Simulink and Stateflow are tools for Model-Based Design that support a variety of mechanisms for modeling hybrid dynamics. Each of these tools has different strengths. In this paper, a new modeling construct is presented that combines these strengths to enable graphical modeling of hybrid dynamics within a single Stateflow chart. A new type of Stateflow state that acts as a Simulink subsystem is developed to facilitate graphical modeling of continuous dynamics using Simulink blocks inside Stateflow. Remote textual and graphical state access using new state-accessor blocks enables continuous states to be used in transition guards and reset actions. Key features of this new formalism are illustrated using various examples with hybrid dynamics.

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The Micromechanical Flying Insect (MFI) project aims to create a 25 mm (wingtip to wingtip) flapping wing micro air vehicle inspired by the aerodynamics of insect flight. A key challenge is generating appropriate wing trajectories. Previous work showed a lift of 506muN at 160 Hz using feedforward control. In this paper, refinements to the MFI design including those in [2] increased wing beat frequency to 275 Hz and lift to 1400muN using pure sinusoidal drive for a fixed benchtop experiment. We show through simplified aerodynamic models that not only do sinusoidal actuator drives produce close to maximal lift, but significantly improved wing trajectories due to non-sinusoidal actuator drives are practically unobtainable due to actuator limitations.

Compliant mechanisms provide an attractive alternative to conventional rigid mechanisms in the design of ultra low-cost precision positioning systems. The desirable performance characteristics of these mechanisms including freedom from backlash, long life, light weight, and ease of fabrication/assembly make them an ideal solution to the problem of inexpensive precision positioning for microassembly. This paper presents a design for a 2 axis precision positioning system which makes use of large displacement compliant mechanisms, a room temperature and pressure molding fabrication process, commodity hardware, and a piecewise linear interpolation compensation scheme to achieve positioning performance suitable for automated assembly of sub-centimeter robotic and mechatronic devices

This paper discusses the biomimetic design and assembly of a 3g self-contained crawling robot fabricated through the integrated use of various microrobot technologies. The hexapod structure is designed to move in an alternating tripod gait driven by two piezoelectric actuators connected by sliding plates to two sets of three legs. We present results of both the kinematic and static analyses of the driving mechanism that essentially consists of three slider cranks in series. This analysis confirmed the force differential needed to propel the device. We then review various other microrobot technologies that have been developed including actuator design and fabrication, power and control electronics design, programming via a finite state machine, and the development of bioinspired fiber arrays. These technologies were then successfully integrated into the device. The robot is now functioning and we have already fabricated three iterations of the proposed device. We hope with further design iterations to produce a fully operational model in the near future

Piezoelectric actuators are advantageous for microrobots due to their light weight, high bandwidth, high force production, low power consumption, and simplicity of integration. However, the main disadvantage of either stack or cantilever piezoelectric actuators are the high drive voltages required for adequate force and displacement. This especially limits the ability for such actuators to be used in autonomous microrobots because of the weight and complexity of necessary power electronics. This paper approaches the design of all the component parts of an autonomous piezoelectric robot as a linear constraint on the weight and efficiency of those components. It then focuses on the choice and optimization of the power electronics section of the robot, specifically exploring three different high voltage generation methods. Finally, one of these power electronics designs is implemented and its behavior is experimentally explored

Mechanisms utilizing rigid links and relatively small flexural joints are very suitable for fabrication at the meso scale. The Micromechanical Flying Insect (MFI) project at UC Berkeley has developed a simple fabrication method which works very well at the scale where the links are a few millimeters in length and the flexures are few hundred microns in length. Previous analysis has concentrated on the geometry of the composite material links for creating rigid links. Recently, we have found that for useful performance, detailed analysis is required of the flexures also. This paper presents a brief analysis of the issues involved in the design of the flexural components of such mechanisms.

This paper presents the design, fabrication, and force measurement of a centimeter scale micro underwater vehicle mimicking a boxfish. The principles of locomotion of real boxfish have been investigated thoroughly from a biological point of view, but attempts to replicate such a device within the research community of Micro Underwater Vehicles (MUV) have been quite limited. The authors have developed a electromechanical device with rigid body propelled by a oscillating tail fin and steered by a pair of independent side fins. The oscilating motions of the fins are independently controlled by PZT bimorph actuators driving four-bar mechanisms for motion amplification. The goal is to build a centimeter-length microrobotic fish capable of sustained autonomous swimming, which can then be used in marine micro-organism sensing, underwater ship wreck explorations, in-pipe inspections, and in forming underwater sensor networks. In this paper, we present the system concept design, fabrication and preliminary experimental measurements.

In the following work, we develop a characterization method using miniature fiberoptic position sensors for the Micromechanical Flying Insect (MFI) 1, a centimeter sized micro aerial vehicle being developed at the University of California, Berkeley. Sensing the state of a structure of this scale is challenging due to limited sensor technology and difficulty in constraining the structure. We developed a unique fiberoptic reflection position sensor and associated circuitry that yields a high resolution (approximately 5 µ m of linear motion), appropriate scale, and real time method for sensing the state of the MFI. Also included is the development of a clamping technique for the 2 wing, 4 degree of freedom MFI designed to expose actuator surfaces to be sensed while properly grounding the MFI without introducing added compliance or stiffness to the airframe. We include characterization data for a 2 DOF (flapping and rotation for one wing) wing structure, a clamped 4 DOF motor core of the MFI, and one side of an entire 4 DOF MFI.

The use of high performance composite materials provides a substantial performance improvement for microrobotics. Such materials have great benefits over common MEMs materials such as better fracture toughness and fatigue properties than semiconductors, and higher stiffness to weight ratios than most metals. Composite structures yield remarkable improvements in microrobotic links and joints, as well as greater performance actuators while allowing complicated microrobotic mechanisms to be easily rapid prototyped. The use of such materials in the construction of the 4DOF, 26 joint Micromechanical Flying Insect has reduced the thorax inertia by a factor of 3 and given a 20% increase in resonant frequency over previous designs while cutting construction time from weeks to days.

This paper presents some recent improvements in the fabrication and control of the micromechanical flying insect (MFI), a centimeter sized aerial vehicle currently being developed at the University of California, Berkeley. We report a lift of 506 /spl mu/N from a single wing, which is sufficient for a 100 mg machine to lift itself off the ground. This lift matches very well with predictions based on quasi steady state models. We present some recent improvements in thorax fabrication leading to the development of a light weight platform (/spl sim/ 100 mg), which generates 400 /spl mu/N of lift with a single wing. We also present a new sensor mechanism, which makes it possible to sense the motion of the actuators without having to add anything to the structure itself.

This paper presents an analysis of the major mechanical component (the thorax) of the micromechanical flying insect (MFI), a centimeter sized aerial vehicle currently in development at UC Berkeley. We present a description of the kinematics of the mechanism which converts piezoelectric actuation into complex 3D wing motion. A complete non-linear modeling of the system based on the Lagrangian energy technique is presented. A design methodology is presented in order to achieve optimal matching conditions. Two kinds of sensors which are presently utilized on the MFI are described. Experimental results are presented which validate some of the modeled non-linear aspects of the mechanism.

Considers a 2 DOF resonant thorax structure signed and fabricated for the MFI project. Miniature piezoelectric PZN-PT unimorph actuators were fabricated and used to drive a four-bar transmission mechanism. The current thorax design utilizes two actuated four-bars and a spherical joint to drive a rigid wing. Rotationally compliant flexure joints have been tested with lifetimes over 10/sup 6/ cycles. Wing spars were instrumented with strain gauges for force measurement and closed-loop wing control.