A Helping hand

Recovery of arm movement is the objective of a research project supported by FAPESP on robotic exoskeletons

By Elton Alisson

Agência FAPESP – For a person without physical limitations, raising a fork or a glass of water to one’s lips may seem commonplace. But for anyone who doesn’t have movement in their arms, this seemingly simple task can mean a radical life change which translates into more independence, among other benefits.

In order to ensure that in the future, people with motor disabilities can recover abilities like this one, researchers from Universidade de São Paulo’s Polytechnic School have initiated a research project “Motor control analysis of the upper limb Phase 1 - development of a biomimetic robotic exoskeleton.” Financed by FAPESP, the project aims to study the motor control of the arm using a robotic device that simulates the functions of a human limb.   

Based on the understanding of motor control involved in movements like ingesting foods, scientists intend to develop a robotic exoskeleton – a prosthesis using robotic technology – capable of broadening the movement of patients who present some muscular contraction, but who cannot manage to move their arms, or make predefined movements for people who do not have any capacity for muscular contraction.
 
“The objective is to develop an exoskeleton to apply movements similar to those of a human arm to an orthosis,”explained project coordinator, Arturo Forner Cordero, of the Biomechatronics Lab of the Polytechnic School’s Department of Engineering Mechatronics and Mechanical Systems, in an interview with Agência FAPESP. An orthosis is an external device applied to the body to modify functional or structural aspects of a neuromusculoskeletal system.

In order to test the concept, the group developed a prototype of a robotic exoskeleton for an arm capable of applying force on the elbow. In the coming months, they intend to introduce another exoskeleton which is also capable of applying movements on the shoulder and wrists to study motor control of the arm.

After integrating the device to an electromyographic system and another for visual representation, the researchers hope to obtain information about different levels of control over the human motor system, like reflex modulations and integration of sensory information. They also expect to develop a prosthesis capable of reproducing the movements of a human arm through partnerships with medical centers and associations that deal with the application of othosis in physically disabled patients.

“Today, the behavior of a robotic arm is very different from a human arm. Our idea is to develop prosthetics run on electric batteries which closely mimic the movements and functions of the human arm,” explains Cordero.

Active prostheses and ortheses

According to the researcher, currently the majority of orthosis and prostheses utilized by physically disabled people are passive, i.e. they are largely for esthetic purposes. But, in the last few years, active systems have begun to be developed, including exoskeletons.

Cordero attributes the heightened interest in developing these exoskeletons to, among other things, the increased life expectancy of physically disabled people, the development of robotics and military interest in exoskeleton technology. 

In the 1990s, the Universitiy of California at Berkeley began construction of exoskeletons to increase the physical abilities of soldiers in the U.S. armed forces.

Japan developed the HAL-5, a full-body exoskeleton projected to enable the aged and people with motor disabilities to walk, climb stairs and go about their daily activities. And the beginning of 2006 marked the launch of the Enhanced Sensory Bipedal Rehabilitation Robot (ESBiRRO) project, in which Cordero participated, for development of a bi-ped robot and a lower limb exoskeleton working around the hip region.

At Poli/USP, the arm exoskeleton development project will inaugurate activities at the Biomechatronic Lab, which is focused on neuromotor studies aided by exoskeletons. “The laboratory will be one of the first of its kind focused on exoskeleton development in Brazil,” says Cordero.

In addition to the arm exoskeleton, Brazilian researchers are conducting another project funded by the National Council for Scientific and Technological Development (CNPq) to create a leg exoskelton, which according to Cordero poses the scientific challenge of being made smaller than the arm exoskeleton.

“Normally, leg motor control is much better defined than arms. While legs allow one to walk, run or go up and down stairs, among other things, the arms do many more different actions, and this is an additional complication,” he says.