Folding Assembly by Means of Dual-Arm Robotic Manipulation

In this paper, we consider folding assembly as an assembly primitive suitable for dual-arm robotic assembly, that can be integrated in a higher level assembly strategy. The system composed by two pieces in contact is modelled as an articulated object, connected by a prismatic-revolute joint. Different grasping scenarios were considered in order to model the system, and a simple controller based on feedback linearisation is proposed, using force torque measurements to compute the contact point kinematics. The folding assembly controller has been experimentally tested with two sample parts, in order to showcase folding assembly as a viable assembly primitive.Comment: 7 pages, accepted for ICRA 201

An approach to reducing parameter uncertainty for robotic surface assembly tasks

In contrast to hard automation, which relies on the precise knowledge of all parameters and special-purpose machinery, the goal of flexible assembly is to overcome the inherent uncertainty in the location of the parts. The main result of this dissertation is that, for rigid, non-deformable objects, more accurate estimates of parameters, which describe their position and orientation in Cartesian space, can be obtained through active part interaction and estimation using numerical methods. If the objects have large polyhedral or convex features, the parameter estimation problem can be recasting terms of fitting the collected empirical data to a suitable geometrical model. The planning and execution steps are treated as conceptually separate from the estimation.Additionally, an algorithm for automatic conversion of a compliant path from the Cartesian to the joint space of a general-purpose, 7 degrees of freedom robotic arm is described. This allows for the assembly strategies to be planned in terms of objects'topological features in the task frame. A `back-drivable' Barrett WAM robotic arm without a force sensor was used in all experiments, and approximate compliant motion was achieved by relying on torque limits and impedance. Consequently, the primary focus is on planning, control, and assembly without force sensing. The underlying concepts, however, are much more general and could be extended to incorporate force feedback. Grasping is outside of the scope of this work, and it is assumed throughout that one of the parts is rigidly attached to the end-effector of the robot

A versatile and reconfigurable microassembly workstation

In this paper, a versatile and reconfigurable microassembly workstation designed and realized as a research tool for investigation of the problems in microassembly and micromanipulation processes and recent developments on mechanical and control structure of the system with respect to the previous workstation are presented. These developments include: (i) addition of a manipulator system to realize more complicated assembly and manipulation tasks, (ii) addition of extra DOF for the vision system and sample holder stages in order to make the system more versatile (iii) a new optical microscope as the vision system in order to visualize the microworld and determine the position and orientation of micro components to be assembled or manipulated, (iv) a modular control system hardware which allows handling more DOF. In addition several experiments using the workstation are presented in different modes of operation like tele-operated, semiautomated and fully automated by means of visual based schemes