arXiv subjects

Hamza Tariq

Publications and source records attributed to Hamza Tariq.

4 recordsLinked to original sources

arXiv2026

Dual Path Following for an Aerial Manipulator Under State and Input Constraints via Transverse Feedback Linearization

This paper studies dual path following for a quadrotor carrying a three-degree-of-freedom arm. The center of mass of the combined system must follow a vehicle path and the end effector must follow a second path, while the arm respects its joint limits and avoids its singular postures. The vehicle and the arm are mechanically coupled, so one controller must handle both paths. With the center of mass and the end-effector path coordinates as outputs, and a dynamic extension of the thrust, the system admits a normal form without internal dynamics. We characterize the states where this normal form fails. We formulate the transverse feedback linearizing controller as a quadratic program that relaxes only the speed of the end effector along its path and imposes safety and actuator limits as inequality constraints. The program reduces to a scalar problem with a closed-form solution. If it remains strictly feasible for all time, the feedback is locally Lipschitz, both paths are invariant and attractive, and every constraint holds. In the physics engine Drake, the controller resolves a conflict between the two speed references by slowing the end effector while both paths remain invariant. By contrast, a cascade with a safety filter leaves both paths. Code and animations are available at https://gradslab.github.io/am_dual_pf-/

cs.RO↗

arXiv2026

Decentralized Safe Path Following for Multiple Quadrotors on Intersecting Paths with Theoretical Guarantees

This paper studies decentralized safe path following for multiple quadrotors on intersecting paths, where safety requires both collision avoidance and strict adherence to pre-assigned routes. The proposed controller reformulates transverse feedback linearization as a constrained quadratic program with four equality constraints: two enforce convergence to and strict adherence to the path, and two prescribe the desired speed and heading. Safety is achieved by relaxing only the along-path speed constraint, while the path and heading constraints remain hard. Under the stated assumptions, and for admissible initial conditions, the controller guarantees that all agents converge to and thereafter follow their assigned paths, avoid collisions, and avoid attitude singularities. We evaluate the controller in the Drake physics engine on non-planar intersecting paths and compare it against two nominal-plus-safety-filter cascades. Code and additional results are available at https://gradslab.github.io/safe_multiquad_pf/.

eess.SY↗

arXiv2026

A Relaxed Quadratic-Program-based Framework for Trajectory Tracking of Unicycle Robots with Singularity Avoidance

Dynamic feedback linearization (DFL) is a classical technique for trajectory tracking of unicycle-type mobile robots, but the resulting DFL-based controller becomes singular when the linear velocity vanishes, rendering standard DFL-based controllers unsuitable for stop-and-reverse maneuvers. This paper proposes a quadratic-program (QP)-based optimal control framework that avoids this singularity, while establishing local Lipschitz continuity of the resulting feedback law. Our approach reformulates the DFL constraints as an equality-constrained QP with a slack variable, ensuring feasibility for all states and reference signals, including at points where the robot's velocity vanishes. By introducing slack variables and tunable parameters, we demonstrate that the singular configuration can be avoided for a large class of reference trajectories. The effectiveness of the proposed approach for trajectory tracking is demonstrated through ROS 2-Gazebo simulations on a TurtleBot3 Waffle robot. The code is available at https://gradslab.github.io/DFL_QP_Unicycle/

cs.RO↗

arXiv2025

Exploring the Effects of Generalized Entropy onto Bardeen Black Hole Surrounded by Cloud of Strings

This work explores the thermodynamic characteristics and geothermodynamics of a Bardeen black hole (BH) that interacts with a string cloud and is minimally connected to nonlinear electrodynamics. To avoid the singularities throughout the cosmic evolution, we consider an entropy function which comprises five parameters. In addition, by employing this entropy function for the specific range of parameters, we obtain the representations of BH entropy based on the holographic principle. Moreover, we employ this entropy function to investigate its impact on the thermodynamics of the BH by studying various thermodynamic properties like mass, temperature, heat capacity, and Gibbs free energy for numerous scalar charge and string cloud values. To support our investigation, we use various geothermodynamics formalisms to evaluate the stable behavior and identify different physical scenarios. Furthermore, in this analysis, we observe that only one entropy formalism provides us with better results regarding the thermodynamic behavior of the BH. Moreover, it is shown that one of the entropy models provides a thermodynamic geometric behavior compared to the other entropy models.

gr-qc↗