Electronic device with EMG sensor based scaling control output and related methods

An electronic device may include an EMG sensor to be coupled to a user. The electronic device may include a control device configured to generate a control output based upon a control input and to change a scaling between the control input and the control output based upon the EMG sensor. The EMG sensor may include a pair of EMG sensors, with each EMG sensor being associated with a respective one of opposing muscles of the user.

TECHNICAL FIELD

The present disclosure relates to the field of electronic devices, and, more particularly, to control devices and related methods.

BACKGROUND

Input devices are ubiquitous in the digital age, and are commonly used for converting user input into an output signal for a device to be controlled. Indeed, input devices are applied in a wide variety of devices, ranging from video games/simulator controllers to complex robotic systems (e.g. manufacturing, ordinance disposal, search and rescue missions, environmental analysis, or inspection at toxic sights).

In typical input devices, the input device measures user inputs using one or more sensors and converts the sensed user input into corresponding output signals that are transmitted to the destination electronic device to be controlled. For example, in the robotic system application, the user inputs will cause it to move in a desired manner in accordance with the transmitted output signals. In one common input device for the robotic system, a joystick device measures angle and direction of mechanical input, and generates the output signal.

In the typical input device, the conversion of the sensed user input into the output signal is based upon a static scaling factor. Although this static scaling factor does provide for predictable touch and feel in the input device, this may not be desirable when the user and associated application demands both fine control as well as twitchy/fast/responsive controls.

SUMMARY

Generally, an electronic device may include at least one electromyography (EMG) sensor to be coupled to a user. The electronic device may include a control device configured to generate a control output based upon a control input and to change a scaling between the control input and the control output based upon the at least one EMG sensor.

Additionally, the at least one EMG sensor may comprise a pair of EMG sensors, and each EMG sensor may be associated with a respective one of opposing muscles of the user. The control device may be configured to set the control output to a constant based upon the at least one EMG sensor exceeding a threshold.

In some embodiments, the control device may comprise an input device to be manipulated by the user, and an actuator responsive to the input device. In other embodiments, the control device may comprise a touchscreen input device to be manipulated by the user, and a visual indicator responsive to the touchscreen input device.

Also, the electronic device may further comprise a garment to be worn by the user and carrying the at least one EMG sensor. The at least one EMG sensor may comprises an electrode in contact with a respective muscle of the user. The control device may be configured to change the scaling based upon at least one other biometric value from the user. The control device may be configured to change the scaling without user interaction.

Another aspect is directed to a method for making an electronic device. The method may include coupling at least one EMG sensor to a user, and operating a control device configured to generate a control output based upon a control input and to change a scaling between the control input and the control output based upon the at least one EMG sensor.

DETAILED DESCRIPTION

The input device with the static scaling factor may not be desirable when the user and associated application demand finer control. For example, for devices that are used to perform a variety of tasks, optimizing the controller sensitivity based on the task being performed ensures the ideal speed and precision. Properly balancing speed and precision of the controller improves the user experience, safety, and performance level.

Controller sensitivity may be considered as a ratio between the device output and the controller input. This ratio of the device to the controller can include the magnitude and speed of controller displacement as well as magnitude, speed, and torque of the device displacement, depending on the desired control method for that particular device or application.

In some prior art approaches, the user may manually adjust the controller sensitivity. In electronic applications, manually adjusting controller sensitivity may require the user to stop what they are doing, open a menu, and adjust the sensitivity by guessing how much they should adjust it by. In some mechanical applications, the users have buttons on the controller used to adjust the sensitivity. In prior art approaches, because of the annoyance of manual calibration of controller sensitivity, users may sacrifice performance by using a default controller sensitivity rather than interrupt the task to manually adjusting their controller sensitivity.

To give users the full benefits of a controller sensitivity ideal to the task being performed, the controller sensitivity should be automatically adjusted, as disclosed herein. In cases where a priori knowledge of the task is available, automatically adjusting the controller sensitivity may be possible. However, in many cases, a priori knowledge is unavailable. In some mechanical applications, there is no knowledge by the device of what task it is performing, forcing it to rely solely on human input. Automatically adjusting the controller sensitivity without a priori knowledge of the task is a problem addressed by the electronic device disclosed herein.

Referring initially toFIGS. 1-2, an electronic device10according to the present disclosure is now described. The electronic device10illustratively comprises a pair of EMG sensors11a-11bto be coupled to a user12. Of course, in some embodiments, a single EMG sensor could be used. Each EMG sensor11a-11bis associated with a respective one of opposing muscles of the user12. In other words, the opposing muscles of the user12are muscles that move in opposite directions, that is, they are agonist and antagonist muscle pairs (e.g. triceps and biceps). As will be appreciated, coactivation of these opposing muscles is indicative of joint stability.

The electronic device10illustratively includes a control device13configured to generate a control output14based upon a control input15and to change a scaling16between the control input and the control output based upon the pair of EMG sensors11a-11b. In particular, the control device13is configured use the pair of EMG sensors11a-11bto detect muscle coactivation in the respective one of opposing muscles of the user12(i.e. the control device is monitoring for coactivation).

In some embodiments, the electronic device10illustratively includes a biometric sensor21(shown with dashed lines and can be omitted depending on the embodiment) coupled to the control device13and configured to generate another biometric value. The other biometric value may comprise one or more of heart rate, concentration measured by electroencephalogram (EEG), breathing rate, and skin conductance response (galvanic skin response). The control device13may be configured to change the scaling16based upon at least the other biometric value from the user12. In some embodiments, the control device13may be configured to change the scaling16without user interaction (i.e. this is an automatic adjustment).

InFIG. 2, each of the pair of EMG sensors11a-11billustratively includes an electrode17in contact with a respective muscle of the user12, and an EMG circuit20coupled to the electrode. In some embodiments, each of the pair of EMG sensors11a-11bincludes a plurality of electrodes (e.g. 3 electrodes). The first electrode is located at the base of the muscle, and the second electrode is located in the middle of the muscle. The first and second electrodes provide the electrical difference therebetween. The third electrode functions as the right leg drive, which is used to set a reference point and eliminate environmental electrical noise by grounding a neutral part of the user's body, such as their right leg for cardiograms or their elbow.

The EMG circuit20is shown with dashed lines, and in other embodiments, the EMG circuit20could be integrated within the control device13. In some embodiments, the control device13is coupled to each of the pair of EMG sensors11a-11bvia a wired connection. In other embodiments, the control device13is coupled to each of the pair of EMG sensors11a-11bvia a wireless connection (e.g. Bluetooth, Zigbee).

Referring now toFIG. 3, a chart30illustrates the scaling16for an example embodiment of the control device13. As mentioned above, the control device13is configured use the pair of EMG sensors11a-11bto detect muscle coactivation, and the detection process comprises signal processing of the EMG output signals from the pair of EMG sensors to produce a muscle coactivation value.

In one example embodiment, the control device13is configured to determine the muscle coactivation value by comparing amplitudes of the EMG output signals from the pair of EMG sensors11a-11b. Here, the control device13is configured to detect near identical amplitudes (±5% of maximum amplitude) of the EMG output signals from the pair of EMG sensors11a-11b. In another embodiment, the signal processing for detection of opposing muscle coactivation may use the teachings disclosed in, for example: Ervilha et al. “A simple test of muscle coactivation estimation using electromyography.” Brazilian journal of medical and biological research=Revista brasileira de pesquisas medicas e biologicas vol. 45,10 ( ) 977-81. doi:10.1590/S0100-879X2012007500092, the entire contents of which are hereby incorporated by reference in their entirety.

In the illustrated chart30, the greater the percentage, the greater the muscle activation and joint stability. In Case 1 shows a fast sensitivity scenario, and a zero muscle coactivation value from the pair of EMG sensors11a-11b. In other words, the user is exhibiting no muscle coactivation, and is “loose” so to speak. Because of this, the scaling16for this case is 1:1 (i.e. no change). Case 2 shows a precise sensitivity scenario. Here, the muscle coactivation value is 40%, indicating some muscle coactivation. Because of this, the scaling16is 5:3 so as to provide greater precision.

In Case 3, the muscle coactivation value is maxed out at 100%. In other words, the user is exhibiting maximum muscle coactivation, and is extremely tense, if not panicked. Because of this, the control device13is configured to zero the scaling16at 1:0. In other words, there is no control output for safety reasons, and the control device13is in an emergency stop mode; the control device13is configured to set the control output to a constant (e.g. the illustrated zero value) based upon the pair of EMG sensors11a-11bexceeding a threshold (i.e. a coactivation maximum threshold).

