The prototyping facility of the Human Engineering Research Laboratories, consisting of 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 Computer Numerical Control (CNC) machines capable of cutting and shaping metal, plastic, and other materials. The shop contains two manual mills and a manual lathe, which are traditional machine shop equipment to perform simple and routine machining tasks on bar, sheet, and round stock. This shop also includes three CNC mills and a CNC lathe that are capable of completing complex machining jobs at very high speed 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. In addition to these milling and turning machines, the machine shop also includes 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 high speed.
The technical computing laboratory functions as a destination for HERL personnel to work on Computer Aided Design (CAD) software, create CNC machine code with Computer Aided Manufacturing (CAM) software, and access the CNC and rapid prototyping machines in order to create and upload jobs to those machines. Also, this laboratory serves as classroom space for the technical education that goes on 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, wood, and painting/finishing facilities allow HERL personnel to prepare materials (metal, plastic, wood, composites, etc) to be shaped and machined, cut and join metal parts, and 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. The SLA machine cures 0.004” layers of a photosensitive plastic resin with laser light to create parts. While each machine has its own set of pros and cons, they each 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.
HERL’s testing laboratory is set up to perform many of the ISO and ANSI/RESNA standards tests for manual and powered wheelchairs as well as lower-limb prosthetics. These testing facilities, which include hydraulic material testing frames, environmental test chamber, and wheelchair fatigue testing machines allow HERL’s researches to determine the safety and efficacy of their designs for mobility aids as well as test the quality of mobility products already on the market. Furthermore, as one of the only independent wheelchair testing facilities in the country, HERL is frequently contacted by mobility device manufacturers to perform tests required by regulatory agencies on their products. Because of this well-equipped facility and extensive experience with standards testing for wheelchairs, HERL is a contributor to the on-going development of international and North American standards for wheelchairs in order to ensure that individuals with disabilities have access to high quality devices.
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.