Design, analysis and kinematic control of highly redundant serial robotic arms

The use of robotic manipulators in industry has grown in the last decades to improve and speed up industrial processes. Industrial manipulators started to be investigated for machining tasks since they can cover larger workspaces, increasing the range of achievable operations and improving flexibility. The company Nimbl’Bot developed a new mechanism, or module, to build stiffer flexible serial modular robots for machining applications. This manipulator is a kinematic redundant robot with 21 degrees of freedom. This thesis thoroughly analysis the Nimbl’Bot robot features and is divided into three main topics. The first topic regards using a task priority kinematic redundancy resolution algorithm for the Nimbl’Bot robot tracking trajectory while optimizing its kinetostatic performances. The second topic is the kinematic redundant robot design optimization with respect to a desired application and its kinetostatic performance. For the third topic, a new workspace determination algorithm is proposed for kinematic redundant manipulators. Several simulation tests are proposed and tested on some Nimbl’Bot robot designs for each subjects

Task priority based design optimization of a kinematic redundant robot

International audienceThis paper presents and defines a new design optimization method for kinematic redundant robot manipulators based on their applications. Kinematic redundant manipulators can reach a pose with an infinite number of postures. So, identifying the best robot design and configuration for a set of desired tasks is a highly complex non-linear problem. This approach employs a task priority control algorithm to perform a task oriented robot design optimization. The design parameters are replaced by controllable prismatic or revolute virtual joints and controlled by the algorithm to accomplish the desired tasks. Therefore, this new method finds an optimal robot design for a set of tasks taking advantage of the robot kinematic redundancy. This method is evaluated on a highly kinematic redundant manipulator, which tracks a set of paths with its end-effector while maintaining good kinetostatic performance

Workspace Determination of Kinematic Redundant Manipulators using a Ray-Based Method

Determining the workspace of a robotic manipulator is extremely significant for knowing its abilities and planning the robot application. There exist several techniques for the robot workspace determination. However, these methods usually are affected by computational redundancy, like in the case of Monte Carlo based methods, or their implementation is difficult. Moreover, the workspace analysis of kinematic redundant manipulators is even more complex. This paper introduces a ray-based workspace determination algorithm, easy to implement and not affected by computational redundancy. The proposed method can be applied to any type of serial robot, but it is tested only on spatial kinematic redundant robots. The results show how the approach can clearly determine the boundary of the robot workspace in a short period of time. Finally the time and quality performance of the ray-based method results are compared to the Monte Carlo one demonstrating the improvement of the proposed method