Advancement of Robots With Double Encoders for Industrial and Collaborative Applications

The paper deals with the control strategies ad- vancement for robots with double encoders for industrial ap- plications and human-robot collaboration. It addresses both external force/torque detection, classification the nature of the force applied to the manipulator as well as selection of an appro- priate reaction strategy for either human-robot collaboration and technological process execution. In contrast to previous works, the external force is estimated based on the stiffness model and double encoders technology. To estimate the validity of the implemented compliance error estimation and compensation techniques based on the reduces stiffness model additional analyses were done. It showed that a widely used reduced stiffness model for the com- pliance error compensation is able to compensate about 90% of the end-effector errors caused by the external loading. Proposed control algorithms and reaction strategies were validated by a simulation study and experimental study with a collaborative robot with torque sensors Kuka IIWA LBR 14

Parameter identification and model based control of direct drive robots

Imperial Users onl

Workshop on "Robotic assembly of 3D MEMS".

Proceedings of a workshop proposed in IEEE IROS'2007.The increase of MEMS' functionalities often requires the integration of various technologies used for mechanical, optical and electronic subsystems in order to achieve a unique system. These different technologies have usually process incompatibilities and the whole microsystem can not be obtained monolithically and then requires microassembly steps. Microassembly of MEMS based on micrometric components is one of the most promising approaches to achieve high-performance MEMS. Moreover, microassembly also permits to develop suitable MEMS packaging as well as 3D components although microfabrication technologies are usually able to create 2D and "2.5D" components. The study of microassembly methods is consequently a high stake for MEMS technologies growth. Two approaches are currently developped for microassembly: self-assembly and robotic microassembly. In the first one, the assembly is highly parallel but the efficiency and the flexibility still stay low. The robotic approach has the potential to reach precise and reliable assembly with high flexibility. The proposed workshop focuses on this second approach and will take a bearing of the corresponding microrobotic issues. Beyond the microfabrication technologies, performing MEMS microassembly requires, micromanipulation strategies, microworld dynamics and attachment technologies. The design and the fabrication of the microrobot end-effectors as well as the assembled micro-parts require the use of microfabrication technologies. Moreover new micromanipulation strategies are necessary to handle and position micro-parts with sufficiently high accuracy during assembly. The dynamic behaviour of micrometric objects has also to be studied and controlled. Finally, after positioning the micro-part, attachment technologies are necessary

Evaluation of automated decisionmaking methodologies and development of an integrated robotic system simulation

A generic computer simulation for manipulator systems (ROBSIM) was implemented and the specific technologies necessary to increase the role of automation in various missions were developed. The specific items developed are: (1) capability for definition of a manipulator system consisting of multiple arms, load objects, and an environment; (2) capability for kinematic analysis, requirements analysis, and response simulation of manipulator motion; (3) postprocessing options such as graphic replay of simulated motion and manipulator parameter plotting; (4) investigation and simulation of various control methods including manual force/torque and active compliances control; (5) evaluation and implementation of three obstacle avoidance methods; (6) video simulation and edge detection; and (7) software simulation validation

Advanced Strategies for Robot Manipulators

Amongst the robotic systems, robot manipulators have proven themselves to be of increasing importance and are widely adopted to substitute for human in repetitive and/or hazardous tasks. Modern manipulators are designed complicatedly and need to do more precise, crucial and critical tasks. So, the simple traditional control methods cannot be efficient, and advanced control strategies with considering special constraints are needed to establish. In spite of the fact that groundbreaking researches have been carried out in this realm until now, there are still many novel aspects which have to be explored