Also, the control device13is configured to set the control output to the constant (e.g. the illustrated zero value) based when the signals from pair of EMG sensors11a-11bare not available, in other words, the pair of EMG sensors11a-11bhave been disconnected (i.e. exceeding a coactivation minimum threshold). That is, if the pair of EMG sensors11a-11bis disconnected from the user12, the control device13is configured to zero the control output for safety.

Also, although the exemplary chart30shows three levels of the scaling16or controller sensitivity, in some embodiments, there may be more levels of scaling. Also, in other embodiments, the scaling16may operate on a formulaic progression (e.g. a linear formula) with regards to the muscle coactivation value.

The control output14is transmitted to the device to be controlled, which can be any electronically controlled device. For example, in some embodiments, the device to be controlled is one of a mechanical actuator (FIG. 5), a touchscreen device (FIG. 6), a radio controlled vehicle, a video game, an exoskeleton suit, heavy machinery, such as explosive ordinance disposal robots, or robot assisted laparoscopic surgery.

Another aspect is directed to a method for making an electronic device10. The method includes coupling a pair of EMG sensors11a-11bto a user12, and operating a control device13configured to generate a control output14based upon a control input15and to change a scaling16between the control input and the control output based upon the pair of EMG sensors.

Referring now additionally toFIG. 4, another embodiment of the electronic device110is now described. In this embodiment of the electronic device110, those elements already discussed above with respect toFIGS. 1-2are incremented by 100 and most require no further discussion herein. This embodiment differs from the previous embodiment in that this electronic device110illustratively includes the electronic device comprising a garment122(e.g. the illustrative sleeve) to be worn by the user112and carrying a plurality of electrodes117a-117c. Helpfully, the garment122permits the user112to easily wear the plurality of electrodes117a-117while controlling the electronic device110. In particular, in this embodiment, the plurality of electrodes117a-117each includes a button connector for wired connection. Of course, in other embodiments, wireless communication can be used, and the button connectors would be omitted.

Referring now additionally toFIG. 5, another embodiment of the electronic device210is now described. In this embodiment of the electronic device210, those elements already discussed above with respect toFIGS. 1-2are incremented by 200 and most require no further discussion herein. This embodiment differs from the previous embodiment in that this electronic device210illustratively includes the control device213comprising an input device223(e.g. a joystick) to be manipulated by the user212, and an actuator224responsive to the input device (i.e. a mechanical application).

Referring now additionally toFIG. 6, another embodiment of the electronic device310is now described. In this embodiment of the electronic device310, those elements already discussed above with respect toFIGS. 1-2are incremented by 300 and most require no further discussion herein. This embodiment differs from the previous embodiment in that this electronic device310illustratively includes the control device313comprising a touchscreen input device323(e.g. a touchscreen display in mobile communications device) to be manipulated by the user312. The control device313illustratively comprises a processor325configured to perform the scaling316between the control input315and the control output314. The touchscreen input device323is configured to display a visual indicator324responsive to the touchscreen input device.

Advantageously, electronic device10,110,210,310may adjust controller sensitivity without a priori knowledge of the task being performed using biofeedback in the form of an electromyogram. Moreover, this controller sensitivity adjustment is performed without user action.

As will be appreciated, when performing precise movements, muscles become tense more than when performing imprecise movements. This tensing of muscles is due to muscle coactivation being used to increase joint stiffness, thus increasing limb stability. The EMG sensors of the electronic device10,110,210,310can be used to detect muscle coactivation. From the muscle coactivation levels recorded by the electromyogram in the electronic device10,110,210,310, it can be determined how precisely the user intends to move based upon the user's tenseness.

When making precise movements, muscles within the same muscle group oppose one and other, whereas when not making precise movements, only one muscle in the muscle group is being primarily activated. Because the opposing muscles within a muscle group tense prior to movement, the users intention can be determined prior to the user making any input to the controller. Depending on the intent of the user the controller sensitivity can be increased or decreased. The electronic device10,110,210,310may improve automatic controller sensitivity, and may provide advances in mechatronics, increased usage in safety critical industrial/military applications, and the desire to improve performance and safety.