초록 ▼

A method and apparatus for guiding a vehicle to intercept a target is described. The method iteratively estimates a time-to-go until target intercept and modifies an acceleration command based upon the revised time-to-go estimate. The time-to-go estimate depends upon the position, the velocity, and

A method and apparatus for guiding a vehicle to intercept a target is described. The method iteratively estimates a time-to-go until target intercept and modifies an acceleration command based upon the revised time-to-go estimate. The time-to-go estimate depends upon the position, the velocity, and the actual or real time acceleration of both the vehicle and the target. By more accurately estimating the time-to-go, the method is especially useful for applications employing a warhead designed to detonate in close proximity to the target. The method may also be used in vehicle accident avoidance and vehicle guidance applications.

대표청구항 ▼

What is claimed is: 1. A method of guiding a vehicle to a target, the method comprising the steps of: providing the vehicle with a processor unit, a position unit, a velocity unit, an acceleration unit, and a control unit; and controlling an acceleration of the vehicle according to a first equation

What is claimed is: 1. A method of guiding a vehicle to a target, the method comprising the steps of: providing the vehicle with a processor unit, a position unit, a velocity unit, an acceleration unit, and a control unit; and controlling an acceleration of the vehicle according to a first equation: wherein: A is an acceleration command calculated by the processing unit, the control unit controlling the vehicle based upon the thus calculated acceleration command A, r is a vehicle-to-target position vector determined by the position unit, v is a net vehicle-to-target velocity determined by the velocity unit based upon a velocity of the vehicle and a velocity of the target, a is a net vehicle-to-target acceleration determined by the acceleration unit based upon an acceleration of the vehicle and an acceleration of the target, and τ is a time-to-go estimate determined by the processor according to a second equation: 2. A method of guiding a vehicle to a target in accordance with claim 1, wherein a time-to-go solution to the second equation is approximated by the equation: wherein: description="In-line Formulae" end="lead"d=2( r cos β+ v2)-3 v2 cos2γ,description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"e=2 v3 cos3γ-2 v cos γ( r cos β+ v2)+2 v r cos α,description="In-line Formulae" end="tail" description="In-line Formulae" end="lead" v=v/a, description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"cos γ=a쨌v/av, description="In-line Formulae" end="tail" description="In-line Formulae" end="lead" r=r/a, description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"cos β=a쨌r/ar, description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"cos α=v쨌r/vr, description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"a=|a|,a≠0,description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"v=|v|, anddescription="In-line Formulae" end="tail" description="In-line Formulae" end="lead"r=|r|.description="In-line Formulae" end="tail" 3. A method of guiding a vehicle to a target in accordance with claim 1, wherein a time-to-go solution to the second equation is approximated by the equation: wherein: description="In-line Formulae" end="lead"d=2( r cos β+ v2)-3 v2 cos2γ,description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"e=2 v3 cos3γ-2 v cos γ( r cos β+ v2)+2 v r cos α,description="In-line Formulae" end="tail" description="In-line Formulae" end="lead" v=v/a, description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"cos γ=a쨌v/av, description="In-line Formulae" end="tail" description="In-line Formulae" end="lead" r=r/a, description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"cos β=a쨌r/ar, description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"cos α=v쨌r/vr, description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"a=|a|,a≠0,description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"v=|v|, anddescription="In-line Formulae" end="tail" description="In-line Formulae" end="lead"r=|r|.description="In-line Formulae" end="tail" 4. A method of guiding a vehicle to a target in accordance with claim 1, wherein a time-to-go solution to the second equation is approximated by the equation: description="In-line Formulae" end="lead"τ=(r0/v0)f(N, α0),description="In-line Formulae" end="tail" wherein: r0 is an initial vehicle-to-target distance, v0 is an initial net vehicle-to-target speed, and N is a proportional navigation constant. 5. A method of guiding a vehicle to a target in accordance with claim 4, wherein f(N,α0) is approximated by: 6. A method of guiding a vehicle to a target in accordance with claim 4, wherein f(N,α0) is approximated by: description="In-line Formulae" end="lead"f(N,α0)≈[1+p1( N)α0+p2(N)α0 2+p3(N)α03+p 4(N)α04+p5( N)α05], anddescription="In-line Formulae" end="tail" p1(N), p2(N), p3(N), p4(N), and p5(N) are polynomials of N. 7. A method of guiding a vehicle to a target in accordance with claim 4, wherein f(N,α0) is approximated by: 8. A method of guiding a vehicle to a target in accordance with claim 7, wherein tan2α02. 10. A method of guiding a vehicle to a target in accordance with claim 4. 11. The method of claim 10, wherein N is one of 3, 4, and 5. 