History of the

Early days

Back in 1983 John Hilton, the inventor of the Spaceball®*, embarked on a masters degree in mechanical engineering at the University of Sydney, Australia. He had just completed five years of study gaining a Computer Science degree and a Mechanical Engineering degree.

Around that time the Mechanical Engineering department acquired a ComputerVision CADDS4 system. Mr. Hilton’s unusual combination of degrees coupled with the availability of a CAD system naturally led to a keen interest in Computer Aided Design (CAD).

In studying the various 3D CAD systems available at the time it puzzled Mr. Hilton as to why they all used 2D input devices and dial boxes for controlling the 3D image. Researching various literature he found several types of 3D and 6D devices going back to 1965 where Ivan Sutherland had developed a head mounted display - the forerunner for today’s cyberspace head mounted displays. (6D devices provide simultaneous 3D translate and 3D rotate control.) The devices allowed a handle of some description to be moved around with the hand and the image on the screen to move correspondingly. It appeared researchers were following the thought, “If only I could hold it in my hand.” But these devices were only used in research labs and never in commercial applications. Maybe cost was the issue? But in searching the literature, even the military, known to be not as cost-sensitive, did not use any of these devices for real purposes.

Mr. Hilton came to the conclusion that ergonomics was the issue as it was not practical to use these non-ergonomic 6D digitizers for CAD users. It was impractical to use a device that had to be held in the air for more than ten minutes let alone an entire working day..

To solve the problem Mr. Hilton conceived of a static grip, preferably a ball, which sensed a 3D push for moving a 3D cursor around in several views.

To design such a device Mr. Hilton considered the ‘flow of force’ from the grip to the base and wanted to detect all components of this flow. To detect all the components required the detection of the 3D torque as well. Drawing heavily on the Theory of Mechanism and Machines, Mr. Hilton evolved a ‘perfectly constrained’ mechanism with three arms, three hinges and three ball joints to sense and measure this flow of force.

Perhaps a word of explanation is appropriate. There are six degrees of freedom between any two rigid bodies, three translational and three rotational. Each basic mechanical joint between two rigid bodies has between 1 and 5 degrees of freedom and between 1 and 5 degrees of constraint - the sum of these always being six. A perfectly constrained body is one where the joints provide exactly six degrees of constraint. Less constraint and the body can move, more and the body is over-constrained.

It was difficult finding a low cost sensor to measure the small displacements of this fledgling invention. Again the books were researched and all the basic sensing approaches of inductive, capacitive, resistive, optical fringe counting, interference gratings and optical mask sensing were considered. Unfortunately suitable commercial sensors proved to be quite expensive. Being a poor but innovative university student Mr. Hilton discovered a cheap light dependent resistor (LDR) from a local electronics store and a 12V lamp from a car’s interior light produced an accurate result. It actually detected loud sounds in the room as well! The first working device consisted of a very crude prototype interfaced to a home computer that Mr. Hilton had built from a kit. This device moved a 3D cursor, shown as a point in a top view and another point in a front view. But it only worked well in the dark!

Blocking ambient light out was a challenge. In talking about the problem with another researcher they suggested the use of infrared sensors. These worked perfectly and the same style of sensor continues to be used in the Astroid today.

Mr. Hilton’s Masters thesis was originally titled, “A 3D Force Sensing Joystick” but ended up being “Development of a Device for Simultaneous Measurement of a Spatial Force and a Spatial Torque for Manual Control.” Quite a mouthful! It was also the very first University of Sydney thesis that was printed double sided – but that is another story.

The ‘Screwball’

About this time the device was given the name ‘Screwball’. This was derived from the Theory of Mechanism and Machines where spatial relative motion of a rigid body is called a motion screw and a spatial force and torque between two rigid bodies is called an action screw.

One of the university lecturers, aware of the unique nature of the Screwball, suggested applying for a patent and recommended a patent attorney. A provisional patent was filed in December 1985.

In preparing the provisional patent application Mr. Hilton considered how someone might design around it. The original Screwball had relatively long arms that were external to the grip. The basic geometry of the Screwball resolved the spatial force and torque into three pairs of parallel forces. The first Screwball had three of these forces intersecting at the centre of the device. By shifting the basic geometry so the parallel forces in each pair were located either side of the centre a new type of Screwball design was possible that would not have been covered by the patent draft. This modified design was included in the provisional patent and proved to be far more suitable for a commercial product.
The Spaceball
By this stage Mr. Hilton had begun full time work for an Australian IT company that, amongst other things, distributed Evans & Sutherland (E&S) graphics terminals into Australia. One customer was a computer animation studio that used E&S terminals and had purchased one of the early camera’s used for pioneering computer animation for movies. Mr. Hilton developed computer animation software to be used by animators for creating Australian and overseas computer animated television logos and commercials. This work on computer animation software dovetailed well into his continuing, but now part time, Screwball thesis work.

He showed an early prototype to two of the directors. They took an interest and provided seed funding to develop a professional prototype. This was used for demonstrations to key North American companies using E&S equipment. The response was very positive so a company was formed, a private investor found, and development of the Model 1003 began.

The name, Screwball, was clearly not suitable so a list of about 25 alternative names were collected. “Spaceball” was the winning name as it is now commonly known in the CAD industry.

The Spaceball 1003 was ready for shipping in August 1988 when Mr Hilton moved to Boston, MA in the USA. Over the course of the next 11 years Mr. Hilton oversaw the development of the Spaceball 2003, SpaceController, Spaceball 3003, Spaceball Avenger, SpaceOrb 360, Sphere360 and the Spaceball 4000. The technology evolved through four generations as new, better and less expensive designs were produced. These were sold by a succession of companies; Spatial Systems Pty. Ltd., Spatial Systems Inc., Spaceball Technologies Inc., Spacetec IMC Corporation and Labtec Inc.

The

After returning to Australia in 1999 Mr. Hilton continued to ponder the design. One day another inventive spark flashed through his mind; a four arm design was better! The Spaceball technology had been based on six arms arranged like a 3D cross. A four arm design, arranged to form the corners of a tetrahedron, allowed considerable simplification of the construction. The whole central construction could be moulded as one unit!

A patent was applied for, Spatial Freedom formed, and the astroid was born.

*Excluding the Spaceball 5000.
Spaceball is a registered trademark of Logitech International S.A.