4.2.1.2 Gesture Recognition

The Colibri Suite’s gesture recognition model detects and classifies hand movement patterns performed inside the sensing area.

Using advanced random classification based on Hidden Markov Model (HMM), industry best gesture recognition rate is being achieved.

The Colibri Suite includes a set of predefined hand gestures which contains Flick, Circular and Symbol gestures as the ones outlined below:

Flick Gestures

Figure 4-2. Flick Gestures

A Flick gesture is a unidirectional gesture in a quick flicking motion. An example may be a hand movement from West to East within the sensing area, from South to North, etc.

Circular Gestures

Figure 4-3. Circle Gestures
A circular gesture is a round-shaped hand movement defined by direction (clockwise/counterclockwise) without any specific start position of the user’s hand. Two types of circular gestures are distinguished by GestIC technology:
  1. AirWheel
    • An AirWheel is the recognition of continuously-performed rotations inside the sensing area and provides information about the rotational movement in real time. It provides continuously counter information which increments/decrements according to the movement’s direction (clockwise/counterclockwise). The AirWheel can be adjusted for convenient usage in various applications (e.g., volume control, sensitivity adjustment or light dimming).
  2. Discrete Circles
    • Discrete Circles are recognized after performing a hand movement inside the sensing area. The recognition result (direction: clockwise/counterclockwise) is provided after the hand movement stops or the hand exits the detection area. The Discrete Circles are typically used as dedicated application control commands.

Hold and Presence Gestures

Hold/Presence gestures are recognized through the detection of a hand within a configurable detection area. After the hand is detected as being present in this area, a timer will be started. If the hand stays within the detection area until a certain timer value is reached, the Presence gesture is detected. The timer value is configurable. The Presence gesture is typically used for lighting up backlights as if the hand is in the detection area and does not move; a second timer is started.

Presence and Hold gestures are triggered upon a time-out in a defined Status flag. If a Status flag is active during a certain amount of time, after its last rising edge, the corresponding gesture is triggered.

The Status flags that can trigger one of these gestures are:
  • Hand Presence flag is active while the user's hand is in the sensing space.
  • Hand Inside flag is active while the user's hand is in the sensing space approximately centered above the sensor.
  • Hand Hold flag is active while the hand is not moving and one of the above Status flags is active, the selection depends on ActiveOutside.

The behavior of the Status flags and corresponding gestures can be adjusted to suit a specific application. The Gesture and Presence/Hold state visualization windows offer immediate feedback upon adjustment.

The adjustable parameters are:
  1. ActiveOutside
    • Chooses if Hand Hold flag and Presence gesture can be active when the user is outside the sensor, but still in sensing space.
      • ActiveOutside checked (default) means that Hand Presence is required to set Hand Hold and that Presence Duration starts counting on the rising edge of Hand Presence Status flag;
      • ActiveOutside unchecked means that Hand Inside is required to set Hand Hold and that Presence Duration starts counting on the rising edge of Hand Inside Status flag.
  2. Presence Duration
    • This is the time during which the selected Status flag must be active to trigger a Presence gesture. This time starts counting on the last rising edge of the selected Status flag. The gesture is only triggered once for each rising edge of the flag.
  3. Hold Duration
    • This is the time during which the Holding Hand flag must be active to trigger a Hold gesture. This time starts counting on the last rising edge of the Holding Hand flag. The gesture is only triggered once for each rising edge of the flag.
  4. Hold Tremble Threshold
    • This value specifies how much the hand can move and still be considered as holding. For high values, the hand can move while the Hand Hold flag is still high. For low values, only a slight movement is necessary to clear the Hand Hold flag.

Sensor Touch Gestures

Figure 4-4. Sensor Touch

A Sensor Touch is a multi-zone gesture that reports up to five concurrently-performed touches on the system’s electrodes.

The Sensor Touch provides information about touch and tapping:
  1. The Sensor Touch indicates an event during which a GestIC electrode is touched. This allows distinction between short and long touches.
  2. The Tap and Double Tap signalize short taps and double taps on each system electrode. The tap length and double tap interval are adjustable.
    • Single Tap Delay: A single tap is detected when touching the surface of an electrode first and after the hand is pulled out of the touch area. The Single Tap is only detected when the timing between the touch and the release of the touch event is smaller than the adjusted delay. Increasing the time allows the user more time to perform the tap. The range for the adjusted delay can range between 0s and 1s.
    • Double Tap Delay: The double tap is detected when two taps are performed within the adjusted delay. The range for the adjusted delay can range between 0s and 1s. The smaller the selected delay is, the faster the two taps have to be executed.
Figure 4-5. Sensor Touch Diagram