Assisted takeoff

• US 10,061,327 B2
• Filed: 07/28/2015
• Issued: 08/28/2018
• Est. Priority Date: 03/27/2014
• Status: Active Grant

• Current Assignee: SZ DJI Technology Co., Ltd. (d/b/a DJI) (iFlight Technology Company Limited)
• Original Assignee: SZ DJI Technology Co., Ltd. (d/b/a DJI) (iFlight Technology Company Limited)
• Inventors: Shi, Jun, Pan, Xu Yang
• Primary Examiner(s): Bonzell, Philip J
• Application Number:
  US14/811,448
• Publication Number:
  US 20150331426A1
• Time in Patent Office: 1,127 Days
• CPC Class Codes: B64C 27/00 Rotorcraft; Rotors peculiar thereto
• CPC Class Codes: B64C 29/00 Aircraft capable of landing or taking-off vertically, e.g. vertical take-off and landing [VTOL] aircraft rotorcraft B64C27/00
• CPC Class Codes: B64D 31/06 actuated automatically
• CPC Class Codes: B64U 10/10 Rotorcrafts
• CPC Class Codes: B64U 10/14 with four distinct rotor axes, e.g. quadcopters
• CPC Class Codes: B64U 10/70 Convertible aircraft, e.g. convertible into land vehicles
• CPC Class Codes: B64U 2101/60 for transporting passengers; for transporting goods other than weapons
• CPC Class Codes: B64U 2201/00 UAVs characterised by their flight controls
• CPC Class Codes: B64U 2201/10 autonomous, i.e. by navigating independently from ground or air stations, e.g. by using inertial navigation systems [INS]
• CPC Class Codes: B64U 30/20 Rotors; Rotor supports
• CPC Class Codes: G05B 11/42 for obtaining a characteristic which is both proportional and time-dependent, e.g. P. I., P. I. D.
• CPC Class Codes: G05D 1/042 specially adapted for aircraft
• CPC Class Codes: G05D 1/0669 specially adapted for vertical take-off

Abstract

Systems, methods, and devices are provided for assisted takeoff of an aerial vehicle. The aerial vehicle may takeoff using a first control scheme and switch to a second control scheme for normal flight when a takeoff threshold is met. The first control scheme optionally does not use integral control while the second control scheme may use integral control. The aerial vehicle may determine that a takeoff threshold is met, based on an output to a motor of the aerial vehicle and/or an acceleration of the aerial vehicle.

Claims

1. A method of assisted takeoff of a movable object, said method comprising:

increasing output to an actuator that drives a propulsion unit of the movable object under a first feedback control scheme, wherein the output to the actuator results in the increase of an altitude of the movable object;

determining, with aid of a processor, whether the movable object has met a takeoff threshold based on at least one of the output to the actuator, a velocity of the movable object, or an acceleration of the movable object; and

controlling the output to the actuator using a second feedback control scheme different from the first feedback control scheme when the movable object has met the takeoff threshold, wherein the first feedback control scheme results in proportional-derivative control for the vertical or lateral direction of the movable object and the second feedback control scheme results in proportional-integral-derivative control for the vertical or lateral direction of the movable object.

2. The method of claim 1, wherein the movable object is an aircraft capable of vertically taking off and/or landing.

3. The method of claim 1, wherein determining whether the movable object has met the takeoff threshold is performed without using signals from a source external to the movable object or using signals reflected to the movable object.

4. The method of claim 1, further comprising receiving a command to increase the altitude of the movable object, wherein the command is provided by a remote terminal.

5. The method of claim 1, wherein the first feedback control scheme has an integral value of zero.

6. The method of claim 1, wherein the second feedback control scheme has an integral value that is not zero.

7. The method of claim 1, wherein the movable object is an unmanned aerial vehicle comprising a plurality of rotors configured to generate lift for the aerial vehicle.

8. The method of claim 1, wherein the output to the actuator is determined based on command signals from a flight controller or measured using one or more sensors.

9. The method of claim 1, wherein the takeoff threshold is met when:

the output to the actuator is greater than a first predetermined output value and the acceleration of the movable object in a vertical direction exceeds a predetermined acceleration value, or

the output to the actuator is greater than a second predetermined output value.

10. The method of claim 9 wherein the takeoff threshold is met when the output to the actuator is greater than the second predetermined output value, and wherein the second predetermined output value is different from the first predetermined output value.

11. The method of claim 10, wherein the takeoff threshold is met when the output to the actuator is greater than the second predetermined output value, and wherein the second predetermined output value is greater than the first predetermined output value.

12. A system for assisted takeoff of a movable object, said system comprising:

an actuator of the movable object, wherein an output to the actuator drives a propulsion unit of the movable object and results in the increase of an altitude of the movable object; and

one or more processors, individually or collectively configured to;

determine whether the movable object has met a takeoff threshold based on at least one of the output to the actuator, a velocity of the movable object, or an acceleration of the movable object, and

generate a signal used to control the output to the actuator using a first feedback control scheme when the movable object has not met the takeoff threshold, and using a second feedback control scheme different from the first feedback control scheme when the movable object has met the takeoff threshold,

wherein the first feedback control scheme results in proportional-derivative control for the vertical or lateral direction of the movable object and the second feedback control scheme results in proportional-integral-derivative control for the vertical or lateral direction of the movable object.

13. The system of claim 12, wherein the one or more processors are on-board the movable object.

14. The system of claim 12, wherein the one or more processors are provided on an external device separate from the movable object.

15. The system of claim 12, wherein the movable object is an unmanned aerial vehicle comprising a plurality of rotors configured to generate lift for the unmanned aerial vehicle.

16. The system of claim 12, wherein the one or more processors are configured to determine whether the movable object has met the takeoff threshold without using signals from a source external to the movable object or using signals reflected to the movable object.

17. The system of claim 12, wherein the takeoff threshold is met when one or more of the following conditions are met:

the output to the actuator is greater than a first predetermined output value and the acceleration of the movable object in a vertical direction exceeds a predetermined acceleration value, or

the output to the actuator is greater than a second predetermined output value.

18. The system of claim 12 wherein the output to the actuator is determined based on command signals from a flight controller or measured using one or more sensors.