Project Goals

• Develop a compact automated indentation test frame for integration within a robotic scanning station

• Fit the complete mechanism within a 6.5 × 7.5 × 5.5 in. work envelope

• Provide repeatable, low-backlash linear motion for controlled material indentation

• Measure applied force through integrated load-cell instrumentation

• Create a functional Phase 1 prototype to validate the mechanical and control-system architecture

Key Constraints

• Commercially available test frames were too large for the available scanner envelope

• Components outside the allowable volume could interfere with the robotic scanner head

• Precision motion required minimizing backlash throughout the drive system

• Final system design targeted loads up to approximately 200 N

• Prototype had to integrate the mechanism, instrumentation, electronics, and controls within a very compact package

• Machining lead times required functional validation before all-metal construction could be completed

Engineering Approach

• Modeled the complete mechanical assembly and all custom mechanical components

• Designed a custom recirculating-ball lead screw and nut using 1/8 in. steel ball bearings

• Machined the lead screw and several other components in-house, including using a drill press as a vertical lathe

• Designed the involute gear transmission, linear-guidance system, bearing interfaces, and structural components

• 3D printed the prototype structure and additional mechanical components to reduce development lead time

• Drilled, tapped, fitted, assembled, and adjusted the complete mechanical prototype

• Selected the stepper motor, load cell, motor driver, signal-conditioning hardware, microcontrollers, switches, and supporting electronics

• Designed and wired the embedded control system and wrote the microcontroller firmware for motion control and load measurement

• Used physical testing to evaluate motion, structural behavior, packaging, and system operation

Result

• Built a fully functioning Phase 1 electromechanical prototype

• Custom ball-screw mechanism achieved virtually zero backlash

• Drive system provided approximately 0.78 µm indexable linear displacement

• Successfully integrated stepper positioning, limit control, and 20 kg load-cell force measurement

• Validated the mechanical architecture, embedded controls, instrumentation, and packaging within the required scanner envelope

• Established a functional foundation for the intended machined-metal system

Project Summary Video