INTRODUCTION OF COMPLIANT MACHINES AND IT’S HISTORY

 

when you think of a machine a robot or a mechanism you likely think of a collection of rigid bodies that work together to achieve a desired task which in the case of jansen linkage is locomotion but when you consider the machines that nature designs you probably don't think of clunky rigid bodies connected together by well-defined joints. Plants and animals tend to be soft bendable and flexible and they use this compliance to achieve tasks that are far more advanced than even the most impressive machines that humans have designed.

Nature's Compliance

Although its true that some of the rigid machines that humans have designed have managed to outperform nature's compliant machines like jet that can fly much faster than any living creature can but no one denies that nature's flying machines are masterpieces of design that are far more maneuverable, agile and energy efficient than any aircraft humans have ever built. In fact designs that are compliant are advantageous for many reasons. The advantages of compliant designs are repeatable, scalable, human safe, adaptable, lightweight, lower cost, easier to maintain, easier to fabricate, friction free, hysteresis free, more robust, passively deployable, easier to exactly constrain, easier to not under constrain, easier to achieve symmetry, more accurate, soft electricity free and more energy efficient and also they minimize part count, require minimal or no assembly accommodate imperfections and the list goes on and on and on so it begs the question if the benefits of compliance are so numerous and significant and if nature is predominantly selected for compliance over rigidity after billions of years of constant design iteration why don't we design more machines that are compliant? well because compliant machines are harder to design than rigid machines.

I believe some of the most exciting future technologies will be enabled by compliance.

Things deform flex and bend around us all the time. Let me give you some common everyday examples of compliant items that use elastic deformation to function and you may be surprised just how many flexible things impact your life on a daily basis.

Bow and Arrow

Long before recorded history early humans recognize the importance of things that elastically deform and use compliance to help them survive although no one knows exactly who invented the first bow and arrow. Archaeological evidence suggests that they were used in africa as early as 62 000 bc during the middle stone age by deforming an elastic bow using an arrow loaded against a taut string. Early humans discovered that they could rapidly convert the bow's deformation energy into the arrow's kinetic energy and thereby launch the arrow with substantially more speed and accuracy than could be achieved by simply throwing the arrow by hand. If you consider the impact this ancient invention had on our ancestors ability to hunt and defend themselves it's reasonable to conclude that humanity itself may owe much of its continued survival to compliant inventions like the bow, the art that decorates the walls of some egyptian tombs even shows that bows were used for other purposes beyond hunting and war.

This piece from the tomb of eureka mir depicts egyptians using a bow to drill holes and beads by wrapping the tension string of the bow around sticks and then quickly rotating the sticks by moving the bow back and forth bellows is another ancient compliant invention that had a hand in dramatically accelerating human progress. It's interesting to recognize that historians named the major periods of history such as the bronze and iron ages according to the materials that enabled the technological advances of the time the discovery.

Bellows 

Ancient cultures so heavily relied so if compliant technologies such as bows and bellows had such an impact on our ancestors ability to survive and thrive in the world they lived in what effect do compliant technologies have on our lives today well before I spring into that discussion let me first define what compliance even is before we get ahead of ourselves with examples to understand what compliance is.

It's helpful to first understand what stiffness is since they are closely related principles stiffness is the extent to which a body resists deformation in response to an applied load more specifically a body exhibits stiffness when it resists an applied load with a counter force that is a function of how much the body is displaced by the applied load.

compliance is essentially the opposite of stiffness mathematically speaking a spring's compliance c is 

the inverse of its stiffness k this means that the stiffer a spring is the less compliant it is and the less stiff a spring is the more compliant it is so compliant springs deform over larger ranges more easily meaning with less force than stiff springs. 

Published by-

1) AAYUSH SURAWAR

2) SAMARTH TAKBHATE

3) DEVASHISH TAMBADE

4) UMESH WANARE

5) CHINTAN VORA