Browsing by Author "Russell, Donald L."

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Open Access
Myoelectric Control Using Modulated Minimum Jerk Movement
(1994) Russell, Donald L.
A new control system for elbow prostheses is proposed. The system would use myoelecuic activity (MEA) meastuements to modulate the execution of a maxirnally smooth, minimum jerk movement A prosthesis controller may extract information from MEA meastuements about both the intended movement, for example elbow flexion, and about the time course of the movement including, for example, average speed and duration. Recent advances in myoelectric signal measurement have identified a deterministic portion of MEA at the onset of movement This information has been used to determine gross movement information, including movement direction and joint selection Common prosthetic control schemes would then generate a movement with either constant velocity or with the velocity proportional to measured MEA. These movements are simple in concept but appear unnatural and are difficult to control during interactive tasks. In contrast, a minimum jeik movement has interesting properties that make it a plausible choice as a movement primitive Each minitnum jerk segment can be parameterized with three par ameter s Commonly these are chosen to be start time, finish time and average velocity. Researchers have proposed methods by which these movements can be combined by straightfor ward super-position tecluilques to yield natural movements This paper discusses minimum jerk movements as prosthesis movement primitives and presents a control system architecture that uses deterministic information from MEA for movement selection and MEA amplitude estimates for on-line modulation of movement parameters Application of this type of control system should result in smooth prosthetic movements.
Open Access
PROGRESS TOWARDS A BIOMIMETIC PROSTHETIC ARM
(2002) Russell, Donald L.
Detailed design of a prototype prosthetic limb based on biomimetic principles has been completed. This paper will update the progress that has been made toward the creation of a new, high-performance limb. The limb uses antagonistic actuators with low and variable stiffness to create dynamics and interaction properties similar to those of a healthy arm. Theoretical examination of the mechanical design has yielded several interesting results and an accurate estimate of the performance and improved efficiency levels of the limb. The results have been used to understand several fundamental issues regarding the design of such a limb. Prototype construction is underway and reflects overcoming several design challenges by careful use of standard components.