In HyunKi, Cho Kyu-Jin, Kim KyuRi, Lee BumSuk
Department of Mechanical and Aerospace Engineering, Seoul National University, Seoul, Republic of Korea.
IEEE Int Conf Rehabil Robot. 2011;2011:5975394. doi: 10.1109/ICORR.2011.5975394.
It is important for a wearable robot to be compact and sufficiently light for use as an assistive device. Since human fingers are arranged in a row in dense space, the concept of traditional wearable robots using a rigid frame and a pin joint result in size and complexity problems. A structure without a conventional pin joint, called a jointless structure, has the potential to be used as a wearable robotic hand because the human skeleton and joint can replace the robot's conventional structure. Another way to reduce the weight of the system is to use under-actuation. Under-actuation enables adaptive grasping with less number of actuators for robotic hands. Differential mechanisms are widely used for multi-finger under-actuation; however, they require additional working space. We propose a design with a jointless structure and a novel under-actuation mechanism to reduce the size and weight of a hand exoskeleton. Using these concepts, we developed a prototype that weighs only 80 grams. To evaluate the prototype, fingertip force and blocked force are measured. Fingertip force is the force that can be applied by the finger of the hand exoskeleton on the object surface. The fingertip force is about 18 N when actuated by a tension force of 35 N from the motor. 18 N is sufficient for simple pinch motion in daily activities. Another factor related to performance of the under-actuation mechanism is blocked force, which is a force required to stop one finger while the other finger keeps on moving. It is measured to be 0.5 N, which is sufficiently small. With these experiments, the feasibility of the new hand exoskeleton has been shown.
对于可穿戴机器人来说，紧凑且足够轻便以便用作辅助设备是很重要的。由于人类手指在密集空间中排成一排，使用刚性框架和销关节的传统可穿戴机器人概念会导致尺寸和复杂性问题。一种没有传统销关节的结构，称为无关节结构，有潜力用作可穿戴机器人手，因为人体骨骼和关节可以替代机器人的传统结构。减轻系统重量的另一种方法是采用欠驱动。欠驱动能使机器人手用较少数量的致动器实现自适应抓握。差动机构广泛用于多指欠驱动；然而，它们需要额外的工作空间。我们提出一种具有无关节结构和新型欠驱动机构的设计，以减小手部外骨骼的尺寸和重量。利用这些概念，我们开发了一个仅重80克的原型。为了评估该原型，测量了指尖力和阻挡力。指尖力是手部外骨骼的手指可施加在物体表面上的力。当由电机施加35 N的拉力驱动时，指尖力约为18 N。18 N对于日常活动中的简单捏合动作来说足够了。与欠驱动机构性能相关的另一个因素是阻挡力，它是在另一个手指继续移动时阻止一个手指所需的力。测量结果为0.5 N，足够小。通过这些实验，已证明了新型手部外骨骼的可行性。
