System theoretic process analysis of electric power steering for automotive applications

The automotive industry is constantly challenged with meeting and exceeding customer expectations while reducing time to market of new products in order to remain competitive. Providing new features and functionality into vehicles for customer satisfaction is becoming more challenging and driving design complexity to a higher level. Although traditional methods of Product Development Failure Mode identification such as FMEA (Failure Mode and Effect Analysis) or FTA (Fault Three Analysis) have been used to analyze failures in automotive systems, there are limitations when it comes to design errors, flawed requirements, human factors implications, and component interaction accidents in which all components operated as required but the system behavior was not as expected. In order to determine if there is room for improvement in current automotive product development process, this thesis applies Dr. Nancy Leveson's Systems-Theoretic Process Analysis (STPA) technique to compare and contrast with a Failure Modes and Effects Analysis (FMEA) approach as used in the automotive industry through a case study. A formal method of comparing results is proposed. This study found limitations with FMEA in terms of identifying unsafe interactions between systems, anticipating human error and other behaviors dependent on human interaction, identifying engineering design flaws, and producing requirements. STPA was able to find causes that had a direct relationship with those found in FMEA while also finding a portion of causes related to a higher level of abstraction of those in FMEA. STPA also found a subset of causes that FMEA was not able to find, which relate mainly to engineering design flaws and system interaction.

Department dc:contributor.department

Massachusetts Institute of Technology. Engineering Systems Division.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2015

Author dc:creator

• Sotomayor Martínez, Rodrigo

Advisor dc:contributor.advisor

• John Thomas and Nancy G. Leveson.

• Engineering Systems Division.
• System Design and Management Program.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/105318

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/105318