Dynamically Stable 3D Quadrupedal Walking with Multi-Domain Hybrid System Models and Virtual Constraint Controllers

Hybrid systems theory has become a powerful approach for designing feedback controllers that achieve dynamically stable bipedal locomotion, both formally and in practice. This paper presents an analytical framework 1) to address multi-domain hybrid models of quadruped robots with high degrees of freedom, and 2) to systematically design nonlinear controllers that asymptotically stabilize periodic orbits of these sophisticated models. A family of parameterized virtual constraint controllers is proposed for continuous-time domains of quadruped locomotion to regulate holonomic and nonholonomic outputs. The properties of the Poincare return map for the full-order and closed-loop hybrid system are studied to investigate the asymptotic stabilization problem of dynamic gaits. An iterative optimization algorithm involving linear and bilinear matrix inequalities is then employed to choose stabilizing virtual constraint parameters. The paper numerically evaluates the analytical results on a simulation model of an advanced 3D quadruped robot, called GR Vision 60, with 36 state variables and 12 control inputs. An optimal amble gait of the robot is designed utilizing the FROST toolkit. The power of the analytical framework is finally illustrated through designing a set of stabilizing virtual constraint controllers with 180 controller parameters.Comment: American Control Conference 201

New ICE concept for hybrid application

Due to increasingly strict regulations on automobile CO2 emission around the world, this thesis focuses on the development of the control strategies of a plug-in series hybrid electric vehicle (HEV) with the goal of minimizing CO2 emission. The thesis consists of three parts. The first target is to set up an electric vehicle (EV) model, which is the base of a plug-in series hybrid electric vehicle. The electric machine and battery are sized, and range capability and energy consumption are evaluated for a vehicle running in EV mode. The second objective is the assessment of the reference performance of the Range Extender (R-EX) architecture through the dynamic programming (DP) function in MATLAB, in terms of minimizing CO2 emissions in the charge-sustaining condition. The third one is the development of the rule based control strategy through the analysis of the DP results by rules extraction. In this thesis, a B-segment hatchback passenger car is modelled. The simulations were carried out along seven standard driving cycles that were developed to model different road conditions. This thesis also evaluates the effect of different values of auxiliary power on the electric range, energy consumption and thresholds of the rule-based control strategy. A sensitivity analysis of the carbon intensity of electricity is performed from a worldwide perspective. Finally, the minimum values of CO2 emission and the optimal engine operating points over different driving cycles are obtained from the dynamic programming; two flow charts of the proposed rule-based control strategies are derived, which are implementable for an electrical control unit to determine the power split between different energy sources

Feedback Control of an Exoskeleton for Paraplegics: Toward Robustly Stable Hands-free Dynamic Walking

This manuscript presents control of a high-DOF fully actuated lower-limb exoskeleton for paraplegic individuals. The key novelty is the ability for the user to walk without the use of crutches or other external means of stabilization. We harness the power of modern optimization techniques and supervised machine learning to develop a smooth feedback control policy that provides robust velocity regulation and perturbation rejection. Preliminary evaluation of the stability and robustness of the proposed approach is demonstrated through the Gazebo simulation environment. In addition, preliminary experimental results with (complete) paraplegic individuals are included for the previous version of the controller.Comment: Submitted to IEEE Control System Magazine. This version addresses reviewers' concerns about the robustness of the algorithm and the motivation for using such exoskeleton

On the Controlling of Multi-Legged Walking Robots on Stable and Unstable Ground

In this chapter, we developed and investigated numerically a general kinematic model of a multi-legged hybrid robot equipped with a crab-like and/or mammal-like legs. To drive the robot’s limbs, a novel generator of gait was employed and tested. The simulation model developed in Mathematica is suitable for virtual study and visualization of the locomotion process. In contrast to our previous papers, in this study we focused especially on precise control of the position of the robot during walking in different directions. In our study we were able to simultaneously control all six spatial degrees of freedom of the robot’s body, as well as all the robot’s legs. Therefore, the investigated robot can be considered and used as a fully controlled walking Stewart platform. What is more, the used algorithm can also be successfully employed to coordinate and control all limbs of the robot on unstable or vibrating ground. As an example, it can be used to stabilize spatial position of the robot when the supporting ground becomes vibrating or unstable, and it will keep the robot stable and prevent it from falling over. Eventually, the developed simulation algorithms can be relatively simply adopted to control real constructions of different multi-legged robots

Real Time Animation of Virtual Humans: A Trade-off Between Naturalness and Control

Virtual humans are employed in many interactive applications using 3D virtual environments, including (serious) games. The motion of such virtual humans should look realistic (or ‘natural’) and allow interaction with the surroundings and other (virtual) humans. Current animation techniques differ in the trade-off they offer between motion naturalness and the control that can be exerted over the motion. We show mechanisms to parametrize, combine (on different body parts) and concatenate motions generated by different animation techniques. We discuss several aspects of motion naturalness and show how it can be evaluated. We conclude by showing the promise of combinations of different animation paradigms to enhance both naturalness and control

In silico case studies of compliant robots: AMARSI deliverable 3.3

In the deliverable 3.2 we presented how the morphological computing ap- proach can significantly facilitate the control strategy in several scenarios, e.g. quadruped locomotion, bipedal locomotion and reaching. In particular, the Kitty experimental platform is an example of the use of morphological computation to allow quadruped locomotion. In this deliverable we continue with the simulation studies on the application of the different morphological computation strategies to control a robotic system

Experimental characterization of a supercapacitor-based electrical torque-boost system for downsized ICE vehicles

The need to improve fuel economy and reduce the emission of CO2 and other harmful pollution from internal-combustion-engine vehicles has led to engine downsizing. However, downsized turbocharged engines exhibit a relatively low torque capability at low engine speeds. To overcome this problem, an electrical torque boost may be employed while accelerating and changing gear and to facilitate energy recovery during regenerative braking. This paper describes the operational requirements of a supercapacitor-based torque-boost system, outlines the design and sizing of the electrical drive-train components, and presents experimental characterization of a demonstrator system