NASA Tech Briefs, October 2004

Topics include: Relative-Motion Sensors and Actuators for Two Optical Tables; Improved Position Sensor for Feedback Control of Levitation; Compact Tactile Sensors for Robot Fingers; Improved Ion-Channel Biosensors; Suspended-Patch Antenna With Inverted, EM-Coupled Feed; System Would Predictively Preempt Traffic Lights for Emergency Vehicles; Optical Position Encoders for High or Low Temperatures; Inter-Valence-Subband/Conduction-Band-Transport IR Detectors; Additional Drive Circuitry for Piezoelectric Screw Motors; Software for Use with Optoelectronic Measuring Tool; Coordinating Shared Activities; Software Reduces Radio-Interference Effects in Radar Data; Using Iron to Treat Chlorohydrocarbon-Contaminated Soil; Thermally Insulating, Kinematic Tensioned-Fiber Suspension; Back Actuators for Segmented Mirrors and Other Applications; Mechanism for Self-Reacted Friction Stir Welding; Lightweight Exoskeletons with Controllable Actuators; Miniature Robotic Submarine for Exploring Harsh Environments; Electron-Spin Filters Based on the Rashba Effect; Diffusion-Cooled Tantalum Hot-Electron Bolometer Mixers; Tunable Optical True-Time Delay Devices Would Exploit EIT; Fast Query-Optimized Kernel-Machine Classification; Indentured Parts List Maintenance and Part Assembly Capture Tool - IMPACT; An Architecture for Controlling Multiple Robots; Progress in Fabrication of Rocket Combustion Chambers by VPS; CHEM-Based Self-Deploying Spacecraft Radar Antennas; Scalable Multiprocessor for High-Speed Computing in Space; and Simple Systems for Detecting Spacecraft Meteoroid Punctures

Magnetically levitated hysteresis motor driven linear stage for in-vacuum transportation tasks

This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2019Cataloged from PDF version of thesis.Includes bibliographical references (pages 241-246).This thesis presents a new in-vacuum reticle transportation mechanism for extreme ultraviolet (EUV) photolithography machines. In the photolithography process, the reticle is a quartz plate that contains a pattern of the integrated circuit, which needs to be transported between a storage position and the exposure stage. In next-generation EUV lithography machines, the reticle handling system must satisfy the following requirements: (1) transport the reticle through a distance of 2 meters, (2) the height of the mechanism needs to be within 100 mm, (3) operate in vacuum, and (4) satisfy ultra-tight contamination requirements. To fulfill these requirements, a conventional robotic reticle handler is inadequate. In this work, we designed, built, and tested a magnetically-levitated linear stage prototype, targeting at the reticle transportation application. Compared with robot manipulators, linear stages typically require less volume for long-distance transportation tasks.Magnetic suspension is used to eliminate mechanical contact and thereby avoid particle generation that can contaminate the reticle. The stage's linear motion is driven by linear hysteresis motors, which allows using solid-steel motor secondaries on the moving stage. This is desirable for in-vacuum operation, since permanent magnets can out-gas in high vacuum when not encapsulated. The magnetic suspension of the stage is achieved using a novel linear bearingless slice motor design, where the stage's magnetic suspension in three degrees of freedom, including vertical, pitch, and roll, are achieved passively. This compact design effectively reduces the number of sensors and actuators being used. The prototype system has successfully levitated the moving stage. The resonance frequency of the passively levitated degrees of freedom is approximately 10 Hz, and the suspension bandwidth of the actively-controlled degrees of freedom is about 60 Hz.The stage's maximum thrust force is 5.8 N under a 2.5 A current amplitude, which corresponds to a stage acceleration of 1200 M/s². This is able to satisfy the acceleration requirement for reticle transportation task. The stage was tested to track a reticle handling reference trajectory, where the maximum position tracking error of our linear stage is 50 [mu]m. The stage's lateral displacements during motion is below 50 [mu]m, which is well below making mechanical contact to the side walls. To our knowledge, this work represents the first study of linear hysteresis motors, and the first linear bearingless slice motor design. Hysteresis motors are a type of electric machine that operates using the magnetic hysteresis effect of the secondary material. Since the magnetization in the rotor lags behind the external field, a thrust force/torque can be generated.In prior usage, hysteresis motors have been operated in open-loop, which makes them unsuitable for applications where dynamic performance is critical. As a part of this thesis work, we also studied the modeling and closed-loop torque and position control for hysteresis motors. The proposed control method was tested with three rotary hysteresis motors, including two custom-made motors of different rotor materials and one off-the-shelf hysteresis motor. Experimental results show that position control for all three motors can reach a bandwidth of 130 Hz. To our best knowledge, this is the first work that enabled high-bandwidth torque and position control for hysteresis motors, which allows this motor to be used for servo applications.Sponsored by ASMLby Lei Zhou.Ph. D.Ph.D. Massachusetts Institute of Technology, Department of Mechanical Engineerin

