This paper presents a microassembled robot called the Articulated Four Axes Microrobot (AFAM). Target application areas include micro and nano part manipulation and probing. The robot consists of a cantilever actuated along four axes: in-place$X, Y$and$YAW$; out-of-plane pitch. The microrobot size spans a total volume of$3~{\rm mm}\times 1.5~{\rm mm}\times 1~{\rm mm}$($XYZ$), and operates within a workspace envelope of$50~\mu{\rm m}\times 50~\mu{\rm m}\times 75~\mu{\rm m}$($XYZ$). This is by far the largest operating envelope of any micropositioner with nonplanar dexterity. As a result it can be classified as a new type of three-dimensional microrobot and a candidate for miniaturizing top-down assembly systems to dimensions under$1~{\rm cm}^{3}$. A key feature in this design is a cable-like microwire that transforms in-plane actuator displacement into out-of-plane pitch and yaw motion (via flexure joints). Finite-element analysis simulation followed by microfabrication and assembly processes developed to prototype the designs are described. The microrobot is designed to carry an AFM tip as the end effector and accomplish nanoindentation on a polymer surface. The tip attachment technique and nanoindentation experiments have also been described in this paper. Open loop precision has been characterized using a laser interferometer which measured an average resolution of 50 nm along$XYZ$, repeatability of 100 nm and accuracy of 500 nm. Experiments to determine microrobot reliability are also presented.

Reliable manufacturability has always been a major issue in commercialization of complex and heterogeneous microsystems. Though successful for simpler and monolithic microdevices such as accelerometers and pressure sensors of early days, conventional surface micromachining techniques, and in-plane mechanisms do not prove suffice to address the manufacturing of today's wide range of microsystem designs. This has led to the evolution of microassembly as an alternative and enabling technology which can, in principle, build complex systems by assembling heterogeneous microparts of comparatively simpler design; thus reducing the overall footprint of the device and providing high structural rigidity in a cost efficient manner. However, unlike in macroscale assembly systems, microassembly does not enjoy the flexibility of having ready-to-use manipulation systems or standard off-the-shelf components. System specific designs of microparts and mechanisms make the fabrication process expensive and assembly scheme diverse. This warrants for a modular microassembly cell which can execute the assembly process of multiple microsystems by reconfiguring the kinematics setup, end-effectors, feedback system, etc.; thus minimizing the cost of production. In this paper, we present a multiscale assembly and packaging system (MAPS) comprising of 20 degrees of freedom (DoFs) that can be arranged in several reconfigurable micromanipulation modules depending on the specific task. The system has been equipped with multiple custom-designed microgrippers and end-effectors for different applications. Stereo microscopic vision is achieved through four high-resolution cameras. We will demonstrate the construction of two different microsystems using this microassembly cell; the first one is a miniature optical spectrum analyzer called microspectrometer and the second one is a MEMS mobile robot/conveyor called Arripede.

Microassembly is an enabling technology for micro manufacturing that offers well-known pathways to building heterogeneous microsystems with a higher degree of robustness and more complex designs than monolithic fabrication. The success of assembly in micro domain, however, is directly related to the level of precision automation employed. Control and planning are two defining factors for the microassembly yield and its cycle time. Assembly at the microscale harbors many difficult challenges due to scaling of physics, stringent tolerance budget, high precision requirements, limited work volumes, and so on. These difficulties warrant new control and planning algorithms, different than their macro-scale counterparts. In this paper, we use precision metrics to formalize a hybrid controller for automated MEMS assembly. In the past, we formulated the “high yield assembly condition (HYAC)”, which gives a quantitative condition for the success and failure of compliant microassembly. Using this quatitative tool, we formalize a precision-adjusted hybrid controller switching between open, closed, and calibrated operation in the microassembly cell. Simulation and experimental results for the assembly of a microspectrometer are presented to indicate that the proposed hybrid controller lead to high yields at faster cycle times than traditional precision control methods.

