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Watson Industries, Inc. 

 

SPS-P230 Rev A 10/17/2017 

 

Position Mode 
Position or “P” mode is a relative positioning mode. It uses the rate gyros to detect motion on the 
pan axis and hold the platform in the last commanded position relative to the vehicle. The tilt axis 
operates differently. In Position mode, as well as Inertial Mode, the tilt axis stays stabilized and 
will maintain an inertial position irrespective of vehicle motions.  Position Mode is activated by 
pressing the Position Mode button on the Joystick Controller. When the platform is operating in 
position mode, the LED on the position mode button will be illuminated. 

Error Correction 

Short-term disturbances will not affect the stable mount system, but as these errors become longer 
term, joystick commands will become necessary to correct them. Two common sources of long-
term errors for the “P” mode are discussed below. 
 
Centrifugal Force:   
The centrifugal force from turns at a significant speed could pull the pointing angle into error over 
time, depending on the pointing angle.  If this is a problem, setting the system time constant to a 
higher time interval may help. 

 

Delta Velocity (Acceleration):   
The compensation for forward acceleration is the same as the centrifugal force compensation. 

Safety Features 

Over-current detection: 

There is current sensing for each axis of this system that is connected to the micro controller.  If 
sustained excessive motor current is detected (i.e. greater than one amp on either axis), the system 
will reduce the drive circuit gain by a factor of 4 to reduce the drive current. The gain will be held 
low for 2 seconds after the current is below the limit.  Since the components of the system are 
balanced, the only regular cause of sustained over current is driving against resistance such as an 
obstruction.  Such a load on the system could cause the motor to burn out and this must be 

Vehicle Motion

Vehicle Motion

Position Mode

Inertial Mode

 

Summary of Contents for SPS-P230

Page 1: ... P230 Rev A 10 17 2017 1 STABILIZED PAN AND TILT PLATFORM SYSTEM OWNER S MANUAL PART NUMBER SPS P230 WATSON INDUSTRIES INC 3035 MELBY STREET EAU CLAIRE WI 54703 Phone 715 839 0628 FAX 715 839 8248 email support watson gyro com ...

Page 2: ...ut 15 Servo System Pinout 16 RS 232 Input Commands 16 Warning 17 Appendix A 19 Appendix B 22 Activating Command Mode Double Spacebar Mode 22 Determining Output Channels 22 Setting Output Channels 23 Adjust Time Constant 23 Set Joystick Tilt Axis Parameters 24 Set Joystick Pan Axis Parameters 25 Set New Home Position 26 Set Baud Rate 27 Watson Industries prides itself on solving customer problems a...

Page 3: ...ted Details of the operation and adjustments are provided to allow the owner to obtain optimum performance from this product Watson Industries has many years of experience developing stabilized platform sensor packages for camera and antenna applications Now we have taken the next step and are offering a complete system Watson Industries also provides custom systems for special requirements Our sy...

Page 4: ... platform motions to less than 10 Arc Seconds Furthermore Watson Industries has installed two gyros and a triaxial accelerometer that are used to calculate corrective commands to the drive motors The two gyros are rugged vibrating structure gyroscopes whose angular rate signals are converted from analog to 16 bit digital form The effects of temperature variation on the DC bias of the gyros are dig...

Page 5: ... buttons that are used to inform the operator or to control the operation of the SPS P230 in different ways Operation Start Up The system is automatic Once power is applied the stabilized platform system will drive to its preset home position with any errors corrected by using a short time constant The time constant of the corrections is increased in increments until it reaches the full operationa...

Page 6: ...ll drive to a preset Home pointing angle based on the potentiometer reading for each axis After initialization the unit can be commanded to return to this pointing angle by pressing the Home Button on the Joystick Controller The stable platform will hold this angle until any joystick motion is detected Full ranges of offsets to this starting point within mechanical limits are settable by the user ...

