Faculty and students in the PO program have access to the Human Engineering Research Laboratories (HERL). Any specific customized part of a prosthetic project can be easily designed and prototyped at the HERL machine shop. The prototyping facility of the Human Engineering Research Laboratories (HERL), consisting of about 11,000 square feet, utilizes state of the art technology to support the design, fabrication, and other technical aspects of the rehabilitation and assistive technology research projects underway at HERL. The prototyping facility is divided into eight sections: machine shop, rapid prototyping, welding shop, painting and finishing shop, stock storage and preparation, testing laboratory, electronics laboratory, and technical computing laboratory.
The HERL machine shop contains a wide variety of manual and CNC (computer numerical control) machines capable of cutting and shaping metal, plastic, and other materials. The shop contains two manual mills and a manual lathe, which are traditional pieces of machine shop equipment to perform simple and routine machining tasks on bar, sheet, and round stock. However, HERL also possesses three CNC mills and a CNC lathe which are capable of completing much more complex machining jobs at very high speeds and accuracy. Two of the CNC mills are 3-axis machines that utilize automatic tool changing mechanisms and through-spindle-coolant to achieve cutting speeds of up to 15,000 RPM and feed rates of up to 700 inches per minute to perform machining operations in the x, y, and z directions. The third CNC mill, also capable of the same speed and feed rates, is a 5-axis machine, which adds two rotational axes in order to achieve the machining of even more complex shapes, such as spheroids and undercuts. HERL’s CNC lathe allows for complicated and high speed turning operations to be carried out on round stock. In addition, this machine has live-tooling features that allow for milling operations to take place alongside turning operations. The HERL machine shop also boats a CNC wire EDM machine, a CNC tubing bender, and computer controlled laser cutters. The wire EDM uses a series of electric discharges through a wire electrode to cut intricate shapes in any electrically conductive material up to thirteen inches thick. The CNC tubing bender allows HERL to make accurate and repeatable bends in round and square tubing up to two inches in diameter. The laser cutting machines utilize image files to cut plastic and wood as well as etch metal at a high speed. The technical computing laboratory functions as a destination for HERL personnel to work on CAD (computer aided design) software, create CNC machine code with CAM (computer aided manufacturing) software, and access the CNC and rapid prototyping machines in order to create and upload jobs to those machines. Also, the laboratory is often used as a classroom space for the technical education that occurs at HERL in the fields of design, fabrication, electronics, and computer programming.
In addition to the equipment in the machine shop, the stock preparation, welding, and painting/finishing facilities allow HERL personnel to prepare material (metal, plastic, wood, composites, etc) to be shaped and machined, to cut and join metal parts, and to perform the finishing touches in order to make professional quality parts and devices. There is also a dedicated assembly area stocked with hardware and other supplies necessary to construct the devices once all the parts have been fabricated.
HERL’s rapid prototyping capabilities encompass the three major additive manufacturing technologies: fused deposition modeling (FDM), selective laser sintering (SLS), and stereolithography (SLA). HERL’s FDM machine creates plastic parts by melting strands of material and depositing them in 0.010” layers. The SLS machine creates parts by using laser technology to melt 0.004” layers of plastic or metal powder together. Finally, the SLA machine cures 0.004” layers of a photosensitive plastic resin with laser light to create parts. These machines allow HERL personnel to build prototypes of parts and devices with little man-hours in order to confirm or deny design choices before committing the time and effort needed to machine parts.
The electronics laboratory serves to support hardware and software development at HERL. Part of the lab consists of software programming, electronics prototyping, and debugging stations, which are equipped with oscilloscopes, meters, power supplies, soldering irons, and function generators. The lab also possesses a PCB (printed circuit board) milling machine, which can create near-production quality boards designed in software that are ready for components to be populated and put to use collecting data, processing signals, or controlling other hardware in HERL’s many robotics-related projects.