Patient Cart Stabilization System

Step 1: Define Requirements

• Generated a set of comprehensive system requirements through careful consideration of the surgical environment in which the robot will operate, the tendencies of it's users and the desired behavior of the stabilization system

• Predictive failure mode analysis informed logical pathway towards a solution

Step 2: Investigative Testing

• Conducted study on patient cart mass & center of gravity.

  • A 6 DOF robot like Vera 1 has a wide range of poses which influence the system's center of gravity. By measuring the weight distribution over each caster, I calculated the immediate center of gravity & the total mass.

• Test results guided the technical performance needs of the stabilization system.

Step 3: Evaluate Stabilization System Options

• While most all other hardware on the Vera 1 system is custom, the best option for this project was to research available OTS systems that may be applicable

• Research via competitor analysis and vendor outreach indicated a variety of options.

  • Electromechanical, pneumatic, Manual & Hydraulic devices existed, each with their own tradeoffs

• Each option was evaluated via a Pugh matrix. Primary option was configured with the vendor to comply with regulations and include necessary features & capabilities.

• Secondary option was specified and feasibility was confirmed.

Step 4: Design Mounting Hardware

• Stabilizing large robots involves high loads and failures risk serious patient harm

• Iterative CAD design along with FEA analysis and DFM considerations inform the design.

• OR Ground-clearance constraints and the need for the design to be retrofittable demand a fully recessed, compact solution.

Step 5: Prototype Evaluation

• Benchtop testing to understand performance predicates installation on the Vera 1 system.

• Partnered with both Electrical & Controls Engineers to confirm power specifications, implement redundant sensors and align on system behavior.

• Capabilities are confirmed to meet spec and safety measures are in place to prevent malfunction and prevent risk to patients & users.

• Initial trials indicate successful stabilization through optical tracking of key points on the Vera 1 system.

Step 6: Full Scale Implementation

• Detailed design review and in-depth DFMEA study inform both risks and ways to mitigate them. Design iteration and testing via updates verify improvements.

• Procured enough stabilization systems to retrofit all existing pre-release Vera 1 robots ahead of critical pre-submission medical studies.

• Broad scale installation verifies reliability and performance criteria.

• Project is effectively complete! Monitor for failures and move on to the next challenge!