US3833846A
Expired / Lapsed
US
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Digital velocity sensor for motor braking
Assignee: Unisys Corp
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Filing: 1973-08-30
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Granted: 1974-09-03
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Expires: 1993-08-30
Abstract
Abstract A method and apparatus for digitally controlling the braking energy to a motor so as to eliminate under-shoot or over-shoot. A digital differentiator is used to generate a narrow-width pulse for every rise and fall of a motor tachometer pulse output. The period of these pulses is proportional to the motor velocity and the pulses are used to continuously reset a digital counter. When braking is required, a control flip-flop is ''''set'''' causing braking energy to be sent to the motor by way of a low dissipation digital driver. The duration of application of this braking energy is controlled by the digital counter which is clocked at a rate such that at normal operating speeds for the motor, the counter is reset to begin a new count long before a predetermined count is reached. Once the control flip-flop has been ''''set'''' and the braking energy is being supplied to the motor, the reset pulses from the digital differentiator will be generated less frequently, the counter will be reset less often, and the clock count between successive resets will become greater. Eventually, when the speed of the motor has been substantially reduced and is approaching zero, the counter will be able to reach the predetermined count before being reset and a signal representative of the attainment of this predetermined count is used to ''''reset'''' the control flip-flop thereby turning off the supply of braking energy to the motor.
Inventors
- 👤 T Schmalzriedt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 08:24
CPC Classifications
H; H02; H02P; H02P3/00; H02P3/06
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
109 words
A motor braking control system wherein a motor operating at a normal motor speed is braked in response to the application of a braking current comprising: tachometer means associated with said motor for generating tachometer signals proportional to the speed of said motor; counter means for counting at a fixed predetermined clock rate; means responsive to said tachometer signals for resetting said counter means at a rate sufficient to prevent the attainment of a predetermined count until the speed of said motor has been reduced to a predetermined fraction of said normal motor speed; and means responsive to the attainment of said predetermined count for removing said braking current.
Claim 2
Dependent Claim
109 words
A motor braking control system wherein a motor operating at a normal motor speed is braked in response to the application of a braking current comprising: tachometer means associated with said motor for generating tachometer signals proportional to the speed of said motor; counter means for counting at a fixed predetermined clock rate; means responsive to said tachometer signals for resetting said counter means at a rate sufficient to prevent the attainment of a predetermined count until the speed of said motor has been reduced to a predetermined fraction of said normal motor speed; and means responsive to the attainment of said predetermined count for removing said braking current.
Claim 3
Dependent Claim
60 words
The motor braking control system of claim 1 wherein said means for removing said braking current includes a bistable element operable in a first state to enable the application of braking current to said motor and triggerable to a second state in response to the attainment of said predetermined count for disenabling the application of braking current to said motor.
Claim 4
Dependent Claim
98 words
The motor braking control system of claim 2 wherein said bistable means includes a JK flip-flop and a digital driving means, wherein the output of said JK flip-flop is coupled to said digital driving means, and wherein said digital driving means is responsive to a first state of said JK flip-flop for applying braking current to said motor and to a second state of said JK flip-flop for removing braking current from said motor and wherein said JK flip-flop is responsive to the attainment of said predetermined count for changing from said first state to said second state.
Claim 5
Dependent Claim
18 words
The motor braking control system of claim 1 wherein said counter means includes a clocked binary ripple counter.
Claim 6
Dependent Claim
45 words
The motor braking control system of claim 4 wherein said binary ripple counter includes four JK flip-flop stages and wherein the transition of the final flip-flop stage which occurs on the eighth clock pulse is used to provide said signal representative of the predetermined count.
Claim 7
Dependent Claim
55 words
The motor braking control system of claim 5 wherein said resetting means includes digital differentiator means and wherein the output of said digital differentiator means is fed to the ''''clear'''' input of each of the stages of said binary ripple counter for resetting said counter at a rate proportional to the speed of the motor.
Claim 8
Dependent Claim
39 words
The motor braking control system of claim 6 wherein said digital differentiator means includes: means responsive to said tachometer signals for generating a series of negative-going, narrow-width, reset pulses at each positive and negative transition of the tachometer signals.
Claim 9
Dependent Claim
153 words
The motor braking control system of claim 6 wherein said digital differentiator means includes: means for receiving said tachometer signals from said tachometer signal generator; means for inverting said tachometer signals; a first flip-flop having a first input supplied with said tachometer signals and a second input supplied with inverted tachometer signals and a second flip-flop having its first input supplied with inverted tachometer signals and its second input supplied with said non-inverted tachometer signals; a NAND gate having one input coupled to the high output of said first flip-flop and a second output coupled to said source of inverted tachometer pulses, and a second NAND gate having one input coupled to the high output of said second flip-flop and a second input coupled to said source of non-inverted tachometer pulses; and means for combining the output of said first and second NAND gates for producing said train of negative-going, narrow-width reset pulses.
