Situation-driven control of a robotic wheelchair to follow a caregiver

Recently, several robotic/intelligent wheelchairs that have autonomous functions to get to some goals or user-friendly interfaces, have been proposed. Although it is desirable for wheelchair users to go out alone, caregivers often accompany them. Therefore it is important to consider reducing caregivers´ load and support their activities. Hence, we have proposed a robotic wheelchair that can move with a caregiver side by side by observing his/her behaviors such as body position and orientation. This way of motion enables easy communication between the wheelchair user and the caregiver. However, caregivers cannot always move with the wheelchair side by side. For instance, they may step forward of the wheelchair to open a door, and they may step aside when pedestrians are approaching in narrow corridors. To cope with these situations we propose a new robotic wheelchair that can move with a caregiver collaboratively depending on the situation. A laser range sensor is used for observing the environment around the wheelchair. When any obstacles are found in its travelling direction, the wheelchair gives up moving with the caregiver side by side and follows him/her behind. When the caregiver stops at a door, the wheelchair waits for him/her to open the door and follows him/her while avoiding obstacles. The wheelchair returns to move side by side with the caregiver when it enters wide space. We propose a motion control method based on the potential field method, which enables the wheelchair to take an appropriate position with respect to the caregiver depending on the situation.