MIT SEMINAR SERIES IN MANUFACTURING AND PRODUCTIVITY
Place: Room 35-225 Time: 12:00 P.M. Tuesday, March 7, 2006
Ph.D. Student, Mechanical Engineering
The design of existing suspension systems typically involves a compromise solution for the conflicting requirements of comfort and handling. For instance, cars need a soft suspension for better comfort, whereas a stiff suspension leads to better handling. Cars need high ground clearance on rough terrain, whereas a low center of gravity (CG) height is desired for swift cornering and dynamic stability at high speeds. To eliminate these trade-offs, we have proposed a novel design for a customizable automotive suspension system with independent control of stiffness, damping and ride-height.
This system is capable of providing the desired performance depending on user preference, vehicle speed, road conditions and maneuvering inputs. I will outline the design, fabrication and controls of the customizable suspension prototype. I will discuss applications of variable stiffness and variable ride-height suspension system to achieve improved vehicle dynamics. Application to vehicle dynamics control required bandwidth and power input beyond the capability of the first prototype. To eliminate the bandwidth restrictions of the prototype, we developed a variable-stiffness pneumatic suspension system capable of instantaneous stiffness change with essentially no power input and no ride-height change. This is done by using an air spring and connecting the air spring volume to multiple auxiliary volumes through On-Off valves. By adequately choosing N unequal auxiliary volumes we can get 2^N stiffness settings. We are in the process of incorporating this in a car suspension.
I will report the current status of the fabrication, and the tests we propose to conduct on the suspension system. The proposed variable stiffness isolator is capable of instantaneous stiffness change with no power input and no dimension change; moreover the isolator is inexpensive, robust and light. As a result, it is readily applicable to several other vibration isolation applications with conflicting stiffness requirements (such as a precision motion stages) or time-varying stiffness requirements (such as prosthetic limbs) and these applications will be highlighted in the talk.