Adaptive servomotor control
AssigneeMotorola, Inc.
InventorNicholas W. Andrews
Life of this patent
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Abstract
A servomotor controller provides high speed servomotor positioning be means of an on line adaptive state-feedback control algorithm. Servomotor position and velocity are the feedback states and each has an associated gain selected by means of a servomotor characterization scheme. The mechanical break frequency is used to select optimum gains and a high speed estimation technique is used to determine the mechanical break frequency. Position step change may also be used to select optimum gains. Gain tables are produced by an off-line simulation technique.
Claims3
In a servomotor apparatus of the type comprising a servomotor, a servomotor controller and feedback means for providing feedback from said servomotor to said servomotor controller, the improvement comprising:
- characterization means for periodically evaluating the equation:
- ##EQU18## where Wm is mechanical break frequency, .theta. (t) is motor shaft position with time,
- K.sub.mv .OMEGA. is the back EMF constant of the servomotor,
- E is the voltage input to the servomotor, and
- t is time;
- and
- gain selection means for selecting one of a plurality of gain sets in response to said characterization of said servomotor, said selected gain set being supplied to said servomotor controller.
A servomotor apparatus comprising:
- a servomotor;
- means for selectively applying a drive voltage to said servomotor;
- feedback means for providing indications of a shaft position and a shaft velocity of said servomotor;
- characterization means for periodically evaluating the equation:
- ##EQU19## where W.sub.m is mechanical break frequency, .theta. (t) is motor shaft position with time,
- K.sub.mv .OMEGA. is the back EMF constant of the servomotor,
- E is the voltage input to the servomotor, and
- t is time;
- gain selection means for responding to said characterization means to select one of a plurality of gain sets;
- and
- controller means for receiving said indications of servomotor shaft position and shaft velocity, said selected gain set and a desired servomotor shaft position and for controlling said means for selectively applying a drive voltage in response thereto.
A method of controlling a servomotor comprising the steps of:
- monitoring a difference between an actual state of said servomotor and a desired state thereof;
- estimating a mechanical break frequency of said servomotor by evaluating the equation:
- ##EQU20## where W.sub.m is the mechanical break frequency, .theta. (t) is motor shaft position with time,
- K.sub.mv.OMEGA. is the back EMF constant of the servomotor,
- E is the voltage input to the servomotor, and
- t is time;
- selecting a gain set from a plurality of gain sets responsive to said estimation of said mechanical break frequency;
- applying said gain set to said difference between said desired and actual states of said servomotor;
- determining a drive signal responsive to said application of said gain set to said difference;
- and
- applying said drive signal to said servomotor.
Dependencies are inferred from the claim text.