IPIDController
Inherits: IAuthorizable, IModifiable
Functions
seedProposer
Returns the address allowed to call computeRate method
function seedProposer() external view returns (address _seedProposer);
params
Getter for the contract parameters struct
function params() external view returns (PIDControllerParams memory _pidParams);
Returns
| Name | Type | Description |
|---|---|---|
_pidParams | PIDControllerParams | The PID controller parameters struct |
_params
Getter for the unpacked contract parameters struct
function _params()
external
view
returns (
uint256 _integralPeriodSize,
uint256 _perSecondCumulativeLeak,
uint256 _noiseBarrier,
uint256 _feedbackOutputUpperBound,
int256 _feedbackOutputLowerBound
);
Returns
| Name | Type | Description |
|---|---|---|
_integralPeriodSize | uint256 | The minimum delay between two computeRate calls |
_perSecondCumulativeLeak | uint256 | The per second leak applied to priceDeviationCumulative before the latest deviation is added [ray] |
_noiseBarrier | uint256 | The minimum percentage deviation from the redemption price that allows the contract to calculate a non null redemption rate [wad] |
_feedbackOutputUpperBound | uint256 | The maximum value allowed for the redemption rate [ray] |
_feedbackOutputLowerBound | int256 | The minimum value allowed for the redemption rate [ray] |
deviationObservation
Returns the last deviation observation, containing latest timestamp, proportional and integral terms
function deviationObservation() external view returns (DeviationObservation memory __deviationObservation);
Returns
| Name | Type | Description |
|---|---|---|
__deviationObservation | DeviationObservation | The last deviation observation struct |
_deviationObservation
Raw data about the last deviation observation
function _deviationObservation() external view returns (uint256 _timestamp, int256 _proportional, int256 _integral);
Returns
| Name | Type | Description |
|---|---|---|
_timestamp | uint256 | The timestamp when this observation was stored |
_proportional | int256 | The proportional term stored in this observation |
_integral | int256 | The integral term stored in this observation |
controllerGains
Returns the Kp and Ki values used in this calculator
The values are expressed in WAD, Kp stands for proportional and Ki for integral terms
function controllerGains() external view returns (ControllerGains memory _cGains);
_controllerGains
Raw data about the Kp and Ki values used in this calculator
function _controllerGains() external view returns (int256 _kp, int256 _ki);
Returns
| Name | Type | Description |
|---|---|---|
_kp | int256 | This value is multiplied with the proportional term |
_ki | int256 | This value is multiplied with priceDeviationCumulative |
getBoundedRedemptionRate
Return a redemption rate bounded by feedbackOutputLowerBound and feedbackOutputUpperBound as well as the timeline over which that rate will take effect
function getBoundedRedemptionRate(int256 _piOutput) external view returns (uint256 _redemptionRate);
Parameters
| Name | Type | Description |
|---|---|---|
_piOutput | int256 | The raw redemption rate computed from the proportional and integral terms |
Returns
| Name | Type | Description |
|---|---|---|
_redemptionRate | uint256 | The bounded redemption rate |
computeRate
Compute a new redemption rate
function computeRate(uint256 _marketPrice, uint256 _redemptionPrice) external returns (uint256 _redemptionRate);
Parameters
| Name | Type | Description |
|---|---|---|
_marketPrice | uint256 | The system coin market price |
_redemptionPrice | uint256 | The system coin redemption price |
Returns
| Name | Type | Description |
|---|---|---|
_redemptionRate | uint256 | The computed redemption rate |
getGainAdjustedPIOutput
Apply Kp to the proportional term and Ki to the integral term (by multiplication) and then sum P and I
function getGainAdjustedPIOutput(
int256 _proportionalTerm,
int256 _integralTerm
) external view returns (int256 _piOutput);
Parameters
| Name | Type | Description |
|---|---|---|
_proportionalTerm | int256 | The proportional term |
