US4535405A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Control and force-sensing method and apparatus for motors
Assignee: UMI MICROBOT Inc
•
Filing: 1982-09-29
•
Granted: 1985-08-13
•
Expires: 2002-09-29
Abstract
Abstract A method and apparatus for controlling a stepper motor and for force sensing and force control. Stepper motor drive waveforms are provided which are constructed of a sequence of stairsteps, the size and duration thereof being determined as a function of the desired rotational velocity of the stepper motor. Means and a method for accelerating the stepper motor by varying the step size and step duration of the stairsteps in the drive waveform are discussed. Additionally, means and a method are discussed for sensing and controlling the force applied by the stepper motor to a load by way of evaluating the displacement of the actual position of the stepper motor shaft from the commanded or desired position of the shaft. Means and a method for implementing a compliant function in a similar manner are described.
Inventors
- 👤 John W. Hill
- 👤 Anthony J. Sword
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 10:13
CPC Classifications
G; G05; G05B; G05B19/00; G05B19/02; G05B19/18; G05B19/416; G05B19/19; G05B19/40; G05B2219/00; G05B2219/30; G05B2219/41; G05B2219/41189; G05B2219/41208; G05B2219/42; G05B2219/42152; G05B2219/42171; G05B2219/42198; G05B2219/43; G05B2219/43083; G05B2219/45; G05B2219/45083
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
105 words
A method of measuring a torque being applied by the shaft of a brushless motor to a load which is driven by the shaft of the brushless motor, comprising the steps of calibrating the brushless motor for angular displacement versus magnitude of applied load to form a calibration table; commanding the brushless motor to a designated angular position; measuring the actual angular position of the shaft of the brushless motor; determining the angular displacement between the commanded and the actual positions; and converting the angular difference into a torque quantity by obtaining, from the calibration table, the torque quantity which corresponds to the angular difference.
Claim 2
Independent Claim
105 words
A method of measuring a torque being applied by the shaft of a brushless motor to a load which is driven by the shaft of the brushless motor, comprising the steps of calibrating the brushless motor for angular displacement versus magnitude of applied load to form a calibration table; commanding the brushless motor to a designated angular position; measuring the actual angular position of the shaft of the brushless motor; determining the angular displacement between the commanded and the actual positions; and converting the angular difference into a torque quantity by obtaining, from the calibration table, the torque quantity which corresponds to the angular difference.
Claim 3
Dependent Claim
96 words
The method, as recited in claim 1, wherein the calibration step includes the steps of applying a predetermined position command to the brushless motor when the brushless motor shaft is unloaded; determining the actual angular position of the shaft corresponding to the unloaded brushless motor shaft; loading the shaft with a first predetermined load; determining the difference in actual angular position of the shaft which corresponds to the first predetermined load; applying additional loads and determining the corresponding difference in actual angular positions; and forming a calibration table relating load versus difference in actual angular position.
Claim 4
Dependent Claim
72 words
The method, as recited in claim 1, wherein desired displacement data are provided which correspond to the desired force to be applied, further including the steps of a. comparing the angular displacement to the desired displacement data; b. incrementing the commanded position by a predetermined amount in the direction of desired change; and c. repeating steps (a) and (b) until the actual angular displacement is substantially equal to the desired displacement data.
Claim 5
Independent Claim
101 words
A method of measuring a torque being applied by a shaft of a brushless motor to a load which is driven by the shaft of the brushless motor, wherein the brushless motor has been calibrated for angular displacement versus magnitude of applied load to form a calibration table, the method comprising the steps of commanding the brushless motor to a designated angular position; measuring the actual angular position of the shaft of the brushless motor; determining the angular difference between the commanded and the actual positions; and converting the angular difference into a torque quantity which corresponds to the angular displacement.
Claim 6
Independent Claim
101 words
A method of measuring a torque being applied by a shaft of a brushless motor to a load which is driven by the shaft of the brushless motor, wherein the brushless motor has been calibrated for angular displacement versus magnitude of applied load to form a calibration table, the method comprising the steps of commanding the brushless motor to a designated angular position; measuring the actual angular position of the shaft of the brushless motor; determining the angular difference between the commanded and the actual positions; and converting the angular difference into a torque quantity which corresponds to the angular displacement.
Claim 7
Dependent Claim
63 words
The method of claim 4, wherein the position of the brushless motor is changed by way of a series of steps in a drive waveform in which each step commands the brushless motor to a different position, further including the step of repeating the measuring and determining steps for each step in the drive waveform so that a dynamic force measurement is obtained.
Claim 8
Dependent Claim
82 words
The method of claim 4, wherein in the commanding step, the brushless motor is commanded to a position which corresponds to the application of a desired amount of force as defined by the calibration table, further including the steps of repeating the measuring and determining steps; and further determining whether the angular difference is greater than the desired amount of force, so as to detect whether an excessive force is being applied by the shaft of the brushless motor to the load.
Claim 9
Dependent Claim
83 words
The method of claim 4 wherein the brushless motor has been calibrated for angular displacement versus magnitude of applied load for a number of different drive current levels, and futher wherein the commanding step further includes the step of selecting a particular drive current; and further wherein the converting step includes the step of the selecting the torque quantity which corresponds to the angular displacement for the particular drive current being used, so that force measurement with a particular sensitivity can be obtained.
Claim 10
Dependent Claim
12 words
The method of claim 1 wherein the brushless motors are stepper motors.
Claim 11
Dependent Claim
12 words
The method of claim 4 wherein the brushless motors are stepper motors.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-08-12 | 1989-02-11 | 1989-08-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-08-12 | 1993-02-11 | 1993-08-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-08-12 | 1997-02-11 | 1997-08-13 | $7700.00 | Window Closed / Lapsed |