Monocular Visual-Inertial and Robotic-Arm Calibration in a Unifying Framework

Reliable and accurate calibration for camera,inertial measurement unit(IMU)and robot is a critical prerequisite for visual-inertial based robot pose estimation and surrounding environment perception.However,traditional calibrations suffer inaccuracy and inconsistency.To address these problems,this paper proposes a monocular visual-inertial and robotic-arm calibration in a unifying framework.In our method,the spatial relationship is geometrically correlated between the sensing units and robotic arm.The decoupled estimations on rotation and translation could reduce the coupled errors during the optimization.Additionally,the robotic calibration moving trajectory has been designed in a spiral pattern that enables full excitations on 6 DOF motions repeatably and consistently.The calibration has been evaluated on our developed platform.In the experiments,the calibration achieves the accuracy with rotation and translation RMSEs less than 0.7°and 0.01 m,respectively.The comparisons with state-of-the-art results prove our calibration consistency,accuracy and effectiveness.

Rule based vs Optimization based Workload Control with and without Exogenous Lead Times:An Assessment by Simulation

Order release is a key production planning and control function,specifically in high variety contexts.A large literature on release methods that balance the workload consequently emerged.These Workload Control methods can be rule based,using a simple greedy heuristic,optimization based or optimization based with lead times that are exogenous.Although all three types of methods have the same objective,their performance has never been compared.Using simulation,this study shows that a better on time delivery performance of jobs can be achieved by the two optimization based release methods.Most importantly,optimization based methods that assume lead times to be exogenous significantly outperform alternative methods in terms of tardiness performance.Rule based and optimization based Workload Control without exogenous lead times overemphasize average lateness reduction,which leads to sequence deviations that offset performance improvements through balancing.In contrast,Workload Control methods that assume lead times to be exogenous limit sequence deviations,which leads to a significant reduction in dispersion of lateness.This has important implication for the future design of order release methods,and managerial practice.