| 摘要 |
A goniometer comprising a rotor and a support base having therebetween three or four balls or rollers constrained to follow arcuate paths to provide rotation of the rotor, relative to the support base, about an axis of rotation external to the rotor, the balls being constrained to be spaced apart in at least two dimensions to ensure a three point spaced contact with the rotor and the support base.
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