Claim 10
Dependent Claim
156 words
The motor braking control system of claim 7 wherein said digital differentiator includes: a JK flip-flop; means for supplying a source of tachometer pulses to the ''''J'''' input of said flip-flop; means for supplying inverted tachometer pulses to the ''''K'''' input of said flip-flop; a first NAND gate means coupled to the ''''Q'''' output of said flip-flop and to said source of tachometer signals for generating a negative-going, narrow-width pulse at the leading edge of each of said tachometer pulses; a second NAND gate means coupled to the ''''Q'''' output of said flip-flop and to said source of inverted tachometer pulses for generating a second set of negative-going, narrow-width pulses at the trailing edge of each of said tachometer pulses; and means for combining said first and said second set of signals so as to generate a series of negative-going, narrow-width, reset pulses occurring at both the positive and the negative transitions of said tachometer pulses.
Claim 11
Dependent Claim
119 words
A digital duration controller for determining the duration of application of a braking signal to a servo motor, said controller comprising: means for generating digital tachometer pulses at a rate proportional to the speed of said servo motor; a resettable binary counter operable at a fixed clock rate; digital differentiator means responsive to said tachometer pulses for generating reset pulses at a rate proportional to the speed of said servo motor; and means responsive to a condition existing when the rate of generation of said reset pulses has been reduced to some value indicative of a predetermiend reduction in motor speed and coupled to said counter means for terminating the application of a braking signal to said servo motor.
Claim 12
Dependent Claim
119 words
A digital duration controller for determining the duration of application of a braking signal to a servo motor, said controller comprising: means for generating digital tachometer pulses at a rate proportional to the speed of said servo motor; a resettable binary counter operable at a fixed clock rate; digital differentiator means responsive to said tachometer pulses for generating reset pulses at a rate proportional to the speed of said servo motor; and means responsive to a condition existing when the rate of generation of said reset pulses has been reduced to some value indicative of a predetermiend reduction in motor speed and coupled to said counter means for terminating the application of a braking signal to said servo motor.
Claim 13
Dependent Claim
115 words
In a motor braking system wherein the speed of the motor is reduced by the application of braking energy, a digital circuit for controlling the duration of application of the braking current so as to prevent over-shoot, said digital circuit comprising: means for establishing a predetermined interval of time; means for generating a series of pulses indicative of the speed of the motor; and means responsive to said speed indicative pulses for permitting the continued application of said braking current until the speed of said motor has been substantially reduced and for removing said braking current from said motor whenever one of said speed indicative pulses does not occur in said predetermined interval of time.
Claim 14
Dependent Claim
115 words
In a motor braking system wherein the speed of the motor is reduced by the application of braking energy, a digital circuit for controlling the duration of application of the braking current so as to prevent over-shoot, said digital circuit comprising: means for establishing a predetermined interval of time; means for generating a series of pulses indicative of the speed of the motor; and means responsive to said speed indicative pulses for permitting the continued application of said braking current until the speed of said motor has been substantially reduced and for removing said braking current from said motor whenever one of said speed indicative pulses does not occur in said predetermined interval of time.
Claim 15
Independent Claim
126 words
A method for digitally determining the duration of application of a braking signal to a servo motor comprising the steps of: counting at a fixed clock rate; generating signals indicative of the speed of said servo motor; establishing a timed clock interval such that the occurrence of one of said speed indicative signals during said interval will establish the beginning of a new time interval and the lack of occurrence of one of said speed indicative pulses in said interval will indicate that the speed of the motor has fallen below a predetermined value; monitoring said speed indicative pulses over said established interval; and removing braking energy from the servo motor whenever one of said speed indicative signals does not occur during said established time interval.
Claim 16
Independent Claim
126 words
A method for digitally determining the duration of application of a braking signal to a servo motor comprising the steps of: counting at a fixed clock rate; generating signals indicative of the speed of said servo motor; establishing a timed clock interval such that the occurrence of one of said speed indicative signals during said interval will establish the beginning of a new time interval and the lack of occurrence of one of said speed indicative pulses in said interval will indicate that the speed of the motor has fallen below a predetermined value; monitoring said speed indicative pulses over said established interval; and removing braking energy from the servo motor whenever one of said speed indicative signals does not occur during said established time interval.
Claim 17
Independent Claim
129 words
A method of controlling the duration of application of a braking signal to a servo motor so as to eliminate over-shoot, said method comprising the steps of: providing braking energy to the servo motor; generating signals indicative of the speed of said motor; establishing a predetermined time interval such that the occurrence of a speed indicative pulse within the interval signifies that the motor speed has not been sufficiently reduced to terminate the braking energy; monitoring for the occurrence of one of said speed indicatiVe signals during said established time interval; restarting said time interval in response to the occurrence of one of said speed indicative pulses; and terminating the application of braking energy to said servo motor whenever no speed indicative pulses occur during said established time interval.
Claim 18
Independent Claim
129 words
A method of controlling the duration of application of a braking signal to a servo motor so as to eliminate over-shoot, said method comprising the steps of: providing braking energy to the servo motor; generating signals indicative of the speed of said motor; establishing a predetermined time interval such that the occurrence of a speed indicative pulse within the interval signifies that the motor speed has not been sufficiently reduced to terminate the braking energy; monitoring for the occurrence of one of said speed indicatiVe signals during said established time interval; restarting said time interval in response to the occurrence of one of said speed indicative pulses; and terminating the application of braking energy to said servo motor whenever no speed indicative pulses occur during said established time interval.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-09-02 | 1978-03-04 | 1978-09-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-02 | 1982-03-04 | 1982-09-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-02 | 1986-03-04 | 1986-09-03 | $7700.00 | Window Closed / Lapsed |