_integralTerm | int256 | The integral term |
Returns
| Name | Type | Description |
|---|---|---|
_piOutput | int256 | The sum of P and I |
getGainAdjustedTerms
Independently return and calculate P * Kp and I * Ki
function getGainAdjustedTerms(
int256 _proportionalTerm,
int256 _integralTerm
) external view returns (int256 _proportionalGain, int256 _integralGain);
Parameters
| Name | Type | Description |
|---|---|---|
_proportionalTerm | int256 | The proportional term |
_integralTerm | int256 | The integral term |
Returns
| Name | Type | Description |
|---|---|---|
_proportionalGain | int256 | The proportional gain |
_integralGain | int256 | The integral gain |
getNextDeviationCumulative
Compute a new priceDeviationCumulative (integral term)
function getNextDeviationCumulative(
int256 _proportionalTerm,
uint256 _accumulatedLeak
) external returns (int256 _priceDeviationCumulative, int256 _timeAdjustedDeviation);
Parameters
| Name | Type | Description |
|---|---|---|
_proportionalTerm | int256 | The proportional term (redemptionPrice - marketPrice) |
_accumulatedLeak | uint256 | The total leak applied to priceDeviationCumulative before it is summed with the new time adjusted deviation |
Returns
| Name | Type | Description |
|---|---|---|
_priceDeviationCumulative | int256 | The new priceDeviationCumulative |
_timeAdjustedDeviation | int256 | The new time adjusted deviation |
breaksNoiseBarrier
Returns whether the P + I sum exceeds the noise barrier
function breaksNoiseBarrier(uint256 _piSum, uint256 _redemptionPrice) external view returns (bool _breaksNb);
Parameters
| Name | Type | Description |
|---|---|---|
_piSum | uint256 | Represents a sum between P + I |
_redemptionPrice | uint256 | The system coin redemption price |
Returns
| Name | Type | Description |
|---|---|---|
_breaksNb | bool | Whether the P + I sum exceeds the noise barrier |
getNextRedemptionRate
Compute and return the upcoming redemption rate
function getNextRedemptionRate(
uint256 _marketPrice,
uint256 _redemptionPrice,
uint256 _accumulatedLeak
) external view returns (uint256 _redemptionRate, int256 _proportionalTerm, int256 _integralTerm);
Parameters
| Name | Type | Description |
|---|---|---|
_marketPrice | uint256 | The system coin market price |
_redemptionPrice | uint256 | The system coin redemption price |
_accumulatedLeak | uint256 | The total leak applied to priceDeviationCumulative before it is summed with the proportionalTerm |
Returns
| Name | Type | Description |
|---|---|---|
_redemptionRate | uint256 | The upcoming redemption rate |
_proportionalTerm | int256 | The upcoming proportional term |
_integralTerm | int256 | The upcoming integral term |
timeSinceLastUpdate
Returns the time elapsed since the last computeRate call
function timeSinceLastUpdate() external view returns (uint256 _timeSinceLastValue);
Events
UpdateDeviation
Emitted when the state of the controller is updated
event UpdateDeviation(int256 _proportionalDeviation, int256 _integralDeviation, int256 _deltaIntegralDeviation);
Parameters
| Name | Type | Description |
|---|---|---|
_proportionalDeviation | int256 | The new proportional term |
_integralDeviation | int256 | The new integral term |
_deltaIntegralDeviation | int256 | The delta between the new and the previous integral term |
Errors
PIDController_OnlySeedProposer
Throws if the caller of updateRate is not the seed proposer
error PIDController_OnlySeedProposer();
PIDController_ComputeRateCooldown
Throws if the call to updateRate is too soon since last update
error PIDController_ComputeRateCooldown();
PIDController_CannotSetPriceDeviationCumulative
Throws when trying to set the integral term with the integral gain set on
error PIDController_CannotSetPriceDeviationCumulative();
Structs
PIDControllerParams
struct PIDControllerParams {
uint256 integralPeriodSize;
uint256 perSecondCumulativeLeak;
uint256 noiseBarrier;
uint256 feedbackOutputUpperBound;
int256 feedbackOutputLowerBound;
}
DeviationObservation
struct DeviationObservation {
uint256 timestamp;
int256 proportional;
int256 integral;
}
ControllerGains
struct ControllerGains {
int256 kp;
int256 ki;
}