Ambulatory Estimation of XCoM using Pressure Insoles and IMUs

Ambulatory gait assessment using minimal sensors has quite an impact for different applications requiring localised sensing. ForceShoes™ was developed as one such solution. It consists of two IMUs, and two 6DoF force and moment (F&M) sensors on each foot1. Additionally, an ultrasound system was added 2. The complete system, also referred to as Ambulatory Gait and Balance System (AGBS), is used to measure ambulatory kinematics and kinetics of the feet while walking. The AGBS has been validated against standard systems2,3. Using the measured F&M, and position estimations from IMUs, the low and high-frequency information of Center of Mass (CoM) is estimated. This was used to estimate the Extrapolated Center of Mass (XCoM)4. XCoM along with base of support provides information about stability during walking4. The unique advantage of the AGBS is its portability and ambulatory measurement when compared to standard systems. The F&M sensors in the AGBS however, are quite bulky, making it heavier and taller than normal shoes. As an alternative, using 1D pressure sensors was studied. Pressure sensors are thin and easy to slip as insoles in shoes. Therefore, they show potential in making the ambulatory system less bulky.