Smart power mode management inertial measurement system and smart power mode management method

Abstract

Embodiments of the present disclosure relate to a smart power mode management inertial measurement system and a smart power mode management method. An embodiment inertial measurement system includes at least one motion sensor that outputs motion data having output data rate (ODR) periods and a control unit coupled to the motion sensor to control operation of the control unit based on power mode switching of the motion sensor, each ODR period including, according to the power mode switching, a first phase in which the motion sensor is controlled in a low power consumption state and a subsequent measurement phase in which the motion sensor is controlled to perform a measurement of generation of measurement data. Based on at least one check related to the measurement data generated in the measurement phase, the control unit adaptively adjusts a duration of the ODR period.

Description

[0001] Cross Reference to Related Applications

[0002] This application claims the benefit of Italian application No. 102019000013434 filed on July 31, 2019, which is incorporated herein by reference. TECHNICAL FIELD

[0003] The present solution relates to an inertial measurement system with intelligent power mode management and to a corresponding intelligent power mode management method. BACKGROUND

[0004] Inertial measurement systems are known, comprising one or more inertial sensors or motion sensors (for example, in the case of so-called 6x or 6 degrees of freedom (dof), an inertial measurement system of three-axis accelerometer and three-axis gyroscope) and an associated control unit which controls the operation of the inertial sensors and interfaces with an associated external electronic device, for example a portable or wearable electronic device.

[0005] In particular, inertial measurement systems are known in which the inertial sensors are manufactured with MEMS (Micro-Electro-Mechanical System) technology, comprising: a micromechanical structure comprising at least one inertial mass formed by a detection electrode, detection means, for example coupled to the inertial mass to generate at least one motion quantity in response to the movement of the inertial mass, for example along three axes of an associated reference system (in the case of a three-axis sensor), and possibly actuation means (in the case of an active micromechanical structure, as in a gyroscope sensor), for example comprising actuation electrodes, and an associated electronic circuit (for example, an ASIC - Application Specific Integrated Circuit) coupled to the micromechanical structure and comprising a reading or processing portion configured to process the motion quantity generated by the same micromechanical structure and to generate at the output a detection signal (for example, an acceleration signal in the case of an accelerometer sensor, or an angular rate signal in the case of a gyroscope sensor) indicative of the detected motion, and possibly an actuation or driving portion (in the case of an active micromechanical structure) to provide suitable actuation signals to the actuation means.

[0006] The micromechanical structure can be made from a first die of semiconductor material and the associated electronic processing circuit can be made from a second die of semiconductor material, and both the first and the second die can be housed in the same package of the inertial sensor.

[0007] Due to their reduced footprint and power consumption, inertial measurement systems are often used in electronic devices, for example portable (or hand-held) or wearable electronic devices.

[0008] For example, a digital (or smart) pen (or pencil or stylus) is a portable pen-like device designed to be coupled to an electronic device acting as a host apparatus (e.g. a tablet computer, a phablet, a smartphone, a laptop computer, a smart TV, a monitor, etc.) and can have several functions in addition to the function of taking notes and making drawings.

[0009] Those additional functions can include a pointing function, the digital pen-like device acting in this case as an "air pointer", designed to implement a HID (Human Interface Device) pointer (or mouse) interface or protocol, so as to generate displacement data (in particular, information associated with the displacement between the current and previous positions of the same digital pen-like device) and send them to the host apparatus to move in terms of screen frame coordinates in the display of the same host apparatus. The host apparatus is thus able to move, on the corresponding display screen frame, the displayed object (e.g. a cursor or similar element) on the basis of the received displacement data.

[0010] The digital pen-like device can thus comprise an inertial measurement system, for example comprising an accelerometer and a gyroscope sensor, to monitor the movements of the same device and allow the implementation of the "air pointer" function defined above and possible additional functions such as gesture recognition functions.

[0011] As is known, new generations of handheld devices, such as the digital pen-like devices discussed above, are required to have very small dimensions (e.g. with an ultra-thin design) with very strict size constraints and therefore limit the performance in terms of battery (thus requiring very low power consumption). Moreover, these devices have to meet the expected requirements in terms of user experience, including higher accuracy and precision, reduced latency, fluidity, etc., in particular with respect to the air pointer function or other extended functions discussed above.

