Fig 1: Soteria on Mrs.Mcgonagall
Mrs. McGonagall, a resident of the Hogsmeade old-age home, just received a new Soteria, a hip exoskeleton. This device is designed to assist the user while walking, helping her to maintain balance, hence preventing her from falling over.
Mrs. McGonagall wakes up in the morning, gets up from her bed, and gets dressed for the day. She straps on her fully-charged hip exoskeleton, Soteria, which includes a main frame that houses all the electrical components and a waist band that fits securely around her waist. Mrs. McGonagall also fits the thigh braces of the Soteria in place. She presses the power button to turn it on.
She then puts on her shoes and heads to the market. She has been advised to get a certain amount of physical activity per day, so she takes the longer route to the market. As she walks, the Soteria constantly measures her pelvic pose and hip angle. It then computes her center of mass velocity, acceleration and angular acceleration. It detects the leg in swing and uses the predictive algorithms to constantly compute Mrs. McGonagall’s desired foot placement. Using this information, Soteria plans a desired trajectory for Mrs. McGonagall’s legs and compares it to her current swing leg trajectory constantly.
Mrs. McGonagall tires a little from walking and she tends to sway and fall over. Soteria detects the leg in swing, performs the computations and notes that the difference between the planned trajectory and Mrs. McGonagall’s current leg trajectory exceeds a certain threshold. Hence Soteria computes the torque to be applied to Mrs. Mcgonagall’s leg to correct her trajectory. Soteria ensures that the torque is within safety limits. Soteria then applies this compensatory torque by driving the motors to actuate the frame. Mrs. McGonagall is assisted and stabilized and continues walking to the market.
The market was very crowded that day. Mrs McGonagall was pushed as she was trying to get to the fruit shop. Soteria detects the deviation from the desired trajectory and applies compensatory torque like before to stabilize Mrs. McGonagall. She continues her daily activities, with Soteria strapped on.
At the end of the day, before she goes to bed, Mrs. McGonagall removes the Soteria and leaves it for charging.