While at Active Shock, Inc., I designed several parts of a semi-active shock absorber system for the driver’s seat of a construction vehicle. The system varied the damping rate based on seat position and velocity to provide a smooth, soft ride during normal operation while preventing operator-induced oscillations and potentially dangerous bottoming or topping out. Cost and size were both much lower on this shock than on any of our previous projects. To address cost, I designed certain parts for powder metallurgy, injection molding, and robotic welding, and I worked with a Chinese supplier to communicate tolerancing and design intent for machined pieces. To overcome space constraints, I tested, designed, prototyped, and implemented a position sensor system that used a Hall effect sensor to measure the change in field of a magnet clamped to a rotating bar elsewhere in the seat linkage. I also worked with our software engineer to build a calibration routine and trained our customer on installation and troubleshooting. This shock is in several construction and transit vehicles today.