A controller gathers information from the user through biosensors and from the machine through mechanical sensors. The controller then decides on a course of action and sends signals to the user and to the prosthetic device. It controls the movements and actions of the limb by sending signals to the actuator to make the limb move. The controller relies on computer programming and mathematical modeling to correctly translate the user’s intent into mechanical actions. In addition, it also uses these programming and modeling techniques to translate machine feedback into biological feedback for the user.
An actuator is the motor that moves the prosthetic limb. It is usually modeled after how the human body moves. The actuator can add or replace the user’s native muscle. Its movement is governed by the controller; it can also relay mechanical information back to the controller.
Research
Universities across the world are currently conducting research for the field of biomechatronics. Universities such as Massachusetts Institute of Technology, the University of Twente in the Netherlands, and the University of California all have special laboratories where they conduct the latest research into biomechatronics. Below are some of the current areas of study.
Analyzing Human Motions
In order to design machines that function like human body parts, we must first analyze how humans move. Dr. Peter Veltink and his colleagues at the University of Twente are analyzing how humans walk by measuring body movements with a camera system, ground reactive forces with force plates in the floor, and muscle activity with electromyography (University of Twente). Electromyography is the recording of the electrical activity produced by muscle contractions (Freudenrich). Scientists gather this information and use it to build computer and mathematical models. These models help them design devices that imitate human movements.
Human-Machine Interface
The ultimate goal of biomechatronics is to use machines to assist or supplant biological parts of the human body. Ideally we should be able to control these mechanical parts as we would control our normal body. Human-machine interfacing looks into interpreting signals from the brain and using those signals to move mechanical parts. Currently there are extensive studies into the use of electrodes to direct mechanical devices. These electrodes can be implanted into the brain or connected to the nerves of the user. They listen for electric activity inside the brain or from the nerves; they then send an electrical signal to move a piece of machinery or even to move a cursor on a computer screen. Claudia Mitchell, a former Marine and amputee, had been testing a new kind of prosthetic arm developed by Dr. Todd Kuiken at the Rehabilitation Institute of Chicago (Rehabilitation Institute of Chicago). The nerves that headed for her arm are redirected to her chest. Electrodes are planted on her skin that listen for the electric activities sent by those nerves, and send an electric signal to her robotic arm. So she can control her robotic arm by thinking about moving her missing arm.
Using Living Muscles as Actuators
Mechanical motors currently do not possess the flexibility of living muscle by any standards. After all they are just electrical motors and wires directed by electrical signals. Real living muscles make for much more dynamic actuators. Hugh Herr of MIT is working on a robotic fish that is propelled by living muscle taken from frog legs (Herr). The frog legs are attached to either side of the tail and of the spine of the robot. Electrodes connected to the stimulator are attached to the leg muscles. The muscles on either side are stimulated alternatively; these actions mimic the swimming motion of a fish. This is one example of the use of living muscles as actuators.
Research at the University of Waterloo
There is a significant amount of research being conducted in the field of biomechatronics in graduate programs around the globe. The University of Waterloo currently offers graduate studies in Intelligent Human-Machine Systems / Optomechatronics Laboratories under Professor Jonathan Kofman (Kofman). The areas of research include biomechatronics, optomechatronics (3D computer imaging), and robotics. Students from the math faculty can participate in research at our own university.
Biomechatronics is an exciting field in medical science that is quickly expanding as new technologies enable machines to mimic human body parts more realistically. Interested students and faculty should look into the many areas of research available in this field. After all, biomechatronics is about improving the lives of people who have lost parts of their bodies by allowing them to live as normal people. Hence this research has a clear positive effect on peoples’ well being.
Works Cited
Freudenrich, Craig. “How Biomechatronics Work”. HowStuffWorks. March 30, 2008. <http://health.howstuffworks.com/biomechatronics.htm>.
University of Twente. “Ambulatory measurement of body movements and ground reaction forces (FreeMotion)”. University of Twente. March 30, 2008. <http://bss.ewi.utwente.nl/research/biomechatronics/freemotion.doc/index.html>.
“Computer Imaging Assists With Facial Reconstructive Surgery.” Science Daily. 22 March 2007. 1 March 2008. <http://www.sciencedaily.com/releases/2007/03/070319175705.htm>
