Development of Tribosensor System Using Neural Networks

本课题的目的是开发一种具有人的手指感觉的柔性智能触觉传感器系统。在有限元分析的基础上对传感器进行了设计，并在铝管周围铺设了海绵橡胶片和PVDF薄膜作为传感器材料。为了保护PVDF薄膜，提高灵敏度，引入玻璃纸胶带和纱布作为指纹。针对信号复杂的特点，提出了十点平均高度法、对称点图法和FFT积分法三种数据处理方法对表面粗糙度进行定性和定量评价。在超细纸、报纸和卫生纸上进行了实验，结果表明所提出的触觉传感器对这些纸张的识别是有效的。在此基础上，开发了一种基于主动传感的柔性双指微型夹持器，用于微小软物体的特性识别和夹持力调节。该夹持器由两个由压电双晶片驱动的柔性手指组成。在一个手指的表面粘接一个半导体染色计。在压电驱动器上施加测试阶跃电压，驱动夹持器夹持物体时，用应变计测量了夹持器对称和反对称模态的固有频率。然后用测量的固有频率来评估物体的质量和刚度。最后，根据先前测量到的物体信息，采用PID和模糊控制算法设计了抓取物体的力调节器。理论和实验结果表明，所提出的软微小目标识别方法和力调节器设计简单有效。

The purpose of this project is to development a soft intelligent tactile sensor system having the sense of human's finger. The sensor is designed first on FEM analysis and then constructed by layring the sponge rubber sheet and the sensory meterial of PVDF film around an aluminum pipe. For protection of PVDF film and improvement of the sensitivity, a cellophane tape and a gauze are introduced pretended as fingerprint. Since the signals are very complicated, three data processing methods, such as, ten points average height, symmetrized dot pattern method and FFT integration method, are proposed to evaluate the surface roughness both qualitatively and quantitatively. The experimental results obtained on superfine paper, newspaper and toilet paper are presented and it is found that the proposed tactile sensor is efficient for recognition of these papers.Further, two-fingered flexible miniature gripper was developed for identification of the properties of minute soft objects by active sensing and for force regulating pinch of the objects. The gripper is consisting of two flexible fingers actuated by piezoelectric bimorph strips. A semi-conductor stain gauge is bonded on the surface of one finger. The natural frequencies of symmetric and antisymmetric modes were measured by the strain gauge when the gripper is driven to pinch an object by applying a testing step voltage to the piezoelectric actuator. The mass and stiffness of the object are then evaluated by the measured natural frequencies. Finally a force regulator for grasping the object is designed by the PID and Fuzzy control algorithms based the information measured previously from the object. Both theoretical and experimental results show that the proposed identification method and the design of the force regulator for soft minute objects are simple and efficient in practical use.