| 主权项 |
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; andcorrecting 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. |
