Latest Advancements In Robotic Limbs Technology

Robotic limbs greatly improve the quality of life for many people. Innovative advancements in science and technology offer ways to help people who have lost limbs or suffered from paralysis. Robotic limbs are especially useful because they allow people to regain control of their bodies and function normally again. Some robotic limbs are intended to replace missing limbs, however others, known as SRL’s, or supernumerary robotic limbs, give you more limbs than you would have normally and can augment or increase a person’s functionality when performing various tasks. One example of an advancement in robotic limbs is a third arm which can be controlled via an electrode cap.

The developers of this device created different algorithms to read the brain activity associated with performing different actions. When a person thinks about doing something, different sections of their brain light up, creating a unique sequence. The cap picks up on the brain activity and uses an algorithm to interpret that activity, then performs the task using the third arm. This type of device is known as a BMI or brain-machine interface (Waltz). The interesting thing about this device is the fact that it can distinguish between thoughts directed at it, and thoughts directed at the user’s own two normal arms. The main uses for people who have both of their limbs for this device are to help with multitasking. The researchers who worked on developing this project gathered 15 healthy volunteers to wear the electrode cap and perform different activities, so that the device could read their brain activity. First, the participants balanced a board without the arm. Next, the researchers had them think about grabbing a water bottle.

The machine sensed the intention of the participants and performed the task, grabbing the bottle. Finally, they were asked to do both tasks at once. Participants were able to do it on average three quarters of the time. The best participants were able to do it about 85% of the time, while the worst were able to do it 52% of the time (Waltz). Interestingly, the practice of doing these two tasks together improved the multitasking ability of the participants. Also, the participants were able to multitask much faster than the researchers predicted. This means that this device could be used to improve the multitasking ability of individuals who are not missing limbs. There are other examples of supernumerary limbs as well, such as exoskeleton hands for quadriplegics and dual robotic arms controlled by inertia. Similarly, researchers have developed a way for quadriplegics to regain the use of their hands. This was done using an exoskeleton worn around individuals’ hands, controlled by thoughts and eye movements. This device was tested with six quadriplegic individuals who were successful in using the device to pick up small objects such as coffee cups, eat donuts, squeeze sponges and sign documents. The individuals were able to perform these tasks outside of a laboratory setting in real life situations, which is a dramatic improvement over previous robotic controlled limbs. The device works similarly to the third arm mentioned previously, by wearing an electrode cap with sensors that detect brain activity. An algorithm translates these into signals performed by the device. The process takes about a second with this device, which is not fast enough to perform tasks such as catching a ball, which would require fast reflexes. However, it is fast enough to perform tasks such as turning a doorknob. The reason the device can be used in busy environments is due to the addition of sensors placed near the eyes that detect voluntary eye movements.

This study is related to a previous one in which paraplegics were able to regain the ability to walk using an exoskeleton worn around the lower body. Participants were able to regain voluntary leg movements and the sensation of pain after 12 months of training. Perhaps the hand exoskeleton could be used in the same way to restore function to the hands. If so, that would have a dramatic impact. Developers have also experimented with limbs which are attached at the shoulders as well as the waist. These limbs can be used to assist in tasks which require more than two hands, or when both hands are occupied with a task. One example of this is a situation in which an individual is involved in construction and needs two hands to hold a beam above his head, while simultaneously screwing it into place. Another example would be if an individual needs to open a door while holding something in both hands. “The SRL shoulder robot uses two arms mounted on your shoulders such that the reaction forces on them are aligned with the spine. Each arm has five degrees of freedom, with interchangeable and customizable end effectors, and the complete systems weighs about 4. 5 kilograms, or 10 pounds” (Ackerman). To resolve the potential control issue with the SRL, rather than using manual control, the SRL observes the actions the user takes, makes predictions accordingly, and performs tasks based on those predictions. To do this, the user wears two inertial measurement units, or IMU’s, on the wrists and a third at the third at the base of the shoulder mount. The SRL uses data gathered from the IMU’s, based on demonstration learning, and decides what is the most helpful position to be in. The researchers test different “behavioral modes” to program the limbs and combine the most significant behavioral modes so that the limbs act like an extension of the user’s own body. This project was designed to prevent workplace injury by assisting aging workers so that they would not have to perform strenuous tasks manually.

Also, the reason the developers created arms as opposed to a full exoskeleton is to create more options and versatility in the design. Related to the desirability of these developing technologies and everyday life is the topic of anthropomorphism in robotic limbs. Anthropomorphism refers broadly to the application of human characteristics to an object. In this context, it refers to the capability of these devices to appear and behave similarly to human limbs. In their article, “Anthropomorphic robotic hands: a review,” Erika Nathalia Gama Melo, Oscar Fernando Avilés Sánchez, and Darío Amaya Hurtado discuss in detail the characteristics and advantages of anthropomorphic features, specifically in robotic hands. Some of the main aspects to be considered However, the use of these prosthetics can raise ethical and legal questions. For example, if someone uses a robotic arm to sign a legal document, was that document technically signed by a human? Might it be possible to take advantage of such technology to forge a person’s signature? Are robotic prosthetics “hackable”? All these questions present ethical and legal problems that might arise with the use of robotic limbs.