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  • Safety Barrier Certificates for Heterogeneous Multi-Robot Systems 

    Wang, Li; Ames, Aaron; Egerstedt, Magnus B. (Georgia Institute of Technology, 2016-07)
    paper presents a formal framework for collision avoidance in multi-robot systems, wherein an existing controller is modified in a minimally invasive fashion to ensure safety. We build this framework through the use of ...
  • Multi-Contact Locomotion on Transfemoral Prostheses via Hybrid System Models and Optimization-Based Control 

    Zhao, Huihua; Horn, Jonathan; Reher, Jacob; Paredes, Victor; Ames, Aaron D. (Georgia Institute of TechnologyInstitute of Electrical and Electronics Engineers, 2016-03)
    Lower-limb prostheses provide a prime example of cyber-physical systems (CPSs) requiring the synergistic development of sensing, algorithms and controllers. With a view towards better understanding CPSs of this form, this ...
  • Correct-By-Construction Adaptive Cruise Control: Two Approaches 

    Nilsson, Petter; Hussien, Omar; Balkan, Ayca; Chen, Yuxiao; Ames, Aaron A. D.; Grizzle, Jessy; Ozay, Necmiye; Peng, Huei; Tabuada, Paulo (Georgia Institute of Technology, 2016-07)
    Motivated by the challenge of developing control software provably meeting specifications for real world problems, this paper applies formal methods to adaptive cruise control (ACC). Starting from a Linear Temporal Logic ...
  • Multi-Contact Bipedal Robotic Locomotion 

    Zhao, Huihua; Herei, Ayonga; Ma, Wen-loong; Ames, Aaron D. (Georgia Institute of TechnologyCambridge University Press, 2015)
    This paper presents a formal framework for achieving multi-contact bipedal robotic walking, and realizes this methodology experimentally on two robotic platforms: AMBER2 and ATRIAS. Inspired by ...
  • Towards Real-Time Parameter Optimization for Feasible Nonlinear Control with Applications to Robot Locomotion 

    Powell, Matthew J.; Ames, Aaron D. (Georgia Institute of Technology, 2016-07)
    This paper considers the application of classical control methods, designed for unconstrained nonlinear systems, to systems with nontrivial input constraints. As shown throughout the literature, unconstrained classical ...
  • Unification of Locomotion Pattern Generation and Control Lyapunov Function-Based Quadratic Programs 

    Chao, Kenneth Y.; Powell, Matthew J.; Ames, Aaron D.; Hur, Pilwon (Georgia Institute of TechnologyInstitute of Electrical and Electronics Engineers, 2016-07)
    This paper presents a novel method of combining real-time walking pattern generation and constrained nonlinear control to achieve robotic walking under Zero-Moment Point (ZMP) and torque constraints. The proposed method ...
  • Time Dependent Control Lyapunov Functions and Hybrid Zero Dynamics for Stable Robotic Locomotion 

    Kolathaya, Shishir; Hereid, Ayonga; Ames, Aaron D. (Georgia Institute of TechnologyInstitute of Electrical and Electronics Engineers, 2016-07)
    Implementing state-based parameterized periodic trajectories on complex robotic systems, e.g., humanoid robots, can lead to instability due to sensor noise exacerbated by dynamic movements. As a means of understanding ...
  • First Steps Toward Translating Robotic Walking To Prostheses: A Nonlinear Optimization Based Control Approach 

    Zhao, Huihua; Horn, Jonathan; Reher, Jacob; Paredes, Victor; Ames, Aaron D. (Georgia Institute of TechnologySpringer, 2016)
    This paper presents the first steps toward successfully translating nonlinear real-time optimization based controllers from bipedal walking robots to a self-contained powered transfemoral prosthesis: AMPRO, with the ...
  • Work those Arms: Toward Dynamic and Stable Humanoid Walking that Optimizes Full-Body Motion 

