback control. The feedforward signal represents actuator performance while the feedback signal is the position signal phase difference. In the second operational configuration, a velocity profile signal is applied to the model and the actuator is forced to track the model by means of feedforward plus feedback control. The feedback signal is again the position signal phase difference but the feedforward signal is a predetermined signal representing the desired actuator current to execute the velocity profile. The sampled data servo positioning system may be the access motion control system of a sector servo disk file.
76 Citations
13 Claims
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1. A sampled data servo positioning system for moving a member between a current and a target position comprising:
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an actuator responsive to applied drive signals to move such a member; a position transducer movable with the member for producing signals in response to motion thereof; position signal generating means responsive to the position transducer signals to produce at least one incremental position signal representative of the position of the member at sampling times; a model responsive to an input signal to produce at least one continually available model incremental position signal; profile signal generating means for generating a profile signal, corresponding to a predetermined velocity profile, as an input signal for the model; phase comparing means for comparing and indicating the phase difference between the sampled and model position signals at the sampling times; actuator feedforward signal generating means for generating a feedforward control signal for the actuator corresponding to the predetermined velocity profile; and stage indicating means for indicating various stages of the motion in accordance with predetermined conditions; the system being characterized by switching means responsive to the stage indicating means to switch the system between first and second operational configurations, by a source of saturation control signals of opposite polarity for application to the actuator to cause maximum acceleration or deceleration thereof, and by means for deriving a continuous performance signal representative of actuator motion; and
wherein, in the first operational configuration, the switching means connects the saturation control signal source to the actuator and connects a combination of the actuator performance signal as a feedforward input and the position phase difference signal as a feedback input to the model so that the model tracks the actuator system,and wherein, in the second operational configuration, the switching means connects the model input profile signal to the model, and connects a combination of the actuator feedforward control signal as a feedforward input and the position phase difference signal as a feedback input to the actuator so that the actuator tracks the model. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification