Fan speed algorithm
$begingroup$
I'm a programmer an I think my problem related to mathematics!
I want when CPU have a static percentage of load (for example $10%$) fan also have static rpm (Rotations per minute). But for now I have very change in fan speed when CPU have a static percentage of load.
I try the follow algorithm and have this problem:
if (temp > max_temp)
speed := full_speed
else if (temp < min_temp)
speed := min_speed
else
speed := min_speed +
(full_speed - min_speed)*((temp - min_temp)/(max_temp - min_temp))
optimization algorithms recursive-algorithms algorithmic-game-theory scoring-algorithm
asked Feb 5 '15 at 14:11
DaniyalDaniyal
1092
$endgroup$
add a comment |
$begingroup$
I'm a programmer an I think my problem related to mathematics!
I want when CPU have a static percentage of load (for example $10%$) fan also have static rpm (Rotations per minute). But for now I have very change in fan speed when CPU have a static percentage of load.
I try the follow algorithm and have this problem:
if (temp > max_temp)
speed := full_speed
else if (temp < min_temp)
speed := min_speed
else
speed := min_speed +
(full_speed - min_speed)*((temp - min_temp)/(max_temp - min_temp))
optimization algorithms recursive-algorithms algorithmic-game-theory scoring-algorithm
asked Feb 5 '15 at 14:11
DaniyalDaniyal
1092
$endgroup$
$begingroup$
It appears that this code uses temperature rather than load (which I think is better). How often do you adjust the speed (i.e., run this code)? - And how granular are your temp sensor and your speed actor?
$endgroup$
– Hagen von Eitzen
Feb 5 '15 at 14:14
$begingroup$
@HagenvonEitzen Thanks for your attention, I can't use CPU load because CPU frequency can change (And meaning of cpu load change), I run this code for ever and temp sensor and speed actor acts immediately.
$endgroup$
– Daniyal
Feb 5 '15 at 14:20
add a comment |
$begingroup$
I'm a programmer an I think my problem related to mathematics!
I want when CPU have a static percentage of load (for example $10%$) fan also have static rpm (Rotations per minute). But for now I have very change in fan speed when CPU have a static percentage of load.
I try the follow algorithm and have this problem:
if (temp > max_temp)
speed := full_speed
else if (temp < min_temp)
speed := min_speed
else
speed := min_speed +
(full_speed - min_speed)*((temp - min_temp)/(max_temp - min_temp))
optimization algorithms recursive-algorithms algorithmic-game-theory scoring-algorithm
asked Feb 5 '15 at 14:11
DaniyalDaniyal
1092
$endgroup$
I'm a programmer an I think my problem related to mathematics!
I want when CPU have a static percentage of load (for example $10%$) fan also have static rpm (Rotations per minute). But for now I have very change in fan speed when CPU have a static percentage of load.
I try the follow algorithm and have this problem:
if (temp > max_temp)
speed := full_speed
else if (temp < min_temp)
speed := min_speed
else
speed := min_speed +
(full_speed - min_speed)*((temp - min_temp)/(max_temp - min_temp))
optimization algorithms recursive-algorithms algorithmic-game-theory scoring-algorithm
optimization algorithms recursive-algorithms algorithmic-game-theory scoring-algorithm
asked Feb 5 '15 at 14:11
DaniyalDaniyal
1092
asked Feb 5 '15 at 14:11
DaniyalDaniyal
1092
edited Feb 7 '15 at 6:49
Daniyal
asked Feb 5 '15 at 14:11
DaniyalDaniyal
1092
asked Feb 5 '15 at 14:11
DaniyalDaniyal
1092
asked Feb 5 '15 at 14:11
DaniyalDaniyal
1092
1092
$begingroup$
It appears that this code uses temperature rather than load (which I think is better). How often do you adjust the speed (i.e., run this code)? - And how granular are your temp sensor and your speed actor?
$endgroup$
– Hagen von Eitzen
Feb 5 '15 at 14:14
$begingroup$
@HagenvonEitzen Thanks for your attention, I can't use CPU load because CPU frequency can change (And meaning of cpu load change), I run this code for ever and temp sensor and speed actor acts immediately.
$endgroup$
– Daniyal
Feb 5 '15 at 14:20
add a comment |
$begingroup$
It appears that this code uses temperature rather than load (which I think is better). How often do you adjust the speed (i.e., run this code)? - And how granular are your temp sensor and your speed actor?
$endgroup$
– Hagen von Eitzen
Feb 5 '15 at 14:14
$begingroup$
@HagenvonEitzen Thanks for your attention, I can't use CPU load because CPU frequency can change (And meaning of cpu load change), I run this code for ever and temp sensor and speed actor acts immediately.
$endgroup$
– Daniyal
Feb 5 '15 at 14:20
$begingroup$
It appears that this code uses temperature rather than load (which I think is better). How often do you adjust the speed (i.e., run this code)? - And how granular are your temp sensor and your speed actor?
$endgroup$
– Hagen von Eitzen
Feb 5 '15 at 14:14
$begingroup$
It appears that this code uses temperature rather than load (which I think is better). How often do you adjust the speed (i.e., run this code)? - And how granular are your temp sensor and your speed actor?
$endgroup$
– Hagen von Eitzen
Feb 5 '15 at 14:14
$begingroup$
@HagenvonEitzen Thanks for your attention, I can't use CPU load because CPU frequency can change (And meaning of cpu load change), I run this code for ever and temp sensor and speed actor acts immediately.
$endgroup$
– Daniyal
Feb 5 '15 at 14:20
$begingroup$
@HagenvonEitzen Thanks for your attention, I can't use CPU load because CPU frequency can change (And meaning of cpu load change), I run this code for ever and temp sensor and speed actor acts immediately.
$endgroup$
– Daniyal
Feb 5 '15 at 14:20
add a comment |
1 Answer
1
active
oldest
votes
$begingroup$
This is a control problem rather than mathematics, but as there is no Control SE we might as well discuss it here.
In the absence of limiting you need to adjust the fan speed to achieve whatever you desire, I will assume you wish to control the temperature $c$ to a set value $c_{dem}$ by varying the fan speed $v$.
One of the simplest ways of doing this is using proportional control, this would use approximate knowledge of the relationship between the fan speed and temperature $c=f(v)$, then set the fan speed accordingly. The problem with this is that the relationship between fan speed and temperature is not fixed but depends on a number of factors you don't know, like the ambient temperature and the processor loading.
The next simplest way of approaching this is derivative control (which is what I would recomend), where the rate of change of fan speed is set proportional to the temperature error:$$
v'=k(c-c_{set})
$$
With such a control law the fan speed arrives at a constant value when the temperature error is zero. There is a problem here in choosing an appropriate gain $k$ in that we don't know the relationship between fan speed and temperature. You will probably need to find an acceptable gain by trial and error.
The control law will need to be discretised for use in your code, this should give you something like:$$
v_{new}=v_{old}+k Delta t (c-c_{set})
$$
where $Delta t$ is the control loop update time step.
answered Feb 6 '15 at 9:05
Conrad TurnerConrad Turner
2,8522611
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add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
This is a control problem rather than mathematics, but as there is no Control SE we might as well discuss it here.
In the absence of limiting you need to adjust the fan speed to achieve whatever you desire, I will assume you wish to control the temperature $c$ to a set value $c_{dem}$ by varying the fan speed $v$.
One of the simplest ways of doing this is using proportional control, this would use approximate knowledge of the relationship between the fan speed and temperature $c=f(v)$, then set the fan speed accordingly. The problem with this is that the relationship between fan speed and temperature is not fixed but depends on a number of factors you don't know, like the ambient temperature and the processor loading.
The next simplest way of approaching this is derivative control (which is what I would recomend), where the rate of change of fan speed is set proportional to the temperature error:$$
v'=k(c-c_{set})
$$
With such a control law the fan speed arrives at a constant value when the temperature error is zero. There is a problem here in choosing an appropriate gain $k$ in that we don't know the relationship between fan speed and temperature. You will probably need to find an acceptable gain by trial and error.
The control law will need to be discretised for use in your code, this should give you something like:$$
v_{new}=v_{old}+k Delta t (c-c_{set})
$$
where $Delta t$ is the control loop update time step.
answered Feb 6 '15 at 9:05
Conrad TurnerConrad Turner
2,8522611
$endgroup$
add a comment |
$begingroup$
This is a control problem rather than mathematics, but as there is no Control SE we might as well discuss it here.
In the absence of limiting you need to adjust the fan speed to achieve whatever you desire, I will assume you wish to control the temperature $c$ to a set value $c_{dem}$ by varying the fan speed $v$.
One of the simplest ways of doing this is using proportional control, this would use approximate knowledge of the relationship between the fan speed and temperature $c=f(v)$, then set the fan speed accordingly. The problem with this is that the relationship between fan speed and temperature is not fixed but depends on a number of factors you don't know, like the ambient temperature and the processor loading.
The next simplest way of approaching this is derivative control (which is what I would recomend), where the rate of change of fan speed is set proportional to the temperature error:$$
v'=k(c-c_{set})
$$
With such a control law the fan speed arrives at a constant value when the temperature error is zero. There is a problem here in choosing an appropriate gain $k$ in that we don't know the relationship between fan speed and temperature. You will probably need to find an acceptable gain by trial and error.
The control law will need to be discretised for use in your code, this should give you something like:$$
v_{new}=v_{old}+k Delta t (c-c_{set})
$$
where $Delta t$ is the control loop update time step.
answered Feb 6 '15 at 9:05
Conrad TurnerConrad Turner
2,8522611
$endgroup$
add a comment |
$begingroup$
This is a control problem rather than mathematics, but as there is no Control SE we might as well discuss it here.
In the absence of limiting you need to adjust the fan speed to achieve whatever you desire, I will assume you wish to control the temperature $c$ to a set value $c_{dem}$ by varying the fan speed $v$.
One of the simplest ways of doing this is using proportional control, this would use approximate knowledge of the relationship between the fan speed and temperature $c=f(v)$, then set the fan speed accordingly. The problem with this is that the relationship between fan speed and temperature is not fixed but depends on a number of factors you don't know, like the ambient temperature and the processor loading.
The next simplest way of approaching this is derivative control (which is what I would recomend), where the rate of change of fan speed is set proportional to the temperature error:$$
v'=k(c-c_{set})
$$
With such a control law the fan speed arrives at a constant value when the temperature error is zero. There is a problem here in choosing an appropriate gain $k$ in that we don't know the relationship between fan speed and temperature. You will probably need to find an acceptable gain by trial and error.
The control law will need to be discretised for use in your code, this should give you something like:$$
v_{new}=v_{old}+k Delta t (c-c_{set})
$$
where $Delta t$ is the control loop update time step.
answered Feb 6 '15 at 9:05
Conrad TurnerConrad Turner
2,8522611
$endgroup$
This is a control problem rather than mathematics, but as there is no Control SE we might as well discuss it here.
In the absence of limiting you need to adjust the fan speed to achieve whatever you desire, I will assume you wish to control the temperature $c$ to a set value $c_{dem}$ by varying the fan speed $v$.
One of the simplest ways of doing this is using proportional control, this would use approximate knowledge of the relationship between the fan speed and temperature $c=f(v)$, then set the fan speed accordingly. The problem with this is that the relationship between fan speed and temperature is not fixed but depends on a number of factors you don't know, like the ambient temperature and the processor loading.
The next simplest way of approaching this is derivative control (which is what I would recomend), where the rate of change of fan speed is set proportional to the temperature error:$$
v'=k(c-c_{set})
$$
With such a control law the fan speed arrives at a constant value when the temperature error is zero. There is a problem here in choosing an appropriate gain $k$ in that we don't know the relationship between fan speed and temperature. You will probably need to find an acceptable gain by trial and error.
The control law will need to be discretised for use in your code, this should give you something like:$$
v_{new}=v_{old}+k Delta t (c-c_{set})
$$
where $Delta t$ is the control loop update time step.
answered Feb 6 '15 at 9:05
Conrad TurnerConrad Turner
2,8522611
answered Feb 6 '15 at 9:05
Conrad TurnerConrad Turner
2,8522611
answered Feb 6 '15 at 9:05
Conrad TurnerConrad Turner
2,8522611
answered Feb 6 '15 at 9:05
Conrad TurnerConrad Turner
2,8522611
2,8522611
add a comment |
add a comment |
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$begingroup$
It appears that this code uses temperature rather than load (which I think is better). How often do you adjust the speed (i.e., run this code)? - And how granular are your temp sensor and your speed actor?
$endgroup$
– Hagen von Eitzen
Feb 5 '15 at 14:14
$begingroup$
@HagenvonEitzen Thanks for your attention, I can't use CPU load because CPU frequency can change (And meaning of cpu load change), I run this code for ever and temp sensor and speed actor acts immediately.
$endgroup$
– Daniyal
Feb 5 '15 at 14:20