Human-Interactive Robotics Lab (HIRoLab), Department of Mechanical Engineering-Engineering Mechanics, Michigan Technological University , Houghton, MI , USA.
Front Bioeng Biotechnol. 2016 May 2;4:36. doi: 10.3389/fbioe.2016.00036. eCollection 2016.
This paper describes the design of an ankle-foot robotic prosthesis controllable in the sagittal and frontal planes. The prosthesis was designed to meet the mechanical characteristics of the human ankle including power, range of motion, and weight. To transfer the power from the motors and gearboxes to the ankle-foot mechanism, a Bowden cable system was used. The Bowden cable allows for optimal placement of the motors and gearboxes in order to improve gait biomechanics such as the metabolic energy cost and gait asymmetry during locomotion. Additionally, it allows flexibility in the customization of the device to amputees with different residual limb sizes. To control the prosthesis, impedance controllers in both sagittal and frontal planes were developed. The impedance controllers used torque feedback from strain gages installed on the foot. Preliminary evaluation was performed to verify the capability of the prosthesis to track the kinematics of the human ankle in two degrees of freedom (DOFs), the mechanical efficiency of the Bowden cable transmission, and the ability of the prosthesis to modulate the impedance of the ankle. Moreover, the system was characterized by describing the relationship between the stiffness of the impedance controllers to the actual stiffness of the ankle. Efficiency estimation showed 85.4% efficiency in the Bowden cable transmission. The prosthesis was capable of properly mimicking human ankle kinematics and changing its mechanical impedance in two DOFs in real time with a range of stiffness sufficient for normal human walking. In dorsiflexion-plantarflexion (DP), the stiffness ranged from 0 to 236 Nm/rad and in inversion-eversion (IE), the stiffness ranged from 1 to 33 Nm/rad.
本文介绍了一种可在矢状面和额状面控制的踝足机器人假肢的设计。该假肢的设计符合人体踝关节的机械特性，包括功率、运动范围和重量。为了将电机和齿轮箱的动力传递到踝足机构，使用了鲍登线系统。鲍登线允许将电机和齿轮箱最佳放置，以改善步态生物力学，例如运动时的代谢能量成本和步态不对称性。此外，它允许根据截肢者不同的残肢尺寸灵活定制设备。为了控制假肢，在矢状面和额状面都开发了阻抗控制器。阻抗控制器使用安装在脚上的应变计的扭矩反馈。进行了初步评估，以验证假肢在两个自由度 (DOF) 下跟踪人类踝关节运动学、鲍登线传输的机械效率以及假肢调节踝关节阻抗的能力。此外，通过描述阻抗控制器的刚度与踝关节实际刚度之间的关系来表征系统。效率估计表明，鲍登线传输的效率为 85.4%。假肢能够正确模拟人类踝关节运动，并在两个自由度实时改变其机械阻抗，其刚度范围足以满足正常人类行走。在背屈-跖屈 (DP) 中，刚度范围从 0 到 236 Nm/rad，在内翻-外翻 (IE) 中，刚度范围从 1 到 33 Nm/rad。
