HGAR: A Transformable Ground–Aerial Robot with Dual-Mode Manipulation and Robust Control for Autonomous Pick-and-Place Tasks

This paper presents the development and validation of a novel Hybrid Ground–Aerial Robot (HGAR) that integrates aerial mobility with terrestrial navigation and dual-mode manipulation capabilities for advanced autonomous pick-and-place operations in both structured and unstructured environments. The HGAR features a dual-locomotion system, combining a quadrotor platform for flight with a differential-wheeled mechanism for ground traversal, interconnected by a compact transformation mechanism that enables seamless mode switching. The robot supports two distinct manipulation configurations: a 3-DOF aerial manipulator for in-flight object interaction and a 4-DOF ground manipulator, where the propeller arm serves as an actuated link during terrestrial tasks. Comprehensive kinematic and dynamic models are developed for both operational modes, accompanied by a novel inverse kinematics (IK) formulation for accurate point-to-point task-space tracking. A Robust Internal-Loop Compensator (RIC) ensures stable flight control under external disturbances, while conventional PID controllers manage manipulator joint motion. The integrated system is validated through MATLAB/ADAMS co-simulation, demonstrating accurate object manipulation, trajectory tracking, and disturbance rejection. Simulation results indicate position errors below 5 mm and orientation deviations within ±2.5°, task duration reduced by 23% compared to conventional UAV systems, confirming the robot’s effectiveness in dynamic, multi-modal environments. These results underscore the potential of HGAR for deployment in real-world applications such as search-and-rescue missions, autonomous inspection, and logistics in confined or partially accessible areas.