Task-Priority Control of Redundant Robotic Systems using Control Lyapunov and Control Barrier Function based Quadratic Programs

This paper presents a novel task-priority control framework for redundant robotic systems based on a hierarchy of control Lyapunov function (CLF) and control barrier function (CBF) based quadratic programs (QPs). The proposed method guarantees strict priority among different groups of tasks such as safety-related, operational and optimization tasks. Moreover, a soft priority measure in the form of penalty parameters can be employed to prioritize tasks at the same priority level. As opposed to kinematic control schemes, the proposed framework is a holistic approach to control of redundant robotic systems, which solves the redundancy resolution, dynamic control and control allocation problems simultaneously. Numerical simulations of a hyper-redundant articulated intervention autonomous underwater vehicle (AIAUV) is presented to validate the proposed framework.Comment: 21st IFAC World Congres

Singularity-free Formation Path Following of Underactuated AUVs: Extended Version

This paper proposes a method for formation path following control of a fleet of underactuated autonomous underwater vehicles. The proposed method combines several hierarchic tasks in a null space-based behavioral algorithm to safely guide the vehicles. Compared to the existing literature, the algorithm includes both inter-vehicle and obstacle collision avoidance, and employs a scheme that keeps the vehicles within given operation limits. The algorithm is applied to a six degree-of-freedom model, using rotation matrices to describe the attitude to avoid singularities. Using the results of cascaded systems theory, we prove that the closed-loop system is uniformly semiglobally exponentially stable. We use numerical simulations to validate the results.Comment: Extended version of a paper, to appear in Proc. 2023 IFAC World Congress, 13 pages (9p + 4p appendices), 5 figure

Stability analysis of snake robot locomotion based on Poincaré maps

Abstract — This paper presents an analysis of snake locomotion that explains how non-uniform viscous ground friction conditions enable snake robots to locomote forward on a planar surface. The explanation is based on a simple mapping from link velocities normal to the direction of motion into propulsive forces in the direction of motion. From this analysis, a controller for a snake robot is proposed. A Poincaré map is employed to prove that all state variables of the snake robot, except for the position in the forward direction, trace out an exponentially stable periodic orbit. I

Output feedback tracking of ships

Abstract-In this brief, we consider output feedback tracking of ships with position and orientation measurements only. Ship dynamics are highly nonlinear, and for tracking control, as opposed to dynamic positioning, these nonlinearities have to be taken into account in the control design. We propose an observer-controller scheme which takes into account the complete ship dynamics, including Coriolis and centripetal forces and nonlinear damping, and results in a semi-globally uniformly stable closed-loop system. Furthermore, a gain tuning procedure for the observer-controller scheme is developed. Experimental results are presented where the observer-controller scheme is implemented onboard a Froude scaled 1:70 model supply ship. The experimentally obtained results are compared with simulation results under ideal conditions and both support the theoretical results on semi-global exponential stability of the closed-loop system