Getting a handle on improved operation23 August 2017
While telemanipulator design and operation has evolved over the decades, the look and feel of the handle that is gripped by the operator has remained relatively static. Amos Avery and Steve Williams explain how a new design could improve operator efficiency.
One of the most significant days in the evolution of hazardous-material handling in industrial applications occurred in 1949. On that day inventor Ray Goertz first publicly demonstrated, at the behest of the US Atomic Energy Commission for use at its Argonne National Laboratory, his invention that would come to be known as a telemanipulator.
Four years earlier, three scientists from the Massachusetts Institute of Technology had founded Central Research Laboratories (CRL) and begun working on developing safer methods for handling hazardous and toxic products. CRL began developing command-remote telemanipulators that could be used for the safe and efficient handling
of nuclear materials by eliminating the need for the human operator to have direct contact with what could be extremely harmful and hazardous substances.
Since then, CRL has manufactured and installed more than 7800 telemanipulators in 22 countries. The company strives to continually improve and develop innovative transfer systems, glove ports, telemanipulator tools and power-assist equipment technologies.
In the ensuing decades, the design and operation of telemanipulators have undergone a series of technical enhancements and improvements. But since the invention of the first telemanipulators, the handle design has stayed roughly the same, though there have been calls for its refinement.
The current iteration of most of history’s greatest inventions bare scant resemblance to their version 1.0 – think of automobiles, cell phones and personal computers, for example. Somehow, though, telemanipulator handles went decades without any significant changes in their design. The call for design modifications, however, gained steam in recent years as ergonomic concerns became more pronounced, while the awareness of claims of repetitive-stress injuries became more common. As a longtime developer and manufacturer of telemanipulator systems, CRL heard the calls for a better design and, working with the experts at SRI•Ergonomics, set about to answer the industry’s need for a more ergonomic telemanipulator handle. The result of this commitment is the Versa VR8 Handle System.
When considering the capabilities of the handle of a telemanipulator, there are two main areas of focus: operation and construction.
Most common telemanipulator handle designs have been around since the late 1950s, employing what is known in the industry as an “opposed-grip” or “ambidextrous-style” handle, with very few modifications made in the way they are designed and operate in that time. However, in recent years, increased global scrutiny has been placed on how ergonomical a piece of equipment is. This prompted CRL to design a better handle.
In considering the operation of traditional telemanipulators, the following ergonomic shortcomings were found in handles:
- The handle was too short. It could be modified in order to deliver better feel and stability for the user.
- The tang, or hilt, at the top of the grip was too pointed and did not always conform to the shape of the hand.
- Operators who used two hands on the telemanipulator as a way to reinforce grip strength or handle heavier loads would encounter areas on the top of the handle where the hand could come into contact with moving components.
- The activation buttons on the handle were small or had sharp edges, which put stress on the fingers.
- The finger loops on the handle were adjustable, but would not swivel, which limited their range of motion and overall adjustability.
Some telemanipulator operators tried to modify the handle themselves, which reduced the effectiveness of the telemanipulator and made it more risky for the operator to use.
The way the telemanipulator handle was constructed could also badly affect manufacturing, maintenance and downtime costs. For example:
- The telemanipulator’s electrical system is controlled by micro-switches that had to be soldered into the unit’s handle.
- Traditional handles require a series of special tools to assemble and maintain them, including specific types of screwdrivers, Allen wrenches and snap-ring pliers.
- The handle is typically bolted to the end of the telemanipulator. Time and tools are necessary to remove it.
The challenge was to come up with an alternative that improves the experience for the operator and optimises construction. CRL, which aligned in 2009 with automation, workholding and containment-solutions provider Destaco, a Dover company based in Auburn Hills, Missouri, USA, responded to the challenge.
First, extensive field research and focus group studies were conducted gain insight into handle use and ways to improve the design. CRL also contracted with SRI•Ergonomics at Ohio State University in Columbus, Ohio, to test and assess the viability of potential new handle designs. SRI•Ergonomics’ review took into account eight ergonomic principles of hand-tool design:
- Grip type
- Handle shape
- Handle diameter
- Handle length
- Handle surface
- Handle material
- Sharp edges
After completing testing in early 2016, SRI•Ergonomics provided feedback to CRL on how improve the new handle. Armed
with this insight and ergonomic assessment data, CRL further refined and ultimately developed the Versa® VR8 handle system. This met all of the parameters for ergonomic operation in different wrist positions (neutral, palmer flexion, dorsiflexion, radial deviation and ulnar deviation), and can be used by operators with varying hand sizes, dominant- hand orientations and hand strength.
Some highlights of the Versa VR8 include:
- A redesigned tang/hilt at the top of the handle that is smaller and more sculpted in order to fit the shape of the hand.
- Finger grips on the top and a knob on the front that make it easier and safer to hold and control in two-handed applications.
- Finger loops that are on swivels, which allow the operator to retain more consistent grip pressure during all ranges of motion.
- Multiple adjustment points that can accommodate different-sized hands with an adjustment range of 1”, as opposed to the 0.5” range in legacy handles.
The Versa VR8’s electrical components have connectors, which eliminate the need for soldering and allow each switch to be independently removed and replaced. In response to consumer feedback, more uniform, maintenance-friendly fasteners have been used. Uniformly-sized pivot pins with a spring-loaded clip, which allows all of them to be inserted and removed by hand, have replaced all of the snap rings in the handle’s construction.
Finally, rather than having the handle bolted to the telemanipulator, the Versa VR8 is attached via a quick-release clamp and tong cable coupling that can be undone by hand. This will help drastically cut maintenance times, since there is no need to undo soldering and use multiple tools to remove the handle. If maintenance is needed, the handle can be popped off and replaced with a spare in a matter of seconds.
This also means that there may come a day when each operator will have his or her own personal handle that can be swapped out with the handle of the departing person during a shift change, which again will reduce downtime and result in more efficient and ergonomically friendly operations.
Amos Avery is a Contract Mechanical Engineer and Steve Williams is General Manager – Remote Handling for DESTACO, Auburn Hills, MI, and at Central Research Laboratories, Red Wing, MN.