Modelling and Simulation of a Manipulator with Stable Viscoelastic Grasping Incorporating Friction

Design, dynamics and control of a humanoid robotic hand based on anthropological dimensions, with joint friction, is modelled, simulated and analysed in this paper by using computer aided design and multibody dynamic simulation. Combined joint friction model is incorporated in the joints. Experimental values of coefficient of friction of grease lubricated sliding contacts representative of manipulator joints are presented. Human fingers deform to the shape of the grasped object (enveloping grasp) at the area of interaction. A mass-spring-damper model of the grasp is developed. The interaction of the viscoelastic gripper of the arm with objects is analysed by using Bond Graph modelling method. Simulations were conducted for several material parameters. These results of the simulation are then used to develop a prototype of the proposed gripper. Bond graph model is experimentally validated by using the prototype. The gripper is used to successfully transport soft and fragile objects. This paper provides information on optimisation of friction and its inclusion in both dynamic modelling and simulation to enhance mechanical efficiency

Manufacturing process applications team (MATeam)

Activities of the manufacturing applications team (MATeam) in effecting widespread transfer of NASA technology to aid in the solution of manufacturing problems in the industrial sector are described. During the program's first year of operation, 450 companies, industry associations, and government agencies were contacted, 150 manufacturing problems were documented, and 20 potential technology transfers were identified. Although none of the technology transfers has been commercialized and put in use, several are in the applications engineering phase, and others are in the early stages of implementation. The technology transfer process is described and guidelines used for the preparation of problems statements are included

Analysis and Design of a Gear Shifting Mechanism for Transmission Based Actuators

The fundamental idea of Transmission Based Actuators (TBA) is to incorporate a multi-speed transmission to spread a servomotor’s torque speed characteristics across a wider output speed range. TBA uses multi-speed transmissions such that heavy, high-torque motors can be traded for high-speed, reduced mass motor-transmission combinations. TBA design consists of a D.C. Brushless motor, discrete gear transmission and a fixed reduction. Of these, the fundamental to the proof of principle of TBA is the design of the discrete gear transmission. Basically the DVT is a three-speed gearbox consisting of 3 sets of epicyclic gears. Every planetary gear set is a two-degree of freedom system. In the present design one input is always the sun gear and the other is the ring gear. The motor gives one input to the planetary gear and the second input to the planetary gear set is obtained by locking the band brakes such that the ring gear speed is zero. Three different speeds are obtained by selectively and synchronously locking the three annular ring gears using corresponding external flexible band brakes. The complete dynamic model of the Gear Shifting Mechanism (GSM) has been developed and the braking torque has been estimated. The gear shifting mechanism primarily consists of a band brake, a series of mechanical linkages and electrical actuator. It is used to stop the ring gear, rotating at a very high speed and hold it to obtain the desired gear ratio. . Then a brake test stand has been designed and built to test the functionality of the GSM. The effective braking torque and the system time constant were measured for both dry and wet conditions. The obtained test results have been analyzed with respect to the predicted simulated results

Inverse modeling of the stewart foot

The Stewart's leg is used today in the majority of parallel robotic systems, such as the Stewart platform, but also in many other types of mechanisms and kinematic chains, in order to operate them or to transmit motion. A special character in the study of robots is the study of inverse kinematics, with the help of which the map of the motor kinematic parameters necessary to obtain the trajectories imposed on the effector can be made. For this reason, in the proposed mechanism, we will present reverse kinematic modeling in this paper. The kinematic output parameters, ie the parameters of the foot and practically of the end effector, ie those of the point marked with T, will be determined for initiating the working algorithm with the help of logical functions, "If log(ical)", with the observation that here they play the role of input parameters; it is positioned as already specified in the inverse kinematics when the output is considered as input and the input as output. The logical functions used, as well as the entire calculation program used, were written in Math Cad

Positional modeling of the 2T6R robot mechanism

The positional modeling of the 2T6R robot mechanism is done for inverse kinematics, i.e. when the imposed positions of the end effector T, imposed, belonging to the final element 3, are known and the necessary positions and speeds of the two input motors, the two leading elements, are determined, 1 and 6. It is proposed to solve a simple algorithm in the program MathCad 2000, which uses for initiation the logical function If Log. The kinematic output parameters, i.e. the parameters of the foot and practically of the final effector, i.e. those of the point marked with T, will be determined for initiating the working algorithm using the logical functions, "If log (ical)", with the observation that here plays the role of parameters input; is positioned as already specified in reverse kinematics when the output is considered as input and input as output. The logical functions used, as well as the entire calculation program used, were written in Math Cad 2000

The NASA SBIR product catalog

The purpose of this catalog is to assist small business firms in making the community aware of products emerging from their efforts in the Small Business Innovation Research (SBIR) program. It contains descriptions of some products that have advanced into Phase 3 and others that are identified as prospective products. Both lists of products in this catalog are based on information supplied by NASA SBIR contractors in responding to an invitation to be represented in this document. Generally, all products suggested by the small firms were included in order to meet the goals of information exchange for SBIR results. Of the 444 SBIR contractors NASA queried, 137 provided information on 219 products. The catalog presents the product information in the technology areas listed in the table of contents. Within each area, the products are listed in alphabetical order by product name and are given identifying numbers. Also included is an alphabetical listing of the companies that have products described. This listing cross-references the product list and provides information on the business activity of each firm. In addition, there are three indexes: one a list of firms by states, one that lists the products according to NASA Centers that managed the SBIR projects, and one that lists the products by the relevant Technical Topics utilized in NASA's annual program solicitation under which each SBIR project was selected

Index to 1986 NASA Tech Briefs, volume 11, numbers 1-4

Short announcements of new technology derived from the R&D activities of NASA are presented. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This index for 1986 Tech Briefs contains abstracts and four indexes: subject, personal author, originating center, and Tech Brief Number. The following areas are covered: electronic components and circuits, electronic systems, physical sciences, materials, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences

Kinematic and dynamic study of a manipulator 1T6R

The paper presents in detail a method of calculating the forces acting on a 1T6R robot manipulator. To determine the reactions (forces in kinematic torques), you must first determine the inertial forces in the mechanism to which one or more payloads of the robot can be added. The torsion of the inertial forces is calculated using the masses of the machine elements and the accelerations at the centers of mass of the elements of the mechanism, so that the positions, speeds, and accelerations acting on it, ie its complete kinematics, will be determined. Equations of the dynamics are also determined through an original method

Micro-manufacturing : research, technology outcomes and development issues

Besides continuing effort in developing MEMS-based manufacturing techniques, latest effort in Micro-manufacturing is also in Non-MEMS-based manufacturing. Research and technological development (RTD) in this field is encouraged by the increased demand on micro-components as well as promised development in the scaling down of the traditional macro-manufacturing processes for micro-length-scale manufacturing. This paper highlights some EU funded research activities in micro/nano-manufacturing, and gives examples of the latest development in micro-manufacturing methods/techniques, process chains, hybrid-processes, manufacturing equipment and supporting technologies/device, etc., which is followed by a summary of the achievements of the EU MASMICRO project. Finally, concluding remarks are given, which raise several issues concerning further development in micro-manufacturing

Aeronautical engineering: A continuing bibliography with indexes (supplement 202)

This bibliography lists 447 reports, articles and other documents introduced into the NASA scientific and technical information system in June 1986