[0012] In order to reduce power consumption, it is known for the inertial measurement system to implement a low-power operating mode for the corresponding inertial sensors with so-called power mode switching.

[0013] In particular, according to a time frame division method, each output data rate (ODR) period (i.e. the time interval between the consecutive outputs of two inertial data from the inertial measurement system) is divided into consecutive operating intervals or phases: a first time interval, during which the inertial sensors operate with reduced power consumption; a second time interval, for example a "stabilization interval"; and a third time interval, for example a "measurement interval", during which the measurement of the quantities to be detected is performed (after the system has been properly stabilized) in order to generate the inertial data provided at the output (in a known manner, the measurement can imply taking an average on a certain number of measurements or samples to generate the measured data).

[0014] In detail, in the known solutions, the first time interval can correspond to a "shutdown" interval, in which the inertial sensor is not powered (i.e. the micromechanical structure and at least part of the associated electronic circuit are not powered), such as in an accelerometer sensor (or other sensors with passive micromechanical structures), in which the current consumption tends to zero (i.e. the power consumption is limited to only the leakage current); or possibly to a "sleep" interval, such as in a gyroscope sensor (or other micromechanical structure sensors comprising an active part, which is biased to perform an actuation movement, for example a resonant oscillation movement required for angular rate detection in the case of a gyroscope sensor), with reduced power consumption (at least part of the micromechanical structure is biased so as to maintain its movement, while in the electronic circuit the reading part is not powered and the driving part is powered at least partially).

[0015] It is noted that the sleep interval described above is required in order to reduce its power consumption, and at the same time have a fast turn-on and settling time (due to the fact that both the driving part of the electronic circuit and the active part of the micromechanical structure (for example the oscillating mass) remain on, while the reading part of the same electronic circuit is turned off).

[0016] Furthermore, due to the fact that at least part of the micromechanical structure and / or the electronic circuit is on in order to allow the working condition state to settle, the settling interval requires a power consumption higher than the power consumption of the shutdown or sleep interval.

[0017] The measurement interval is performed with the on of all the micromechanical structures and electronic circuits; this in turn can require a consumption higher than the settling interval.

[0018] In this regard, Figure 1A a graph is shown in an inertial system due to the current consumption I c of an accelerometer sensor, in which during each ODR period (denoted with T ODR , the following consecutive intervals are present: a first shutdown interval (denoted with T OFF , a subsequent settling interval (denoted with T SET and a final measurement interval (denoted with T MEAS , after which the motion data are ready at the output (denoted by the corresponding data ready interrupt signal DRDY).

[0019] In a corresponding manner, Figure 1B a graph is shown in an inertial system due to the current consumption of a gyroscope sensor, in which during each ODR period T ODR , the following consecutive intervals are present: a first "sleep" interval (denoted with T SLEEP , a subsequent settling interval (again denoted with T SET and a final measurement interval (again denoted with T MEAS .

[0020] In known inertial measurement systems, the duration of the time interval discussed above is set by design, according to the characteristics of the sensor and of the application, so that the output data rate interval (T ODR ) is also fixed and set by design. SUMMARY

[0021] The Applicant has realized that these known solutions can not be sufficient to guarantee the expected power consumption and user experience requirements for the inertial measurement systems of next generation portable or wearable devices, such as the digital pen-like devices discussed above.

[0022] Therefore, there is a need for an improved inertial measurement system that allows to generate inertial data (e.g. for implementing pointing functions in digital pen-like devices), minimizing the current consumption, guaranteeing data accuracy and reliability and therefore user experience.

[0023] The object of the present solution is to (at least partially) meet the above needs.

[0024] According to the present solution, as defined in the appended claims, an inertial measurement system and a corresponding method are provided. BRIEF DESCRIPTION OF DRAWINGS

[0025] For a better understanding of the present application, preferred embodiments will now be described, by way of non-limiting example only, and with reference to the accompanying drawings, in which:

[0026] Figures 1A-1B a graph of quantities related to a known inertial measurement system is shown;

[0027] Figure 2 is a schematic block diagram of an inertial measurement system according to an embodiment of the present solution;

[0028] Figures 3A-3B a graph of quantities related to the current consumption of the inertial measurement system of Figure 2 is shown;

[0029] Figure 4 an indicative graph of the detected motion quantities in the inertial measurement system of Figure 2 is shown;