    Hubicki, Christian M.; Hereid, Ayonga; Grey, Michael X.; Thomaz, Andrea L.; Ames, Aaron D. (Georgia Institute of TechnologyInstitute of Electrical and Electronics Engineers, 2016-05)
    Humanoid robots are designed with dozens of actuated joints to suit a variety of tasks, but walking controllers rarely make the best use of all of this freedom. We present a framework for maximizing the use of the full ...
  • Realizing Dynamic and Efficient Bipedal Locomotion on the Humanoid Robot DURUS 

    Reher, Jacob; Cousineau, Eric A.; Hereid, Ayonga; Hubicki, Christian M.; Ames, Aaron D. (Georgia Institute of TechnologyInstitute of Electrical and Electronics Engineers, 2016-05)
    This paper presents the methodology used to achieve efficient and dynamic walking behaviors on the prototype humanoid robotics platform, DURUS. As a means of providing a hardware platform capable of these behaviors, the ...
  • 3D Dynamic Walking with Underactuated Humanoid Robots: A Direct Collocation Framework for Optimizing Hybrid Zero Dynamics 

    Hereid, Ayonga; Cousineau, Eric A.; Hubick, Christian M.; Ames, Aaron D. (Georgia Institute of TechnologyInstitute of Electrical and Electronics Engineers, 2016-05)
    Hybrid zero dynamics (HZD) has emerged as a popular framework for dynamic and underactuated bipedal walking, but has significant implementation difficulties when applied to the high degrees of ...
  • Realization of Stair Ascent and Motion Transitions on Prostheses Utilizing Optimization-Based Control and Intent Recognition 

    Zhao, Huihua; Reher, Jacob; Horn, Jonathan; Paredes, Victor; Ames, Aaron D. (Georgia Institute of TechnologyInstitute of Electrical and Electronics Engineers, 2015-08)
    This paper presents a systematic methodology for achieving stable locomotion behaviors on transfemoral prostheses, together with a framework for transitioning between these behaviors—both of which are realized experimentally ...
  • Robustness of Control Barrier Functions for Safety Critical Control 

    Xu, Xiangru; Tabuada, Paulo; Grizzle, Jessy W.; Ames, Aaron D. (Georgia Institute of TechnologyElsevier, 2015)
    Barrier functions (also called certificates) have been an important tool for the verification of hybrid systems, and have also played important roles in optimization and multi-objective control. The extension of a barrier ...
  • Parameter Sensitivity and Boundedness of Robotic Hybrid Periodic Orbits 

    Kolathaya, Shishir; Ames, Aaron D. (Georgia Institute of TechnologyElsevier, 2015)
    Model-based nonlinear controllers like feedback linearization and control Lyapunov functions are highly sensitive to the model parameters of the robot. This paper addresses the problem of realizing these controllers in a ...
  • A Hybrid Systems and Optimization-Based Control Approach to Realizing Multi-Contact Locomotion on Transfemoral Prostheses 

    Zhao, Huihua; Horn, Jonathan; Reher, Jacob; Paredes, Victor; Ames, Aaron D. (Georgia Institute of TechnologyInstitute of Electrical and Electronics Engineers, 2015)
    This paper presents a systematic methodology utilizing multi-domain hybrid system models and optimization based controllers to achieve human-like multi-contact prosthetic walking experimentally on a custom-built prosthesis: ...
  • Continuity and Smoothness Properties of Nonlinear Optimization-Based Feedback Controllers 

    Morris, Benjamin J.; Powell, Matthew J.; Ames, Aaron D. (Georgia Institute of TechnologyInstitute of Electrical and Electronics Engineers, 2015)
    Online optimization-based controllers are becoming increasingly prevalent as a means to control complex high-dimensional nonlinear systems, e.g., bipedal and humanoid robots, due to their ability to balance multiple control ...
  • Correct Software Synthesis for Stable Speed-Controlled Robotic Walking 

    Dantam, Neil; Hereid, Ayonga; Ames, Aaron; Stilman, Mike (Georgia Institute of Technology, 2013-06)
    We present a software synthesis method for speed- controlled robot walking based on supervisory control of a context-free Motion Grammar. First, we use Human-Inspired control to identify parameters for fixed speed walking ...