Towards a bionic bat: A biomimetic investigation of active sensing, Doppler-shift estimation, and ear morphology design for mobile robots.

Institute of Perception, Action and BehaviourSo-called CF-FM bats are highly mobile creatures who emit long calls in which much of the energy is concentrated in a single frequency. These bats face sensor interpretation problems very similar to those of mobile robots provided with ultrasonic sensors, while navigating in cluttered environments. This dissertation presents biologically inspired engineering on the use of narrowband Sonar in mobile robotics. It replicates, using robotics as a modelling medium, how CF-FM bats process and use the constant frequency part of their emitted call for several tasks, aiming to improve the design and use of narrowband ultrasonic sensors for mobile robot navigation. The experimental platform for the work is RoBat, the biomimetic sonarhead designed by Peremans and Hallam, mounted on a commercial mobile platform as part of the work reported in this dissertation. System integration, including signal processing capabilities inspired by the bat’s auditory system and closed loop control of both sonarhead and mobile base movements, was designed and implemented. The result is a versatile tool for studying the relationship between environmental features, their acoustic correlates and the cues computable from them, in the context of both static, and dynamic real-time closed loop, behaviour. Two models of the signal processing performed by the bat’s cochlea were implemented, based on sets of bandpass filters followed by full-wave rectification and low-pass filtering. One filterbank uses Butterworth filters whose centre frequencies vary linearly across the set. The alternative filterbank uses gammatone filters, with centre frequencies varying non-linearly across the set. Two methods of estimating Doppler-shift from the return echoes after cochlear signal processing were implemented. The first was a simple energy-weighted average of filter centre frequencies. The second was a novel neural network-based technique. Each method was tested with each of the cochlear models, and evaluated in the context of several dynamic tasks in which RoBat was moved at different velocities towards stationary echo sources such as walls and posts. Overall, the performance of the linear filterbank was more consistent than the gammatone. The same applies to the ANN, with consistently better noise performance than the weighted average. The effect of multiple reflectors contained in a single echo was also analysed in terms of error in Doppler-shift estimation assuming a single wider reflector. Inspired by the Doppler-shift compensation and obstacle avoidance behaviours found in CF-FM bats, a Doppler-based controller suitable for collision detection and convoy navigation in robots was devised and implemented in RoBat. The performance of the controller is satisfactory despite low Doppler-shift resolution caused by lower velocity of the robot when compared to real bats. Barshan’s and Kuc’s 2D object localisation method was implemented and adapted to the geometry of RoBat’s sonarhead. Different TOF estimation methods were tested, the parabola fitting being the most accurate. Arc scanning, the ear movement technique to recover elevation cues proposed by Walker, and tested in simulation by her, Peremans and Hallam, was here implemented on RoBat, and integrated with Barshan’s and Kuc’s method in a preliminary narrowband 3D tracker. Finally, joint work with Kim, K¨ampchen and Hallam on designing optimal reflector surfaces inspired by the CF-FM bat’s large pinnae is presented. Genetic algorithms are used for improving the current echolocating capabilities of the sonarhead for both arc scanning and IID behaviours. Multiple reflectors around the transducer using a simple ray light-like model of sound propagation are evolved. Results show phase cancellation problems and the need of a more complete model of wave propagation. Inspired by a physical model of sound diffraction and reflections in the human concha a new model is devised and used to evolve pinnae surfaces made of finite elements. Some interesting paraboloid shapes are obtained, improving performance significantly with respect to the bare transducer