Context-based mobility analysis and recognition

1. A mobile device comprising:

an inertial sensor generating inertia signals;

a high power module, wherein the high power module consumes more power than the inertial sensor, wherein the high power module is a gps receiver;

a processor programmed to determine whether the mobile device is being carried by a user who is walking based upon the inertia signals, wherein the processor operates a state machine including a walking state based upon the determination that the user is walking, wherein the processor deactivates the high power module based upon being in the walking state, wherein the state machine includes a stopped state and a transition from the walking state to the stopped state based upon a determination that the user has stopped walking based upon the inertia signals, wherein the processor is programmed to analyze the inertia signals between 4 Hz and 10 Hz to determine whether the user is walking, wherein processor is programmed to activate the gps receiver periodically when in the stopped state and determines a current speed, wherein the state machine remains in the stopped state based upon a determination that the current speed is less than a speed threshold, wherein the state machine includes a transition from the stopped state to a driving state based upon a determination that the current speed is greater than the speed threshold, wherein the gps receiver is activated when the state machine is in the driving state, wherein the state machine includes a transition from the driving state to a halted state based upon a determination that the current speed has dropped below a driving speed threshold.

2. A method for operating a mobile device including the steps of:

a) determining whether the mobile device is being carried by a user who is walking based upon inertial signals reflecting motion of the mobile device between 4 Hz and 10 Hz, wherein the motion signals are generated by an inertial sensor;

b) operating with a processor a state machine, including entering a walking state based upon the determination that the mobile device is being carried by the user who is walking in said step a);

c) operating the mobile device in a low power mode based upon being in the walking state, said step of operating in the low power mode including deactivating a gps receiver;

d) transitioning from the walking state to a stopped state based upon a determination that the user has stopped walking based upon the inertia signals;

e) periodically activating the gps receiver when in the stopped state to determine a current speed;

f) maintaining the state machine in the stopped state based upon the current speed in said step e);

g) transitioning from the stopped state to a driving state based upon the current speed in said step e);

h) activating the gps receiver based upon said step g);

i) transitioning the state machine from the driving state to a halted state based upon a determination of the current speed after said step g).

3. The method of claim 2 wherein said step a) is performed based upon motion of the mobile device.

4. The method of claim 2 wherein the inertial sensor is an accelerometer.

5. The method of claim 2 wherein the halted state is distinct from the stopped state.

6. The method of claim 2 wherein the state machine can enter the halted state only from the driving state and wherein the state machine can enter the stopped state only from the walking state.

7. The method of claim 6 wherein said step a) further includes the step of comparing an amplitude of the inertial signals between 4 Hz and 10 Hz to amplitudes of frequencies outside of 4 Hz to 10 Hz to determine whether the mobile device is being carried by a user who is walking.

8. The mobile device of claim 1 wherein the halted state is distinct from the stopped state.

9. The mobile device of claim 1 wherein the state machine can enter the halted state only from the driving state and wherein the state machine can enter the stopped state only from the walking state.

10. A mobile device comprising:

an inertial sensor generating inertia signals;

a high power module, wherein the high power module consumes more power than the inertial sensor, wherein the high power module is a gps receiver;

a processor programmed to determine whether the mobile device is being carried by a user who is walking based upon the inertia signals, wherein the processor operates a state machine, the state machine including a walking state, a driving state, a stopped state and a halted state, wherein the state machine enters the walking state is based upon the determination that the user is walking, wherein the processor deactivates the high power module based upon being in the walking state, wherein the state machine includes a transition from the walking state to the stopped state based upon a determination that the user has stopped walking based upon the inertia signals, wherein processor is programmed to activate the gps receiver periodically when in the stopped state and determines a current speed, wherein the state machine remains in the stopped state based upon a determination that the current speed is less than a speed threshold, wherein the state machine includes a transition from the stopped state to a driving state based upon a determination that the current speed is greater than the speed threshold, wherein the gps receiver is activated when the state machine is in the driving state, wherein the state machine includes a transition from the driving state to the halted state based upon a determination that the current speed has dropped below a driving speed threshold.

11. The mobile device of claim 9 wherein the state machine can enter the halted state only from the driving state and wherein the state machine can enter the stopped state only from the walking state.

12. The mobile device of claim 11 wherein the processor compares a first amplitude of a first range of frequencies of the inertial signals to a second amplitude of a second range of frequencies of the inertial signals to determine whether the mobile device is being carried by a user who is walking.

13. The mobile device of claim 10 wherein the processor compares a first amplitude of a first range of frequencies of the inertial signals to a second amplitude of a second range of frequencies of the inertial signals to determine whether the mobile device is being carried by a user who is walking.