Method of estimating the corner accelerations of a vehicle based on signals provided by an imu

A method for obtaining at least one signal indicative of an acceleration {umlaut over (z)}10f at least one corner i of a vehicle,

• wherein said vehicle comprises an IMU configured to provide at least four signals, a first signal az representative of an acceleration of said IMU along a vertical axis passing through said IMU, a second signal ωx representative of an angular velocity of said IMU around a longitudinal axis passing through said IMU and perpendicular to said vertical axis, a third signal ωy representative of an angular velocity of said IMU around a transverse axis passing through said IMU and perpendicular to said vertical axis and to said longitudinal axis, and a fourth signal oz representative of an angular velocity of said IMU about said vertical axis;
• wherein said at least one corner i has a relative position [xi, yi, zi]T with respect to said IMU defined as a function of said longitudinal axis, transverse axis and vertical axis and is connected, substantially in a rigid way, to said IMU;
• wherein said acceleration {umlaut over (z)}i is directed along an axis parallel to said vertical axis passing through said relative position [xi, yi, zi]T of said at least one corner i;
• said method comprising the steps of:
• a. filtering said first signal az with a band pass filter to obtain a first filtered signal
• a
• z
• bp
• ;
• b. filtering said second signal ωx with a derivative filter to obtain the angular acceleration {dot over (ω)}x around the longitudinal axis;
• c. filtering said third signal ωy with said derivative filter to obtain angular acceleration {dot over (ω)}y around the transverse axis;
• d. calculating, for each corner i, a fifth signal {umlaut over (z)}idiff representative of the relative motion of the corner i with respect to the IMU, wherein said fifth signal {umlaut over (z)}idiff is calculated, by means of the kinematic equations of the rigid body, namely as
• z
• ¨
• i
• diff
• =
• [
• -
• ω
• .
• y
• +
• ω
• x
• ⁢
• ω
• z
• ω
• .
• x
• +
• ω
• y
• ⁢
• ω
• z
• -
• ω
• y
• 2
• -
• ω
• x
• 2
• ]
• ×
• [
• x
• i
• ,
• y
• i
• ,
• z
• i
• ]
• T
• =
• -
• x
• i
• ⁢
• ω
• .
• y
• +
• y
• i
• ⁢
• ω
• .
• x
• -
• z
• i
• ⁢
• ω
• y
• 2
• +
• y
• i
• ⁢
• ω
• y
• ⁢
• ω
• z
• -
• z
• i
• ⁢
• ω
• x
• 2
• +
• x
• i
• ⁢
• ω
• x
• ⁢
• ω
• z
• ;
• And
• e. calculating, for each corner i, said acceleration {umlaut over (z)}i of said at least one corner i as the sum between said first filtered signal
• a
• z
• bp
• and said fifth signal {umlaut over (z)}idiff, i.e. {umlaut over (z)}i=az+{umlaut over (z)}idiff.