Whether an infant reaches for its toes, or someone reaches for a pencil as it rolls off a countertop, grasping items with our hands is basic human instinct. Researchers at Arizona State University’s Neural Control of Movement Laboratory are discovering that this simple task is not so simple. In fact, the grasping action is the final step in a series of complex processes that comprise our sense of touch. Inefficiencies or disruptions to any link in this chain of processes will directly impact our ability to use our hands. This makes research in the field of neural motor control quintessential to the advancement of rehabilitation technology and treatment. ATI’s Multi-Axis Force/Torque Sensors are helping researchers break down the human sense of touch by providing feedback–in real time–as the process occurs.
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Qiushi Fu studies sensorimotor processes at the Neural Control of Movement Laboratory. The lab’s research focuses on the hand as a model for understanding motor learning and control. Fu’s experiments focus on the human sense of touch. He utilizes ATI’s smallest F/T Sensors to look deeper into sensory feedback (the communication between the brain and muscles of the hand), during grasping and manipulation trials.
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When we reach for an object, our brain first gathers information from our environment and cross-references similar situations from the past. Using both visual cues and memories, we can estimate the amount of rise force and grip strength needed to manipulate the object without dropping or crushing it. Once we have it in hand, our brain continues receiving feedback from the grasping process. This allows us to make adjustments to our grip and hand position as we are performing the task. All of this happens instantly, in our subconscious. Through trial and error, we learn to perfect this common, functional movement. The more we reach and grasp, the greater our field of reference, and the better we can estimate the forces needed to manipulate objects. Since it’s something we do almost every day, we develop proficient skill.
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What if we lost our sense of touch? What if we were unable to depend on our hand-eye coordination to manipulate objects? Would we be able to make ourselves breakfast or get dressed in the morning? Would we be able to drive to work? Would we be able to work at all?
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Qiushi Fu has devised many different experiments to investigate how the brain controls finger forces during grasping and manipulation. Fu says, “The result could allow us to evaluate the impact of neurological disorders in hand control, and assist neural rehabilitation process [sic].”
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In Fu’s experiments, ATI’s F/T Sensors are enclosed within an object. The subject manipulates the object while the sensors provide instant force feedback data from six axes (forces Fx, Fy, Fz, and torques Tx, Ty, and Tz). The sensors also report the center of pressure of each fingertip and capture the feedback to the brain. By reverse engineering the process with the aid of F/T Sensors, Fu gets a much more comprehensive view of the manipulation process, from start to finish. Fu explains, “This information will tell us the speed of response, the role of sensory feedback, as well as other physiological measures.”
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These experiments are intended to measure and record data in a “real life” situation. Ensuring the sensors do not impact the subject’s choice of how to manipulate the objects is a high priority. ATI’s smallest F/T Sensors, Nano17 and Nano25 (17mm and 25mm in diameter, respectively), are easy to conceal within the test object. This maximizes grasp surface and guarantees the subject has complete freedom to choose how to manipulate the objects.
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Fu chose ATI’s F/T sensors in part for the compact size, but also for the superior quality. He says, “ATI F/T Sensors provide excellent accuracy, robustness, and sensitivity to our research.” The design of the F/T sensors is ideal for detecting the subtle changes in fingertip forces during Fu’s trials. Silicon strain gauges within the F/T transducer body act as signal amplifiers and cancel out noise distortion. Precise and accurate measurements by the ATI F/T Sensor lead to high quality data, which gives Fu and his team even more confidence in their findings.
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Our sense of touch enables us to use our hands and fingers more efficiently than any other species. We have learned that the brain, the muscles of the hand, and the fingers all play an integral role. If any of these pieces isn’t functioning properly, our sense of touch, and thus our ability to use our hands, is compromised. Fortunately, neural control researchers like Quishi Fu will contribute to the development of assistive robotic solutions to restore patients’ mobility, and in some cases, their independence.
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As the population ages, the number of people living with debilitating health issues will continue to rise. For patients with reduced motor control caused by neurological disorders, traumatic injuries, stroke, or other illness, assistive robotic solutions provide hope for better quality of life. ATI is so proud to be a part of the neural control research at Arizona State University.
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Click here for more information on our Force/Torque Sensors.
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For more info, visit the Neural Control of Movement Laboratory at ASU web page!
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