[0030] Figures 5A-5B a graph of quantities related to the current consumption of the inertial measurement system of Figure 2 according to another embodiment is shown; and

[0031] Figure 6 is a schematic block diagram of a system comprising an electronic device (e.g. a digital pen-like device) incorporating the inertial measurement system of Figure 2 and the associated host electronic apparatus. DETAILED DESCRIPTION

[0032] Figure 2 An inertial measurement system 1 is shown, comprising at least one inertial sensor 2, e.g. a MEMS accelerometer or a gyroscope triaxial sensor (or, in the case of a 6x inertial measurement system, both an accelerometer and a gyroscope sensor) and an associated control unit 4, e.g. a microcontroller unit (or microprocessor unit, or any other suitable computing or processing unit).

[0033] In particular, as discussed earlier, the inertial sensor 2 comprises:

[0034] a micromechanical structure 2a, which, in the case of a "passive" structure, comprises at least one inertial mass and associated detection means coupled to the inertial mass to generate at least one motion quantity in response to the movement of the inertial mass; moreover, in the case of an "active" structure, the micromechanical structure 2a comprises actuation means coupled to the same inertial mass (or to another mass or element) to cause the movement of the same inertial mass (or of the other mass or element) according to a received driving signal; and

[0035] an associated electronic circuit 2b (ASIC) coupled to the micromechanical structure 2a and comprising a reading portion configured to process the motion quantity generated by the micromechanical structure 2a and to generate at the output at least one detection signal S det indicative of the detected motion, and, in the case of an active structure, a driving portion to provide the appropriate driving signal S dr to the actuation means of the same micromechanical structure 2a.

[0036] As schematically shown, the micromechanical structure 2a and the associated electronic circuit 2b receive a bias signal Val, e.g. from a power supply source, e.g. a battery (not shown here); in particular, the bias signal is provided to the detection and actuation means of the micromechanical structure 2a and to the reading and driving portions of the electronic circuit 2b.

[0037] The control unit 4 is configured to activate a power-down mode (with reduced power consumption) in which the bias of at least part of the micromechanical structure 2a and of the associated electronic circuit 2b is switched off.

[0038] As will be discussed in detail hereinafter according to an aspect of the present solution, the control unit 4 is configured to implement an automatic power mode switching of the inertial sensors 2 of the same inertial measurement system 1. In other words, as in the known solutions, the time frame division of each output data rate (ODR) period is not fixed by design, but is dynamically and adaptively decided by the control unit 4, during the operation of the inertial measurement system 1, based on the execution of checks related to the measured motion data.

[0039] In particular, the ODR period is again divided into distinct phases or time intervals, namely: a first phase, during which the inertial sensors 2 operate with reduced power consumption (as will be discussed hereinafter, however, this first phase is always an "off phase for any kind of inertial sensors 2, i.e. for both passive and active sensors); a second phase, a "stabilization" phase; and a third phase, a "measurement" phase, during which the measurement of the quantities to be detected is performed in order to generate the motion data to be provided at the output.

[0040] According to an aspect of the present solution, a fourth phase, the so-called "check" phase, is introduced after the "measurement", during which the control unit 4 performs one or more checks related to the quality and reliability of the measurement data (these checks are generally indicated hereinafter as "sanity checks").

[0041] Based on the sanity checks, the control unit 4 dynamically and adaptively adjusts the output data rate of the inertial measurement system 1. In particular, in case the sanity checks are not passed (or are not satisfactory), another measurement phase is performed, followed by another "check" phase, in which sanity checks related to the other measurement data are performed. This process is iteratively repeated until the sanity checks are passed (i.e. are deemed satisfactory), thus providing the measurement data at the output.

[0042] Figure 3A The time frame division of the ODR period of the inertial sensors 2 (e.g. accelerometer or gyroscope sensors) of the inertial measurement system 1 is shown, in this case, in which the reliability check performed by the control unit 4 is successful, and in particular corresponds to a current consumption I c .

[0043] In detail, the ODR period is divided, in this case, into the following consecutive intervals: a first "off interval (again denoted by T OFF ); a subsequent stabilization interval (again denoted by T SET ); a measurement interval (again denoted by T MEAS ); and a subsequent check interval (denoted by T CHECKthe integrity of the data measured during the interval is checked.

