Biometric Devices: Jaw Movement to Control a Wheelchair
HMI, or Human-Machine Interaction is a field that is rapidly advancing as technology becomes more sophisticated. Development teams all over the world are seeking more ways to integrate interaction with machines into our daily lives. Eye tracking is just one of many HMI technologies that have emerged.
In a study published at The University of Essex, UK, researchers Lai Wei and Huosheng Hu have presented a new human-machine interaction (HMI) device designed for hands-free control of electric wheelchairs. They’ve incorporated both forehead electromyography (EMG) signals and color face image information to identify winking and jaw clenching movements. In the study, the researchers used five winking and jaw clenching movement patterns, which are mapped into five control commands that drive a simulated wheelchair in an office environment.
Biometric mobility control is something that has been seen with both eye tracking and other facial movements to help people with severe physical disabilities such as spinal cord injury, quadriplegia, hemiplegia, and amputation. People with such afflictions cannot control an electric wheelchair using a traditional joystick and hand movements, so there are many minds out there attempting to create alternatives that would enable freedom; some other examples being Eye-Com Corporation’s eye controlled wheelchair and the sniff controlled wheelchair being developed in Israel.
The human face is a remarkable area for studying HMI methods of course – facial image information plays a key role in understanding intentions by computer. Using Haar feature-based (we’ve mentioned Haar features in previous posts) Boosting cascade face detection technique, researchers were able to set up an essential foundation from which to work.
The two researchers designated jaw-clenching movements created when a person contracts the masseter and buccinators muscles with a jaw clenching, chewing-like movement. Three specific jaw-clenching movements were named as continuous jaw movement (CJC), single jaw clenching movement (SJC), and double jaw clenching movement (DJC). Those used in collaboration with Eye Close Movements (Winking) such as left eye close (LEC) and right eye close (REC), created a system for the study.
The five recognizable facial movements were applied to an electrical wheelchair controller using a manual joystick method as a reference. A substitute control method comprising six control commands were utilized – commands like Go Forward (GF), Turn Left (TL), Turn Right (TR), Reduce Speed (RS), Stop (ST) and Go Backwards (GB). These were synched up, so that when the left eye close pattern was detected, the chair would turn left. When continuous jaw movement was employed, the chair was given the command to then go forward.
EMG and Visual based HMI for hands-free control of an intelligent wheelchair
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