Manipulators with flexible links: A simple model and experiments

A simple dynamic model proposed for flexible links is briefly reviewed and experimental control results are presented for different flexible systems. A simple dynamic model is useful for rapid prototyping of manipulators and their control systems, for possible application to manipulator design decisions, and for real time computation as might be applied in model based or feedforward control. Such a model is proposed, with the further advantage that clear physical arguments and explanations can be associated with its simplifying features and with its resulting analytical properties. The model is mathematically equivalent to Rayleigh's method. Taking the example of planar bending, the approach originates in its choice of two amplitude variables, typically chosen as the link end rotations referenced to the chord (or the tangent) motion of the link. This particular choice is key in establishing the advantageous features of the model, and it was used to support the series of experiments reported

Flexible robot control: Modeling and experiments

Described here is a model and its use in experimental studies of flexible manipulators. The analytical model uses the equivalent of Rayleigh's method to approximate the displaced shape of a flexible link as the static elastic displacement which would occur under end rotations as applied at the joints. The generalized coordinates are thereby expressly compatible with joint motions and rotations in serial link manipulators, because the amplitude variables are simply the end rotations between the flexible link and the chord connecting the end points. The equations for the system dynamics are quite simple and can readily be formulated for the multi-link, three-dimensional case. When the flexible links possess mass and (polar moment of) inertia which are small compared to the concentrated mass and inertia at the joints, the analytical model is exact and displays the additional advantage of reduction in system dimension for the governing equations. Four series of pilot tests have been completed. Studies on a planar single-link system were conducted at Carnegie-Mellon University, and tests conducted at Toshiba Corporation on a planar two-link system were then incorporated into the study. A single link system under three-dimensional motion, displaying biaxial flexure, was then tested at Carnegie-Mellon

1006-44 A Prognostic Factor in Coronary Artery Disease (CAD): Platelet-Dependent Thrombin Generation in Patients with CAD

We examined platelet-dependent thrombin generation in patients with coronary artery disease (CAD). Thrombin generation was measured according to the method of Aronson et al (Circulation, 1992). 0.5ml of platelet rich plasma (PRP, 15×104/ml) was prepared, and 40mM of CaCl, was added to start clotting. 0.5mM of S-2238 was added to each sample in a microtiter plate every 10min, and the plate was read kinetically at a wavelength of 405nm on a microtiter plate reader. The patients with CAD devided into 3 groups.Thrombin generation 20 min after CaCI2, additon is:Control (n=12)48±10(mOD)Stable angina (SAP) (n=15)79±27Unstable angina (UAP) (n=15)**562±155Acute myocardial infarct (AMI) (n=43)**440±269**p<0.01 compared to SAPThe patients with UAP and AMI showed marked increase in thrombin generation compared to SAP and control subjects. AMI patients with severe coronary artery disease (Group B) showed higher levels of thrombin generation (Group A, Gensini score<32: 382±248 mOD vs Group B, Gensini score> 31: 578±238, P<0.05). LVEF of group A is significantly higher than that of group B (P < 0.05). These findings indicate that patients with UAP and AMI have an evidence of hypercoagulable states and that platelet-dependent thrombin generation may play an important role in pathophysiology of UAP or AMI, and may be a prognostic factor in CAD

Conveyance of texture signals along a rat whisker

Neuronal activities underlying a percept are constrained by the physics of sensory signals. In the tactile sense such constraints are frictional stick–slip events, occurring, amongst other vibrotactile features, when tactile sensors are in contact with objects. We reveal new biomechanical phenomena about the transmission of these microNewton forces at the tip of a rat’s whisker, where they occur, to the base where they engage primary afferents. Using high resolution videography and accurate measurement of axial and normal forces at the follicle, we show that the conical and curved rat whisker acts as a sign-converting amplification filter for moment to robustly engage primary afferents. Furthermore, we present a model based on geometrically nonlinear Cosserat rod theory and a friction model that recreates the observed whole-beam whisker dynamics. The model quantifies the relation between kinematics (positions and velocities) and dynamic variables (forces and moments). Thus, only videographic assessment of acceleration is required to estimate forces and moments measured by the primary afferents. Our study highlights how sensory systems deal with complex physical constraints of perceptual targets and sensors

Liquid-Phase Packaging of a Glucose Oxidase Solution with Parylene Direct Encapsulation and an Ultraviolet Curing Adhesive Cover for Glucose Sensors

We have developed a package for disposable glucose sensor chips using Parylene encapsulation of a glucose oxidase solution in the liquid phase and a cover structure made of an ultraviolet (UV) curable adhesive. Parylene was directly deposited onto a small volume (1 μL) of glucose oxidase solution through chemical vapor deposition. The cover and reaction chamber were constructed on Parylene film using a UV-curable adhesive and photolithography. The package was processed at room temperature to avoid denaturation of the glucose oxidase. The glucose oxidase solution was encapsulated and unsealed. Glucose sensing was demonstrated using standard amperometric detection at glucose concentrations between 0.1 and 100 mM, which covers the glucose concentration range of diabetic patients. Our proposed Parylene encapsulation and UV-adhesive cover form a liquid phase glucose-oxidase package that has the advantages of room temperature processing and direct liquid encapsulation of a small volume solution without use of conventional solidifying chemicals

Analysis of the Vertical Driving Performance of Multiple Connected Pipe-Climbing Microrobots with Magnetic Wheels

In this study, we analyzed the vertical driving performance of multiple connected magnetic wheel-driven microrobots when moving up and down a small cylinder that simulated a pipe. The dynamics of pipe climbing by the magnetic wheel-driven microrobot were analyzed considering the magnetic attraction force and slip; a vertical climbing simulator was developed considering the hoop force and external force from the adjacent microrobots to determine the magnetic attraction force required for multiple connected microrobot pipe climbing. A prototype of an independent vertical climbing microrobot, 5 mm long, 9 mm wide, and 6.5 mm high, and prototypes of 10 microrobots were manufactured to evaluate the vertical driving performance. The usefulness was verified by showing that three driving microrobots can move seven non-driving microrobots comprising 60% of their own weight up and down along a small cylinder

ABSTRACT MULTI-STEP SEQUENTIAL BATCH SELF-ASSEMBLY OF THREE-DIMENSIONAL MICRO-STRUCTURES USING MAGNETIC FIELD

We have developed a process for multi-step sequential batch self-assembly of complex three-dimensional ferromagnetic micro-structures. The process uses the magnetic torque generated by an external magnetic field perpendicular to the substrate to lift hinged-structures. In our previous study, we found that a non-dimensional factor that depends on its shape determines the sensitivity of the micro hinged-structures to a magnetic field. This factor can be used as a criterion in designing a process for sequential batch self-assembly, because the factor indicates the differences in the sensitivity. In this study, we designed multi-step sequential assembly by using the non-dimensional factor. Four-step sequential batch assembly was demonstrated using this method. 1

Three-Axis Ground Reaction Force Distribution during Straight Walking

We measured the three-axis ground reaction force (GRF) distribution during straight walking. Small three-axis force sensors composed of rubber and sensor chips were fabricated and calibrated. After sensor calibration, 16 force sensors were attached to the left shoe. The three-axis force distribution during straight walking was measured, and the local features of the three-axis force under the sole of the shoe were analyzed. The heel area played a role in receiving the braking force, the base area of the fourth and fifth toes applied little vertical or shear force, the base area of the second and third toes generated a portion of the propulsive force and received a large vertical force, and the base area of the big toe helped move the body’s center of mass to the other foot. The results demonstrate that measuring the three-axis GRF distribution is useful for a detailed analysis of bipedal locomotion