[0044] In this example, the integrity check is successful, so the motion data is provided at the output of the inertial measurement system 1 (e.g. a "data-ready" interrupt signal is generated); therefore the "check" interval is immediately followed by the subsequent "off" interval of the next ODR period.

[0045] In this case, the current consumption during the "off" interval is close to zero, substantially due to leakage effects.

[0046] Figure 3B The time frame division of the ODR period (and the corresponding current consumption I C , in this case the first integrity check performed by the control unit 4 is not successful.

[0047] In this case, after the first "check" interval, a further phase is implemented: a further "measure" phase; and a further subsequent "check" phase, during which the integrity of the newly measured data is checked.

[0048] In this case, the second integrity check is successful, so the measured motion data is provided at the output of the inertial measurement system 1 ; therefore the second "check" interval is immediately followed by the subsequent "off" interval of the next ODR period.

[0049] Therefore, the control unit 4 adaptively adjusts the output data rate period (T ODR , in particular increasing the duration of the same output data rate period T ODR , to take into account the further measure and check intervals.

[0050] The adaptive ODR period approach discussed reconciles the need to reduce the device current consumption with the ability to maximize the quality of the user experience (e.g. in terms of accuracy and reliability of the measured data).

[0051] According to an aspect of the present solution, the first phase of the ODR period corresponds to an "off" phase (with minimum power consumption, substantially due to leakage effects) independent of the type of inertial sensor 2, i.e. both in the case where the inertial sensor 2 has a passive micro-mechanical structure 2a (e.g. an accelerometer sensor) and in the case where the inertial sensor 2 has an active micro-mechanical structure 2a (e.g. a gyroscope sensor). In particular, in the "off" phase, the micro-mechanical structure 2a of the inertial sensor 2 (e.g. the oscillating resonant mass of a gyroscope sensor) and the electronic circuit 2b associated therewith of the inertial sensor 2 are switched off.

[0052] The above features are possible thanks to the presence of the sanity check discussed, allowing to discard the measurements after the switch-off in case the stabilization phase is not sufficient to stabilize the micromechanical structure 2a and the electronic circuit 2b to the operating conditions.

[0053] With tests and simulations, the Applicant has realized that, for passing the sanity check and providing reliable data at the output of the inertial measurement system 1, an average of two, at most three consecutive measurement and check phases are necessary.

[0054] In fact, this is due to the fact that the ODR period is, in any case, generally much lower than the time interval required by the active part of the micromechanical structure 2a (e.g. the resonant oscillating mass of a gyroscope sensor) to completely stop the corresponding movement after the switch-off. In other words, the time required by the micromechanical structure 2a to return to the desired state of motion is generally short, thanks to the fact that, in any case, there is a residual motion at the end of the "switch-off" phase.

[0055] More specifically, the sanity check discussed above is implemented by the control unit 4, able to guarantee the generation of the motion data when the following conditions are satisfied:

[0056] the micromechanical structure 2a of the inertial sensor 2 is correctly operating in the operating conditions (e.g. the resonant oscillating movement of the gyroscope mass has the expected characteristics); and

[0057] the electronic circuit 2b and the related signal processing and driving chain are stabilized to the desired operating conditions.

[0058] Therefore, the passing of the sanity check, which directly controls the ODR period (as discussed above), with the adaptive adjustment, allows to guarantee the generation of the motion data (e.g. for the pointer calculation) with minimum current consumption, but still with the correct and desired level of integrity.

[0059] According to another aspect of the present solution, the control unit 4 is further configured to evaluate the amount of motion detected by the inertial sensor(s) of the inertial measurement system 1 and, based on the evaluated amount of motion, to adaptively and dynamically adjust the duration of the "switch-off" phase (i.e. the duration of the first interval of the ODR period).

[0060] In particular, the control unit 4 is configured to evaluate the amount of motion on the basis of the motion data that have passed the above discussed sanity check (in the current ODR period and in one or more previous ODR periods) and to implement: a first duration of the "off" phase (of the next ODR period) in the case where the amount of motion is lower than a certain threshold (for example, indicative of a rest state for the inertial measurement system 1 and the associated electronics); or a second duration, lower than the first duration, in the case where the amount of motion is higher than a respective threshold (which can or can not be equal to the above mentioned certain threshold).

