Inchworm car seat drive : designing a linear actuator that mimics inchworm motion

Abstract

A continuing goal in the automobile seat drive industry is to design lighter, smaller, more economical seat drives that offer excellent long-term performance. The way to achieve this goal is to minimize the number of parts and part complexity while meeting all safety and functional requirements. Current seat drives which use motorized lead screws are large and heavy. An alternative solution that the industry is exploring to replace the lead screw seat drive is a simple linear actuator. The goal of this project is to design an inchworm motion linear actuator that may be used as part of the seat drive system to provide fore-aft motion. The resulting final design is a simple system that consists of two modules, an actuation module and a clamping module. The actuation module is a simple motor-wobble plate assembly and the clamping module consists of spring-loaded jamming plates. The final prototype succeeded in inching the shaft forward in one direction, but failed at shifting directions. This failure can be remedied in future work by the introduction of an actuation guide plate as well as the more accurate and detailed machining of components.