Simulation and construction of a 2-DOF wire driven robotic arm with 3-D workspace

Inspired by the muscle arrangement of the octopus and skeleton of the snakes, a wire-driven serpentine robot arm has been simulated and constructed in this article. The robot links which are connected via flexible beam act as the snake backbone. Instead of using motors at each joint, four sets of wire are employed as octopus muscles to drive the robot arm. For the spatial inverse kinematics, after determining the generalized coordinates of the system, governing algebraic equations of the system including constraint equations of the joints and cables and favorable movements have been determined. For displacement analysis, these equations have been solved using the Newton-Raphson method. Using this method robot workspace has also been determined.For the inverse dynamics of the robot, cables tension force has been considered as external forces. Using Embedding technique with specified constraint matrix, mass matrix and acceleration vectors that are determined from inverse kinematics, cables tension force and torque of motors are specified. To validate the snake robot model, a prototype has been built and programmed for some circular and arcuate routs. Travelled pass by end effector have been obtained. Comparing the results with the desired path, accuracy of the designed robot has been investigated.