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Electromagnetic Compatibility Test of Kibo's manipulator main arm
An Electromagnetic Compatibility Test of Kibo's manipulator main arm was conducted at the Tsukuba Space Center from Oct 5 to Oct 19, 1999.

What is an Electromagnetic Compatibility Test?
Electromagnetic Compatibility
Test Facility
Kibo's onboard equipment must be able to operate as designed, but that is not enough. NASA also needs to confirm that the noise this equipment generates does not affect other equipment inside Kibo or the International Space Station (ISS). Similarly, NASA must also confirm that the equipment is not affected by the noise generated by other equipment.

Two types of Electromagnetic Compatibility tests were conducted to confirm the conditions above. A noise radiation test was conducted, in which the frequency and the level of the noise that Kibo's main arm generates were measured to confirm that the main arm does not affect other electric and electronic devices. A radio sensitivity test was also conducted to confirm that the manipulator main arm functions appropriately without being affected by the noise generated by other electric and electronic devices.

This Electromagnetic Compatibility Test is being conducted on electric and electronic devices such as PCs, printers and microwave ovens. Every country has Electromagnetic Compatibility regulations. Products that do not satisfy these regulations are not allowed to be distributed in that country's market.

Several methods are being devised to suppress radio frequency noise, such as grounding, twisted-pair cable, and shielded cable the core of which is covered by a shield which is made of netted thin conductive lines.


What is Kibo's Manipulator?
Main arm and small fine arm

Kibo's manipulator is a robot arm composed of three elements; the main arm, which is used to manipulate heavy objects up to maximum seven tons; the small fine arm, which is attached to the end of the main arm to be used to perform fine manipulation for up to maximum 300kg objects, and the manipulator console to control both arms. This manipulator supports experiments and maintenance operations by exchanging equipment on Kibo's Exposed Facility.





What measurements are conducted in the Electromagnetic Compatibility test.
Noise radiation test
Noise wave measurement
This test measures the level of noise generated by the main arm. For this test, the main arm was placed in a shield room and the joint motors were drove by supplying power and control signals. A shield room is a room which is protected against external radio wave and is free from internal radio wave reflection. The frequency of the noise generated by the main arm ranges from 14KHz to 15.5GHz. By changing the receiving antenna according to the target frequency bands, the noise level were recorded. As a result, the main arm noise level was confirmed to be lower than the threshold indicated below.


Noise radiation test threshold
Frequency
Main arm noise radiation level
14KHz to 10MHzWithin 56dB microV/m
10MHz to 259MHzFor different frequencies, within 56 to 86 microV/m
259MHz to 10GHzFor different frequencies, within 46 to 72dB microV/m
13.5GHz to 15.5GHzWithin 76dB microV/m

Driving the main arm is an ideal method for measuring the noise level. However since the main arm is designed to be driven in a microgravity environment, only the motor was driven so that excessive load will not be imposed on the main arm's components.
Radio wave sensitivity test
Noise radiation
This test is conducted to confirm that the main arm is not affected by external noise. Again, the main arm was placed in the shield room and a wide frequency range of noise between 14KHz to 15.5GHz was applied to the main arm following the rule shown below. This is the reverse of the noise radiation test. Under this condition, a control signal was sent to the main arm to drive it, and the reaction signal from the main arm was recorded. The main arm was confirmed to be free from the noise generated by other equipment by confirming that the recorded signal is normal.


Radio sensitivity test threshold
Frequency
Noise radiation level surrounding the main arm
14KHz to 200MHz
5V/m
200MHz to 8GHz
60V/m
8GHz to 10GHz
20V/m
2.2GHz
161V/m
8.5GHz
79V/m
14.8GHz to 15.2GHz
250V/m


Shield room
Shielded room
The shield room is protected from externally generated radio signals. In addition, all room walls are covered with material that absorbs radio signals, so that radio signals are not reflected inside the room. We are surrounded by broadcast and communications radio signals. A shield room enables us to measure radio signal levels without influence of other radio signals.


Future tests planned for the main arm
In the future, two tests are scheduled to be conducted on the main arm. A Modal Survey test will be conducted to confirm the vibration frequency that causes resonance in the main arm. A functional test will be conducted by driving the main arm on the horizontal plane to confirm that the main arm functions normally. These two tests will conclude the series of tests conducted only on the main arm itself. Following these tests, an integrated system test will be conducted, with the manipulator connected to the manipulator console.


Last Updated : December 20, 1999
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