Design and Fabrication of Chainless Bicycle

Today's life we meet number of difficulties in transportation. There are number of drives to transmit the power. We have concentrated on bicycle where the efforts while peddling is not efficiently turned to work. In bicycle chain drive is used. Due to the chain drive there is loss of power in transmission. So our idea is to replace chain drive by kinematic links for higher transmission. This project is developed for the users to rotate the back wheel of a bicycle using kinematic links. Power transmission through chain drive is the oldest and widest used method in case of bicycle. In this paper we implemented the chain less transmission to the bicycle to overcome the various disadvantages of chain drive. Recently, due to advancements in kinematic link technology, a small number of modern link-driven bicycles have been introduced. Usually in bicycle, chain and sprocket method is used to drive the back wheel. The link drive only needs in small amount of lubrication using a grease to keep the links running quiet and smooth. A link drive bicycle is a bicycle that uses a link drive instead of a chain which contain four set of link at both the ends to make a new kind of transmission system for bicycle for getting high reliability system, and more safe system. Link-driven bicycle have used four bar mechanism where a conventional bicycle connected in one end pedal link and another connected in wheel. This pedal link actuate to drive a wheel. The use pedals to be actuate in 45 degrees wheels can rotating at 180 degrees. According to the direction of motion of pedal, the wheel will be moved forward. This avoids the usage of chain and sprocket method. This “chinless” drive system provides smooth quite and efficient transfer of energy from the pedals to the rear wheel. It is attractive in look compare with chain driven bicycle. Keywords: Chainless bicycle, four bar mechanism, kinematic link technology.

Mechanism isomorphism identification based on artificial fish swarm algorithm

The aim of this paper is to propose a practical solution for mechanism kinematic chain isomorphism identification – an artificial fish swarm algorithm. The artificial fish model of mechanism isomorphism identification is established, and behavioral way of the artificial fish is designed. According to isomorphism identification features of topological graph, the process of mechanism isomorphism identification based on artificial fish swarm algorithm is confirmed. The rationality and reliability of artificial fish swarm algorithm on the isomorphic identification of mechanism have been illustrated by a specific example, which provides a new method for intelligent CAD system design of mechanism. It builds a basis for future work in isomorphism identification of mechanism with high efficiency. Isomorphic identification of mechanism will contribute to rational qualitative analysis of mechanism design, perfection of irrationality can be done timely, which is the key factor for mechanical manufacturing. In this paper, we introduce the mechanism kinematic chain firstly, then optimization of artificial fish swarm algorithm is illustrated, and it is shown that how fish swarm algorithm is applied to mechanism kinematic chain. Finally, the feasibility and efficiency of the method are verified by the example of 10 bars, and the complex mechanism can be identified by the example of 14 bars and 18 bars.

Topology optimization of linkage mechanisms simultaneously considering both kinematic and compliance characteristics

Studies on the topology optimization of linkage mechanisms have thus far focused mainly on mechanism synthesis considering only kinematic characteristics describing a desired path or motion. Here, we propose a new topology optimization method that synthesizes a linkage mechanism considering not only kinematic but also compliance (K&C) characteristics simultaneously, as compliance characteristics can also significantly affect the linkage mechanism performance; compliance characteristics dictate how elastic components, such as bushings in a vehicle suspension, are deformed by external forces. To achieve our objective, we use the spring-connected rigid block model (SBM) developed earlier for mechanism synthesis considering only kinematic characteristics, but we make it suitable for the simultaneous consideration of K&C characteristics during mechanism synthesis by making its zero-length springs multifunctional. Variable-stiffness springs were used to identify the mechanism kinematic configuration only, but now in the proposed approach, they serve to determine not only the mechanism kinematic configuration but also the compliance element distribution. In particular, the ground-anchoring springs used to anchor a linkage mechanism to the ground are functionalized to simulate actual bushings as well as to identify the desired linkage kinematic chain. After the proposed formulation and numerical implementation are presented, case studies are considered. In particular, the effectiveness of the proposed method is demonstrated with a simplified two-dimensional vehicle suspension design problem. This study is expected to pave the way to advance the topology optimization method for general linkage mechanisms whenever K&C characteristics must be simultaneously considered for mechanism synthesis.

Analysis of Parasitic Motion in Compliant Mechanisms Using Eigenwrenches and Eigentwists

Parasitic motion is undesired in precision mechanisms, it causes unwanted kinematics. These erroneous motions are especially apparent in compliant mechanisms. Usually an analysis of parasitic motion is only valid for one type of mechanism. Kinematic information is imbedded in the compliance matrix of any mechanism; an eigenscrew decomposition expresses this kinematic information as screws. It uses screw theory to identify the lines along which a force yields a parallel translation and a rotation yields a parallel moment. These lines are called eigenwrenches and eigentwists. Any other load on the compliant mechanism will lead to parasitic motion. This article introduces two parasitic motion metrics using eigenscrew decomposition: the parasitic resultant from an applied screw and the deviation of an actual degree of freedom from a desired degree of freedom. These metrics are applicable to all compliant mechanism and allow comparison between two compliant mechanisms. These metrics are applied to some common compliant mechanisms as an example.

Analysis and Design of a Shape Memory Alloy Actuated Arm to Replicate Human Biomechanics

Shape memory alloy actuators paired in an antagonistic arrangement can be used to produce mechanisms that replicate human biomechanics. To investigate this proposal, the biomechanical articulation of the elbow by means of the biceps brachii muscle are compared with that of a shape memory alloy actuated arm. Initially, the movement of the human arm is modeled as a single degree of freedom rocker-slider mechanism. Using this model, a purely kinematical analysis is performed on the rigid body rocker-slider. Force analysis follows by modeling the muscle as a simple linear spring. Torque, rocking angle, and energy are calculated for a range of rocker-slider geometries. Actuator characterization of the SMA wire is conducted by experimentally determining the stress-strain curves for the martensite detwinned and full austenite states. Using the experimentally obtained stress-strain curves, nonlinear and linear theoretical actuator characteristic curves are produced for the isolated SMA wire. Using the theoretical actuator characteristic curve on the rocker-slider mechanism, kinematic and force analyses are performed for both the nonlinear and linear actuated mechanisms. To compare to biomechanics, a literature survey is performed on human musculotendon and skeletal lengths and introduced to the kinematic analysis. Examination of biological and mechanical results are then discussed.

KINEMATICS OF THE V MECHANISM USED FORELECTRIC SWITCHERS BASED ON SPECIALISED SOFTWARE

This paper is representing a continuing research of the doctoral thesis "Geometrical analysis and synthesis of mechanisms in the electrotechnical field". Using two Mathcad programs as mathematics analysis software and Solidworks as graphical analysis software it is dimensioned the new kinematics scheme of the high voltage V mechanism. Kinematic analysis is based on the mathematical model presented in the doctoral thesis mentioned above and graphical modeling and analysis is conducted to compare and complete the research regarding the V mechanism triadic chain 5R + T type.