Tendon-operated dexterous manipulators such as Cedric are generally more complex in design and are more difficult to assemble than designs that locate the servo motors directly in the fingers and hand. While adequate manipulation performance for many everyday tasks may be attained with non-tendonized manipulators, the cost is typically high due to the use of brushless DC servos, planetary gearing and, in many cases, rare earth magnets in the motors. In contrast, tendon-operated hands can use larger, less-costly servo motors by distributing them throughout the forearm and upper arm.
The market introduction of extremely powerful and cost-effective servos developed within the R/C (radio control) hobby industry is the key to the CED manipulator arm’s high performance-to-cost ratio. CED uses Hitec RCD’s HSR-5990 robot servos which incorporate aluminum heat sinks and electronic overload protection; necessary features as these tiny powerhouses can draw up to five amps under load. Heat removal in a manipulator arm packed with as many as 30 servos and covered in silicone skin (a likely configuration for use in clean rooms) becomes critical for reliable continuous operation under load. Air cooling ducts and optional water cooling have been designed into CED to deal effectively with this issue.
CED's basis of design facilitates its production using a self-configuring manufacturing system under development at Page 5. Upon full implementation of this technology the cost of CED will approach that of raw materials, components and subassemblies alone; there will be a vanishingly small labor contribution to the product cost. For most applications, stocking of spare arms will be cost effective and make repairs quick and simple. CED arms that have been damaged will be unplugged and new or refurbished units plugged in without the use of tools. The damaged units will be disassembled with all parts being directed to appropriate recycling centers. CED units that are generally worn but have no structural damage will be disassembled, fitted with new components and reassembled autonomously (with teleoperator intervention, of course, being available through the system).