Nursing care robots become more human with improved control method

The researchers at Ritsumeikan University in Kyoto said robots are becoming an increasingly important part of human care, with the aim of the new technique created to help improve the safety and efficacy of robotics care.

“In recent years, shortage of caregivers has become a serious social problem as the result of a falling birth rate and an ageing population,” said Changan Jiang, an assistant professor of mechanical engineering at the university.

Nursing care robots are already in use in several care facilities, with the UK Government seeking to use the technology at nursing homes throughout the country. However, these robots come with their limitations.

Robots responsible for lifting a patient from a bed to a chair, for example, must be heavily supervised by a human care provider. Furthermore, the control method the robot uses to lift and hold a person must also tackle the issue of friction, as the weight of the human could cause the robot’s arms to stall in mid-movement.

In the paper, Jiang and co-author Satoshi Ueno report the development in a computer simulation of a method to control the movement of a nursing care robot’s arm to make a safe and comfortable posture without having to compensate for the friction between care-receivers and the robot’s arms.

“In a real-world application, the friction cannot be ignored and it will affect the arms’ performance of holding and the lifting-up motion,” Jiang explained. “In our research, instead of compensating the friction, we utilise static friction reasonably during holding and lifting up of an object. This is the most important idea of our research.”

The team added that static friction keeps an object at rest. For example, a truck climbing a steep ramp must have enough force to propel itself upwards; otherwise, static friction between the truck and the road will grind the movement to a halt and keep the truck still.

With nursing care robots, the researchers made the static friction work for them by applying it to a two-link object – the robot’s equivalent of a human arm.

By assuming the arm is working from a state of static friction, with the care-receiver’s body acting as a buffer that keeps the arms from moving, the team programmed the arm to keep the body at rest.

As a result, the care-receiver has a safe and comfortable experience and the robot’s arm doesn’t need to work to compensate whatever friction is introduced.

Next, the researchers plan to add a third link to the control method, which will represent a torso.

“We plan to extend the two-link object to a three-link one, which is more similar to a human’s body and to design a new control method to realise a safe and comfortable holding and lifting-up motion,” Jiang said.

The results of the study were published in the journal IEEE/CAA Journal of Automatica Sinica.

In May 2019, University of Exeter researchers demonstrated that robotic pets could benefit older people living in care homes, providing much of the pleasure and comfort of real pets, as well as increasing social activity.