Latest Papers

ASME Journal of Mechanisms and Robotics

  • Mechanical Characterization of Supernumerary Robotic Tails for Human Balance Augmentation
    on August 31, 2023 at 12:00 am

    AbstractHumans are intrinsically unstable in quiet stance from a rigid body system viewpoint; however, they maintain balance, thanks to neuro-muscular sensory control properties. With increasing levels of balance related incidents in industrial and ageing populations globally each year, the development of assistive mechanisms to augment human balance is paramount. This work investigates the mechanical characteristics of kinematically dissimilar one and two degrees-of-freedom (DoF) supernumerary robotic tails for balance augmentation. Through dynamic simulations and manipulability assessments, the importance of variable coupling inertia in creating a sufficient reaction torque is highlighted. It is shown that two-DoF tails with solely revolute joints are best suited to address the balance augmentation issue. Within the two-DoF options, the characteristics of open versus closed loop tails are investigated, with the ultimate design selection requiring trade-offs between environmental workspace, biomechanical factors, and manufacturing ease to be made.

Design and Evaluation of a Smooth-Locking-Based Customizable Prosthetic Knee Joint


Limb loss affects many people from a variety of backgrounds around the world. The most advanced commercially available prostheses for transfemoral amputees are fully active (powered) designs but remain very expensive and unavailable in the developing world. Consequently, improvements of low-cost, passive prostheses have been made to provide high-quality rehabilitation to amputees of any background. This study explores the design and evaluation of a smooth-locking-based bionic knee joint to replicate the swing phase of the human gait cycle. The two-part design was based on the condyle geometry of the interface between the femur and tibia obtained from magnetic resonance (MR) images of the human subject, while springs were used to replace the anterior and posterior cruciate ligaments. A flexible four-bar linkage mechanism was successfully achieved to provide not only rotation along a variable instantaneous axis but also slight translation in the sagittal plane, similar to the anatomical knee. We systematically evaluated the effects of different spring configurations in terms of stiffness, position, and relaxion length on knee flexion angles during walking. A good replication of the swing phase was achieved by relatively high stiffness and increased relaxation length of springs. The stance phase of the gait cycle was improved compared to some models but remained relatively flat, where further verification should be conducted. In addition, 3D printing technique provides a convenient design and manufacturing process, making the prosthesis customizable for different individuals based on subject-specific modeling of the amputee’s knee.

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