Cylindrical Peg-In-Hole assembly has been the benchmark force-controlled robotic assembly. It involves two main stages. The first one aims at placing the peg center within the clearance region of the hole center, known as the search phase. The next step is to correct the orientational misalignment, known as the insertion phase. The insertion has been widely researched as compared to the search phase. Search is generally done by locating the hole center using a vision-sensor or by using blind search techniques. An intelligent search in which a neural network is trained with the moment-profile over the hole surface and then tries to infer the hole center based on the current moment values, works for a parallel peg only and also requires the moment profile over the complete hole and hence is not general. This paper generalizes this approach for the tilted peg case. Another intelligent strategy is precession-based hole search, but again, it requires the tilt of the peg and peg's center to be known to perform precession. We need a general-purpose intelligent search strategy that can work without any knowledge of the environment (like hole diameter, peg tilt, etc.). In this paper, we suggest search strategies using mathematical optimization techniques. These strategies do not require any a priori information about the working environment. Simulation results are presented.

Purpose This paper aims to provide a solution to the first phase of a force-controlled circular Peg-In-Hole assembly using an industrial robot. The paper suggests motion planning of the robot’s end-effector so as to perform Peg-In-Hole search with minimum a priori information of the working environment. Design/methodology/approach The paper models Peg-In-Hole search problem as a problem of finding the minima in depth profile for a particular assembly. Thereafter, various optimization techniques are used to guide the robot to locate minima and complete the hole search. This approach is inspired by a human’s approach of searching a hole by moving peg in various directions so as to search a point of maximum insertion which is same as the minima in depth profile. Findings The usage of optimization techniques for hole search allows the robot to work with minimum a priori information of the working environment. Also, the iterative nature of the techniques adapts to any disturbance during assembly. Practical implications The techniques discussed here are quite useful if a force-controlled assembly needs to be performed in a highly unknown environment and also when the assembly setup can get disturbed in between. Originality/value The concept is original and provides a non-conventional use of optimization techniques, not for optimization of some process directly but for an industrial robot’s motion planning.

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About Emerald www.emeraldinsight.comEmerald is a global publisher linking research and practice to the benefit of society. The company manages a portfolio of more than 290 journals and over 2,350 books and book series volumes, as well as providing an extensive range of online products and additional customer resources and services.Emerald is both COUNTER 4 and TRANSFER compliant. The organization is a partner of the Committee on Publication Ethics (COPE) and also works with Portico and the LOCKSS initiative for digital archive preservation. AbstractPurpose -The purpose of this paper is to conduct a reliable remote manipulation with good contact perception of the remote site. The long-term experience of the authors' repeatedly confirm that the highest relevance lies in monitoring the wrench acting at a structurally weak point of the work piece rather than monitoring the wrench experienced by the robot end-effector. Design/methodology/approach -The approach followed here is to sense the wrench at the interface of the robot end-effector and the environment. Position and orientation data and environment model are used to arrive at the contact point in real time. The intent of remote contact procedure is understood based on the knowledge of motion trajectory. All the above information is used to develop a wrench transformation to obtain the force diagrams. Findings -The haptic solutions greatly suffer from objectivity, and therefore may result in inconsistency in an operator's role. Intermediary telepresence through the visual communication of the wrench at the remote site in the form of force diagram provides excellent consistency across the operators and operations. Observing six components of the wrench in separate graphs does not provide on-line error estimate. Force diagrams suggested in the paper are found to be highly effective in perceiving the wrench. Practical implications -The contact mode operations like assembly, surgery, docking, etc. still suffer due to the lack of easily perceivable wrench visualization. This paper provides solution to such practical issues. Originality/value -The concept is original, and has evolved steadily over a period of time. Figure 20Master screen depicting the commanded trajectory, actual trajectory followed by the remote manipulator along with 3-D visualization of the manipulator and the force diagram in force feedback window Intermediary telepresence for remote manipulation Varsha Shirwalkar, Dwarakanath T.A. and Gaurav Bhutani

The need for dextrous manipulation arises when the physical dimensions and mechanical properties of the materials to be handled may not be known precisely.For such applications the gripper should be able to control the position of its finger or the force which it exerts on the object, and also be able to detect slip and take corrective action. This paper describes certain aspects of design involved and experiments carried out using a deztrous gripper which is being developed for nuclear applications. 0-7803-361 2-7-4/97 $5.00 @ 1997 IEEE