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Methods and apparatus for maintaining a constant tension on an electrical cord of a robot

  • US 5,498,940 A
  • Filed: 12/30/1993
  • Issued: 03/12/1996
  • Est. Priority Date: 12/30/1992
  • Status: Expired due to Fees
First Claim
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1. A self-propelled member, comprising:

  • a body;

    a spool mounted on said body for rotation;

    an electric power cord wound on said spool for extension and retraction in response to rotation of said spool in respective directions;

    a spring connected to said spool biasing said spool for rotation in a direction for retracting said cord;

    sensor means for sensing whether said cord is being extended or retracted and the extent of such extension or retraction;

    motor means connected to said spring and operated by said sensor for displacing said spring in a spring-tightening direction and a spring-relaxing direction in response to retraction and extension, respectively, of said cord by an amount proportional to the sensed extent of cord extension or retraction for maintaining a generally constant tension on said cord; and

    a shaft arranged coaxially with respect to an axis of rotation of said spool, said spring comprising a spiral plate having an inner end affixed to said shaft and an outer end affixed to said spool, said motor connected to said shaft for rotating said shaft to relax or tighten said spring.

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