Three-dimensional manipulation of teams of quadrotors

Patent metadata

Field	Value
Publication number	US-9599993-B2
Application number	US-201314397761-A
Country	US
Kind code	B2
Filing date	Apr 30, 2013
Priority date	Apr 30, 2012
Publication date	Mar 21, 2017
Grant date	Mar 21, 2017

Abstract

A system and method is described for controlling flight trajectories of at least two flying vehicles towards goal positions. The system includes at least two flying vehicles with onboard inertial measurement units for determining and updating orientation, angular velocities, position and linear velocities of the at least two flying vehicles, a motion capture system to detect current position and velocity of each of the at least two flying vehicles, and a base controller in communication with the motion capture system and in communication with the plurality of flying vehicles. The base controller calculates for each of the flying vehicles, at predetermined intervals of time, optimum trajectory paths using piece-wise smooth polynomial functions, applying weighting factors, and enforcing overlap constraints.

First claim

What is claimed:

1. A trajectory generation method for controlling states of at least two vehicles towards goal positions and orientations, the method comprising the steps of:
determining orientation and angular velocities of the vehicles;
controlling the orientation and angular velocities of the vehicles by controlling at least one motor of the vehicles;
determining current position and velocity of each of the vehicles;
controlling the position and velocity of each of the vehicles by specifying the desired orientation and angular velocities and the net thrust required from the at least one motor;
calculating for each of the vehicles, at predetermined intervals of time, optimum trajectory paths by using piece-wise smooth polynomial functions, applying relative cost weighting factors among the at least two vehicles and enforcing inter-vehicle overlap constraints;
based on the calculated optimum trajectory paths, sending commands to each of the vehicles to control, individually, their state, causing such vehicles to follow the calculated optimum trajectory path while avoiding collisions; and
updating current position and velocity of each of the vehicles.

2. A method as in claim 1 , wherein each state of a vehicle comprises its orientation and angular velocity, and position and linear velocity.

3. A method as in claim 1 , wherein an orientation error is estimated and the orientation is controlled on-board of each of the vehicles.

4. A method as in claim 1 , wherein the weighting factors applied to each of the at least two vehicles are dissimilar.

5. A method as in claim 1 , wherein the method is iteratively executed at a plurality of said pre-determined intervals of time.

6. A method as in claim 1 , further comprising using integer constraints to enforce collision constraints with obstacles and other vehicles and to optimally assign goal positions for said at least two vehicles.

7. A method as in claim 6 , wherein said integer constraints are used to find the optimal goal assignments for the flying vehicles by applying for each quadrotor q and goal g the following integer constraints:
x T q ( t nw )≦ x g +Mβ qg

x T q ( t nw )≧ x g −Mβ qg

y T q ( t nw )≦ y g +Mβ qg

y T q ( t nw )≧ y g −Mβ qg

z T q ( t nw )≦ z g +Mβ qg

z T q ( t nw )≧ z g −Mβ qg

where β qg is a binary variable used to enforce an optimal goal assignment.

8. A method as in claim 7 , further comprising applying the following constraint to guarantee that at least n g quadrotors reach the desired goal positions:
Σ q=1 n q Σ g=1 n g β qg ≦n g n q −n g .

9. A method as in claim 1 , wherein the at least two vehicles comprises at least two flying vehicles.

10. A trajectory generation method for controlling states of at least two flying vehicles towards goal positions and orientations, the method comprising the steps of:
determining orientation and angular velocities of the flying vehicles;
controlling the orientation and angular velocities of the flying vehicles by controlling at least one motor of the flying vehicles;
determining current position and velocity of each of the flying vehicles;
controlling the position and velocity of each of the flying vehicles by specifying the desired orientation and angular velocities and the net thrust required from the at least one motor;
calculating for each of the flying vehicles, at predetermined intervals of time, optimum trajectory paths by using piece-wise smooth polynomial functions, applying weighting factors and enforcing overlap constraints;
based on the calculated optimum trajectory paths, sending commands to each of the flying vehicles to control, individually, their state, causing such flying vehicles to follow the calculated optimum trajectory path while avoiding collisions; and

updating current position and velocity of each of the flying vehicles,
wherein calculating an optimum trajectory path for each flying vehicle comprises generating trajectories that smoothly transition through n w desired waypoints at specified times, t w while minimizing the integral of the k r th derivative of position squared for n q quadrotors in accordance with the equation:

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Assignees

• Univ Pennsylvania

Inventors

• Kumar Vijay
• Kushleyev Aleksandr
• Mellinger Daniel

Classifications

• B64U2201/00

  UAVs characterised by their flight controls · CPC title

• G05D1/104 Primary

  involving a plurality of aircrafts, e.g. formation flying (traffic control systems for aircraft G08G5/00) · CPC title

• B64C39/024

  of the remote controlled vehicle type, i.e. RPV · CPC title

• B64C2201/14

  Operations & Transport · mapped topic

• G08G5/04

  Physics · mapped topic