Design of a 3-Degree-of-Freedom Hip Exoskeleton with Partial Moment Sensing Capability

In the design of rehabilitation exoskeletons, the human hip joint presents a challenge due to its high degrees of freedom and significant torque requirements. In traditional hip exoskeleton designs, some degrees of freedom are passively driven, leading to notable deficiencies in stability and accuracy, making it difficult to replicate the wearer's natural gait. Moreover, misalignment arises from inconsistencies between the rotational centers of different degrees of freedom and the hip joint, which not only affects user experience but also negatively impacts training effectiveness. This paper presents a 3-DOF hip exoskeleton design characterized by three active degrees of freedom and a biomimetic joint layout, aligning the rotational centers of all three degrees of freedom at a single point. Compared to traditional hip exoskeletons, this design offers greater flexibility and adaptability. Additionally, a torque sensor was developed to measure the hip abduction-adduction (HAA) degree of freedom. Torque acquisition experiments were conducted to validate the feasibility and accuracy of the proposed design in practical applications. The experimental results demonstrated that the designed torque sensor accurately detected joint torque variations under different loads, providing reliable data support for intention recognition and rehabilitation assessment. This not only confirmed the rationality of the design but also offered valuable insights for further optimization and improvement.