One of the major issues enduring with micro-scale mechanics has been to design high fidelity miniature machines capable of performing complex operations. Though achieved in some proportion through conventional in-plane and out-of-plane designs, the efficacy of such micro-electromechanical systems (MEMS) structures is highly limited due to complicate fabrication and inadequate robustness. On the other hand, the use of precise robots to assemble MEMS parts of comparatively simpler design to build 3D micromechanical structures has recently emerged as a viable approach. Such modular assemblies of microscale parts typically utilize minimum energy connectors that are multifunctional, e.g., mechanical, electrical etc. The μ3is a 3D microassembly station consisting of 19 DOF arranged into 3 micromanipulators, with additional microgrippers and stereo microscope vision. The platform is capable of motion resolutions of 3nm and is small enough to be used inside of a scanning electron microscope (SEM) for nano-manipulation. In this paper we discuss how systematic identification and calibration of the station, combined with appropriate part connector designs can lead to multi-degree of freedom active MEMS robots assembled on a wafer

This paper presents recent results in configuring a multiscale (macro-micro) robotic assembly platform with modular and reconfigurable characteristics. M3 is a multi-robot system capable of spanning across the macro-meso-micro scales, and has been specifically designed to package MOEMS (Micro Opto Electro Mechanical Systems). The emphasis on packaging (as opposed to assembly) is inclusive of the latter, but it also recognizes that bonding, sealing and attachment processes must also be controlled, and will greatly influence the reliability of the microsystem. The system components include precision robots, microstages, end-effectors and fixtures that accomplish assembly tasks in a shared workspace. The system components are systematically characterized in terms of accuracy and repeatability, and assembly plans are performed using kinematic identification, visual servoing, inverse kinematics, and dynamic vibration suppression. As an application packaging problem, various micro and mesoscale parts are assembled into a MEMS device. The tolerance budget of assembly ranges from 4 microns to 300 microns, while the size of components in the assembly ranges from 126 microns to 30mm. Various end-effectors and fixtures have been designed for use with off-the-shelf hardware (robots and microstages) and were tested for precision performance. The robots are calibrated to accuracies of 10 microns or less. In this paper we present experimental results of precision robot calibration and visual servoing for fiber pigtailing with one of the robots within M3

This paper presents recent results in prototyping of a multiscale (macro-micro) robotic assembly platform with modular and reconfigurable characteristics. The system components include precision robots, microstages, end-effectors and fixtures that accomplish assembly tasks in a shared workspace. The system components are systematically characterized in terms of accuracy and repeatability, and assembly plans are performed using kinematic identification, visual servoing, inverse kinematics, and dynamic vibration suppression. As an application packaging problem, various micro and meso scale parts are assembled into a MEMS device. The tolerance budget of assembly ranges from 4 microns to 300 microns, while the size of components in the assembly ranges from 126 microns to 30 mm. Various end-effectors and fixtures have been designed for use with off-the-shelf hardware (robots and microstages) and were tested for precision performance. The robots and the vision system are calibrated to accuracies of 10 microns or less. Inverse kinematics solutions for the robots have been developed in order to position parts in a global coordinate frame. Conclusions are drawn about implementation of calibration, fixturing and visual servoing in order to assemble within the specified tolerance budget

This work presents a framework of tolerance analysis of microparts in microassembly. Tolerance analysis at the micro scale has not been investigated so far even though tolerance analysis at the macro scale has extensively been investigated to improve an assembly yield. It is important to know the positional uncertainties and statistical distribution of parts before and after untethering to improve assembly yield. Positional misalignments of microparts are extracted from raw CCD images and the statistical distribution of parts variances are computed using clustering and transformation of Gaussian distribution. The distributions are not pure Gaussian in nature as might be expected. There are several location peaks found, usually centered at the fabrication location, and at the hard-stop locators.

Deploying large numbers of sensors has been receiving a lot of attention for detection of hazardous biological or chemical substances in public buildings, airports, shallow water harbors, etc. The sensor-carrying robots are in fact agents that facilitate the repositioning of network nodes in order to increase their coverage and accuracy. Wireless network communication is an essential technology in transmitting the sensed and telemetry information between robots, but it has traditionally been addressed separately from mobile robot navigation. In this work we propose to use a potential field framework to control the behavior of the mobile sensor nodes by combining classical robotic team concepts (obstacle avoidance, goal attainment, flight formation, environment mapping and coverage) with traditional sensor network concepts (node energy minimization, optimal data rate and congestion control, routing in ad-hoc networks). Simulation results are used to illustrate the proposed concepts, and an experimental mobile sensor fleet is built at the author's institution.

