Step counter device with energy-scavenging functionality, and step-counting method

• US 9,587,959 B2
• Filed: 09/24/2013
• Issued: 03/07/2017
• Est. Priority Date: 09/26/2012
• Status: Active Grant

• Current Assignee: STMicroelectronics International N.V. (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Gasparini, Alessandro, Ramorini, Stefano, Cattani, Alberto
• Primary Examiner(s): Park, Hyun
• Assistant Examiner(s): Becker, Brandon
• Application Number:
  US14/034,764
• Publication Number:
  US 20140088917A1
• Time in Patent Office: 1,260 Days
• US Class Current: 1/1
• CPC Class Codes: A43B 3/38 with power sources
• CPC Class Codes: G01C 22/006 Pedometers
• CPC Class Codes: H02M 7/219 in a bridge configuration

Abstract

A step-counter device detects and counts user steps. The device includes a transducer configured to generate an electrical transduction signal in response to user stepping. An energy-scavenging system is coupled to the transducer to generate a power supply voltage in response to the electrical transduction signal. A processing unit is powered by the power supply voltage. The processing unit is further configured to sense the electrical transduction signal and determine whether a user step has occurred and in response to that determination increment a step counter.

Claims

1. A step-counter device, comprising:

a transducer configured to generate an electrical transduction signal as a function of mechanical activity generated during stepping, said electrical transduction signal having a waveform pattern characteristic of a step that comprises, within a given time interval, a first waveform portion immediately followed by a second waveform portion, the first and second waveform portions being of opposite polarity;

a processing unit configured to determine a step based on said electrical transduction signal and consequently increment a step count; and

an energy-scavenging system coupled to said transducer and configured to generate electrical energy for supplying said processing unit from said electrical transduction signal generated as a function of the mechanical activity generated during stepping, wherein a switching operation of said energy-scavenging system causes a plurality of pulses within each of the first waveform portion and the second waveform portion; and

wherein the processing unit is configured to count the plurality of pulses within each of the first and second waveform portions and determine that said step has occurred if a number of counted pulses within the first waveform portion exceeds a first threshold and a number of counted pulses within the second waveform portion exceeds a second threshold.

2. The device according to claim 1, wherein the first and second thresholds are a same threshold.

3. The device according to claim 1, wherein the processing unit completes counting of pulses within each of the first and second waveform portions only if an initial count of said pulses within each of the first and second waveform portions exceeds a minimum threshold.

4. The device according to claim 1, wherein said transducer is of an electromagnetic type and has a characteristic inductance.

5. The device according to claim 4, wherein said energy-scavenging system comprises an interface stage having a first input terminal and a second input terminal coupled to said transducer and configured for operation as a switching converter at a switching duty cycle and using the characteristic inductance of said transducer, said pulses within each of the first and second waveform portions having a duration that is a function of said switching duty cycle.

6. The device according to claim 5, wherein said processing unit includes sensing inputs connected to said first input terminal and said second input terminal of said interface stage, the processing unit configured to process a first signal and a second signal present on said first input terminal and second input terminal, respectively, to determine execution of a step.

7. The device according to claim 6, wherein said energy-scavenging system comprises a storage capacitor on which an output voltage is present, said storage capacitor connected between a first output terminal and a second output terminal of said interface stage;

and wherein said first input terminal and said second input terminal are selectively switched, by said processing unit, in connection to a reference voltage or to said output voltage.

8. The device according to claim 5, wherein said energy-scavenging system comprises a storage capacitor on which an output voltage is present, said storage capacitor connected between a first output terminal and a second output terminal of said interface stage;

and wherein said interface stage comprises a logic control unit and a set of switches designed to be controlled in switching by said logic control unit for cyclically causing storage of energy in said inductor in a first interval of a switching period, and transfer of energy onto said storage capacitor in a second interval of the switching period, at both polarities, positive and negative, of the electrical transduction signal.

9. The device according to claim 8, wherein said logic control unit is configured for controlling switching of said set of switches to optimize a coupling efficiency between said transducer and said interface stage.

10. The device according to claim 9, wherein said first interval has a duration Tdelay and wherein a ratio k is present between the value of the current circulating in said inductor at the end of said first interval and the value of the current circulating in said inductor at the end of said second interval;

wherein said logic control unit is configured to set the values of said duration Tdelay and of said ratio k to optimize said coupling efficiency.

11. The device according to claim 1, wherein said energy-scavenging system comprises a voltage-regulator stage configured to generate a regulated voltage for supplying said processing unit;

and wherein said processing unit is configured to monitor the value of said regulated voltage and to enable operation to determine that said step has occurred only in the case where said regulated voltage has a value higher than a voltage threshold.

12. The device according to claim 1, further comprising a transmission stage operable in response to said processing unit for making a wireless transmission of information associated to said count.

13. The device according to claim 1, having a housing designed to be coupled to a shoe of said user.

14. A method, comprising:

carrying out an operation of transduction for generating an electrical transduction signal as a function of mechanical activity generated during stepping, said electrical transduction signal having a waveform pattern characteristic of a step that comprises, within a given time interval, a first waveform portion immediately followed by a second waveform portion, the first and second waveform portions being of opposite polarity; and

determining from analysis of said electrical transduction signal that a step has occurred and enabling an incrementing of a step count;

wherein carrying out the operation of transduction comprises carrying out an operation of energy scavenging starting from said mechanical activity generated during stepping for the generation of electrical energy on the basis of said electrical transduction signal, a switching operation performed during energy-scavenging causing a plurality of pulses within each of the first waveform portion and the second waveform portion; and

wherein determining comprises counting the pulses within each of the first and second waveform portions and determining that said step has occurred if a number of counted pulses within the first waveform portion exceeds a first threshold and a number of counted pulses within the second waveform portion exceeds a second threshold.

15. The method according to claim 14, wherein determining comprises detecting execution of a step upon occurrence of a characteristic pattern in the plot of said electrical transduction signal.

16. A device, comprising:

a motion transducer configured to generate an electrical transduction signal in response to applied motion, said electrical transduction signal having a waveform pattern characteristic of a step that comprises, within a given time interval, a first polarity waveform portion immediately followed by a second polarity waveform portion, the first and second polarities being opposite of each other;

an energy scavenging device configured to convert said electrical transduction signal into a power supply voltage, wherein a switching operation of said energy-scavenging system causes a plurality of pulses within each of the first polarity waveform portion and the second polarity waveform portion; and

a processing device powered from said power supply voltage and having a sensor input coupled to receive the electrical transduction signal, said processing device configured to;

count the pulses within the first polarity waveform portion;

count the pulse within the second polarilty waveform portion; and

determine that a step has occurred if a number of counted pulses within the first polarity waveform portion exceeds a first threshold and a number of counted pulses in the second polarity waveform portion exceeds a second threshold.

17. The device of claim 16, said processing device further configured to increment a step counter in response to determination that said step has occurred.