Automatic backlash estimation
AssigneeABB AB
InventorTore Hagglund
Life of this patent
Estimating the term…
Abstract
A method is disclosed for automatic estimation of backlash in a control system which includes a controller and a process to be controlled, wherein said controller is capable of performing integrating control of said process using one or more controller parameters to control a process output signal of said process with respect to a setpoint value thereof. The method involves monitoring said process output signal to determine a value reflecting momentary differences between setpoint value and actual value of said process output signal during a time interval; and estimating the backlash from said determined value and said one or more controller parameters.
Claims15
A method for automatic estimation of backlash in a control system which includes a controller and a process to be controlled, wherein said controller is capable of performing integrating control of said process using one or more controller parameters to control a process output signal of said process with respect to a setpoint value thereof, the method being characterized by:
- monitoring said process output signal to determine a value reflecting momentary differences between setpoint value and actual value of said process output signal during a time interval;
- integrating a control error of said process during said time interval and determining said value as
- Δ
-
-
- y
- =
- ∫
- t
- i
- t
- i
- +
- 1
-
-
- e
-
-
- ⅆ
- t
- /
- Δ
-
-
- t
- ,
- where Δt=ti+1−ti and e=ysp−y=(setpoint value of said process output signal)−(actual value of said mass output signal). ;
- and
- estimating the backlash from said determined value and said one or more controller parameters.
An apparatus for automatic estimation of backlash in a control system which includes a controller and a process to be controlled, wherein said controller is capable of performing integrating control of said process using one or more controller parameters to control a process output signal of said process with respect to a setpoint value thereof, the apparatus being characterized by:
- means for monitoring said process output signal to determine a value re\-flecting momentary differences between setpoint value and actual value of said process output signal during a time interval;
- means for integrating a control error of said process during said time interval and determining said value as
- Δ
-
-
- y
- =
- ∫
- t
- i
- t
- i
- -
- 1
-
-
- e
-
-
-
- ⅆ
- t
- /
- Δ
-
-
- t
- ,
- where Δt=ti+1−ti and e=ysp−y=(setpoint value of said process output signal)−(actual value of said process output signal). ;and
- means for estimating the backlash from said determined value and said one or more controller parameters.
A control system having a controller and a process to be controlled, wherein said controller is capable of performing integrating control of said process using one or more controller parameters to control a process output signal of said process with respect to a setpoint value thereof, the control system being characterized by:
- means for monitoring said process output signal to determine a value reflecting momentary differences between setpoint value and actual value of said process output signal during a time interval;
- means for integrating a control error of said process during said time interval and determining said value as
- Δ
-
-
- y
- =
- ∫
- t
- i
- t
- i
- -
- 1
-
-
- e
-
-
-
- ⅆ
- t
- /
- Δ
-
-
- t
- ,
- where Δt=ti+1−ti and e=ysp−y=(setpoint value of said process output signal)−(actual value of said process output signal). ;
- and
- means for estimating the backlash from said determined value and said one or more controller parameters.
A computer program product comprising a non-transitory computer usable medium having computer readable program code stored thereon for execution by a processing device to perform a method of automatic estimation of backlash in a control system which includes a controller and a process to be controlled, wherein said controller is capable of performing integrating control of said process using one or more parameters to control a process output signal of said process with respect to a set-point value thereof, the method being characterized by:
- establishing processing communication between said control system and said processing device to monitor said process,
- monitoring said process output signal to determine a value reflecting momentary differences between a setpoint value and an actual value of said process output signal during a time interval;
- integrating a control error of said process during said time interval and determining said value as
- Δ
-
-
- y
- =
- ∫
- t
- i
- t
- i
- -
- 1
-
-
- e
-
-
-
- ⅆ
- t
- /
- Δ
-
-
- t
- ,
- where Δt=ti+1−ti and e=ysp−y=(setpoint value of said process output signal)−(actual value of said process output signal), ;
- and
- estimating the backlash from said determined value and said one or more controller parameters.