[0061] It is worth noting that it can be possible to implement more durations with respective associated thresholds, or even to implement a continuous function that provides the duration of the "off" phase as a function of the detected amount of motion.

[0062] The adaptive adjustment of the "off" phase thus allows to further reduce the current consumption in the first case and to more closely follow the movements to be detected in the second case, thus preserving the desired detection quality and user experience.

[0063] In this regard, Figure 4 a graph indicative of the detected amount of motion (i.e., of the variation of the motion data detected over time, or in other words, of the detection signal S det ) is shown, in which t i represents the time at which the motion data provided at the output at the end of the respective ODR period pass the sanity check.

[0064] In the interval from tl to t9, since the amount of motion is determined to be higher than the threshold, the first duration of the "off" phase is applied; on the contrary, in the interval from t9 to tl 1, since the amount of motion is determined to be lower than the threshold due to the fact that the ODR period correspondingly increases, the duration of the "off" phase is adaptively increased by said control unit 4.

[0065] It is also worth noting in the same graph that in the interval from tl to t2 and from t3 to t4, the ODR period is adaptively adjusted by the control unit 4 (i.e., for the motion data generated at times t2 and t4), in this case, a further measurement phase is determined to output the motion data due to the sanity check discussed above.

[0066] In a possible embodiment, the control unit 4 is configured to compare the motion data (that have passed the sanity check) at each time t(i) with the motion data output at the previous time t(i-1) in order to evaluate the amount of motion, for example according to the following expression:

[0067] | Data(t(i)) - Data(t(i-1)) | > Th

[0068] where Th is a desired threshold of motion.

[0069] If the above expression is verified, a first duration of the "OFF" phase is applied; conversely, if the above expression is not verified, the duration of the "OFF" phase is suitably increased.

[0070] However, other possible solutions can be implemented by the control unit 4 to determine the amount of motion, for example, comprising the evaluation of the variance, the average value, the maximum or minimum value of the same motion data in a given time interval, and so on.

[0071] Figure 5A The time frame division of the ODR period is shown, in which case the control unit 4 determines that the amount of motion is higher than the threshold, so that a first duration is implemented for the "OFF" phase (again denoted by T OFF ) after the motion data has passed the sanity check at time t2 and, therefore, is provided at the output of the inertial measurement system 1 (it should be noted that the example refers to a context in which the detected motion data passes the sanity check, so that no further measurement phase is required).

[0072] In other words, in the example, with respect to the duration applied at the previous times t1 and t2 for the generation of the motion data, an increased duration is implemented for the "OFF" phase, in order to generate the motion data at time t3.

[0073] Conversely, Figure 5B The time frame division of the ODR period is shown, in which case, after the motion data has passed the sanity check at time t2 (again in the example, the detected motion data passes the sanity check, so that no further measurement phase is required), the control unit 4 determines that the amount of motion is lower than its threshold, for example indicating a rest motion, so that an increased duration (here denoted by T OFF_quiet ) is implemented for the "OFF" phase, which is higher than the first duration T OFF .

[0074] In other words, in the example, with respect to the duration applied at the previous times t1 and t2 for the generation of the motion data, an increased duration is implemented for the "OFF" phase (TOFF_quiet > TOFF) in order to generate the motion data at time t3.

[0075] As discussed previously, the increased "OFF" time allows to obtain a reduced average current consumption I AVG2(relative to) Figure 5A I AVG1 (This represents the average current consumption). Conversely, reducing the "off" time allows for closer monitoring of motion data, thereby increasing detection accuracy.

[0076] Figure 6 A portable or wearable electronic device 10, particularly a digital pen-like device, is schematically shown within its casing or housing 10'. The device includes (as discussed above) an inertial measurement system 1, which includes an inertial sensor 2 and an associated control unit 4.

[0077] Electronic device 10 further includes a management module 12, such as a microcontroller, microprocessor, or any other suitable computing unit, coupled to the inertial measurement system 1 to receive the generated motion detection signal S. det The generated motion detection signal S det Indicates the detected motion and is configured to process the motion detection signal S. det For example, it is used to determine the displacement of the same electronic device between the current and previous positions and generate corresponding displacement data; and a data transmission module 14, such as a Bluetooth Low Energy (BLE) module, is coupled to the management module 12 and is operable to wirelessly send data packets (e.g., including displacement data) to the host device, which is schematically shown here and indicated by 20, to which the electronic device 1 is communicatively coupled.

