• Sajiv Shah

The Need for Force Sensing in Robots

The rise and need for robots that are collaborative and usable in a human work-area is increasing. Many studies have concluded the productivity is maximized not when a human works alone, or large heavy robots work alone, but rather when robots work alongside humans. The large reason for this is humans are good at detecting errors, and setting up tasks that robots can repetitively do one task.

There is one major barrier that is stopping todays robots from working with humans: they are dangerous.

And the reason these robots are dangerous can be attributed to two major characteristics

  1. They are made out of non-compliant hard bodies (aluminum and other metals)

  2. They are not aware of their surroundings and therefore will not be able to sense if they hit an object.

At first the solution to the first problem may seem simple-just cover the damn thing in styrofoam or rubber and voila, its spongy. But in reality, if the second problem isn't solved, solving the first is not relevant. No matter how spongy the shell of a robot is, it can still pin you up against a wall if it has no way of sensing when to stop moving.

That concept led researchers to tackle the second problem. And they did so in many ways. Researches have experimented using camera systems to create 3d maps of a robots surroundings, created electrical feedback loops to sense loads, and created mechanical designs to relay information and create compliance.

It was realized that solely using camera systems may not be useful as the humans and robots move so fast that the feedback speed is simply not practical. Furthermore, cameras do not provide full coverage of all the areas that the robot may come into contact with a human. Camera systems, however, are very useful for object manipulation. Research turned towards using cameras to ensure success in completing tasks.

Therefore, research for sensing surroundings turned to electrical and mechanical methods of calculating the ultimate loads on a robot. All this research is ultimately categorized under force sensing, which is perhaps the most important area of research for collaborative robots. The ability to sense the loads and forces on robots is a huge benefit as robots will then be able to react to sudden loads or forces placed on the robot, wether it be from hitting a human or another object. This not only makes the robots much safer and usable in a collaborative environment, but also allows for easy human operation of these robots. Now, humans can simply tap or push force sensing robots to give them commands to begin or stop a task.

Later, I will be comparing different types of robotic joint mechanisms that implement force sensing and comparing how they perform. I will also talk about a couple electrical methods for force sensing.