Design of a Hybrid Hydraulic Actuation Mechanism for the Delft Cylinder Hand Prosthesis

The development of the Delft Cylinder Hand (DCH) demonstrated the design of a lightweight and functional hydraulic body-powered (BP) hand prostheses. The low friction losses of the hydraulics make it an attractive alternative to a classical mechanic transmission using rigid linkages and Bowden cables. There are benefits and trade-offs associated...

Sensitivity and control of a pneumatic force transducer: A proof of principle

Current upper-limb prostheses are often rejected as a result of high activation forces that are needed for control. Another reason for rejection is the absence of appropriate proprioceptive feedback. In this study, a pneumatic control system was designed that decreased the activation forces and where proprioceptive feedback was provided. The...

Fatigue-free operation of most body-powered prostheses not feasible for majority of users with trans-radial deficiency

Background: Body-powered prostheses require cable operation forces between 33 and 131 N. The accepted upper limit for fatigue-free long-duration operation is 20% of a users’ maximum cable operation force. However, no information is available on users’ maximum force. Objectives: To quantify users’ maximum cable operation force and to relate...

Ipsilateral Scapular Cutaneous Anchor System: An alternative for the harness in body-powered upper-limb prostheses

Background: Body-powered prosthesis users frequently complain about the poor cosmesis and comfort of the traditional shoulder harness. The Ipsilateral Scapular Cutaneous Anchor System offers an alternative, but it remains unclear to what extent it affects the perception and control of cable operation forces compared to the traditional shoulder...

Developing a body-powered co-contraction equivalent: Applied to switch between a lateral and an opposition grip

Myoelectric as well as body-powered hand prostheses, the two commercially available prosthetic control types, have both their specific advantages. Advanced myoelectric prostheses for example have the characteristic of facilitating multiple degrees of freedom due to grip type variation and/or wrist movements. Compared to prosthetic devices with...

Design of a Variable Mechanical Advantage Mechanism for the Delft Cylinder Hand

The Delft Cylinder Hand and similar body powered hand prostheses require an input force that is too high for daily tasks. The force is perceived as uncomfortable and leads to a high rate of users abandoning their prosthesis. Reducing the input force by increasing the mechanical advantage of the system is not feasible, as this would unfavourably...

Bamboo Prehensor for the developing countries

It is estimated that 25 million people around the world suffer from upper limb amputation. 82% of these amputees live in developing countries and usually find it difficult to provide for their families because they depend on physical labor. At first glance it would seem that the solution is simple, the use of a prosthesis. However currently...

Feedback in voluntary closing arm prostheses: Investigation of optimal force feedback in shoulder controlled arm prosthesis operation

High rejection rates indicate that prosthetic users are not satisfied with the performance of their arm prostheses. In theory, one of the advantages of shoulder controlled prosthesis, compared to myo-electric prostheses, is that the user gets direct proprioceptive feedback about opening width and pinch force of his prosthetic hand. However,...