The functional architecture in above figure  demonstrates the function of the exoskeleton system. It depicts the four major subsystems and the flow of data and energy between them. The first main subsystem is the mechanical brace. The mechanical brace is the exoskeleton frame that attaches to the user and houses all the components of the system. The second subsystem is sensing which is comprised of various sensors that are used to determine the motion of the user. The Center of Mass (COM) orientation, velocity, and acceleration, right and left hip angle, velocity, and torque, and the right and left foot contact with the ground will be sensed. The sensed signals will enter the processing subsystem.

The processing subsystem is split into two main parts. The first part removes any undesir- able signal noise and the second part is responsible for performing calculations. Each block in the processing subsystem is responsible for performing a specific calculation. The foot contact infor- mation is used to determine which leg is in swing. The determined swing leg, along with the sensed hip movement is fed into the block that selects the right or left hip signals. The selected hip move- ment signals and COM movement is fed into the block that determines the current trajectory/state. In parallel to the current trajectory calculations, the desired trajectory is also calculated in a two steps. First the sensed hip movement, sensed COM, and calculated swing leg information is fed into the block which determines the optimal landing position. Second, the output along with the sensed COM movement is used to plan the desired trajectory. The desired trajectory and current trajectory are compared to produce an error. This error is ported into the next block where the desired assistive torque is calculated. The assistive torque is limited through a safety threshold.

The calculated assistive torque is passed into the actuation subsystem. The actuation subsystem is responsible for actuating the motors to apply the desired torque. Since the motors are connected to the mechanical brace which is fit onto to the user’s body, the actuation will cause the brace to move and also the user. The entire process is repeated continuously while the system is in use.