A soft, controllably morphable mobile robot is an ideal platform for traversing complex terrain and navigating small holes. iRobot Corporation and the University of Chicago have made use of a phenomenon known as particle jamming to create such a robot. The robot presented in this work uses jamming skin cells to enable controlled morphing and locomotion.

A soft, mobile, morphing robot is a desirable platform for traversing rough terrain and navigating into small holes. In this work, a new paradigm in soft robots is presented that utilizes jamming of a granular medium. The concept of activators (as opposed to actuators) is presented to jam and unjam cells that then modulate the direction and amount of work done by a single central actuator. A prototype jamming soft robot utilizing JSEL (Jamming Skin Enabled Locomotion) with external power and control is discussed and both morphing results and mobility (rolling) results are presented. Future directions for the design of a soft, hole traversing robot are discussed, as is the role and promises of jamming as an enabling technology for soft robotics.

This work presents the design, fabrication, and testing of a novel hexapedal walking millirobot using only two actuators. Fabricated from S2-glass reinforced composites and flexible polymer hinges using the smart composite microstructures (SCM) process, the robot is capable of speeds up to 1 body length/sec or approximately 3 cm/s. All power and control electronics are onboard and remote commands are enabled by an IrDA link. Actuation is provided by shape memory alloy wire. At 2.4 g including control electronics and battery, RoACH is the smallest and lightest autonomous legged robot produced to date.

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.

Piezoelectric bending actuators are an attractive option for driving microrobots due to their light weight, scalability, ease of integration and high bandwidth. However, the only existing energy or power output measurements for piezoelectric bending actuators have been extrapolated from DC values or unloaded AC values and are most likely overestimates. For microrobot applications such as flapping flight, accurate measures of power density are critical. In this work, to properly measure the energy output of a lOmg piezoelectric actuator, a custom dynamometer is designed and constructed to directly measure the power output at various frequencies and conditions. The dynamometer can simulate a pure resistive load at resonant frequencies from 1 to 100Hz. Due to low internal damping and fracture limits, actuators cannot be run in the matched condition at high fields (> 1 V/mum). Using the device, energy output per cycle at 1.6 V/mum was measured to be a maximum of 19.1muJ/cycle (232mum amplitude, 30Hz), giving a delivered energy density per cycle of 1.89J/kg. Internal actuator damping was measured at 1 V/mum to account for an energy loss of only 0.21muJ per cycle (232mum amplitude, 30Hz).

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

We are developing a process to quickly prototype millirobotic systems in which the approach is to identify and develop a construction kit for fabricating almost any design, similar to the kits that are available for larger-scale robots. Two of the basic elements of the kit, the links and flexure joints, have been identified, and an assembly method has been developed. This paper deals with the problem of integrating the wiring in these parts, a significant task on this size scale. This novel feature is achieved through the use of a flexible ribbon cable consisting of three wires made out of patterned copper foil and polyimide. Low melting point solder has been tested successfully to make the electrical interconnect between the parts. We discuss the issues that must be addressed in designing the flexure-wiring combination. In addition, the paper presents the methodology for fabricating structures with integrated wiring using a simple four bar mechanism as an example. Finally, the tests show that the wiring loop over a flexure connecting a distally located sensor on the mechanism maintains both its electrical and mechanical integrity even during large motions. Future work will include the automated assembly of the parts with a low cost assembly tool.

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.

To keep pace with recent advances in micro robotic structures demands actuator technologies which can deliver high power and precise motion. For electroactive material based actuators, high power typically implies either high field or high current drives which may lead to greater nonlinearities such as saturation, softening, and increased loss. Physical modeling of actuators is normally taken to be linear since the range of displacements, applied loads, and applied fields is typically small. If extrapolated to high drive conditions, these linear models significantly over predict the power which can be delivered. For actuators driving dynamic systems, a complete nonlinear model of the system will improve controllability and give more accurate estimations of power delivery capabilities. Here static nonlinearities and dynamic linear and nonlinear parameters are derived for high performance piezoelectric bending actuators.

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.