1. Date of download: 7/8/2016 Copyright © ASME. All rights reserved. From: Stabilization of a Dynamic Walking Gait Simulation J. Comput. Nonlinear Dynam. 2006;2(1):65-72. doi:10.1115/1.2389230 The mechanical simulation walking model was created using ADAMS. The HAT segment is a single rigid body, shown as multiple ellipsoids for visual clarity. The only external forces on the model are the ground reaction forces indicated at the feet. Figure Legend:

2. Date of download: 7/8/2016 Copyright © ASME. All rights reserved. From: Stabilization of a Dynamic Walking Gait Simulation J. Comput. Nonlinear Dynam. 2006;2(1):65-72. doi:10.1115/1.2389230 Ground reaction force contact model Figure Legend:

3. Date of download: 7/8/2016 Copyright © ASME. All rights reserved. From: Stabilization of a Dynamic Walking Gait Simulation J. Comput. Nonlinear Dynam. 2006;2(1):65-72. doi:10.1115/1.2389230 The feedback controller computes the joint torques required to drive the model simulation and consists of two components. The Balance Controller component (Sec. ) determines the stabilized joint trajectories. The Joint Position Controller component (Sec. ) drives the joints to the desired angles by specifying input joint torques to the dynamic model simulation. Figure Legend:

4. Date of download: 7/8/2016 Copyright © ASME. All rights reserved. From: Stabilization of a Dynamic Walking Gait Simulation J. Comput. Nonlinear Dynam. 2006;2(1):65-72. doi:10.1115/1.2389230 Graphical interpretation of the calculation of θp for a single limb. The error in the absolute position of the thigh is due to the rotation of the torso, plus the error in the hip angle: θp=θtorso+(θhip−θhip ̱ des). Figure Legend:

5. Date of download: 7/8/2016 Copyright © ASME. All rights reserved. From: Stabilization of a Dynamic Walking Gait Simulation J. Comput. Nonlinear Dynam. 2006;2(1):65-72. doi:10.1115/1.2389230 Balance controller subcomponents: The Velocity Controller (Sec. ) attempts to maintain a constant speed by determining an appropriate forward pitch thetap ̱ des. The Pitch Controller (Sec. ) attempts to achieve the specified pitch by varying the rate of joint trajectories with a time offset. The Joint Trajectory Calculation (Sec. ) computes the desired joint angles using the input trajectory functions and the current time offset. Figure Legend:

6. Date of download: 7/8/2016 Copyright © ASME. All rights reserved. From: Stabilization of a Dynamic Walking Gait Simulation J. Comput. Nonlinear Dynam. 2006;2(1):65-72. doi:10.1115/1.2389230 Velocity control behavior over the simulation duration. The measured velocity was filtered using a moving window filter with a width of one stride period. Figure Legend:

7. Date of download: 7/8/2016 Copyright © ASME. All rights reserved. From: Stabilization of a Dynamic Walking Gait Simulation J. Comput. Nonlinear Dynam. 2006;2(1):65-72. doi:10.1115/1.2389230 Velocity control behavior of a single step. The torso velocity peaks and falls just after right heel contact (0%) and left heel contact (42%). Figure Legend:

8. Date of download: 7/8/2016 Copyright © ASME. All rights reserved. From: Stabilization of a Dynamic Walking Gait Simulation J. Comput. Nonlinear Dynam. 2006;2(1):65-72. doi:10.1115/1.2389230 Pitch control response over simulation duration. The measured and desired pitch were filtered using a moving window filter with a width of one stride period. The dotted line indicates the desired pitch θp ̱ des, which is the control variable used to modulate the average forward velocity. Figure Legend:

9. Date of download: 7/8/2016 Copyright © ASME. All rights reserved. From: Stabilization of a Dynamic Walking Gait Simulation J. Comput. Nonlinear Dynam. 2006;2(1):65-72. doi:10.1115/1.2389230 Pitch control response over a single step. For the steady-state walking steps, θp (Actual) is approximately equal to the torso orientation, and peaks at right (0%) and left (42%) heel contact events. This behavior is consistent with that observed in experimental measurements of human walking. The dotted line indicates θp ̱ des, the controller’s desired pitch angle, which decreases at heel contact in an attempt to compensate for the peaks in velocity seen in Fig.. Figure Legend: