The experts believe that there is no commonly agreed definition for robotics, they define it as the science and engineering of devices which are reprogrammable, multi-functional, multi-purpose and versatile systems intelligently linking sensing to action. This definition can be extended to soft robotics as the science and engineering of the robots primarily made of soft materials, components and monolithic active structures such that they can safely interact with and adapt to their immediate environment better than the robots made of hard components. Soft robots, that are sometimes called biologically inspired robots, offers unprecedented solutions for applications involving smooth touches, safe interaction with humans, manipulating and grasping fragile objects, crops, and similar agricultural products. Soft robots can be in the form of robot manipulators, grippers, medical robots, agricultural robots, rehabilitation robots and similar, depending on the application.
As noted by a report, robots can be made of a number of rigid links connected to each other with a single degree of freedom rigid or elastic joints, like hyper-redundant manipulators or invertebrate-like robotic topologies, where each joint is controlled independently to realize a task or purpose. This is a classical approach that has been used in many robotic designs and is commonly known as Hard robotics. However, this approach requires intricate algorithms to control (i) the position of each link and whole robot and/or (ii) the contact force during the physical interaction and interface of the robot with its environment. In line with recent progress in soft smart materials or electro-materials and additive manufacturing techniques, the soft robots consist of a monolithic (i.e. whole) body containing actuation and sensing elements, mechanical structure, energy storage units with a minimum foot-print. Such robots are expected to change their effective stiffness in order to provide a desired force or compliance when interacting with their environments including physical interaction with humans.
Let us understand the characteristics of soft and hard robotics systems.
• Where on one hand soft robot-systems are made of flexible, stretchable materials with reversible and variable properties, on the other hand, hard robotics systems are made of hard materials with invariable properties.
• In soft robotics systems, inherent compliance matches its environment whereas in hard robot-systems smooth contact with its environment facilitated by advanced feedback control strategies and sensors.
• The report suggests that the continuum topology with infinite degrees of freedom (DoF) seamlessly housing all of soft robotics systems’ essential elements. Contrary to that, in hard robotics systems, discrete topology with a finite degrees of freedom consisting of rigid elements connected to each other with single DoF joints.
• While soft robotics systems are inherently safe adaptive and tolerant to operate in unknown environments, especially for human-machine interaction, the other one is considered unsafe and intolerant with limited adaptability to operate in unknown environments unless intricate control measures are applied.
• While the former has flexible and stretchable electronics and power sources, hard robotics systems have conventional electronic and power source.
• Soft robot-systems possess high-level behavioral diversity, high level of bio-inspiration, can tolerate low accuracy, low speed, and force applications and is of low weight and cost.
• Hard robot-systems have a low level of behavioral diversity, low level of bio-inspiration, high accuracy, high speed, and force application and high weight and cost.