by Leslie Langnau, Managing Editor
After many years of evaluating and working with motion systems for various clients, UK-based Ball Racing Developments Ltd (BRD) concluded that nothing on the market could accurately simulate a racing car’s motion. So, the management and the engineers developed a new type of system dedicated to the motions experienced in a racing car, particularly the high velocity forces of a Formula One car for use in racing driver training, entertainment, and private owners with a keen interest in motorsport.
The first of this new generation of dedicated driving motion systems was released in November 2007 and sent to a theme park in Macau that wanted accurate motorsport simulators. However, BRD was unhappy with the performance of the equipment offered by its existing supplier of motion control products. The simulation technology specialist wanted a more compact and higher performing motor system, a specification that was ultimately fulfilled by Wood Dale, Ill. based Kollmorgen AKM-7 and AKM-6 brushless AC servomotors and Thomson linear systems.
The motors offer 0.16 to 53 Nm torque and speeds up to 8,000 rpm in a compact frame-size. This is an important factor to BRD, where any weight savings can benefit system performance and reaction times. The AKM motors were about half the size of the conventional servomotors they replaced.
One motor is required for each degree of freedom on the V1-500 motion platform. One AKM-7 motor handles movement in the surge direction (forward and backward acceleration and deceleration). AKM-6 variants handle motion in the side slip (side-to-side lateral thrust) and yaw (angular motion in the horizontal plane) directions. Yaw is achieved by changing the centre of rotation between the front and rear wheel positions. Each motor is powered by a Kollmorgen S600 AC servo drive, a digital servo amplifier.
For two motion platforms bound for Singapore, the engineers decided to include Thomson ball screw and linear guide systems in the same package in order to reduce lead-time and simplify the build process. These platforms were completed in just 10 weeks from signing the order, including design, build, and installation.
Three 40 mm x 40 mm ball screw assemblies move the Formula One car mounted on the motion platform. All are the same length for commonality purposes and each offers 1.2 m of travel. These assemblies consist of a precision rolled screw shaft and a nut (the outer race) with an internal groove and circuits of precision steel balls that re-circulate in the grooves between the screw and nut. This backlash-free anti-friction design converts torque to thrust as either the screw or nut turns and the other component moves in a linear direction. These ball screws have a high lead, which is necessary to generate the required 1 m/sec acceleration.
Alongside the ball screws and supporting the loads and high acceleration forces is a pair of 500 Series Profile Rail linear guide systems. These configurable linear guides meet DIN standard 645-1 requirements. Their rigidity and load capacity withstands the acceleration forces experienced in this realistic F-1 simulation. BRD had the option to plate linear guide bearing systems with thin-dense chrome (TDC) to withstand the exceptionally humid atmosphere in Singapore.
When mechanically complete, the two motion control platforms were linked with visual and sound technology created by BRD by mapping and modeling the Singapore street circuit. Based on BRD’s netKar Pro software platform, anyone can download a free copy of the Singapore night race circuit from www.singtelrace.com and practice driving the difficult track that twists and turns it way around many of Singapore’s famous landmarks. Users can even post lap times to the on-line leader board to see how they compare with others.
The two racing simulators deliver a realistic racing experience, short of being in an actual race car. At one point, crashing into the barriers produced such a sudden jolt that the effect had to be softened by BRD in the interests of health and safety. Approximately 1.0 to 1.5 G force can be generated in each axis of motion by the platform. As an added safety measure all drivers have to wear a four-point racing harness.
There has been plenty of interest from racing teams; a leading Formula One driver tested the V1-500 and managed to reduce his lap time by 0.7 sec. He noted that the system provided him with a greater ‘feel’ for effects present in a real racing environment such as under-steer, over-steer, weight transfer braking and wheel-spin, and helped improve his reactions.