Lua Script for Orbit Stabilization

-- Lua script for chapter 2 of Go Play in Space -- -- 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')