Browsing by Subject "prosthetic arm"

Now showing 1 - 6 of 6
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    ASSESSEMENTS, CONCIDERATIONS AND FITTING OF A TRANS HUMERAL HIGH LEVEL BRACHIAL PLEXUS INJURED INDIVIDUAL WITH HO
    (2005) Limehouse, J.W. "Bill"
    This talk will discuss the assessment and prosthetic problems associated with fitting an individual with a mid level Trans Humeral amputation
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    Clinical Trials of the new Boston Digital(tm) Arm System
    (2002) Farnsworth, Troy; Limehouse, Bill; Hanson, Bill; Mandacina, Steve
    Microprocessor-based controllers for upper-limb powered prostheses have made significant advances over the past few years. These devices allow prosthetists to evaluate the patient and set-up prosthetic controls to optimize performance for the user. This enables the user to obtain a controller that is customized to suit their specific needs and capabilities. The new Boston Digital(tm) Arm System is the first powered elbow prosthesis to offer this advanced technology. This System serves as a “platform” for upper-limb prosthetic control. With five motor controllers, the Boston Digital Arm System can operate hands grippers, wrist rotators, shoulder lock actuators and more. The System is universal − it works with prosthetic devices from any manufacturer, allowing prosthetist to create the optimal prosthesis for their client.
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    IMPROVED CONTROL FOR AN ARTIFICIAL ARM
    (2005) Jones, Ben; Kyberd, Peter
    Successful control of multi-degree of freedom upper limb prostheses generally uses some form of sequential instruction. This is because simultaneous control of multiple inputs requires a considerable concentration to be operated effectively. In contrast, the natural arm is controlled in a parallel manner with a high level of subconscious control. Such control uses feedback, the person is rarely conscious of the feedback information, and most of the control is automatic. Attempts to achieve similar control with a prosthesis would requires a wide bandwidth feedback channel to the controller. This is currently impractical if the controller of a multiple degree of freedom arm is the wearer, because only very low frequency feedback is achievable. The Southampton Arm control philosophy avoids this bottleneck by keeping the low level control within the prosthesis and leaves low bandwidth and strategic control to the operator [1]. This study describes the development of a control system for an artificial arm based on this concept. A joystick was used to input control signals via a harness at the shoulder, allowing a user to manipulate the arm with small movements of their acromium. A co-ordinate control strategy (inverse kinematics or IK) was implemented allowing both the shoulder and elbow joints of the arm to move simultaneously giving a smooth, more life like, motion. A trial was developed to asses the cognitive load required to operate the arm using the Dual Task paradigm. Tests were carried out on 5 subjects, using two different control strategies, IK and a direct control strategy (DC) using two degrees of freedom separately.
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    NEW CONCEPTS IN EXTERNAL POWERED ARM COMPONENTS
    (2005) Prigge, Patrick
    An electrically powered joint can be of considerable support for many unilateral or bilateral above elbow amputees in every day activities. The DynamicArm (Photo 1) represents the next evolutionary step, a milestone in powered elbow prosthetics. It has been designed around previously proven components and also adds new developments that will change the way the amputee interacts with the prosthesis. Multiple control strategies and inputs running in parallel as well as hardware that allows for a more natural operation with much less effort will heighten the level of expectation from every patient wearing this design. This is already the case based on the response of the patients that have been fitted so far. Patients who have had many years experience with powered systems or those who have had experience with hybrid systems report the decrease in mental and physical energy within moments of being fit. Repositioning exercises, switching between components and actively controlling each component seem to be done with ease. Some of the advantages for the amputee are rapid movement and pre-positioning. This allows the patient to lift higher weights and position the elbow without complex control sequences. Because pre-positioning is more easily facilitated the patient will chose to move the component rather than make up for some controllability deficit with a compensation movement of the trunk. High loads can also be held in position without fear that something will be damaged if it is overloaded thanks to the already known locking mechanism of the 12K50 ErgoArm. Built in force sensors protect the system from unlocking in undesirable conditions. The control characteristics follow those of previously designed components like the DMC+ and the SensorHand Speed. Otto Bock electronics follow the logic of „First Signal Wins“ control strategy but a new improvement allows for fast changing between opening and closing the hand or changing from flexing to extending or from supination into pronation. This gives the advantage of being able to fit the patient who co-contracts but still allows for high performance controls. Signal inputs are now digitized by the locking microprocessor and from there are not as susceptible to Electromagnetic Interference. Power consumption Photo 1: DynamicArm system has been reduced because when the system is in free swing, the mechanics are completely de-coupled from the movement of the Automatic Forearm Balance mechanism. New possibilities of control include being able to raise and lower loads at various speeds and repositioning without needing to produce an “unlock” signal. The wrist rotator is controlled by the main electronics which allows for an ultra sensitive control and the possibility to run the wrist motor proportionally and at incredibly low speed allowing for very precise positioning. The terminal devices as before can be controlled with proportional speed and grip force based on the strength of the muscle signal which is supported by having the electronics combined with the hand mechanics. Simultaneous control of the hand and the elbow with using a variety of input devices is now possible. And now for the first time new input devices and new switching methods allow for more flexibility for the amputee to control the prosthesis.
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    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.
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    THE WILMER APPEALING PREHENSOR
    (2005) Plettenberg, Dick H.
    A new type prosthetic prehensor for children aged 4 – 9 has been designed, constructed and build in an attempt to improve the appearance of the split-hook prosthesis. The new prehensor is a mechanically operated voluntary opening device. All mechanical parts are within the frame, and covered by a polyurethane cosmetic cover, which can be made in almost any color desired. Clinical testing of the prehensor by 4 children with a total time of use of over 170 months, revealed the mechanism to be very robust and reliable. The colorful hook cover is highly appreciated by the children. Encouraged by this success, a second larger size has been made intended for children aged 7 - 14. This medium size prehensor is now in clinical use by 1 child for over 12 months. Again, the appearance of the hook is highly appreciated, and again, the mechanism proves to be very reliable.