Summary of Contents for Datawell BV Hippy 40-MkII
- Page 1 Datawell Heave Pitch Roll Sensor Manual Hippy 40-MkII from serial no. 18181 Service & Sales Voltastraat 3 1704 RP Heerhugowaard The Netherlands +31 72 534 5298 +31 72 572 6406 March 20, 2019 www.datawell.nl...
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Page 3: Table Of Contents
Contents 1 Introduction ....................5 2 Principle of operation..................6 2.1 Acceleration measurement ............... 6 2.2 High pass filter for heave measurement ........... 6 2.3 Pitch-roll measurement ................7 3 Connections ....................10 4 Position ......................11 5 Outputs......................12 5.1 Pitch (p) .................... - Page 4 fig. 1...
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Page 5: Introduction
1 Introduction The Hippy measures pitch, roll and heave. Reference plane for the pitch-roll measurements is a gravity stabilised platform with a natural period time of 40 seconds. An accelerometer is mounted on this stabilised platform. The sensor can accept any voltage between 10 and 30 V DC. Output and supply are floating with regard to each other as well as to the housing of the sensor. -
Page 6: Principle Of Operation
2 Principle of operation Acceleration measurement The deflection of the tip of a clamped cantilever is a measure for the acceleration. (Vertical acceleration since the accelerometer is mounted on a gravity stabilised platform). The cantilever is placed in a fluid in which an electric field is present. So the potential of the cantilever is a measure for this deflection. -
Page 7: Pitch-Roll Measurement
Pitch-roll measurement An alternating magnetic field H is generated parallel to pitch axis and another field H different frequency parallel to roll axis (by means of coils A and B, fixed to housing and perpendicular to each other). A pickup coil C, mounted on the stabilised platform (horizontal plane) measures the vertical components of H and H (fig. - Page 8 fig. 3 Calculation of induced voltage Vi is base plane of instrument Vh is horizontal plane (platform plane) OL intersection of both planes Angle between both planes is α Be H = P the magnetic field vector generated parallel to the pitch axis. the projection of OP on horizontal plane.
- Page 9 So roll output r = sin∠POP1 = sinαsinβ Also pitch output p = sin∠ROR1 = sinαcosβ For scale factor see specifications (8.2). α angle between instrument plane and horizontal plane β angle between pitch axis and rotation axis ∠POP angle between pitch axis and horizontal plane ∠ROR angle between roll axis and horizontal plane...
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Page 10: Connections
3 Connections junction box terminal no. 1 Supply − junction box terminal no. 2 pitch junction box terminal no. 3 roll junction box terminal no. 4 Outputs heave junction box terminal no. 5 acceleration junction box terminal no. 6 common junction box terminal no. -
Page 11: Position
4 Position Pitch and roll axis are indicated by V formed cuttings in the rim of the bottom flange. Mount the instrument with arrow (on text plate on lid) in the direction of the bow of the ship (see fig. 10). V formed cuttings in lid and top flange should coincide. -
Page 12: Outputs
5 Outputs Pitch (p) Measures sine of angle γ between roll axis of ship and horizontal plane. p (in volts) = 10 sin γ Output is positive if rear side of ship is lifted. Roll (r) Measures sine of angle γ between pitch axis of ship and horizontal plane. -
Page 13: Platform Offset
6 Platform offset Influence of platform offset Platform offset is directly shown by the pitch and roll outputs if the ship is accurately trimmed (horizontal base plane of Hippy). Platform offset results further in an accelerometer output for horizontal accelerations (cross sensitivity) proportional to the offset. -
Page 14: Transportation
7 Transportation Do not roll or spin Rolling or spinning the Hippy, for example when it is being hoisted may damage the accelerometer beyond repair. The Hippy should not make more than six revolutions in two minutes. Spinning may also lead to an entangled suspension of the stabilised platform which causes in most cases excessive platform tilt. -
Page 15: Specifications
8 Specifications General Temperature range: −5 - +35°C (+35 - +55°C, short term, weeks, only, see also 8.5) Storage temperature range: −5 - +40°C (+40 - +55°C, short term, weeks, only) If an instrument is exposed to low temperatures for a sufficiently long time to reduce the fluid temperature in the instrument to below –5°C, the fluid will be permanent altered. -
Page 16: Pitch-Roll
Pitch-roll Output: Pitch : Junction box terminal no. 3. Roll : Junction box terminal no. 4. Common : Junction box terminal no. 7. Loading resistance min. 10 KΩ. Capacitive loading (cable) max. 0.5 µF. Output is short circuit protected. Scale: Output is proportional to the sine of angle γ... -
Page 17: Heave
Heave Output: Heave : Junction box terminal no. 5. Common : Junction box terminal no. 7. Loading resistance min. 10 KΩ. Capacitive loading (cable) max. 0.5 µF. Scale: 1.0 V/m, maximum range ± 10 m *) Output at terminal 5 positive going for upward movement of the sensor. -
Page 18: Acceleration
Acceleration Output: Acceleration : Junction box terminal no. 6. Common : Junction box terminal no. 7. Loading resistance min. 10 KΩ. Capacitive loading (cable) max. 0.5 µF. Scale: 1.0 V/m/sec², maximum range ± 10 m/sec² *) Output at terminal 6 is positive for upward acceleration. Bandwidth: Low pass third order filter;... -
Page 19: System Check And Calibration (Heave)
9 System check and calibration (heave) Simple System check Connect a recorder with a sensitivity of approximately 2 V to the heave output. The recorder will show a straight line. Have two men lift the Hippy several times within 10 sec to a height of about 0.5 m and lower it without bouncing. -
Page 20: System Check And Calibration Pitch And Roll
10 System check and calibration pitch and roll Scale: Measure pitch output at pitch angle of +90° and again at pitch angle of −90°. (Check with plummet if roll axis is vertical within 5°). The difference of the obtained values has to be: 20 V ± 0.4 V. The same applies for the roll output at roll angles of + and −90°... - Page 21 fig. 5...