This paper presents analytical, simulation and experimental results from a study of compliant insertion tasks in microassembly. Gripper compliance is desirable to compensate for positional errors and to prevent the breakage of a gripper during assembly tasks. An analytical model is derived to study the motion and force profiles during compliant insertion. Thermal bimorph microgrippers with a compliant tip are designed and fabricated using a silicon DRIE process, and are mounted on a precision motion stage. A series of micropeg manipulation tasks such as pick up, rotation, and insertion are successfully performed. Finally, a comb structure is integrated in the gripper to calculate insertion force by measuring the deflection of a gripper, which is essential for automated microassembly.

Thermal bimorphs are a popular actuation technology in MEMS (micro-electro-mechanical systems). Their operating principle is based on differential thermal expansion induced by Joule heating. Thermal bimorphs, and other thermal flexure actuators have been used in many applications, from micro-grippers, to micro-optical mirrors. In most cases open-loop control is used to difficulties in fabricating positioning sensors together with actuator. In this paper we present several methods for extracting reduced-order thermal flexure actuator models based on experimental data, physical principles, and FEA simulation. We then use the models to generate optimal driving signals using input shaping techniques. Both simulation and experimental results are included to illustrate the efficacy of our approach. This framework can also be applied to other types of MEMS actuators, including electrostatic comb drives.

The active surface device is a new type of automation concept to handle multiple objects with high precision. The concept consists of using a massively parallel microactuator array to generate a pressure field on a planar surface. The objects can be translated, rotated, and flipped by controlling this pressure field surrounding the objects. The architecture of the active surface device is designed in a modular manner, which allows the array to be expanded by simply adding modules to the system. A general-purpose test bed has been built to experiment with this new design. An object recognition algorithm and several control techniques have been successfully implemented to perform basic sensing and handling operations. The architecture and mechanisms of this prototype test bed and the implementation of algorithms are presented.

Most common requirements for micromanipulation are high precision, parallel manipulation, cost, etc. In this paper, we examine a manipulation method that may be useful for these requirements. The presented method uses an actively generated friction force field as a driving force of manipulation, and the method can have several actuation modes depending on the sliding condition of the friction force field. Planar dynamics regarding the proposed method were analyzed, and the design of the force field was investigated.

Distributed manipulation is one of several approaches for the handling of multiple parts, especially when the part size is small therefore gripper-free manipulation is preferred. This paper introduces a modified method, called "semi-distributed manipulation" in which a set of centralized actuation units supplies a friction force field in combination with a distributed force switching mechanism. To implement the method, we have developed an array of pneumatic nozzles with two piezoelectric actuators. Vibratory manipulation is analyzed for part translation, rotation and their combination. The design of the force field over the 2-dimensional nozzle array is formulated as an optimization problem, and its extension to parallel manipulation is discussed.

The use of multiple sensing modalities for the autonomous operation and navigation of mobile robots is demonstrated through many vehicles, including the HelpMate mobile courier. We propose a "value measure" for the various resources of such a system, so that the control of sensing processes (and eventually motion processes) can be optimized and continuously calibrated. Value quantity (varying with quality) and task-specific utility can be compared with costs in a higher-level planner of a hierarchical system providing the most efficient use of electrical and computing power. This approach can benefit by using an object-oriented database architecture to enhance task-oriented-focused sensing thereby allowing "closed-loop sensing", that would be guided by a priori information driving a directed-sensing process; it will eventually also be related to motion control, as dictated by the system's current task/plan(s).

A modified magnetic field (MMF) has been used for the generation of robot motion plans of a linked manipulator such as a robot arm, in a complex workspace while veering around enclosing obstacle walls. The MMF method ensures global convergence and collision constraint satisfaction while allowing the application of this method as an online plan generation and control technique in both Cartesian and configuration spaces. Methods for using the MMF to perform both the planning and dynamic control of a robot arm around obstacles and singular configurations are developed in this paper and results shown for a specific workspace configuration.

The increasing demand for robotic applications in unstructured environments is motivating the need for dextrous end-effecters which can cope with the wide variety of tasks and objects encountered in these environments. A new anthropomorphic robot hand (Anthrobot) which was designed for these environments is described. In this paper the problem of developing the kinematics and unit consistent hybrid position/force control of the Anthrobot fingers is considered as the first step toward its utilization for either teleoperation or autonomous operation. A dynamic model of the fingers is identified and used to develop the control laws. The experimental results of applying the control to the Anthrobot are discussed.