12. A guidance system for guiding a vehicle to a target, the guidance system comprising: a position unit for determining a vehicle-to-target position vector r; a velocity unit for determining a net vehicle-to-target velocity v based upon a velocity of the vehicle and a velocity of the target; an acceleration unit for determining a net vehicle-to-target acceleration a based upon an acceleration of the vehicle and an acceleration of the target; a time-to-go unit for determining a time-to-go τ between a vehicle position and a target position according to a first equation: a processor for calculating an acceleration command A according to a second equation: and a control unit for outputting control signals based upon the thus calculated acceleration command A. 13. A guidance system for guiding a vehicle to a target in accordance with claim 12, wherein a time-to-go solution to the first equation is approximated by the equation: wherein: description="In-line Formulae" end="lead"d=2( r cos β+ v2)-3 v2 cos2γ,description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"e=2 v3 cos3γ-2 v cos γ( r cos β+ v2)+2 v r cos α,description="In-line Formulae" end="tail" description="In-line Formulae" end="lead" v=v/a, description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"cos γ=a쨌v/av, description="In-line Formulae" end="tail" description="In-line Formulae" end="lead" r=r/a, description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"cos β=a쨌r/ar, description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"cos α=v쨌r/vr, description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"a=|a|,a≠0,description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"v=|v|, anddescription="In-line Formulae" end="tail" description="In-line Formulae" end="lead"r=|r|.description="In-line Formulae" end="tail" 14. A guidance system for guiding a vehicle to a target in accordance with claim 12, wherein a time-to-go solution to the first equation is approximated by the equation: wherein: description="In-line Formulae" end="lead"d=2( r cos β+ v2)-3 v2 cos2γ,description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"e=2 v3 cos3γ-2 v cos γ( r cos β+ v2)+2 v r cos α,description="In-line Formulae" end="tail" description="In-line Formulae" end="lead" v=v/a, description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"cos γ=a쨌v/av, description="In-line Formulae" end="tail" description="In-line Formulae" end="lead" r=r/a, description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"cos β=a쨌r/ar, description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"cos α=v쨌r/vr, description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"a=|a|,a≠0,description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"v=|v|, anddescription="In-line Formulae" end="tail" description="In-line Formulae" end="lead"r=|r|.description="In-line Formulae" end="tail" 15. A guidance system for guiding a vehicle to a target in accordance with claim 12, wherein a time-to-go solution to the first equation is approximated by the equation: description="In-line Formulae" end="lead"τ=(r0/v0)f(N, α0),description="In-line Formulae" end="tail" wherein: r0 is an initial vehicle-to-target distance, v0 is an initial net vehicle-to-target speed, and N is a proportional navigation constant. 16. A guidance system for guiding a vehicle to a target in accordance with claim 15, wherein f(N,α0) is approximated by 17. A guidance system for guiding a vehicle to a target in accordance with claim 15, wherein f(N,α0) is approximated by: description="In-line Formulae" end="lead"f(N,α0)≈[1+p1( N)α0+p2(N)α0 2+p3(N)α03+p 4(N)α04+p5( N)α05], anddescription="In-line Formulae" end="tail" p1(N), p2(N), p3(N), p4(N), and p5(N) are polynomials of N. 18. A guidance system for guiding a vehicle to a target in accordance with claim 15, wherein f(N,α0) is approximated by: 19. A guidance system for guiding a vehicle to a target in accordance with claim 18, wherein tan2α02. 21. A guidance system for guiding a vehicle to a target in accordance with claim 15. 22. The guidance system of claim 21, wherein N is one of 3, 4, and 5. 23. A missile for intercepting a target, the missile comprising: a position unit for determining a vehicle-to-target position vector r; a velocity unit for determining a net vehicle-to-target velocity v based upon a velocity of the vehicle and a velocity of the target; an acceleration unit for determining a net vehicle-to-target acceleration a based upon an acceleration of the vehicle and an acceleration of the target; a time-to-go unit for determining a time-to-go τ between a vehicle position and a target position according to a first equation: a processor for calculating an acceleration command A according to a second equation: a control unit for outputting a guidance signal based upon the thus calculated acceleration command A; a body; and a control element adapted for changing at least one of a direction and a velocity of the missile, the control element responsive to the thus outputted guidance signal. 24. A missile for intercepting a target in accordance with claim 23, wherein a time-to-go solution to the first equation is approximated by the equation: wherein: description="In-line Formulae" end="lead"d=2( r cos β+ v2)-3 v2 cos2γ,description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"e=2 v3 cos3γ-2 v cos γ( r cos β+ v2)+2 v r cos α,description="In-line Formulae" end="tail" description="In-line Formulae" end="lead" v=v/a, description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"cos γ=a쨌v/av, description="In-line Formulae" end="tail" description="In-line Formulae" end="lead" r=r/a, description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"cos β=a쨌r/ar, description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"cos α=v쨌r/vr, description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"a=|a|,a≠0,description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"v=|v|, anddescription="In-line