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Advancing Piezoelectric Actuated Friction-Inertial Driven In-pipe Robots For Inspection

Posted on:2016-12-29Degree:MasterType:Thesis
Country:ChinaCandidate:Q Z WangFull Text:PDF
GTID:2308330461461475Subject:Power Machinery and Engineering
Abstract/Summary:PDF Full Text Request
Pipes are basic components in the industrial applications such as oil, gas, nuclear, chemical, refrigeration and biomedical engineering. Pipes need to be inspected frequently for no damage. In-pipe robots are important tools for this purpose. Particularly, in-pipe robots actuated by piezoelectric stack are promising due to their salient characteristics which are further attributed to the piezoelectric actuator, including high resolution, fast response, large output force, and small volume. For the convenience of later discussions, such an in-pipe robot is called PA in-pipe robot. However, there are several challenges in constructing a PA in-pipe robot, among which the following two are concerned by this thesis:(1) how to design the actuation system of PA in-pipe robot with consideration of variations in the pipe (e.g., different surface property, different shapes of pipe, etc.) and (2) how to increase the motion speed of a PA in-pipe robot. This thesis was motivated at finding solutions to respond to the aforementioned two challenges. Further, the thesis was restricted to the self-mobile principle of PA in-pipe robots.A preliminary study of the thesis made two propositions. First is that a compliant mechanical amplifier (CMA) attached to the piezoelectric actuator (PA) is an idea to improve the speed of movement of the robot. Second is that design methodology for CMA is not quite systematic and rational in literature and needs to be further developed. Therefore, three specific objectives were defined for this thesis:(1) conceptual design of PA in-pipe robots, (2) development of a systematic design procedure for CMA, and (3) design of a CMA for in-pipe robots.The literature review resulted in the finding that the compliant mechanism is a suitable choice to amplify the motion (i.e., to improve the speed of the in-pipe robot) and the principles of the adjusting mechanism for coping with the different friction on the interior surface of a pipe has two types (active and passive). Then, the thesis was focused on the development of CMA in order to improve the speed of the movement of the piezoelectric friction-inertial driven in-pipe robot. This included the development of an analytical design approach for flexure-hinged amplification mechanism and design of a dedicated CMA for a particular specification for the demonstration and verification purpose.The conclusions drawn from the thesis are:(1) There are two principles to adaptive to different frictional surface of a pipe:passive and active (which needs an extra energy input), and the former is simpler and more reliable while the latter is complex and more accurate; (2) the proposed design methodology for compliant mechanical amplifier is analytical and thus easy to use; (3) the designed CMA for the particular in-pipe robot can improve the speed by nearly 4.5 times (notice:the actual speed is dependent on the stroke of the piezoelectric actuator and its frequency).The main contributions of this thesis are:(1) in the field of compliant mechanism, a promising design methodology for compliant mechanical amplification with the input and output axes being in any relative orientation (e.g., in parallel, etc.); (2) in the field of robotic pipe inspection system, a more efficient and effective robotic inspection robot as opposed to the previous version developed in our laboratory is at born. It is noted that the piezoelectric friction-inertial driven in-pipe robot has the salient advantage of high accuracy in movement, small in size, and simple structure which in favor of the application occasions where highly precise inspection is needed and bulky devices may not be allowed in pipes (e.g., biomedical applications).
Keywords/Search Tags:In-pipe robot, Axiomatic Design theory, piezo-actuator, amplification mechanism
PDF Full Text Request
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