[0078] The electronic device 10 also includes a battery unit 16, configured to provide power to all components of the same electronic device 10, namely, to the following components: the inertial measurement system 1 (in particular to provide a bias signal Val to the micromechanical structure 2a and associated electronic circuit 2b of the same inertial sensor 2), the management module 12, and the transmission module 14.

[0079] As schematically shown, the aforementioned electronic device components may be coupled to the same circuit board (e.g., PCB - printed circuit board) 18 and housed within the housing 10' of the electronic device 10.

[0080] It is worth noting that the management module 12 of the electronic device 10 can also implement the control unit 4 of the inertial measurement system 1 discussed above, or can be clearly and operationally coupled to the same control unit 4.

[0081] According to possible embodiments, the inertial measurement system 1 can be fully implemented in an ASIC circuit.

[0082] As in the same Figure 6As shown, the host device 20 (e.g., a smartphone, tablet phone, or tablet computer) may include: a corresponding communication interface 24 designed to communicate with the data transmission module 14 of the electronic device 10, for example via Bluetooth Low Energy data communication; a main controller 26, such as a microprocessor unit; and a display 28 defining screen frames, on which the movement of a cursor or other similar displayed elements is controlled by the main controller 26.

[0083] Electronic device 10 can provide displacement information to the main controller 26 of host device 20, which is configured to control the movement of the cursor or other similar displayed elements on display 28 according to the same displacement information (electronic device 1 implements an "air pointer" device).

[0084] From the preceding description, the advantages of the solution disclosed herein are already very clear.

[0085] In all cases, the inertial measurement system 1 achieves very low power consumption, especially in motion detection, by adaptively adjusting the output data rate while maintaining the desired performance.

[0086] The inertial measurement system 1 offers a high degree of flexibility and configurability in switching the power mode of the inertial sensor 2 and in checking the data associated with the detected motion, thereby improving the user experience of known solutions.

[0087] Therefore, it is possible to meet the power consumption and performance requirements for portable or wearable electronic devices 10 (e.g., digital pen-like devices that implement air pointing and / or additional functions, such as gesture recognition) that include the same inertial measurement system 1.

[0088] Finally, it is clear that modifications and variations may be made to the content described and illustrated herein without departing from the scope of the invention as defined in the appended claims.

[0089] In particular, different and / or additional motion sensors can be included in the inertial measurement system 1 to generate a detection signal S at the output. det .

[0090] Furthermore, this solution can be applied not only to digital pen-like devices, but also to any electronic device that simultaneously requires low power consumption and an improved user experience.

Claims

1. An inertial measurement system, comprising: at least one motion sensor configured to output motion data having output data rate, ODR, periods; and a control unit coupled to the motion sensor and configured to: control operation of the motion sensor based on a power mode switch, according to which each ODR period comprises: a first phase in which the motion sensor is controlled in a low power consumption state; and a subsequent measurement phase in which the motion sensor is controlled to perform a measurement for generation of measurement data; and adaptively adjust a duration of the ODR period based on at least one check related to the measurement data generated during the measurement phase, wherein each ODR period further comprises: at least one check phase following the measurement phase and designed to perform the at least one check related to the measurement data generated during the measurement phase; and in case the check phase is unsuccessful, at least one further measurement phase following the check phase.

2. The inertial measurement system according to claim 1, wherein the control unit is configured to control the motion sensor to output the measurement data generated in the measurement phase as the motion data and thus end the ODR period, if the check phase is successful, or to output the measurement data generated in the further measurement phase as the motion data, if a further check phase following the at least one further measurement phase is successful.

3. The inertial measurement system according to claim 1, wherein during the check phase the control unit is configured to perform one or more checks related to a quality and reliability of the generated measurement data.

4. The inertial measurement system according to claim 3, wherein the motion sensor comprises a micro-mechanical structure and associated electronic circuitry; and wherein the one or more checks implemented by the control unit are configured to guarantee generation of motion data if: the micro-mechanical structure is correctly operating in a working condition; and the electronic circuitry is stable to a desired operating condition.

5. The inertial measurement system according to claim 4, wherein the control unit is configured to adaptively adjust the duration of the first phase of the ODR period based on evaluating a motion quantity associated with the generated motion data.

