Development and Evaluation of a Quadruped Leg System With PID and Computed Torque Control: From Real-World Actuation to Simulated Dynamics

This paper presents the design, modeling, and evaluation of a planar quadruped leg system built from low-cost hardware and intended as a testbed for control algorithm development. The system features a 2-DOF leg actuated by brushless DC (BLDC) motors with magnetic encoders, and is controlled in real time via a custom embedded controller based on an STM32 microcontroller. A classical Proportional–Integral–Derivative (PID) controller is implemented and experimentally validated under both airborne and payload-bearing conditions. To explore the potential of model-based control, a simulation environment is developed using the same leg geometry and dynamics. Computed Torque Control (CTC) is implemented using the derived inverse dynamics model, including inertia matrix, Coriolis terms, and gravity compensation. Simulation results show that CTC outperforms PID in trajectory tracking when external disturbances or payload variations occur, especially when mass-aware adjustments are included. However, the real-time implementation of CTC on the current hardware is limited by response latency and actuator constraints, highlighting a trade-off between control complexity and hardware feasibility in low-cost systems. The proposed setup offers a reproducible and extensible platform for future work, including real-time CTC deployment, hardware upgrades, and integration into full quadruped locomotion.