Sensor for measuring angular position, and measurement compensation method
View Patent ↗Method for compensating a reference measurement including a measurement of angular position α and a measurement of time T 1 that are simultaneous at the time t 1 , for an angular position sensor of the type including a toothed wheel, includes the following steps: determination of a first measurement α of corresponding angular position at the moment in time t 1 when a reference measurement is desired; triggering of a software acquisition function; substantially simultaneous acquisitions of a second measurement α′ of the angular position and of a measurement T 2 of the time by software acquisition at a time t 2 ; estimation of an error ΔT; and calculation of the compensated measurement of time, T 1 =T 2 −ΔT. A Sensor for measuring angular position, of the type including a toothed wheel, implementing such a compensation method is described.
1. A method of determining an angular position of a crankshaft of an internal combustion engine at a first moment in time t 1 when a reference measurement is desired, using an angular position sensor that includes a toothed wheel driven by the crankshaft, the method comprising the steps of:
causing the angular position sensor to generate and store, in a memory accessible to a processing unit, a first measurement α of the angular position of the crankshaft at the first moment in time t 1 ;
triggering a software acquisition function carried out by the processing unit, the software acquisition function including:
causing the angular position sensor to generate and store, in the memory accessible to the processing unit a second measurement α′ of the angular position of the crankshaft at a second moment in time t 2 , the second measurement α′ taking place after the generation of the first measurement α, and
acquiring, from a time signal generator in communication with the processing unit, a second time value T 2 corresponding to the second moment of time t 2 of the generation of the second measurement α′;
calculating an estimated a time error ΔT between the second time value T 2 of the generation of the second measurement α′ and a first time value T 1 that corresponds to the first moment in time t 1 of the first measurements α;
calculating of the measurement of the first time value t 1 , as T 1 =T 2 −ΔT;
determining the calculated first time value T 1 as a measurement of the first moment of time T 1 at which the first measurement α of the angular position of the crankshaft occurred, and using the first time value T 1 and the first measurement α to allow a mechanical movement of the internal combustion engine to be synchronized with the engine controller for controlling operative events of the internal combustion engine.
2. The method as claimed in claim 1 , where the determination of the first measurement of angular position α comprises a hardware acquisition carried out by a hardware device performing an acquisition of the value of angular position at the moment in time t 1 when a reference measurement is desired, and a software read of said measurement of angular position α thus acquired.
3. The method as claimed in claim 2 , wherein said angular position sensor, at the first moment in time t 1 , generates an interrupt that triggers the software acquisition function.
4. The method as claimed in claim 1 , where the estimated time error ΔT=T 2 −T 1 is calculated according to the formula:
Δ
T
=
Δ
α
Res_dent
*
Dur_dent
,
with:
ΔT corresponding to Δt, which represents the difference between the first moment in time t 1 and the second moment in time t 2 ,
Dur_dent=duration of one tooth of the toothed wheel of the crankshaft,
Res_dent= an angular resolution of the one tooth, calculated as 360° divided by a number of teeth in said toothed wheel, and
Δα= the difference in angular position between a value of angular position at the first moment in time t 1 and a value of angular position at the second moment in time t 2 .
5. A sensor for measuring an angular position of a crankshaft of an internal combustion engine, comprising:
a toothed wheel;
an angular position sensor configured to operate with the toothed wheel to generate a first measurement of an angular position α of the engine within a cycle of the engine at a first moment in time t 1 ; and
a processing device, in a communication with the angular position sensor, configured to carry out the functions of:
carrying out triggering a software acquisition function, including:
acquiring, by way of the measurement sensor and the toothed wheel, a second measurement α′ of the angular position of the crankshaft at a moment in time t 2 , and
acquiring a measurement of a second time value T 2 from a time counter, corresponding to the second moment in time t 2 of acquisition of the second measurement α′;
calculating an estimated time error ΔT between the second time value T 2 , and a first time value T 1 that corresponds to the first moment in time t 1 of the angular position α of the first measurement; and
calculating the first time value T 1 , as T 1 =T 2 −ΔT;
determining the calculated first time value T 1 as a measurement of the first moment of time t 1 at which the first measurement α of the angular position of the crankshaft occurred, and using the first time value T 1 and the first measurement α to allow a mechanical movement of the internal combustion engine to be synchronized with the engine controller for controlling operative events of the internal combustion engine.