Lua Script for Orbit Stabilization

-- Lua script for chapter 2 of "Go Play in Space" - Orbit Stabilization

--

-- Author: David Murley

-- Date: 7/01/2019

-- Version: 1.1

--

--

term.out('Script invoked')

-- Get access to the Delta Gliders GL-01 and GL-02. With the interface handles

-- obtained, access to various controls and flight data are acquired.

hGL1=vessel.get_interface('GL-01')

hGL2=vessel.get_interface('GL-02')

-- Wait until vessels are docked before continuing with script

term.out ('Waiting until vessels are docked before')

term.out (' executing remainder of script')

continue = true

hDckPort = hGL1:get_dockhandle(0)

continue=true

while continue do

 hDckStatus=hGL1:get_dockstatus(hDckPort)

 if hDckStatus ~= nil then

   continue = false

 else

   proc.wait_simdt(5)

 end

end

-- Kill Rotation

term.out('Kill Rotation')

hGL1:set_navmode(NAVMODE.KILLROT)

proc.wait_simdt(10)

-- Undock

term.out('Undock')

hGL1:undock(ALLDOCKS)

-- Set RCS mode on GL-01 to Translation

term.out('Set RCS mode to translate.')

hGL1:set_rcsmode(RCSMODE.LIN)

-- Thrust away from GL-02. The resulting distance from GL-02 is about 35 meters.

term.out('Separation of GL-01 and GL-02 to +/-35 meters')

-- oapi.set_tacc(10)

thrstGrpHdl1=hGL1:get_thrustergrouphandle(THGROUP.ATT_BACK)

hGL1:set_thrustergrouplevel(THGROUP.ATT_BACK,.1)

proc.wait_simdt(11.237)

hGL1:set_thrustergrouplevel(THGROUP.ATT_BACK,0)

proc.wait_simdt(52.777)

thrstGrpHdl2=hGL1:get_thrustergrouphandle(THGROUP.ATT_FORWARD)

hGL1:set_thrustergrouplevel(THGROUP.ATT_FORWARD,.1)

proc.wait_simdt(18.733)

hGL1:set_thrustergrouplevel(THGROUP.ATT_FORWARD,0)

-- oapi.set_tacc(1)

term.out('Separation completed.')

-- Set the prograde autopilot for both vessels to on.

term.out('Set prograde autopilot for both vessels.')

hGL1:set_navmode(NAVMODE.PROGRADE)

hGL2:set_navmode(NAVMODE.PROGRADE)

proc.wait_simdt(25)

-- The following 14 lines set up the annotations that are used to display

-- time to apoapsis for both vessels

hApT1Label = oapi.create_annotation()

hApT1Label:set_pos(0.7,0.7,1,1)

hApT1Label:set_colour({r=1, g=0.7, b=0.3})

hApT1Label:set_text ('ApT (GL-01): ')

hApT1 = oapi.create_annotation()

hApT1:set_pos(0.8,0.7,1,1)

hApT1:set_colour({r=1, g=0.7, b=0.3})

hApT2Label = oapi.create_annotation()

hApT2Label:set_pos(0.7,0.75,1,1)

hApT2Label:set_colour({r=1, g=0.7, b=0.3})

hApT2Label:set_text ('ApT (GL-02): ')

hApT2 = oapi.create_annotation()

hApT2:set_pos(0.8,0.75,1,1)

hApT2:set_colour({r=1, g=0.7, b=0.3})

-- Wait until +/- 20 seconds before apoapsis, then slow time acceleration to 1x.

-- Ignition of main engines on both vessels occurs around +/- 10 seconds before

-- apoapsis. Time acceleration during the waiting period is set to 100x to

-- reduce waiting time for those who are easily bored.

term.out ('Wait until +/- 10 seconds from aoapis. Then fire')

term.out (' main engines to stabilize orbit')

oapi.set_tacc(100)

continue = true

while continue do

 el,op = hGL1:get_elementsex()

 TimeToApoapsis= op.ApT

 hApT1:set_text(TimeToApoapsis)

 el,op=hGL2:get_elementsex()

 TimeToAposis=op.ApT

 hApT2:set_text(TimeToApoapsis)

 if TimeToApoapsis < 20 then

    continue=false

 end

 proc.wait_simdt(1)

end

oapi.set_tacc(1)

-- Track time to apoapsis from time=+/-20 sec in 1x time.

continue=true

while continue do

 el,op = hGL1:get_elementsex()

 TimeToApoapsis1 =op.ApT

 hApT1:set_text(TimeToApoapsis1)

 el,op = hGL2:get_elementsex()

 TimeToApoapsis2=op.ApT

 hApT2:set_text(TimeToApoapsis2)

 if TimeToApoapsis1 <= 10 then

   continue=false

   oapi.del_annotation(hApT1)

   oapi.del_annotation(hApT1Label)

   oapi.del_annotation(hApT2)

   oapi.del_annotation(hApT2Label)

 else

   proc.wait_simdt(1)

 end

end

-- Set up annotations to show orbit eccentricities

hEcc1Label = oapi.create_annotation()

hEcc1Label:set_pos(0.7,0.7,1,1)

hEcc1Label:set_colour({r=1, g=0.7, b=0.3})

hEcc1Label:set_text ('Ecc (GL-01): ')

hEcc1 = oapi.create_annotation()

hEcc1:set_pos(0.8,0.7,1,1)

hEcc1:set_colour({r=1, g=0.7, b=0.3})

hEcc2Label = oapi.create_annotation()

hEcc2Label:set_pos(0.7,0.75,1,1)

hEcc2Label:set_colour({r=1, g=0.7, b=0.3})

hEcc2Label:set_text ('Ecc (GL-02): ')

hEcc2 = oapi.create_annotation()

hEcc2:set_pos(0.8,0.75,1,1)

hEcc2:set_colour({r=1, g=0.7, b=0.3})

-- Stabilize orbits

term.out('Start Stabilization of Orbits')

hGL1:set_thrustergrouplevel(THGROUP.MAIN, 1)

hGL2:set_thrustergrouplevel(THGROUP.MAIN, 1)

continue1=true

continue2 = true

while continue1 or continue2 do

 el=hGL1:get_elements()

 e1 = el.e

 hEcc1:set_text(e1)

 if e1 <= .005 then
   hGL1:set_thrustergrouplevel (THGROUP.MAIN, 0)

   continue1 = false

 end 

 el = hGL2:get_elements()

 e2 = el.e

 hEcc2:set_text(e2)

 if e2 <= .005 then

   hGL2:set_thrustergrouplevel (THGROUP.MAIN, 0)

   continue2 = false

 end

 proc.wait_simdt(1)

end

term.out ('Orbits stabilized.')

term.out ()

term.out ()

-- Wait a few seconds and then delete eccentricity annotations

proc.wait_simdt(10)

oapi.del_annotation(hEcc1)

oapi.del_annotation(hEcc1Label)

oapi.del_annotation(hEcc2)

oapi.del_annotation(hEcc2Label)

term.out ('End Script')