The power of movement: exoskeletons and load cells

Published On: October 12 2023

Science fiction is full of robotic exoskeletons, from Iron Man’s snap-on suit to the giant Jaeger fighting machines in the movie “Pacific Rm”. However, present day exoskeletons are much more about enabling those with neurological and musculoskeletal movement impairments to move more freely.

These kind of applications of technology have become relatively commonplace, so much so that you can even compete in marathons:

“If you need a battery-operated robotic exoskeleton, such as Rewalk, you can now use this to complete the TCS London Marathon. A team of four helpers can also join you for the event, with a maximum of two helpers allowed on the course with you at any one time.”


Exoskelatons and rehabilitation

In this fast-developing field, exoskeletons have been used to extend the capability and availability of “hands-on” rehabilitation therapy. As a paper in “Sensors” explained:

“Traditional physiotherapy rehabilitation systems are evolving into more advanced systems based on exoskeleton systems and Virtual Reality (VR) environments that enhance and improve rehabilitation techniques and physical exercise. In addition … it is possible to design and develop advanced, effective, and low-cost medical tools that patients may have in their homes. “

The paper covered the development of a simple exoskeleton for the rehabilitation of elbow injuries. The force exerted on the two elements of the skeleton (upper and lower arm) were measured through “A Gauge type load cell that is amplified through a Wheatstone bridge.”This paper includes several diagrams showing the load cell positioning – well worth checking out at MDPI.


Upper body exoskeletons

What really caught our eye recently is a complete upper body exoskeleton that is primarily for treatment and rehabilitation and uses robotic arms. This offers far greater scope than fixed format exoskeletons as per the above example:

“By enabling early intervention, functional repetition, and intent-based therapy, Harmony SHR delivers users the ability to improve the efficiency and effectiveness of upper-body rehabilitation.”

According to manufacturers Maxon, one of the problems previously encountered with using robotic arms was that:

“Most robotic arms on the market are not designed to interact with humans safely – they cannot detect a person in their way or move around a person while performing the programmed task. Due to this, typical robots could be very dangerous for people to interact with, especially in a physical therapy application.”

To overcome this, their Harmony SHR upper body exoskeleton is force sensitive and operated through force input from the the user, rather than a set programme. Even a slight force exerted by the user will cause the robotic elements to slow or stop completely. This was achieved by redesigning conventional robotic actuators:

“Harmonic Bionics has developed a patented robotic actuator, which uses a load cell that is mechanically isolated from any extraneous loads. The result is that each load cell can sense the force exerted by only the joint of the robot it is mounted to, while being isolated from the forces being applied to others, thus maximizing the sensing accuracy of the load cell.”


Load cells for your medical research or robotic project

Looking for load cells for your innovative robotics project or medical research?

Call us to discuss your requirements. We can design and supply load cell system to your exact requirements, and have the capacity and experience to build custom load cells for you right here in Reading UK. To discuss your specific requirements: