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Traditionally, an elementary level of programmability in single degree of freedom mechanisms has been achieved with the help of adjustable link lengths. With die advent of servo-actuators multi-degree of freedom (MDOF) mechanisms could not only be used for this purpose but also could achieve continuous adjustability. Amongst MDOF mechanisms there exists a class of devices which can be termed as ’programmable mechanisms’, wherein one of the inputs is driven at a reference speed while the other inputs arc servocontrolled. From the point of view of programmability and rigidity they generally fall between open kinematic chain robots and closed chain single degree of freedom mechanisms.
Programmable mechanisms can be used in the development of automation systems like programmable packaging machines, feeders, sorters, indexes, etc. where coordinated motion (which may vary from batch to batch) is required. Moreover, these mechanisms can be retrofitted into existing hard automation systems to incorporate programmability. Due to torque sharing between the actuators powering the reference-input and the control-inputs, servo-actuators with lower torque ratings can be used.
All MDOF mechanisms contain at least one closed kinematic chain with five or more links. The five-bar mechanism (FBM) is therefore the simplest multidegree of freedom mechanism with a closed-kinematic chain and is a fundamental device in the class of programmable mechanisms. In this thesis, the scope of adopting a two DOF five-bar mechanism as a programmable function generator has been investigated. Both translatory-output and rotary-output function generators have been studied.
A framework has been developed for the design of such systems both with the rotary-output and the translatory-output A method of obtaining a compact five-bar mechanism for function generators has been proposed and applied to a few cases to find the optimal link length ratios.