03-08-2022 | By Robin Mitchell
Recently, researchers have developed pressure sensors using graphene foam that can provide prosthetics and robotic systems with accurate haptic capabilities. What challenges do current robotics face, what did the researchers develop, and how could it improve future robotic systems?
Even though great strides in robotics have been made in the past few decades, numerous challenges still prevent robotics from being used in everyday life. One major challenge faced by robotic systems is their lack of awareness of their surroundings. This is problematic as robotics are often significantly stronger than humans and as such have a great capacity to cause serious harm. As such, robotic systems (especially those used in an industrial environment), are often required to be used in controlled environments with barriers and sensors that deactivate the system should the safety perimeter be breached.
Another challenge faced by robotics is their inorganic movement. While this makes robotics excellent for delicate and controlled movements (such as robotic surgery systems and precision welding), it makes mimicking movements such as walking and running difficult. However, this challenge is also related to software used on robots and the difficulty in trying to develop algorithms that can account for weight shifting.
But above all else, one problem that robotic systems commonly face is touch. As living organisms, we often take our sense of touch for granted as it allows us to accurately determine pressure, detect if something is slipping, and understand the differences between two very similar textures. In fact, it is estimated that humans are able to feel objects as small as 13nm.
Robotics, however, have a serious deficiency in this area, and this prevents robotic systems from being able to accurately feel objects and understand how much force to apply. To get around this, engineers have looked towards flexible grippers that use pneumatics to grab objects as such grippers deform when under pressure, but even this introduces its own issues.
Even though pressure sensors do exist, simply attaching them to the fingertips of a robotic arm doesn’t solve the issue. For example, a single sensor on each finger can inform the robot how much pressure is being applied, but it doesn’t help detect an object slipping, nor does it help determine texture. When considering that each human fingertip has approximately 3000 nerve endings, it’s no wonder why robotics struggle with touch.
Recognising the challenges faced by robotic systems, researchers from Integrated Graphene and the University of West Scotland recently developed a new graphene-based sensor that allows for accurate pressure sensing. The new sensor takes advantage of a graphene foam whose electrical properties change when under mechanical stress. Specifically, the foam exhibits piezoresistive properties whereby the resistance of the sensor changes under mechanical load. The development of the 3D graphene foam sensor comes after a recent announcement by Integrated Graphene which stated their intention to invest £8m to help scale up their graphene manufacturing capabilities.
The researchers are aiming to utilise the sensor in the fingertips of robotic systems, especially those used in prosthetics, to help create haptic sensors that allow for finer control. Additionally, the researchers also believe that graphene foam has potential applications in energy storage technologies due to the conductive nature of graphene and the foams ability to be impregnated with electrolytic compounds.
It goes without saying that a robot that is able to have the same degree of sensation as human fingertips would be able to do extremely intricate tasks and switch from lifting heavy loads to pinching delicate parts. However, simply being able to feel mechanical pressure isn’t enough to create an adaptive robotic system; software is still needed to read the data and determine how much strength to apply. This issue relates back to the inability of robots to be fully aware of their surroundings and what they are doing. As such, any robotic systems deploying pressure sensors will also be heavily reliant on AI to understand how the detected pressure relates to the task.
But pressure sensors will also provide new opportunities for prosthetics. While prosthetics have become advanced, they still suffer from core issues such as the inability to provide the user with a sense of touch. It is this lack of touch that makes using prosthetics challenging, and in many cases can see the wrong amount of force applied to a prosthetic hand. Pressure sensors connected to fingertips would not only provide the sensation of touch, but could even provide the user with the ability to accurately control the amount of pressure generated by the robotic system.