LEE, SHUNG-YUAN
National Yilan Senior High School Student
E-mail:sean7777@smail.ilc.edu.tw
Abstract
The 4-bar parallelograms are extensively adopted in robotic arms due to their simple motion trajectories. When rubber bands are mounted on the relevant pivots of the mechanism, the motor output torque and power required for rotation can usually be reduced. According to the mounting method of the rubber band, it can be generally categorized into two types, namely, the two-point and the three-point type.
The influence of the hanging method of the rubber band on the relationship between the vertical component force and the angle exerted by the parallel 4-bar parallelograms has been investigated. From the experiment, by changing the mounting method as the manipulated variable, the relationship between the load and the angle can be observed and measured, and then the vertical component of the force exerted can thus be obtained from computation. Through data analysis, the relationships among the parameters in the system can be clarified, and its utilization in application can be evaluated.
On the basis of the rotating two-dimensional rectangular reference coordinates for the measurement of the mechanism, the experimental results reveal that the intercept will be significantly affected in the relationship plot between the load and the angle if the magnitude of the upper link from the suspension point in the xdirection is changed; while in contrast, the slope will be dramatically affected if the magnitude of the upper link from the suspension point in the y-direction is changed.
As well as revealed by the corresponding relationship between the load and the angle, comparing the two-point and three-point mounting methods, shows different characteristics. The former shows a linear change, while the latter shows a curved change. In addition, the three-point mounting method shows a higher evaluation in application.
It can be concluded that the study deserves further work for the reduction of energy consumption in the application of the motor on the robotic arm, and, as well as of the related fields such as unpowered human exoskeletons to achieve labor-saving and energy-saving purposes.
Keywords :4-bar parallelogram, force-saving mechanism, and rubber band