Low force level detection system and method
View Patent ↗A method for estimating a force exerted by a first body onto a second body including the steps of providing a motor having at least one detectable motor signal, wherein the motor is adapted to advance the first body into engagement with the second body, determining a first value for the motor signal prior to the first body engaging the second body, determining a second value for the motor signal after the first body engages the second body, and generating a force value based upon a comparison of the second value to the first value.
1. A method for estimating a force value exerted by a brake pad onto a rotor comprising the steps of:
providing an electric motor;
actuating said electric motor to advance an actuator, said actuator being positioned to advance said brake pad into engagement with said rotor, wherein, upon actuation, said electric motor has a motor current;
determining a first value of said motor current representative of a configuration in which said first body is disengaged from said second body during a no-load state of said electric motor;
determining a second value of said motor current, said second value being different from said first value and representative of a second configuration in which said brake pad is engaged with said rotor during a load state of said electric motor; and
calculating the force value according to
F
0
=
κ
2
(
I
F
0
I
NL
-
1
)
,
wherein κ 2 is a constant and I F0 is said second value of said motor current and I NL is said first value of said motor current.
2. The method of claim 1 wherein said force value is a clamping force.
3. The method of claim 1 wherein said first value is generally constant during said no-load state.
4. The method of claim 1 wherein said motor current increases during said no load state.
5. The method of claim 1 further comprising the step of estimating the thickness of said brake pad based at least upon an original thickness of said brake pad and a distance traveled by said actuator.
6. A brake system comprising:
a rotor positioned between at least two brake pads;
an actuator positioned to engage at least one of said brake pads to apply a clamping force to said rotor;
an electric motor adapted to advance said actuator into selective engagement with at least one of said brake pads;
at least one sensor in electrical communication with said electric motor for measuring a motor current of said electric motor; and
a processor connected to said sensor, said processor being adapted to determine a first value of said motor current representative of a configuration in which said actuator does not engage said at least one of said brake pads and a second value of said motor current representative of a configuration in which said actuator does engage said at least one of said brake pads for calculating a force value according to
F
0
=
κ
2
(
I
F
0
I
NL
-
1
)
,
wherein κ 2 is a constant and I F0 said second value of said motor current and I NL is said first value of said motor current.
7. The system of claim 6 wherein said processor includes said sensor.