Compensation of compliance errors in parallel manipulators composed of non-perfect kinematic chains

The paper is devoted to the compliance errors compensation for parallel manipulators under external loading. Proposed approach is based on the non-linear stiffness modeling and reduces to a proper adjusting of a target trajectory. In contrast to previous works, in addition to compliance errors caused by machining forces, the problem of assembling errors caused by inaccuracy in the kinematic chains is considered. The advantages and practical significance of the proposed approach are illustrated by examples that deal with groove milling with Orthoglide manipulator.Comment: Advances in Robot Kinematics, France (2012

Compliance error compensation in robotic-based milling

The paper deals with the problem of compliance errors compensation in robotic-based milling. Contrary to previous works that assume that the forces/torques generated by the manufacturing process are constant, the interaction between the milling tool and the workpiece is modeled in details. It takes into account the tool geometry, the number of teeth, the feed rate, the spindle rotation speed and the properties of the material to be processed. Due to high level of the disturbing forces/torques, the developed compensation technique is based on the non-linear stiffness model that allows us to modify the target trajectory taking into account nonlinearities and to avoid the chattering effect. Illustrative example is presented that deals with robotic-based milling of aluminum alloy

Plan construction and optimization in a multi-agent framework for computer-aided process planning

Up to now, Computer Aided Process Planning (CAPP) had only little impact on industrial practice. Restricted representations did not allow for capturing all relevant aspects of complex real-life problems, the methods were weak in multi-criteria optimization and, even simple CAPP models became computation-ally prohibitive. Here we present a new, multi-agent based approach that tries to overcome these difficulties. Our method is based on the co-operation of domain-specific geometry and technology related agents and a general purpose optimizer engine. While the specific agents, working on the exact geomet-rical representation of the part, available machines and tools, build up the space of the process plans, the solver extracts solutions from this space. A multi-objective evolutionary algorithm is applied to find Pareto sets of solutions that are best according to several criteria, such as changeover and production costs. The operation of the prototype CAPP system is demonstrated through examples in traditional machining

Experimental Study on Cutter Deflection in Multi-axis NC Machining

In five-axis sculptured surface machining, the effect of cutter deflection on tool orientation planning is important. This paper studied themethod for online measurement of cutter deflections along two axes simulation.The measurement equipment was designed and implemented to acquire the displacements of cutter under cutting force online. Acquired data were processed to static values and then compensated by geometric analysis. The cutter deflection conditions were analyzed and divided into different types. The corresponding geometrical equations of the relationship of deflections of measured values and actual values were built. The inter-coupling values were decoupled by solving the geometrical equations. The changing regulations of cutter deflection with tool orientations were analyzed, which could provide support for the study of tool orientation planning. The effectiveness of measurement error compensation was verified by the difference between measured values and actual values of cutter deflections under various tool workpiece inclination angles. This work could be further employed to optimize tool orientations for suppressing the surface errors due to cutter deflections and achieving higher machining accuracy