Research On Key Technologies Of A Pneumatic Soft Omnidirectional Bending Module

The traditional rigid robots mainly achieve movement through rigid joints driven by motor, hydraulic and pneumatic systems, which is fragile and difficult to move on an uneven ground or in an unknown environment. Soft robot has an infinite number of degrees of freedom and easy to achieve versatility, therefore, it can passively deform to fit the environment and reduce wear and resistance, which can solve the problems of rigid robots. A pneumatic soft bending module has been manufactured combined with the soft robotics research topic of state key laboratory of robotics and system. With the omnidirectional bending properties, the soft robot assembled by several modules can complete obstacle avoiding, crawling and other tasksFirstly, a pneumatic soft bending module is designed based on modular design. Three pneumatic actuated chambers of the same size are set uniformly in the circumferential direction of a single module and strain difference is generated through local strain confinement layer. The stress-strain relationship of ultra-flexible silicone material is described by Yeoh model and the mathematical relationship between pressure module and deformation is analyzed, which can provide theoretical basis for finite element modeling of silicone material. Besides, finite element simulation models are established to obtain the effect of different geometry parameters and driving pressure on bending properties. A group of optimum geometrical parameters are selected from the simulation results, which is used to manufacture the soft bending module by casting.Secondly, kinematics and dynamics analysis is carried out. The cross-sectional geometry during deformation in specific state is analyzed and the analytic function of drive pressure and deformation angle is derived based on tendon-driven force model. In response to the situation that the configuration of soft robot is difficult to measure and the displacement sensor is insufficient, a measurement platform of soft module is designed and calibrated to implement the experimental determination of deformation angle. Adequate samples are obtained by measuring a large number of measurement datum and the kinematic model is identified using BP neural network. The kinematics model of module is established based on the theory of piecewise constant curvature, which can provide a basis for the control of soft module. In addition, Lagrange method is also used to establish the dynamics model of soft module.Finally, a soft robot system is built. A charge and discharge module is designed to achieve precise control of the output pressure using. A soft robot control system consisted of host computer/PC, microcontrollers, pressure sensors, power modules and other components is built and a computer interaction platform based on Visual Studio is developed to achieve the communication between PC and microcontroller via RS232 serial port. The soft robot prototype is assembled to carry out experiments of tandem software arm such as obstacle avoiding, multi-finger collaborating, gesture making and crawling under the restricted environment, which can verify the athletic ability of soft bending module.