A method for automatic estimation of backlash in a control system which includes a controller and a process to be controlled, wherein said controller is capable of performing integrating control of said process using one or more controller parameters to control a process output signal of said process with respect to a setpoint value thereof, the method being characterized by:
- monitoring said process output signal to determine a value reflecting momentary differences between setpoint value and actual value of said process output signal during a time interval wherein a start time of said time interval is determined by detecting a first zero crossing of said process output signal with respect to its setpoint value, and an end time of said time interval is determined by detecting a second zero crossing of said process output signal with respect to its setpoint value;
- integrating a control error of said process during said time interval and determining said value as
- Δ
-
-
- y
- =
- ∫
- t
- i
- t
- i
- +
- 1
-
-
- e
-
-
-
- ⅆ
- t
- /
- Δ
-
-
- t
- ,
- where Δt=ti+1−ti and e=ysp−y=(setpoint value of said process output signal)−(actual value of said process output signal). ;
- and
- estimating the backlash from said determined value and said one or more controller parameters.
A control system having a controller and a process to be controlled, wherein said controller is capable of performing integrating control of said process using one or more controller parameters to control a process output signal of said process with respect to a setpoint value thereof, the control system being characterized by:
- means for monitoring said process output signal to determine a value reflecting momentary differences between setpoint value and actual value of said process output signal during a time interval wherein a start time of said time interval is determined by detecting a first zero crossing of said process output signal with respect to its setpoint value, and an end time of said time interval is determined by detecting a second zero crossing of said process output signal with respect to its setpoint value;
- means for integrating a control error of said process during said time interval and determining said value as
- Δ
-
-
- y
- =
- ∫
- t
- i
- t
- i
- +
- 1
-
-
- e
-
-
-
- ⅆ
- t
- /
- Δ
-
-
- t
- ,
- where Δt=ti+1−ti and e=ysp−y=(setpoint value of said process output signal)−(actual value of said process output signal). ;
- and
- means for estimating the backlash from said determined value and said one or more controller parameters.
A method for automatic estimation of backlash in a control system which includes a controller and a process to be controlled, wherein said controller is capable of performing integrating control of said process using one or more controller parameters to control a process output signal of said process with respect to a setpoint value thereof,
- the method being characterized by:
- monitoring said process output signal to determine a value reflecting momentary differences between setpoint value and actual value of said process output signal during a time interval;
- and
- estimating the backlash from said determined value and said one or more controller parameters;
- wherein the backlash is estimated as
- d
- ^
- =
- (
- K
- T
- i
-
- Δ
-
-
- t
- -
- 1
- K
- p
- )
-
- Δ
-
-
- y
- ,
- where
- {circumflex over (d)} is an estimation of a deadband caused by the backlash,
- K and Ti are controller parameters used by said controller for performing integrating control of said process,
- Δt is said time interval,
- Δy is said value reflecting momentary differences between setpoint value (ysp) and actual value of said process output signal (y), and
- Kp is a static process gain of said process.
A method for automatic estimation of backlash in a control system which includes a controller and a process to be controlled, wherein said controller is capable of performing integrating control of said process using one or more controller parameters to control a process output signal of said process with respect to a setpoint value thereof,
- the method being characterized by:
- monitoring said process output signal to determine a value reflecting momentary differences between setpoint value and actual value of said process output signal during a time interval;
- and
- estimating the backlash from said determined value and said one or more controller parameters;
- the backlash being caused by a controllable member in the control system, the method involving verifying that a control signal from said controller to said controllable member as well as said process output signal both have rates of change allowing for process dynamics to be neglected;
- wherein the verification is performed by comparing said time interval to a closedloop time constant of said control system, said comparing is performed by approximating said closed-loop time constant with a time constant among said one or more controller parameters and checking whether said time interval exceeds a threshold value calculated by multiplying said time constant with a predetermined constant;
- and
- wherein said step of estimating the backlash is performed only upon successful verification.
Dependencies are inferred from the claim text.