Adaptive tracking for complex systems using reduced-order models

Reduced-order models are considered in the context of parameter adaptive controllers for tracking workspace trajectories. A dual-arm manipulation task is used to illustrate the methodology and provide simulation results. A parameter adaptive controller is designed to track the desired position trajectory of a payload using a four-parameter model instead of a full-order, nine-parameter model. Several simulations with different payload-to-arm mass ratios are used to illustrate the capabilities of the reduced-order model in tracking the desired trajectory

Constrained trajectory optimization for kinematically redundant arms

Two velocity optimization schemes for resolving redundant joint configurations are compared. The Extended Moore-Penrose Technique minimizes the joint velocities and avoids obstacles indirectly by adjoining a cost gradient to the solution. A new method can incorporate inequality constraints directly to avoid obstacles and singularities in the workspace. A four-link arm example is used to illustrate singularity avoidance while tracking desired end-effector paths

An adaptive controller for enhancing operator performance during teleoperation

An adaptive controller is developed for adjusting robot arm parameters while manipulating payloads of unknown mass and inertia. The controller is tested experimentally in a master/slave configuration where the adaptive slave arm is commanded via human operator inputs from a master. Kinematically similar six-joint master and slave arms are used with the last three joints locked for simplification. After a brief initial adaptation period for the unloaded arm, the slave arm retrieves different size payloads and maneuvers them about the workspace. Comparisons are then drawn with similar tasks where the adaptation is turned off. Several simplifications of the controller dynamics are also addressed and experimentally verified

Ground Simulation of an Autonomous Satellite Rendezvous and Tracking System Using Dual Robotic Systems

A hardware-in-the-loop ground system was developed for simulating a robotic servicer spacecraft tracking a target satellite at short range. A relative navigation sensor package "Argon" is mounted on the end-effector of a Fanuc 430 manipulator, which functions as the base platform of the robotic spacecraft servicer. Machine vision algorithms estimate the pose of the target spacecraft, mounted on a Rotopod R-2000 platform, relay the solution to a simulation of the servicer spacecraft running in "Freespace", which performs guidance, navigation and control functions, integrates dynamics, and issues motion commands to a Fanuc platform controller so that it tracks the simulated servicer spacecraft. Results will be reviewed for several satellite motion scenarios at different ranges. Key words: robotics, satellite, servicing, guidance, navigation, tracking, control, docking

Editorial: Robotic In-Situ Servicing, Assembly and Manufacturing

This research topic is dedicated to articles focused on robotic manufacturing, assembly, and servicing utilizing in-situ resources, especially for space robotic applications. The purpose was to gather resource material for researchers from a variety of disciplines to identify common themes, formulate problems, and share promising technologies for autonomous large-scale construction, servicing, and assembly robots. The articles under this special topic provide a snapshot of several key technologies under development to support on-orbit robotic servicing, assembly, and manufacturing

Closed-loop force control for haptic simulation of virtual environments

Force feedback control is investigated for improving the quality of the haptic feedback in virtual reality applications. Advanced control design can increase the transparency of the haptic device at the haptic interface thereby increasing the realism of the simulation. Force feedback also enables the implementation of admittance control approaches heretofore considered the domain of large robotic platforms. The quality of the haptic interface is "rst quanti"ed, and the standard open-loop impedance approach to haptic control is reviewed. Dual-inputcontrolschemeswithsensoryforcefeedbackarethen introduced, and the resulting quality of the haptic interface is derived. Afour-bar linkage example is used to illustrate the improvement in "delity realized with the various approaches. The tradeoffs encountered in moving to force feedback controllers forhaptic applicationsare alsodiscussed. Nomenclature q joint angle vector,rad qc commanded joint angle vector,rad x position vector,m xd desired positionvector,m xc commanded positionvector,m t actuator torque input vector,N-m t fwd feedforward torque vector,N-m td desired torque input vector,N-m tc commanded torque vector,N-m F force output vector,N Fd desired force output vector,N jZh joint impedance matrix,N-m j ˆZh modeled joint impedance matrix,N-m impedance matrix,N/

Preliminary Assessment of the Utilization of Night Vision Goggles in Airborne Forest Fire Suppression

NRC publication: Ye

NVG External Lighting Effects

NRC publication: Ye

Night Vision Goggle External Lighting Effects

Peer reviewed: YesNRC publication: Ye

Evaluation of Night Vision Technologies using Laboratory and Flight Tests

NRC publication: Ye