Classifications

• • G—PHYSICS
  • G08—SIGNALLING
  • G08C—TRANSMISSION SYSTEMS FOR MEASURED VALUES, CONTROL OR SIMILAR SIGNALS
  • G08C17/00—Arrangements for transmitting signals characterised by the use of a wireless electrical link
  • G08C17/02—Arrangements for transmitting signals characterised by the use of a wireless electrical link using a radio link
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B21/00—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant
  • G01B21/02—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant for measuring length, width, or thickness
  • G01B21/04—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant for measuring length, width, or thickness by measuring coordinates of points
  • G01B21/047—Accessories, e.g. for positioning, for tool-setting, for measuring probes
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B2210/00—Aspects not specifically covered by any group under G01B, e.g. of wheel alignment, caliper-like sensors
  • G01B2210/58—Wireless transmission of information between a sensor or probe and a control or evaluation unit
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04B—TRANSMISSION
  • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
  • H04B1/69—Spread spectrum techniques
  • H04B1/713—Spread spectrum techniques using frequency hopping

Definitions

• a trigger probe for determining the position of a workpiece is described in US Patent No. 4,153,998.
• the probe is moved by the machine relative to a workpiece.
• the probe has a deflectable stylus and delivers a trigger signal when the stylus contacts the workpiece.
• the trigger signal is indicated by the probe switching from one state to another.
• the trigger signal is used by the machine controller to freeze the outputs of scales or other measuring means which indicate the position of the probe. The position of the point of contact on the workpiece surface can thus be determined.
• This method has the disadvantage that as the transmitter transmits a continuous signal which is required to synchronise the transmitter and receiver the system uses a significant proportion of the probe battery power and thus reduces the battery life.
• the measurement device may comprise a measurement probe, for example a touch trigger probe.
• the transmission system uses a world-wide frequency band.
• the first and second stations may be provided with a clock, wherein the clocks are synchronised at least once.
• the first station may transmit a regular transmission and wherein when the second station receives the signal it may synchronise its clock with the first station. If a signal transmitted by the first station is not adequately received by the second station, the signal may be retransmitted by the first station.
• the transmission system comprises a half duplex link.
• the first station may transmit information relating to said measurement event.
• the measurement event may comprise a touch trigger event.
• the information may include data relating to the time of the measurement event.
• the first station may transmit a regular transmission and information relating to the measurement event may be transmitted in an additional transmission.
• Fig 3 is a schematic illustration showing lost hops and event interruptions
• Fig 4 is a schematic illustration showing a probe trigger and delay counters
• Both the probe and machine stations hop between different frequency channels roughly in synchronisation with each other with occasional messages sent between them to synchronise the two stations.
• the probe station initiates each exchange of messages and receives a reply from the machine station.
• the frequency-hopping and synchronisation will now be described in more detail with reference to Fig 2.
• the machine station is listening for messages most of the time whilst the probe station is in its half-on condition most of the time (e.g. as in slots n+1 to n+3 above) .
• the probe station When the probe station is half-on its probe interface and microprocessor will be on and the radio modem will be off.
• the probe interface and microprocessor each use about 2mW of power whilst the radio modem uses significantly more power, about 120mW when switched on.
• the radio modem consumes a similar amount of power whether it is receiving or transmitting.
• the half-on state thus minimises power consumption of the battery powered probe system.
• Fig 2 shows the probe station turning on with a small settling time and then transmitting an "I'm OK" message on frequency channel f(n).
• the probe station then listens for the acknowledgement from the machine station.
• the machine station which is listening on channel f(n) receives this message, synchronises its clock with the probe station and then sends an acknowledgement back on channel f(n).
• the probe station clock therefore acts as the master clock for the system.
• the machine and probe stations are synchronised, they hop between frequency channels at the same time.
• Fig 2 only shows three silent slots and thus three frequency-hops are unused.
• the periodic timer then prompts the probe station to transmit again on f (n+4) and this cycle then repeats until interrupted by some other event (e.g. a lost transmission, a probe trigger or a probe station turn-off signal) .
• the transmitted radio packet from the probe station includes probe data.
• the probe may be seated (S) or the probe may have triggered (T) .
• Other information may also be transmitted in the radio packet, for example the condition of the battery, how many transmissions have been attempted for this message and data relating to the time of a touch trigger event.
• the probe station transmits a message, the machine station receives this message and sends an acknowledgement. However the probe station does not receive this reply for example due to interference.
• Fig 3 shows the re-transmission of the message from the probe station in time slot nl+1.
• the machine station receives nothing, it does not send an acknowledgement. The probe station will therefore receive no message and so will re-transmit the message in slot nl+2.
• the machine station If however after a predetermined time the machine station does not receive the message from the probe station then either the radio link or the probe station has failed and the machine station will set an error output.
• a normal radio frequency power level is used, for example ImW.
• the radio frequency power level may be increased, thus increasing the chance that the message will get through.
• a timer in the probe begins counting from zero.
• the value of this timer tl is latched at the beginning of the next time slot n+1.
• This value tl is transmitted from the probe station to the machine station in a transmission in the next time slot n+1.

Landscapes

• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Computer Networks & Wireless Communication (AREA)
• Arrangements For Transmission Of Measured Signals (AREA)
• Mobile Radio Communication Systems (AREA)
• Transceivers (AREA)
• Position Fixing By Use Of Radio Waves (AREA)
• Monitoring And Testing Of Transmission In General (AREA)

Priority Applications (7)

Applications Claiming Priority (2)

Related Child Applications (2)

Publications (1)

Family

ID=9950125

Family Applications (1)

Country Status (10)

Cited By (22)

Families Citing this family (22)

Citations (4)

Family Cites Families (35)

• 2002
  • 2002-12-23 GB GB0229763A patent/GB0229763D0/en not_active Ceased
• 2003
  • 2003-12-18 EP EP20030782636 patent/EP1576560B1/en not_active Expired - Lifetime
  • 2003-12-18 CN CN2009100085935A patent/CN101482402B/zh not_active Expired - Lifetime
  • 2003-12-18 CN CNB2003801074549A patent/CN100466003C/zh not_active Expired - Lifetime
  • 2003-12-18 EP EP20100004269 patent/EP2214147A1/en not_active Withdrawn
  • 2003-12-18 EP EP10004263.9A patent/EP2216761B1/en not_active Expired - Lifetime
  • 2003-12-18 KR KR20057011769A patent/KR101001244B1/ko not_active Expired - Fee Related
  • 2003-12-18 WO PCT/GB2003/005516 patent/WO2004057552A1/en not_active Ceased
  • 2003-12-18 JP JP2004561635A patent/JP4575781B2/ja not_active Expired - Fee Related
  • 2003-12-18 AT AT03782636T patent/ATE487205T1/de not_active IP Right Cessation
  • 2003-12-18 DE DE60334841T patent/DE60334841D1/de not_active Expired - Lifetime
  • 2003-12-18 US US10/539,344 patent/US7821420B2/en active Active
  • 2003-12-18 AU AU2003290271A patent/AU2003290271A1/en not_active Abandoned
• 2010
  • 2010-05-10 JP JP2010108355A patent/JP5238749B2/ja not_active Expired - Lifetime
  • 2010-09-09 US US12/923,218 patent/US9140547B2/en not_active Expired - Fee Related
• 2013
  • 2013-02-04 JP JP2013019830A patent/JP5390719B2/ja not_active Expired - Fee Related

Patent Citations (4)

Non-Patent Citations (1)

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