Browsing by Author "Shaik, Ahmed Asif."

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Design, modelling and simulation of 2 novel 6 DOF hybrid machines.
(2012) Shaik, Ahmed Asif.; Bright, Glen.
Industrial robot arms are an essential part of automated manufacturing, and perform tasks such as component assembly, welding, light machining, spray painting, etc. They are highly repeatable, can be calibrated to be sufficiently accurate and they eliminate human error. The serial robot architecture is by far the most ubiquitous in modern day manufacturing, as the technology is highly refined in its current state; the machine architecture provides great dexterity and it has a large useful workspace. This architecture however does have some problems, one of which is a large machine moving mass. The primary reason for this lies in the location of its motors and gearboxes. Due to the robot's significant inertia it utilizes a large amount of energy. This thesis focused on the mechanical design, mathematical modelling and simulation of 2 robotic arm designs which had a hybrid nature. They were classified as hybrid due to the fact that their architectures departed from both the classic definitions of serial kinematics manipulators/machines (SKMs) and parallel kinematics manipulators/machines (PKMs). The primary design goal was to merge some of the advantages of both architectures, i.e. a large workspace to footprint ratio and high end-effector dexterity which was found in serial robots, combined with the low inertia of a parallel robot for improved dynamics. Serial and parallel robots were complementary, and these design goals could not co-exist in a single purist robot architecture. The designs had a full complement of 6 DOFs (degrees of freedom), 3 DOFs for spatial position of the wrist and 3 DOFs for orientation of that wrist. They also had a lower machine moving mass, a fact that was thought to improve speed and energy usage. A major contribution of this research PhD project was a comparative energy usage study, which was performed against the serial robot as a measure. This was done for both hybrid designs as well as another model which represented 2 existing patented designs. The purpose of that was to determine if lowering the machine moving mass would improve energy efficiency, and to determine which design was best.
Parallel robot design incorporating a direct end effector sensing system.
(2007) Shaik, Ahmed Asif.; Bright, Glen.
This dissertation details the development of a parallel robot with an integrated direct end effector sensing system, from concept to prototype model and includes details of research, design, simulation, construction, assembly and testing. Current research in parallel robots is insufficient as compared to serial type machines, even though their existence has been known for some time. The reasons are the difficulty in conceptualising unique parallel mechanisms, achieving machines that are capable of high accuracy, solving their complex kinematics, dynamics and control problems. There are many advantages of parallel machines that rival the serial type, and these warrant further studies. The second aspect of this project was the design of a direct end effector sensor system. Many existing automated multi-axis machines operate under overall 'open loop' control. The exact position in space of the end effector or tool head, for those machines, is not sensed directly but is calculated by software monitoring sensors on actuator axes. This sensor system and robot structure was designed specifically for use in the agricultural and general food processing/packaging industries. The accuracy and repeatability of such a machine and its sensor system are in the millimetre range.