Case Study

Needle Insertion Mechanism Case Study

Needle Insertion Mechanism


  • Client trapped in a Design-Build-Test and iterate loop.
    • “Test-to-success” mindset.
  • Required a more effective and predictable approach to develop a robust actuator for needle insertion.
  • Required drop-in solution, spatially constrained, limited power available, complex load profile
Needle insertion mechanism test results


  • Develop an empirically based analytical load profile with ±4-sigma limits
  • Research available motors, identify viable gear reduction ratios
  • Define key functional and testable requirements – “system curve” – and success metrics
    • τ, No Load Speed, stall force
  • Build dynamic model of system
    • M-C simulation to predict robust performance
  • Developed tester and protocols for empirical verification.


  • Identified most robust configurations for implementation
  • Built and tested 10 units
  • Expected ~2x robustness increase
  • Measured 2 to 3x performance increase using the same metrics – empirical and analytical model agreement

Needle insertion mechanism test results

Key Takeaways

  • Analytical model informed by empirical results provided practical and cost-effective down-select process
    • Several viable design alternatives
  • Models predicted Performance – robust by design!
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