Page 7: ...iscussed below Centrifugal Force The centrifugal force from turns at a significant speed could pull the pointing angle into error over time depending on the pointing angle If this is a problem setting the system time constant to a higher time interval may help Delta Velocity Acceleration The compensation for forward acceleration is the same as the centrifugal force compensation Safety Features Ove...

Page 8: ...ndependent from the other safety systems Driving the mount away from this limit is not inhibited Reverse power connection Power is diode protected from voltage polarity reversal Recovery is immediate and without damage Installation The servo system is mounted with careful alignment and bolted together Additionally the payload supplied separately must be attached to the SPS The steps for this proce...

Page 9: ... of the mounting ring of the servo system so that the paint mark on the mounting ring will line up in line with the center position of the intended field of view The stop pin on the servo system also needs to be aligned fore of the center position of intended field of view ...

Page 10: ... do not protrude beyond the mounting ring 4 Once the servo system is aligned secure the four mounting bolts User Payload Once the servo system is correctly installed a payload may be installed on the arm of the servo system The SPS has no counterweight and is limited by this load imbalance to a 99 lb 45 Kg payload WARNING Do not apply power until the installation is complete ...

Page 11: ... Interface Cable is attached to the Joystick Controller box and the 8 pin connector end is connected to the Servo System Make sure the power switch is in the off position up non depressed position Now the power connection is attached to the Joystick Controller Box The mating connector is included Be sure to use the proper gauge wire for this connection as the unit can draw up to 6 Amps of current ...

Page 12: ...ical Size Including Mounting Flanges 6 7 W x 15 8 L x 9 2 H 17 0 x 40 1 x 23 4 cm Weight 28lb 12 7Kg Not including payload Connection RS 232 9 pin female D subminiature On joystick controller Connection Power MS3112E 8 4P 4 pin male On joystick controller Connection Interface MS3102A 16S 1S 7 pin female MS3102A 20 7P 8 pin male On joystick controller On servo controller Interface Cable 5 meter MS3...

Page 13: ... to 99 9 degrees second 5 A five character string representing the power supply voltage starting with a space followed by two digits a decimal point and one digit for up to 35 0 VDC 6 A six character string representing the tilt axis motor current starting with a space then a or a followed by one digit a decimal point and two digits for up to 9 99 Amps 7 A six character string representing the pan...

Page 14: ...ler has a joystick four buttons four led indicator lights and three connectors These items are explained below Joystick The joystick positions the SPS P230 payload A left or right movement of the joystick controls the pan motion of the payload while an up or down movement controls the tilt The joystick is also used to correct any rate bias in the system which is discussed later When the joystick i...

Page 15: ...n and a special rate bias adjustment mode When the SPS P230 is in rate bias adjustment mode the LED on the rate bias button will be illuminated When in this mode joystick motions are added to the system as bias adjustments Moving the joystick in the pan axis will adjust pan rate bias while joystick tilt motions will adjust tilt rate bias Joystick Controller Pinout The joystick controller has three...

Page 16: ...g any non command character and will toggle the output for no output data These and other changes are made non volatile default in the unit on EEPROM by keying in the quote character Double spacebar at initialization is required for access to these commands Note that the setting will cause the mechanical brake to be engaged between frames This is not intended to be an operational mode The command ...

Page 17: ... plus any export and transportation charges outside the United States The warranty described in this paragraph shall be in lieu of any other warranty express or implied including but not limited to any implied warranty of merchantability or fitness for a particular purpose Excluded from any warranty given by Watson Industries are products that have been subject to abuse misuse damage or accident t...

Page 18: ...elby Street Eau Claire WI 54703 ATTN Service Department Telephone 715 839 0628 Fax 715 839 8248 email support watson gyro com Returning the Product Product shall be packaged making sure there is adequate packing around all sides Correspondence shall include Customer s Name and Address Contact Information Equipment Model Number Equipment Serial Number Description of Fault It is the customer s respo...

