Wheelchair controlled by head movements

131,800,000 people in the world use a wheelchair - according to WheelchairFoundation.org. This means that less than 2% of the world's citizens require personal transportation for their physical fitness.

The projected aging of the population will mean that people using wheelchairs will be an increasingly common sight, both in the workplace and in public spaces. A wheelchair is a device supporting people whose motor skills and/or physical strength do not allow or make it difficult to move independently, walking with crutches or using prostheses or other devices.

The development of technology and science allows us to modernize equipment and expand the offer of electric wheelchairs and convenient control systems. During the implementation of this project, the needs of disabled people will be examined and determined in order to automate the wheelchair and develop a system that will allow for intelligent control using voice commands or head movements of the disabled person.

Currently, the needs of society and the individual are increasing, each of us has more and more opportunities for self-fulfillment and active participation in social life. Social transformation makes us transform from local communities into a global community, which poses new challenges for us, especially for people with physical disabilities.

The aim of this project is to help designers in the field and people with physical disabilities to obtain better equipment that will improve the comfort of wheelchair users by increasing the functionality of existing motorized wheelchairs and adding new functions useful in everyday life. Among the solutions considered will be the possibility of introducing new methods of controlling the wheelchair, with particular attention to the level of force that must be put into its operation.

The wheelchair is controlled by the movement of the patient's head. The control method is based on measuring the deflection of an accelerometer or gyroscope mounted on a cap worn by the person sitting in the wheelchair. The wheelchair moves in response to head movements, read by the gyroscope and transmitted to the control microcontroller.

Intuitive forward or backward tilting movement (flexion and extension) moves the wheelchair forwards and backwards. Sideways movement of the head - moving the ear towards the shoulder - directs the wheelchair to the left or right. Head rotation does not activate the wheelchair movement, allowing the user to safely look left and right.Sensors record how the head is tilted. Turning on the system calibrates it to the current head position. The more movement, the faster the wheelchair will go. Pressing a switch in the headrest or elsewhere will stop the wheelchair. The wheelchair will also stop during sudden movements.

The microcontroller control program allows user to set a dead zone, which works similarly to the dead zone on a standard joystick controller. The dead zone is the range where the system will ignore head movements. This allows to ignore small head movements to ensure a smooth ride while riding moving on uneven surfaces such as sidewalks, carpets or thresholds.

The wheelchair is powered by two DC motors, the direction of rotation and speed of which are determined by signals generated by the microcontroller via independent H-bridges. The wheelchair's position is determined using a GPS receiver thanks to the Notecarrier A GPS module.

The wheelchair controller allows for the transmission of telemetric information about its position and speed via numerous communication interfaces, such as: - WiFi using the Notecard WiFi module - Bluetooth thanks to the nRF52840 DK microcontroller - LTE using the Notecard Cellular LTE-M, NB-IoT module The caregiver has full knowledge of the disabled person's location and will be able to communicate with them by voice. In an exceptional situation, they will be able to take control of the wheelchair if the disabled person is unable to control its movement on their own. This method of monitoring will additionally improve the safety of the disabled person and provide them with additional support.

The following elements were used in the project:

• UNIHIKER - IoT Python Single Board Computer with Touchscreen
• Notecarrier A GPS
• Notecard Cellular LTE-M, NB-IoT
• Notecard WiFi
• Swan with low-cost, embeddable, STM32L4-based MCU
• nRF52840 DK
• two DC motors
• two integrated STM H-bridges
• energy balancing systems in batteries