Formulae" end="tail" description="In-line Formulae" end="lead"r=|r|.description="In-line Formulae" end="tail" 25. A missile for intercepting a target in accordance with claim 23, wherein a time-to-go solution to the first equation is approximated by the equation: wherein: description="In-line Formulae" end="lead"d=2( r cos β+ v2)-3 v2 cos2γ,description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"e=2 v3 cos3γ-2 v cos γ( r cos β+ v2)+2 v r cos α,description="In-line Formulae" end="tail" description="In-line Formulae" end="lead" v=v/a, description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"cos γ=a쨌v/av, description="In-line Formulae" end="tail" description="In-line Formulae" end="lead" r=r/a, description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"cos β=a쨌r/ar, description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"cos α=v쨌r/vr, description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"a=|a|,a≠0,description="In-line Formulae" end="tail" description="In-line Formulae" end="lead"v=|v|, anddescription="In-line Formulae" end="tail" description="In-line Formulae" end="lead"r=|r|.description="In-line Formulae" end="tail" 26. A missile for intercepting a target in accordance with claim 23, wherein a time-to-go solution to the first equation is approximated by the equation: description="In-line Formulae" end="lead"τ=(r0/v0)f(N, α0),description="In-line Formulae" end="tail" wherein: r0 is an initial vehicle-to-target distance, v0 is an initial net vehicle-to-target speed, and N is a proportional navigation constant. 27. A missile for intercepting a target in accordance with claim 26, wherein f(N,α0) is approximated by: 28. A missile for intercepting a target in accordance with claim 26, wherein f(N,α0) is approximated by: description="In-line Formulae" end="lead"f(N,α0)≈[1+p1( N)α0+p2(N)α0 2+p3(N)α03+p 4(N)α04+p5( N)α05], anddescription="In-line Formulae" end="tail" p1(N), p2(N), p3(N), p4(N), and p5(N) are polynomials of N. 29. A missile for intercepting a target in accordance with claim 26, wherein f(N,α0) is approximated by: 30. A missile for intercepting a target in accordance with claim 29, wherein tan2α02. 32. A missile for intercepting a target in accordance with claim 26. 33. The missile of claim 32, wherein N is one of 3, 4, and 5. 34. A method of guiding a vehicle to avoid an obstacle, the method comprising the steps of: providing the vehicle with a control unit, a position unit, a velocity unit, an acceleration unit, an offset unit, and a processor unit; and generating a guidance signal with the control unit according to a first equation: wherein: A is an acceleration command calculated by the processing unit, the control unit controlling the vehicle based upon the thus calculated acceleration command A, r is a vehicle-to-target position vector determined by the position unit, v is a net vehicle-to-target velocity determined by the velocity unit based upon a velocity of the vehicle and a velocity of the target, a is a net vehicle-to-target acceleration determined by the acceleration unit based upon an acceleration of the vehicle and an acceleration of the target, ψ is an offset vector required to avoid an obstacle determined by an offset unit, and τ is a time-to-go estimate determined by the processor unit according to a second equation: 35. A method of guiding a vehicle in accordance with claim 34, wherein the guidance signal is at least one of an audible warning and a visual warning. 36. A method of guiding a vehicle in accordance with claim 34 further comprising the steps of: providing the vehicle with a guidance unit; and guiding the vehicle with the guidance unit, the guidance unit being responsive to the thus generated guidance signal. 37. A guidance system for guiding a vehicle to avoid an obstacle, the guidance system comprising: a position unit for determining a vehicle-to-obstacle position vector r; a velocity unit for determining a net vehicle-to-obstacle velocity v; an acceleration unit for determining a net vehicle-to-obstacle acceleration a; a time-to-go unit for determining a time-to-go τ between a vehicle position and a target position according to a first equation: a margin unit for determining an offset vector ψ to avoid an obstacle; a processor for calculating an acceleration command A according to a second equation: and a control unit for outputting a guidance signal based upon the thus calculated acceleration command A. 38. A guidance system for guiding a vehicle in accordance with claim 37, wherein the guidance signal is at least one of an audible warning and a visual warning. 39. A guidance system for guiding a vehicle in accordance with claim 37 further comprising a guidance unit for guiding the vehicle, the guidance unit being responsive to the thus generated guidance signal. 40. A vehicle that avoids an obstacle, the vehicle comprising: a position unit for determining a vehicle-to-obstacle position vector r; a velocity unit for determining a net vehicle-to-obstacle velocity v; an acceleration unit for determining a net vehicle-to-obstacle acceleration a; a time-to-go unit for determining a time-to-go τ between a vehicle position and a target position according to a first equation: a margin unit for determining an offset vector ψ to avoid an obstacle; a processor for calculating an acceleration command A according to a second equation: a control unit for outputting a guidance signal based upon the thus calculated acceleration command A; a body; and a guidance unit adapted for changing at least one of a direction and a velocity of the vehicle, the guidance unit responsive to the thus outputted guidance signal.