Page 19: ... 49 9 º s Temperature TP 40º to 88ºC Status Bits ST 3 ASCII chars representing Octal digits Flag Bits 1 F1 2 ASCII chars representing Octal digits Flag Bits 2 F2 3 ASCII chars representing Octal digits Status Bits The status bits provide operational information that is presented as two ASCII octal digits The first digit is made up of one bit as follows First Digit Mode 1 Position 0 Inertial The Se...

Page 20: ... when the Pan axis is active First Digit Pan Axis Active Pan Angle Positive Stop Limit Pan Angle Negative Stop Limit 6 Yes Yes No 4 2 5 Yes No Yes 4 1 4 Pan Axis Active 4 Yes No No 4 2 Pan Positive Stop Limit 2 No Yes No 2 1 Pan Negative Stop Limit 1 No No Yes 1 The second digit is made from three bits as follows 1 Tilt angle negative stop limit equals a value of 1 when the Tilt potentiometer reac...

Page 21: ...current limit equals a value of 2 when the Tilt motor is overloaded 2 Pan over current limit equals a value of 1 when the Pan motor is overloaded Second Digit Tilt Motor Overload Pan Motor Overload 3 Yes Yes 2 1 2 Yes No 2 2 Tilt Motor Overload 1 No Yes 1 1 Pan Motor Overload 0 No No The third digit is made from two bits as follows 1 Tilt Rate limit equals a value of 2 when the Tilt axis angular r...

Page 22: ...egins after the startup message is transmitted Typically this time period lasts 5 seconds but could be as long as 127 seconds depending on your sensor 6 Wait until after initialization is finished At this point command mode will be activated and the unit will accept keyboard commands Note Most Watson sensors have initialization times that are shorter than 30 sec Any extra keystrokes other than two...

Page 23: ...ettings To make these new settings the default value send a Quotation Mark 7 Press the space bar after quitting or updating the new channels to restart the data flow Adjust Time Constant 1 Activate Command Mode See above 2 Type this will bring up the main menu again 3 Type 1 to show the current time constants The Nominal Time Constant is set at the factory to a value of 64 seconds This is the main...

Page 24: ... change the Tilt joystick s sensitivity Enter the Tilt Joystick Speed Factor with up to two decimal places Note Input values outside the limit range are rejected with ENTRY EXCEEDS LIMITS TRY AGAIN message and the unit returns to the previous message TYPE IN THE NUMBER OF YOUR SELECTION OR Q TO QUIT 1 ADJUST TIME CONSTANT 2 SET JOYSTICK AXIS PARAMETERS 3 SET OUTPUT CHANNELS 4 LIST CURRENT OUTPUT C...

Page 25: ...Pan Joystick Feel Factor Changing this parameter will change the Pan joystick s responsiveness Enter the Pan Joystick Feel Factor with up to two decimal places Note Input values outside the limit range are rejected with ENTRY EXCEEDS LIMITS TRY AGAIN message and the unit returns to the previous message THE CURRENT TILT AXIS STABILITY FACTOR 0 50 ENTER TILT AXIS STABILITY FACTOR 0 05 to 1 00 FOLLOW...

Page 26: ...values outside the limit range are rejected with ENTRY EXCEEDS LIMITS TRY AGAIN message and the unit returns to the previous message Set New Home Position Typing in will bring up the following menu To update the Home Position typing in 2 will bring up the following menu Typing in a 3 will update the Home position to current Servo System Orientation TYPE IN THE NUMBER OF YOUR SELECTION OR Q TO QUIT...

Page 27: ...aud type 3 To change to 4 800 Baud type 4 The baud rate change will take effect immediately To make the new baud rate the default setting send a quote symbol using the new baud rate Otherwise the old baud rate will return the next time the unit is powered up Note The baud rate of the software that is communicating to the sensor will need to be changed to match the new setting 5 Press the space bar...

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