Synthesis Theory and Optimum Design of Four-bar Linkage with Given Angle Parameters

In this paper, a synthesis method is proposed for the 5-point-contact four-bar linkage that approximates a straight line with given angle parameters. The given parameters were the angles and the location of the Ball point. Synthesis equations were derived for a general Ball–Burmester point case, the Ball–Burmester point at an inflection pole, and the Ball point that coincided with two Burmester points, resulting in three respective groups of bar linkages. Next, taking Ball–Burmester point as the coupler point, two out of the three bar-linkage combinations were used to generate three four-bar mechanisms that shared the same portion of a rectilinear trajectory. Computation examples were presented, and nine cognate straight-line mechanisms were obtained based on the Roberts-Chebyshev theory. Considering that the given parameters were angles which was arbitrarily chosen, with the other two serving as the horizontal and vertical axes, so the solution region graphs of the solutions for three mechanism configurations were plotted. Based on these graphs, the distribution of the mechanism attributes was obtained with high efficiency. By imposing constraints, the optimum mechanism solution was straightforwardly identified by the designers. For the angular parameters prescribed in this paper, the solutions for three straight-line mechanism configurations were obtained, along with nine cognate straight-line mechanisms that shared the same portion of the rectilinear trajectory. All the fixed pivot installation locations and motion performances differed, thus providing multiple solutions to the trajectory of the synthesis of mechanisms.

On Dimension Synthesis of Hart’s Inversor III Straight-Line Mechanism As a Precision Robotic End-of-Arm Tool

In flexible manufacturing systems, straight line motions are often required in part handling, assembly, cutting, sealing, or welding operations. Rather than using a high performance industrial robot to execute the path directly, employment of a less precise robot outfitted with an end-of-arm tool comprising an exact straight line mechanism could be more effective in both performance and in cost. Exact straight line mechanisms with pin connections are easy to manufacture and assemble, in comparison to those realized by translational joints where alignment of linear axes or surface could be problematic. Such an issue becomes even more difficult when relatively large stroke and/or high precision of straight line motion is required. In this paper, a study of the kinematic characteristics of a special class of exact straight line mechanisms, Hart’s Inversor Type III, with emphasis toward dimension synthesis, is presented. An analytical approach for sizing the link lengths with respect to a desirable straight line stroke constraint is developed and illustrated with examples. Also presented are stiffness and mechanical advantage characteristics for additional design considerations.

Kinematic Synthesis Using Reinforcement Learning

The presented research demonstrates the synthesis of two-dimensional kinematic mechanisms using feature-based reinforcement learning. As a running example the classic challenge of designing a straight-line mechanism is adopted: a mechanism capable of tracing a straight line as part of its trajectory. This paper presents a basic framework, consisting of elements such as mechanism representations, kinematic simulations and learning algorithms, as well as some of the resulting mechanisms and a comparison to prior art. Series of successful mechanisms have been synthesized for path generation of a straight line and figure-eight.

EFFECT OF STRAIGHT-LINE MECHANISM DESIGN ON THE LOAD DISTRIBUTION IN A CYCLOIDAL GEAR

In the cycloidal gear, the torque is transmitted to the planet gears via an eccentric shaft with central bearings mounted on it. A straight-line mechanism is used to output the torque from the planet gears to the output shaft, a mechanism which consists of rotational sleeves mounted on the pins rigidly connected to the output shaft disc. These sleeves roll off in the holes of the planetary wheel. The forces generated in the straight-line mechanism affect the distribution of forces in the cycloid gearing and the amount of force loading the central bearing. The article presents the influence of the number of bolts of the straight-line mechanism on the load distribution in the cycloidal gear. The research carried out with the simulation program has shown that the smaller the number of pins, the greater the fluctuation of the force acting in the central bearing and the greater unevenness of force distributions in the cycloidal gear. This unevenness may cause a decrease in fatigue life of the meshing and central bearings.

A METHOD FOR DETERMINING THE DISTRIBUTION OF LOADS IN ROLLING PAIRS IN CYCLOIDAL PLANETARY GEAR

The power transmission system in the cycloidal planetary gear is created by a serial connection of three rolling pairs: central cylindrical roller bearings, a set of rolling pins in the straight-line mechanism, and cycloidal meshing. The paper presents the numerical method for determining the distribution of forces acting on each rolling pair of this gear. Unlike analytical methods, numerical methods allow one to find that distribution in corrected meshing. Geometrical dimensions used in the equations of balance for the planetary gear transmission Palmgren`s dependences for the deformation line contact were used to calculate forces between co-operating elements. Once the distribution of load is known, one can predict the fatigue life of Cyclo’s gears in rolling pairs. The fatigue of rolling pairs is a very good criterion to optimize geometrical parameters of the power transmission system.

A Qualitative Survey of Reconfigurable Mechanisms With Industrial Applications

In the field of reconfigurable mechanisms, many ingenious designs have been built and analyzed, however very few have been implemented in industry. An analogous comparison of reconfigurable mechanisms to James Watt’s straight line mechanism is explored to suggest as to why there is a shortage of reconfigurable mechanisms being used. A qualitative survey was undertaken to examine existing mechanisms currently being used and to identify potential applications for reconfigurable mechanisms. Eleven manufacturing plants were visited to identify high frequency motion profiles. From this survey, motion profiles were selected for potential applications of reconfigurable mechanisms. One of the motion profiles, platform transfer, was selected from a possible four identified motion profiles. A proposed reconfigurable mechanism was designed to perform the platform transfer task. The joint of the mechanism consists of two R2P2 joints connected by a P2 joint.