This paper introduces a new feedback algorithm for steering a point robot through an obstacle field. The key innovation is the use of a circulatory field to rotate the robot path around the obstacles instead of the common potential field which repels the robot. This idea is motivated by a charged particle in a magnetic field generated by a current flowing around the obstacle. In constrast, the potential field approach is associated with a repulsive static electric field generated by charges of the same polarity as the robot, on the obstacle. The circulatory field does not generate any spurious local minimum as it does not change the total energy of the system. By combining with an attractive potential field associated with the desired destination, this method achieves global convergence while avoiding collisions with obstacles.

This paper introduces and analyzes a method based on vector-quaternion pairs for accomplishing task-based control. The optimal control paradigm has been extended into quaternion space with a complete definition of the control law required to control a plant in such a space. A complete set of derivations of the quaternion algebra used to accomplish the optimal control have also been developed. The advantage of this approach is that it decouples the position and orientation states, thereby reducing the complexity of the control algorithms. The intended application of this research is task-level control of the five-fingered Anthrobot mounted on a PUMA 760.

Summary form only given. While industrial automation has long been associated with the increase of manufacturing productivity, much of the current motivation behind the development of advanced automation techniques is driven by the need to enhance product quality, increase the safety of the operational environment, and quickly respond to changing consumer demands for new products. In this paper, we introduce some modern principles underlying the design and operation of advanced automation systems, then describe several industrial implementations in both manufacturing and service sectors. Special attention is paid to the concept of mass customization, and its potential impact on the growth of small enterprises. We start with the design stage, then look at the manufacturing process, and discuss the application of advanced automation concepts to the processing of both metals and textiles. The role of computer based modeling and inspection as quality control tools is examined. Finally, we present several recent developments in intelligent robotic systems, and describe their applications. Specific examples involving maintenance and repairs in nuclear power generation plants are discussed.

There are numerous applications in which robots are needed to assist rather than replace human operators. These applications typically involve either work in a dangerous environment or performing tasks that are physically impossible for humans to accomplish by themselves. Robots used in this mode do not need to be autonomous because they can essentially be controlled by the operator. Nonetheless, it is difficult for an operator to flawlessly control a robot with a large number of degrees of freedom. Therefore, an intelligent control system is needed to correct and improve the operator's input to the robot. In this paper the authors discuss a central component in this control system known as the variably-autonomous trajectory generator (VATG). The VATG combines input from the operator with input from one or more autonomous control modules (CM) to generate the robot trajectory. The amount of impact the autonomous CMs will have on the overall trajectory will depend on a number of factors such as the task being performed and the sensing modalities available, hence the authors refer to this type of control as being variably-autonomous.>

This paper presents efficient algorithms for computing new types of distance measures. One of the measures denoted by d/sub rho//sup +/ (A, B) characterizes proximity of non-intersecting objects A and B taking into account their shapes. The second measure denoted by /spl delta/(/spl sigma/; A, B) characterizes the penetration between two intersecting objects. The main contributions include: 1) O(m log n+n log m) algorithms to compute d/sub rho//sup +/ (A, B) and /spl delta/(/spl sigma/; A, B) between convex polyhedra in /spl Rfr//sup 3/ having m and n vertices respectively; and 2) an efficient procedure to compute /spl delta/(/spl sigma/; A, B) between non-polygonal objects described algebraically. We point out the utility of the measures for collision detection between a pair of objects.>

A methodology for reasoning about the state of the environment based on evidence received from some source is developed. It is assumed that the evidence is expressed as a probability mass function defined on a discrete set of mutually exclusive hypotheses about the state of the environment. Given that the quality of the evidence is variable, it follows that the precision of the reasoning process must also vary. The level of specificity and the certainty associated with decisions made at that level depend directly on the quality of the evidence. An indistinguishability measure is used to generate a core set of aggregate focal elements, each of which may consist of logical disjunctions of the basic hypothesis set. Partial dominance is then used to associate a basic probability assignment on the core set. This approach allows simple, quantitative methods to express the variations in the precision associated with decisions. The result is a set of aggregate hypotheses and their support levels that become input to the classification process.>

