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Published on March 31, 2008

For amputees, the dream of having an artificial leg which can work as an integral part of the human body is not far off. Efforts are underway to develop a new type of electronic prosthetic leg, which could help amputees walk more naturally.

With experience in developing the lower part of a humanoid robot and calibrating its walking pattern, the Institute of Field Robotics (Fibo) is working on a new project to build an electronic prosthetic leg.

The new leg, designed to be worn on the upper knee, uses sensor technology to detect the wearer's walking pattern and adjusts itself to allow walking customised for the user, Thodsaporn Bunthae, a researcher at Fibo, said.

He designed the artificial leg with a variable damper, which is similar to a vehicle's choke-up mechanism, to smoothen out and dampen sudden shocks so that the amputee can walk smoothly.

As a more significant feature, Thodsaporn has incorporated a sensor system to make the leg more "intelligent". The system detects all movements to adjust a walking pattern suited to the wearer.

"We have two key sensors in the leg. The first sensor is used to measure the degree of the knee's movement while the second helps detect forces each time the amputee walks," he said.

Thodsaporn said information from the two sensors is processed by an inbuilt computer system which calculates a suitable dampening rate for each individual.

The result is used to help adjust the damper automatically.

"So, whether the wearer walks fast or slow, the sensor will detect all movements at all times and the leg will self-adjust the damper," he said.

The "intelligent leg" will make the amputee's life more comfortable as it will customise itself to the wearer and work out a walking pattern that provides the utmost comfort.

The prosthetic leg with the embedded microprocessor is now under development and the first prototype is expected in the next few months. Fibo has received Bt600,000 funding from the National Electronics and Computer Technology Centre (Nectec) to develop locally made prosthetic legs at affordable prices. It is also working with Sirindhorn National Medical Rehabilitation Centre and the Prostheses Foundation of HRH the Princess Mother to help design the new leg.

As part of this project, Fibo has developed two other models of artificial legs using a variable damper. The first model allows the amputee to make manual adjustments to the dampening rate to suit their walking patterns.

The second model can be used with a remote control to control the damper adjustment wirelessly.

Pongpen Sutharoj

The Nation