Testing Missiles: Precision To The Micron

Tectra Automation, has supplied Bosch Rexroth components to Denel Dynamics, for the construction of a qualifying rig. The rig will be used for the telemetry testing of a sub-system, used on Denel’s new A-Darter air to air combat missile. The contract consists of component supply, assembly, disassembly transportation and reassembly of the rig.

The 11m long rig comprises of two separate systems; a linear guide system and a stable platform. With both systems working in unison, the qualification rig achieves a very stable closed loop mechatronic system. The rig will be used to simulate the A-Darter’s flight path and is crucial to the missile’s development. It allows the sub-system to be tested using developed methodology, without the high expenditure involved in live testing. Due to the precise nature of the equipment being qualified, the rig needs to be very accurate.

“The tolerances we are working with here are incredibly fine. We’re using a stabilising system which incorporates a stand-alone helium neon laser to ensure that the sub-system travels in a straight line and remains level. By using Rexroth components for both the stable platform system and the linear guide system, we have achieved the precision required to ensure the rig performs to the high standards of the weapons industry,” says Jaiveer Waghmare, aeronautical engineer and project manager, Denel Dynamics.

The stable platform utilises a quadrant filter in combination with the free standing laser to achieve a constant reference point. The signal is then sent to a digital signal processor which uses the data generated to stabilise the platform. The stable platform incorporates Rexroth servo-motors, couplings and ball screws to correct for misalignments with accuracy within 0.5 microns.

The linear guide system utilises Rexroth LF 20 S linear guides, which consists of linear bushing, linear shafting and aluminium profiling. “The profiling is easy to work with. The T nut connectors allow additions and adjustments to be made to the rig with absolute accuracy and efficiency,” says Waghmare.

The system utilises a Rexroth motor and belt drive system to propel the stable platform and sub-system at a velocity of 0.2 metres per second. The system rests on adjustable Rexroth support stations, which are positioned one meter apart down the length of the qualifying rig, allowing deviations in ground level to be compensated for accurately.


“Moving the qualifying rig around our premises and to the testing site is not a project to be undertaken lightly. As a result of the fine tolerances involved in this system, there is a chance of damaging the linear guides through improper handling. The damage would be unperceivable to the naked eye, but would tarnish test results. This is why we have enlisted Tectra Automation’s expertise to assemble, disassemble and transport the qualifying rig,” explains Waghmare.

“The level of support we have received from Tectra Automation has been amazing, their products have simplified the testing phase of our sub-system as well as greatly reducing costs,” enthuses Waghmare.