Design and Fabrication of a Continuous Passive Machine

Lim, Jonathan Jie (2020) Design and Fabrication of a Continuous Passive Machine. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

CPM is a slight exercise movement that is widely used in the rehabilitation field for the elderly, sport injuries and post injury patients. The objective of this project is to design and fabricate a CPM machine that is easy to move, user-friendly and low pricing. The design of the Continuous Passive Motion (CPM) machine is through computer software named SolidWorks. The project is a two axes machine make possible with two different model of motor. The 1st axis is at the shoulder area and the second axis is at the wrist area. In this project, the boundaries conditions set are the machine is to be focused on single arm only with changeable sides, part to be focused is on joint and muscle injuries but not bone fracture and patients must have some strength left and are able to consciously put their arm on the machine. The exoskeleton of the design is mainly built with aluminium profile due to its lower price tag, durability and versatility. The electrical components used are the power supply, Programmable Logic Controller (PLC), stepper motors, motor driver, resistors and also transformer. Transformer is used due to the different operating concept of the motor driver. PLC is the main “brain” of the machine. It receives programming codes from the computer and directs the movement of the motor through pulses transmission. By pressing the start button, the prototype machine will move automatically according to the PLC codes. Movement can be altered by changing the codes structure. The testing is made by altering the value set in the programming codes. By using trial and error method, the results of 34˚ to 39˚ within 7 to 9 seconds and 85˚ to 88˚ within 2 to 3 seconds are achieved with both axes able to move in the clockwise (positive) and anticlockwise (negative) directions.