Robotic Joint and Human Joint Comparison


The robotics industry was valued at $18.8 billion in 2018 and is forecast to reach $59.9 billion by 2026.* The demand for robotics and high-quality robotic joints is increasing due to the lower cost of materials and the promised savings by deploying autonomous machines.

However, some people are fearful of this robotic revolution and will continue to argue that robots are stealing our jobs, but the evidence suggests it just isn’t true. McKinsey & Company are a research organization who publish reports on management and industrial processes, and they claim that robots will not take over our jobs.McKinsey’s researchers discovered that employees would see some automation in their lifetime. Still, only about 5% of jobs will be given up to robots, leaving humans to find other ways to provide value.

The ability to build an autonomous robotic device that can mimic human function without the need for rest or management obviously has its benefits. The closer the robot resembles human topology, the better it will equip them to live in our space and use our environment as we do: meaning, fewer modifications need to be made to the production space.

Therefore robotic joints are critical to the evolution of the robot and its place in society. Rozum Robotics is one manufacturer making great leaps in the industry and their new PULSE robots boast modular design with six degrees of freedom, which is almost as many as a human’s upper limb.

So what makes the human joint so inferior? What key advantages do robotic joints have? Let’s find out.

Interesting fact – There are more joints in the human body than there are bones.

There are three main types of joints in the body 

  • Synarthroses (immovable)
  • Amphiarthrosis (slightlymovable).
  • Diarthroses (freelymovable)

For the rest of this article, let’s concentrate on the freely movable joints, of which there are six types:

  1. Ball and socket joints. For example, the hip joints. This joint has movement in all directions, or in other words, it has multi-axial movement.
  2. Hinge joint. For example, the knee joints. This joint only allows movement in a single plane. Itisreferredtoas a uniaxialmovement.
  3. Condyloid joint. For example, the fingers. This permits movement in two planes, allowing flexion, extension, adduction, abduction, and circumduction.
  4. Pivot joint. For example, the forearm or neck. This allows rotational movement of one bone inside another — also uni-axial movement.
  5. Gliding joint. For example, the wrist. Thisallowsslidingmovement.
  6. Saddle joint. For example, the thumb. Affords no rotational movement but allows bi-axial movement.

Replicating human joint movement is extremely difficult using materials available today. The joints themselves can easily be copied, but the way our joints are manipulated by cartilage and fibrous connective tissue is challenging to duplicate. However, while a robotic arm has less freedom it has a far superior range of movement, for example, we can only bend our arm at the elbow in one direction but a robotic joint can move in two directions.

The disadvantages of the human joint

When considering industrial applications, there are some significant disadvantages to the human joint and they are:

  • A human joint is made of soft organic materials and wears out quickly, eventually requiring painful surgery.
  • Comparatively, humans can’t manipulate their joints to perform repetitive tasks to the degree of accuracy that a machine can.
  • Human joints are inherently weak.

Additionally, not all machines need to precisely mimic human movement to carry out their specific function.

A robot is a programmable machine that is designed to have anthropomorphic characteristics. To achieve that the robot design will have a certain number of joints in specific configurations. Each joint is connected to two links: an input and an output link.

The input link is manipulated by a servo or motor to enact a force through the joint to the output link to achieve its intended range of motion.

Photo by Franck V. on Unsplash

There are five types of mechanical robotic joint**

  1. Linear joint – The relative movement between the input/output link is a sliding motion, with the axis of the two links in parallel.
  2. Orthogonal – The relative movement between the input/output link is a sliding motion, but the output link is perpendicular to the input link.
  3. Rotational – This provides rotational relative motion, with the axis of rotation perpendicular to the axes of the input and output links.
  4. Twisting joint – This provides rotary motion, but the axis of rotation is parallel to the axes of the two links.
  5. Revolving joint – The axis of the input link is parallel to the axis of rotation of the joint, and the axis of the output link is perpendicular to the axis of rotation.

The main advantages of robotic joints

  • Robotic joints are designed to carry out repetitive tasks at speed without wearing out or breaking down.
  • Robotic joints have superior strength in comparison to human joints.
  • Robotic joints can be used in hazardous environments where it would otherwise be dangerous to humans.
  • Robotic joints are precise and can consistently carry out tasks within a specific tolerance. Humanscan’t.

Robots are integral to many production facilities around the world. They carry out their duties efficiently with little rest or interaction. They are especially useful in manufacturing processes that require repetitive, high accuracy tasks. Industrial robots are used as a rule in three types of applications: material handling; processing operations; and assembly and inspection.

For example, Amazon, one of the biggest companies in the world, uses robotics for material handling purposes. They use autonomous vehicles that move products around their fulfilment centres day and night. It’s clear to see that robots have earned their place in the modern industry, and this allows humans to concentrate on other areas of the business.

Manufacturers are consistently trying to lower operational costs, and they can achieve it by making fewer mistakes and streamlining operational workflow. That means they will increasingly turn to robots.