The authors utilize a class of Petri nets, called colored Petri nets (C/P-nets), to induce patterns of behavior in synchronization structures. These patterns of behavior locally specify the interactions between the distributed system's processes. The induction of patterns of behavior in synchronization structures results in the specification of coordination structures. A coordination structure is a specification of the interaction behavior of a distributed system's processes in a particular context. C/P-nets are used for the differentiation of the system's context-sensitive variables and the representation of their instantiations. The three possible interactions between any two concurrent processes of the distributed system are specified.>

The problem of planning motions offline for a robot in the presence of obstacles via an algorithm that does not proceed by a discretization of the search space involves defining good heuristics to characterize the proximal relationships between two rigid bodies and the development of algorithms for their computation. Several measures are presented, and schemes for their computation are developed. The performances of the algorithms are determined in terms of their running time. The advantage of the fuzzy model is that it lends itself easily to numerical computation involving manipulation of the coordinates of the extreme points.>

In traditional geometric modeling, it is common to assume that models of objects created are complete and correct. Unfortunately in real life robots and other autonomous machines may have only uncer- tain knowledge of only a portion of an object's geom- etry and therefore we need to be able to create object models that are incomplete and uncertain. Towards this end we have developed mechanisms for represent- ing geometric entities in terms of Dempster-Shafer belief functions. To do this we have extended the no- tion of belief functions to include continuous frames of discernment. A fractal model of the belief func- tions is developed and information theory concepts are applied for reasoning about a sensor data model vis-a-vis reference object models. An implementation of these concepts and experiments involving them are discussed.

The intelligent coordination of multiple robots requires modularization of robots at some level higher than the joint, corresponding task representations, and a concept of time that allows the dynamic specification of task synchronization. The necessary representations of robots and tasks are developed, and the structural and operational semantics of the primitive task and reflex models are specified. A concept of time, called functional time-dependency, that allows the dynamic specification of the distributed semantics during task execution by multiple robots is developed. The utility of functional time-dependency is shown using two examples.>

The authors formulate the model of computation in two parts: an analysis part in which a grasp-based model is represented as a collection of topological and geometric spaces described at various levels of detail, and a synthesis part in which the required transformations to achieve dextrous manipulation are described as a combination of two classes of processes: a postural transformation process (to derive an appropriate hand posture); and a functional transformation process, (to derive an intended hand functionality). It is shown that both the hand posture and the hand functionality can be computed from the symbolic high-level task requirements and object attributes, and can be transformed into numeric low-level joint space variables. Partial simulation results from applications to dextrous manipulation and discussions are given.>

Consideration is given to the planning of multifingered dexterous grasps to meet the physical constraints of some anticipated action. Most of the existing dexterous grasp planning schemes operate on a finite and discrete set of grasps. Such a discrete set obviously hinders the applicability of grasp planning schemes to complex and versatile task requirements. A description is given of a hierarchy of topological and geometrical spaces representing the set of grasps, and a topological algorithm is proposed for the planning of continuous grasps using computational techniques drawn from point-set, combinatorial, and algebraic topology. The topological algorithm is illustrated by a pinch grasp example using a stick model of a four-fingered hand.>

Proposed is a novel model of belief functions based on fractal theory. The model is first justified in qualitative, intuitive terms, then formally defined. Also, the application of the model to the design of an evidential classifier is described. The proposed classification scheme is illustrated by a simple example dealing with robot sensing. The approach followed is motivated by applications to the design of intelligent systems, such as sensor-based dexterous manipulators, that must operate in unstructured, highly uncertain environments. Sensory data are assumed to be (1) incomplete and (2) gathered at multiple levels of resolution.>

The authors present a topological model of prehension for multifingered robot hands which essentially deduces low-level contact wrench parameters in joint space from high-level task specifications, object properties, and a topological space (tetrahedron) of hand shapes. This model is based on a theory of prehensility with control algorithms modeled after the functionalities and sensory-motor activities of the human hand. The authors describe representations at different levels of granularity. They have sketched topological equivalences between high-level and low-level spaces, which preserve three topological properties: power, precision, and support (or equivalently, graspability, manipulability, and supportability). They introduce the notion of functionality distribution of power, precision, and support to a set of hand subconfigurations. They note the subtle difference in support as an independent parameter (from power and precision), and support as a dependent parameter (to strengthen power and precision) and identify general schemes to handle the difference. The model offers a framework in which several existing schemes may be integrated.>

