While bipedal locomotion for humanoid robots has improved significantly over the past 50 years of dedicated research, energy efficiency and load capacity remain challenging considerations in locomotion tasks. The LARMbot V.3 humanoid addresses these issues with custom parallel architectures in a low-cost and compact platform (850 mm in height, 462 mm in leg length, and 3.6 kg in weight) mainly for research and education purposes.

This work presents a performance evaluation of the LARMbot V.3 modular bipedal locomotion system, which is based on a parallel-serial (3-UPR)R mechanism for each leg. This structure offers proper precision, rigidity, and load capacity while maintaining the desired walking performance and movement stability. After we introduce the architecture, a prototype is presented and we describe the design, manufacturing, and assembly. Walking performance tests were conducted in two modes—free motion in the air and with ground contact—to measure power consumption, speed, and movement repeatability.

The tests demonstrated a stable and repeatable gait cycle with a step length of 80 mm, a step height of 20 mm, and a speed of 5 seconds per step. The acquired IMU data confirmed synchronized leg motion and hip orientation deviations within ±15°. Power measurements showed consistent and low values during the tests, with an average power consumption of 5.11 W. These results confirm the efficiency and reliability of the proposed LARMbot V.3 parallel biped locomotion system. This design enables stable and precise movement while maintaining low power consumption, and it is easy to manufacture. The module can serve as a foundation for further improvements and development of parallel locomotion for humanoid robots.