Monitoring aggressive driving operation of a mobile asset

1. A method of monitoring operation of a mobile asset installed with a monitoring device comprising:

installing in the mobile asset an accelerometer device for providing outputs representing accelerations along three orthogonal axes:

low-pass filtering the outputs with one or more filters;

transforming, by said monitoring device, the low-pass filtered outputs to represent acceleration along orthogonal forward, sideways and vertical axes of the mobile asset;

configuring, in said monitoring device, one or more acceleration envelopes to correspond to one or more events, each acceleration envelope defined by a duration of time and an amplitude;

determining, by said monitoring device. a speed of the mobile asset;

comparing, by said monitoring device, the determined speed of the mobile asset to a threshold speed;

determining, by said monitoring device, that the determined speed is above the threshold speed;

determining, by said monitoring device, an acceleration profile of the mobile asset by:

recording over a duration of time a plurality of values of acceleration of the mobile asset, wherein the transformed, low-pass filtered outputs are used to determine the values of acceleration of the mobile asset;

compensating said values of acceleration for gravity (G);

low pass filtering the acceleration along the vertical axis to obtain âz;

calculating a pitch of a slope upon which the mobile asset is moving: ρ=cos −1 (âz/G);

determining a sign of the slope; and

correcting the acceleration along the forward axis by subtracting therefrom G·sin ρ;

comparing, by said monitoring device, the determined acceleration profile of the mobile asset to said acceleration envelopes;

determining, by said monitoring device, that the determined acceleration profile of the mobile asset lies entirely outside at least one of said acceleration envelopes; and

reporting the event that corresponds to said one of said acceleration envelopes.

2. A method according to claim 1 wherein each low-pass filtering is achieved by averaging a series of acceleration data points.

3. A method according to claim 1 further comprising the steps of:

prior to reporting said event, determining, by said monitoring device, that the mobile asset is no longer accelerating; and additionally

determining, by said monitoring device, attitude of the mobile asset.

4. A method according to claim 3 wherein the reporting of the event includes the attitude determined by said monitoring device.

5. A method according to claim 1 , in which gravity is compensated for by high pass filtering the acceleration along the forward axis.

6. The method of claim 1 , further comprising the step of storing said values of acceleration in memory in said monitoring device to establish a temporal record of acceleration of the mobile asset.

7. A method according to claim 1 wherein the reported event is reported as cautionary when the determined acceleration profile of the mobile asset is outside a first acceleration envelope or reported as aggressive when the determined acceleration profile of the mobile asset is outside a second envelope, wherein the second envelope is higher and/or longer in duration than the first envelope.

8. A method according to claim 1 wherein a heading of the mobile asset is determined, by said monitoring device, and the event is based on the heading.

9. A method according to claim 1 wherein the speed is determined, by said monitoring device, from said accelerations.

10. A method according to claim 9 wherein the event is reported because:

the monitoring device determines that the mobile asset experiences a deceleration greater than a threshold deceleration over a predetermined period; and

the monitoring device determines that the mobile asset velocity decreases over said period from above the threshold speed to near zero.

11. An apparatus for monitoring operation of a mobile asset comprising:

three orthogonal accelerometers for providing outputs representing accelerations along three orthogonal axes, said accelerometers installed in the mobile asset;

a low-pass filter connected to each accelerometer output for providing filtered outputs;

a device for transforming the filtered outputs into accelerations along orthogonal forward, sideways and vertical axes of the mobile asset;

a further low-pass filter for further filtering the acceleration along the vertical axis of the mobile asset; and

a device into which is input the further filtered acceleration along the vertical axis and the filtered accelerations along the forwards and sideways axes and which outputs compensated accelerations along orthogonal forward, sideways and vertical axes of the mobile asset;

wherein said device compensates said filtered and further filtered accelerations for gravity (G) and slope on which the mobile asset is moving by:

low pass filtering the acceleration along the vertical axis to obtain âz;

calculating a pitch of a slope: ρ=cos −1 (âz/G);

determining a sign of the slope; and

correcting the acceleration along the forward axis by subtracting therefrom G·sin ρ;

a monitoring device, operative when the mobile asset is moving and the speed of the mobile asset is above a threshold speed,

wherein said monitoring device:

records over a duration of time a plurality of values of compensated acceleration of the mobile asset to form an acceleration profile;

compares the acceleration profile to a predetermined accelerating envelope that is defined by the duration of time and an amplitude;

determines that the profile of compensated acceleration lies entirely outside the acceleration envelope; and

reports an event that corresponds to said acceleration envelope.