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Page 22: Alignment
11 Alignment Alignment of these instruments depends on the purpose for which the instrument is used. For example, for wave compensation of echo soundings, the instrument should be aligned with the transmitter. Generally if the ship is trimmed in horizontal position (as indicated by the inclinometer) the instrument should be fixed in horizontal position and with axes aligned with the ship's pitch and roll axes. - Page 23 fig. 6...
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Page 24: Maintenance And Repair
12 Maintenance and repair In case of underpressure the lid can be lifted by using the threaded hole and one of the screws. See fig. 7 below. fig. 7 12.1 Location of components (see fig. 6 and 8) The sphere which contains the stabilised platform is placed in a cylinder of hard foam at the bottom of the can. - Page 25 fig. 8...
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Page 26: Repair And Pcb Check
12.3 Repair and pcb check 12.3.1 Repair A procedure is given to determine whether the electronics is defective in case of faults. If the cause is outside the electronics repair is only possible at Datawell generally. No procedure is given to determine the fault on the print. If the print is defective, the pcb should be replaced as a whole. -
Page 27: Pcb Check
12.3.2 Pcb check (see fig. 8 for layout) Supplies Power drain approx. 150 mW. Output DC-DC converter: +13.5 V, +5.0 V, −5.0 and −13.5 V. Supply outer coils Tab O.O.C. ÷ tab "⊥": 2.1 V sine wave 590 Hz. Tab I.O.C. ÷... -
Page 28: Coils
Standard sensitivity acceleration Interconnect the indicated side of R35 and R36 to ground (see fig. 8*). Replace the 2.7 MΩ resistor to tab "IN" by a 47 KΩ resistor, connect the other side to point 3 of T1, respectively point 8 of T1 (left side of R37 respectively right side of R39, see fig. 8*) and measure the acceleration in both cases. -
Page 29: Exchange Of Pcb
b) Connect the white and blue lead of the cable “V.M.” with ground (tabs marked ⊥). Leave the tabs for the cables “V.M.” and “I.C.” disconnected. Measure the current between T1 point 1 (right side of C45) and the center lead of coaxial cable “I.C.”. The reading should be between 15 μA and 60 μA, if it is not, the accelerometer is defective. - Page 30 If Hippy is reassembled take care that: 1. Pcb is in the right position, components side up and arrow under print pointing towards marking in the flange. 2. Silicagel bags should not be in direct contact with pcb. Place them in special compartments within bag (see fig. 6). Seal the polyethylene bag careful especially where the leads enter the bag.
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Page 31: Check Of Fluid Level
13 Check of fluid level Check fluid level once in 5 years. Fluid level can be visually checked through perspex lid on sphere. If centre of rubber membrane is pointing upwards (see fig. 9-B) level is sufficient. In case the membrane touches division plate (see fig. 9-A) fluid has to be added. If fluid level is too low contact Datawell. -
Page 32: Modifications
14 Modifications From Hippy 40 serial no. (see first page manual) 18001 Original 18003 Flattened flanges of can, electronics changed. 18033 Dimensions of housing changed. Zero offset of acceleration changed into 1m/sec² MkII added. 18121 Pcb 18-9A... introduced. (15 June 1990) 18181 Pcb 18-10A... -
Page 33: Dimensions And Connections
15 Dimensions and connections fig. 10... -
Page 35: Appendix
Appendix fig. 8a...
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