Robot Types: Conventional & Unconventional

01 Introduction

When most people think of robots, they imagine stiff metal machines moving with precise, serious motions — like something straight out of a sci-fi factory. On the other hand, there are unconventional robots who stretch, squish and jiggle (like jelly) and are the size of a hand.

02 What's the Difference?

Conventional robots often are built as rigid structures (e.g. wheels, arms etc) and are mainly used in a controlled environment for doing repetitive tasks for many hours. An example could be a huge industrial arm in a factory for manufacturing items on a large scale. The main purpose of these types of robots are for speed, precision and most importantly efficiency. This is because they often are allocated 1 specific job that they have to excel in — this also means that they are pre-programmed and have limited flexibility as they follow simple instructions repeatedly.

However, unconventional robots are designed to overcome the rigidity of conventional robots. They achieve this by using different materials that are more specialised for a task. For example, soft robots need more flexible materials like silicone rubber, polyurethane, and hydrogels to grip irregular objects. In addition, unconventional robots are given complex tasks due to their lack of rigidity. For instance, environmental monitoring, disaster rescue, medical procedures etc.

03 Diving Deeper on Conventional Robots

Conventional robots often are made with the engineering principles of: mechanical strength, repeatability, and seamless integration into automated systems — allowing it to work with the other machinery (in a factory or controlled environment). In addition to a rigid metal frame, they also use many common actuation components. Such as:

• Electric servo motors → These are precise electric motors that can control position, speed, and rotation very accurately. They are commonly used for robotic arms where exact movement is needed.
• Hydraulic actuators → These use pressurized liquid to generate very strong force. They are used when robots need to lift heavy loads, like in large industrial robots.
• Pneumatic actuators → These use compressed air to create motion. They are lighter and faster but less powerful, often used for gripping or quick repetitive movements.

An example could include the Delta robot, a conventional robot heavily used in production lines for picking and plucking of items (like coke cans), which uses 3–4 electric servo motors to control its precise and quick movements. Another example is the KUKA KR QUANTEC, a large industrial robotic arm which uses pneumatic actuators for its claws. To aid integration with other robots in an environment, such as conveyor belts, engineers put programmable logic controller sensors and machine vision systems to help co-ordination.

04 Diving Deeper on Unconventional Robots

Unconventional robots are not 'conventional' due to the lack of their rigidity in their design (and are often used for complex tasks). In addition, they use bio inspired materials and softer materials to overcome the rigidity of conventional robots. Such as: silicone rubber, fabric etc. For example, soft grippers can pick up fragile items like fruit without damage, or softer materials allow them to navigate small crawl spaces. They also use biomimicry and copy designs from nature such as an octopus. Because of this they use special actuation components like:

• Pneumatic artificial muscles →Air-powered flexible actuators
• Hydraulic soft actuators →Liquid-powered movement
• Cable-driven tendon systems →Rope-like tension control
• Vacuum-based grippers →Soft suction gripping
• Shape memory alloys →Metals that move when heated
• Dielectric elastomers →Stretchable electric actuators
• Electroactive polymers →Materials that change shape with electricity
• Fluidic elastomer actuators →Inflatable soft chambers

For example, the OctArm uses pneumatic artificial muscles that inflate with air to bend and twist in a flexible manner similar to an octopus arm. Another example is the Soft Robotic Gripper (Harvard), which relies on air-powered chambers to gently grasp fragile items. To aid varying complex tasks, they are often 3D-printed for their special tasks.