6. The inertial measurement system according to claim 5, wherein the control unit is configured to: increase the duration of the first phase in response to the evaluated motion quantity being lower than a motion threshold; and decrease the duration of the first phase in response to the evaluated motion quantity being higher than a respective motion threshold.

7. The inertial measurement system according to claim 5, wherein the control unit is configured to evaluate the motion quantity based on processing the motion data output at an end of a current ODR period and the motion data output at an end of at least one previous ODR period.

8. The inertial measurement system of claim 1, wherein the control unit is configured to activate a power down mode of the motion sensor during the first phase of the ODR period and to deactivate the power down mode of the motion sensor during the measurement phase.

9. The inertial measurement system of claim 1, wherein each ODR period further comprises a stabilization phase, the stabilization phase being interposed between the first phase and the measurement phase, in which the motion sensor is controlled so as to stabilize towards an operating condition.

10. The inertial measurement system of claim 1, wherein the motion sensor is a gyroscopic sensor; wherein the inertial measurement system comprises at least one further motion sensor; and wherein the at least one further motion sensor is an accelerometer sensor.

11. An electronic system comprising: a portable electronic device comprising: an inertial measurement system comprising: at least one motion sensor configured to output motion data having an output data rate (ODR) period; and a control unit coupled to the motion sensor and configured to: control operation of the motion sensor based on a power mode switching, according to which each ODR period comprises: a first phase in which the motion sensor is controlled in a low power consumption state; and a subsequent measurement phase in which the motion sensor is controlled to perform a measurement for generation of measurement data; and adaptively adjust a duration of the ODR period based on at least one check related to the measurement data generated during the measurement phase; and a management module coupled to the inertial measurement system to receive and process the motion data generated at an output of the inertial measurement system, wherein each ODR period further comprises: at least one check phase, subsequent to the measurement phase, and designed to perform the at least one check related to the measurement data generated during the measurement phase; and at least one further measurement phase, following the check phase, in case the check phase is unsuccessful.

12. The electronic system of claim 11, wherein the portable electronic device is a digital pen-like device; wherein the management module is configured to process the motion data generated at an output of the inertial measurement system for determining a displacement of the portable electronic device between a current position and a previous position and to generate corresponding displacement data; and wherein the portable electronic device further comprises a data transmission module coupled to the management module and operable to wirelessly transmit the displacement data to a host device.

13. The electronic system of claim 12, further comprising the host device, wherein the host device comprises: a communication interface in communication with the portable electronic device and receiving the displacement data; a display defining a screen frame; and a host controller configured to control a motion of elements displayed in the screen frame in accordance with the displacement data received from the portable electronic device. ​ 14. A power mode management method in an inertial measurement system, the inertial measurement system comprising at least one motion sensor configured to output motion data having output data rate, ODR, periods, the method comprising: controlling operation of the motion sensor based on a power mode switch, according to which each ODR period comprises: a first phase in which the motion sensor is controlled in a low power consumption state; and a subsequent measurement phase in which the motion sensor is controlled to perform measurements for generation of measurement data; and adaptively adjusting a duration of the ODR period based on at least one check related to the measurement data generated during the measurement phase, wherein each ODR period further comprises: at least one check phase, following the measurement phase, and designed to perform the at least one check related to the measurement data generated during the measurement phase; and at least one further measurement phase, following the check phase, in case the check phase is unsuccessful.

15. The method of claim 14, wherein adaptively adjusting the duration of the ODR period comprises: controlling the motion sensor to output the measurement data generated in the measurement phase as the motion data, and thus ending the ODR period, if the check phase is successful; or to output the measurement data generated in a further check phase, following the at least one further measurement phase, as the motion data, if the further check phase is successful.

16. The method of claim 14, further comprising: performing one or more checks related to quality and reliability of the generated measurement data during the check phase.

17. The method of claim 14, wherein adaptively adjusting the duration of the ODR period comprises: adjusting the duration of the first phase of the ODR period based on evaluating an amount of motion associated with the motion data.

18. The method of claim 17, wherein adjusting the duration comprises: increasing the duration of the first phase in response to the evaluated amount of motion being below a motion threshold; and decreasing the duration of the first phase in response to the evaluated amount of motion being above a respective motion threshold. ​

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