Bowden cable

FIGURE 32.4 Photograph of how a Bowden cable is set up for use as the control cable of a transhumeral (above-the-elbow) body-powered prosthesis. The housing acts as a guide or channel for the control cable, which transmits forces developed by a harnessed body part, in this case the contralateral shoulder, to the prosthesis. Retainers on the housing fasten it to the prosthesis and serve as reaction points in the transmission of force by the cable Photograph courtesy of Mr. C. Heck-athorne of the Northwestern University Prosthetics Research Laboratory.)... 

In a body-powered device, the jjerson uses his or her own muscular power to operate the prosthesis, usually via a cable link called a Bowden cable (Fig. 32.4). A Bowden cable consists of two parts, an outer housing and an inner tension cable. The housing is fixed at both ends and serves as a flexible bridge between two points, maintaining a constant length regardless of any motion. The cable is free to slide within the housing. 

The typical prosthesis control system consists of a Bowden cable with appropriate terminal fittings. The terminal fittings are used to anchor one end of the cable to a body-harness, and the other end to the prosthetic component to be controlled. Between the two end points, the cable crosses the prosthetic joint to be controlled and the physiolog-... 

The basic configuration of Bowden cables in prostheses has changed little over the intervening years and is stiU in use today. In fact, if prehensile function is the primary goal of the prosthetic fitting, the device of choice for most persons with amputations is a body-powered, Bowden-cable-operated prosthesis with a split hook-shaped terminal device. This is in spite of all the technological advances in electronics, computers, and dc motor technology that have occurred since the end of World War H. 

Low technology does not imply wrong or bad technology. In fact, ease of maintenance, ease of repair in the event of failures in the field (one can use a piece of heavy cord to get by if the control cable should break), and the intuitive understanding of pulling on one end of the cable to effect motion at the other are probably major reasons for the success of Bowden cables in prosthetics. This is in addition to the ability of users to sense prosthesis state by the pull or feel of the control cable and harness on their skin. 

For transradial (below-elbow) prostheses, only one Bowden cable is needed to opien and close the terminal device (Fig. 32.5). In transhumeral (above-elbow) prostheses, two Bowden cables are needed, one to lock and unlock the elbow and another to flex and extend the elbow when the elbow... 

In prosthetics, stainless steel Bowden cables come in three sizes Light Duty, Standard Duty, and Heavy Duty. 

The basic configuration is a Standard size multistranded steel cable in a Standard size housing. A heavy-duty user will use a Heavy-Duty multistranded steel cable in a Heavy-Duty housing. Friction is the primary cause of transmission losses in a Bowden cable. If friction is an issue then a Heavy duty housing with a Teflon liner and a Standard size cable can be used. 

The primary sources of control for body-powered devices are biomechanical in nature. Movement, or force, from a body joint or multiple joints is used to change position, or develop a force/ pressure that can be transduced by a harness and Bowden cable and/or mechanical switches. Typically, inputs such as chin and head force/movement, glenohumeral flexion/extension or abduction/ adduction, biscapular and scapular abduction, shoulder elevation and depression, chest expansion, and elbow or wrist movements are used. However, direct force/motion from muscle(s) has also been used by way of surgical procedures such as muscle tunnel cinepiasty (Sauerbruch, 1916) and the Krukenberg cinepiasty (Krukenberg, 1917). 

Uses and applications packaging, monofilament fishing line, tubes for central lubrication systems, fuel and oil pipes, pneumatic and hydraulic control lines, and Bowden cables. 

Veneman J, Kruidhof R, van der Helm FCT, and van der Kooy H, Design of a series elastic- and Bowden cable-based actuation system for use as torque-actuator in exoskeleton-type training robots. Proceedings of the ICOOR, Chicago, United States, June 28-30, 2005. 

Using the example of a power window actuator in a car, in some cases the change of electric motor is only possible in combination with the change of rolls and Bowden cables. According to this all components have to be available. Given the case one Bowden cable breaks, the change of one cable is possible without any further effort. 

For the transradial (below-elbow) prosthetics, only one Bowden cable that is need usually to doing task that resolve open and close function. For the transhumeral (above -elbow) two Bowden cable required in order to give motion for the both transhumeral rotation and also transradial open and close function (Controzzi, 2008). The Bowden cable reacts as a control system where it has been attached at a few appropriate terminal fittings that anchor of the cable to the body-harness... 

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