A massively redundant, tentacle-based robot manipulator is proposed as an alternative to dextrous manipulation by an arm/hand combination. The tentacle is advantageous because it is an all-in-one arm and gripping device capable of a wide variety of configurations and grasps, while maintaining the mechanics of serial manipulators. A method for evaluating the forces and velocities imparted to an arbitrary object by a robot hand is reviewed and extended to include the case where several serial manipulators each come in contact with an object at multiple joints. From this analysis, a quantitative evaluation of grasp manipulability and stability is developed that accounts for multiple object contacts for each serial manipulator in the system. A method of applying both precision and power grasps to three-dimensional objects using a tentacle is presented that allows for easy transition between the two by merely curling or uncurling links from around the object. This method helps reduce the number of complexity of grasp configurations. Numerical simulations of different tentacle manipulators and grasps are given.>

Dexterous grasps for multifingered robot hands are planned. A real-time, joint space finger path planning algorithm is derived for the enclosure phase of grasping motion. The algorithm minimizes the impact momentum of the hand. It uses a preshape Jacobian matrix to map task-level hand preshape requirements into kinematic constraints. A master-slave scheme avoids inter-finger collisions and reduces the dimensionality of the planning problem.>

The continuous spaces of grasps are formulated and an algorithmic procedure is derived for robot hand preshaping. The proposed procedure consists of a mapping from a task space to a topological space of hand configurations using a barycentric coordinate system and a barycentric subdivision scheme. A model implementation architecture is discussed. Examples showing the preshaping of a four-finger hand in preparation for pinch grasping are described. The basis of the approach is both intuitive and mathematical. The intuitive formulation was based primarily on observations of functionalities and motor activities of the human hand. The mathematical formulation is based on point-set topology and combinatorial topology.>

An exact state-space dynamic model for manipulator with flexible links is considered. The Bernoulli-Euler beam equations are used to derive a frequency domain matrix transfer function. This transfer function is then used to computer the Laplace transform of the state vector as a function of lateral position along a single link manipulator. The problem of optimal end-point control of the beam is addressed. A sixth-order state-space model is derived for the manipulator and the controller is based on this model. Several control laws are studied for this model. The manipulator is modeled as eighth-order, but the control law based on the sixth-order model is retained. The six states are estimated from the output of the eighth-order model. These states are fed back to the controller to derive the control torque used to drive the manipulator. A filter is introduced to compensate for spillover. The results are satisfactory, and are illustrated by simulated case studies.>

The kinematics, static force propagation, and stability of tool manipulation by an articulated hand are analyzed. The manipulation of chopsticks is used as a case study to illustrate some fundamental characteristics of tool manipulation. A qualitative requirements analysis for chopstick manipulation is outlined. Emphasis is placed on the characteristics of objects and grasps in fine manipulation.>

A quantitative criterion for measuring the effectiveness of the consensus obtained by pooling evidence from two knowledge sources is introduced. A brief review of the Dempster-Shafer theory of mathematical evidence, which is based on a set-theoretic description of subjective uncertainty, is given. The concept of generalized entropy as a measure of the uncertainty in a knowledge source is also introduced. It is proven that the pooling of evidence by Dempster's rule of combination decreases the total amount of generalized entropy in the knowledge sources. The decrease of entropy corresponds to the focusing of knowledge, and is used as a measure of consensus effectiveness. Several examples are used to illustrate this measure.>

A hierarchical method combining analytical techniques from control theory and heuristic techniques from artificial intelligence is presented and applied to the decentralized control of a prosthetic arm. The dynamic model of the arm is derived, and two complementary performance criteria are suggested for the kinematic and the dynamic evaluation for the system response. The "principle of minimum interaction" is used to decompose the prosthetic system into seven subsystems, one per mechanical degree of freedom. A "suboptimal" control structure for nonlinear systems is proposed in conjunction with a performance adaptive self-organizing control algorithm. Syntactic pattern classification is used for the dynamic coordination of the subsystems. The syntax of the man-machine commands is also examined as part of the function of highest level of the hierarchy, the organizer.