Background of the Invention Field of the Invention

This invention relates to a charging system of unmanned aerial vehicle (UAV), and more particularly relates to an integration of polarity modulator circuit with a consecutive positive and negative charging pad for charging randomly landed UAV.

Description of Related Arts

Unmanned Aerial Vehicle (UAV) is an aircraft without a pilot on board. UAV can be remote controlled by a pilot at a ground control station or can fly autonomously based on the pre-programmed flight plans. UAV is commonly used for policing, aerial photography, agricultural monitoring, product delivery as well as military applications such as reconnaissance and attack roles.

Usually, UAV require lithium-ion battery cell to act as an on board power source. Said battery has limited specific energy intensity and may cause UAV faced the challenge of having relatively short duration of the flight mission. Therefore, UAV need to land on a special charging platform to exchange or recharge the power source in order to increase the operation time. However, UAV may have difficulty to achieve precise landing position due to inconstancy of environment conditions and inaccuracy of landing assistance system. Consequently, the aforementioned issue may cause UAV cannot be recharged immediately after landing and thus delay the operational time of the UAV.

WIPO Publication No. 2015/107199 A1 disclosed a charging apparatus and method for electrically charging energy storage devices of a mobile consumer such as unmanned ground vehicles, a drone, UAV and multicopter. Said charging apparatus comprises a plurality of area-wise distributed primary contact which are insulated against each other and are connectable with at least two counter contacts of mobile consumer; wherein the primary contact are connected with a control unit comprises a micro processor which is connected with an electrical switches for wiring into a right polarity for the charging operation. It is an advantage of the invention that a contact is even then realized when no exact positioning between the primary contact and the counter contact occur. However, the charging apparatus involve high cost which require large amount of components.

United States Publication No. 2015/0097530 A1 disclosed a recharging station and method for recharging an UAV. The recharging station comprises a parking surface with conductive tile connected to the power supply; a switching circuit for allowing selectively an electrical connection between the power supply and any two of the conductive tiles; a controller for determining the position of the aircraft on the parking surface and control the switching circuit to connect different pair of the conductive tiles to the power supply, thereby making the conductive tile the become positive tile and negative tile. The aircraft can land on the parking surface in any orientation for recharging the battery. However, said recharging is only limited to electrical power supply and involve high complexity of interconnection at the charging station.

United States Patent No. 9828093 B2 disclosed a system and method for recharging remotely controlled aerial vehicle, charging station and rechargeable remotely controlled aerial vehicle. Said system comprises an aerial vehicle and a charging station. The aerial vehicle comprises a power source housed within the airframe and a landing gear structure having first electrical contact and second electrical contact. The charging station also comprises first electrical contact and second electrical contact for docking with the first electrical contact and second electrical contact of the aerial vehicle when the power source is needed to be recharged. Said system further comprises a polarity switching circuit for enabling a correct polarity between the power source and the charging station. However, the aerial vehicle need to land on precise contact position on the charging station. WIPO Publication No. 2016/1 13766 A1 disclosed an electrically charging system for drone wherein comprises a ground subsystem and an on drone subsystem. Said ground system comprises a supply grid for supplying current through contact to a drone; a charging carpet on which the supply grid is placed for its charge and a control unit for controlling ground subsystem and communicating with on drone subsystem; wherein the supply grid is composed of a plurality of squared conductive plates supplied with a three-phase current to allow recharging drones whose landing position is randomly rotated. On the other hand, the on drone subsystem comprises a plurality of sockets composed of a plurality of ferrules for contacting with the supply grid; a battery monitor for monitoring at least one battery; at least one charge balancing device connected to the battery, battery monitor and control unit to balance the final operating charge of the drone. Said charging system can reduce the recharge time and optimize charge amount of the drone. However, said charging system is only accepting electrical power supply which may limit power system of the charging system.

According to exist prior arts, there is a need to have an improved and other alternative of charging system that circumvents these limitations by having a simple, cost effective and fully automatic charging system wherein providing solar and Direct Current (DC) power supply for charging more than one UAV at the same time, also could improve charging capability to support charging of UAV in arbitrary landing orientation.

Summary of Invention

It is an objective of the present invention to provide a charging system with improved charging capability which UAV can land in arbitrary orientation for charging.

It is also an objective of the present invention to provide a simple and cost effective charging system for UAV. It is yet another objective of the present invention to provide a fully automatic charging system for UAV.

Accordingly, these objectives may be achieved by following the teachings of the present invention. The present invention relates to a charging system for an UAV : comprising an on board system and an on ground system; wherein the on board system comprises the UAV having a power source, a polarity modulator circuit and at least two skids mounted with a contact pin; characterized in that: the polarity modulator circuit comprises a plurality of diode bridge rectifier to modulate the polarity signal for suitable charging; each of the diode bridge rectifier having two input terminals and two output terminals; wherein each of the input terminal connected to each of the contact pin; the two output terminals connected to the main terminal of the power source; the on ground system comprises a charging platform having a plurality of square plates connected to a power supply; wherein each of the neighbouring square plate comprises opposite polarity for allowing the contact pins to contact with different polarities

Brief Description of the Drawings

The features of the invention will be more readily understood and appreciated from the following detailed description when read in conjunction with the accompanying drawings of the preferred embodiment of the present invention, in which:

Fig. 1 shows a charging system of UAV comprises on board and on ground system.

Fig. 2 shows a charging system of UAV comprises polarity modulator circuit.

Fig. 3 shows solar and DC power supplies for charging UAV.

Fig. 4 shows landing of UAV on the charging platform.

Fig. 5 shows a graph of charge current during the charging process.

Fig. 6 shows a graph of an on board battery voltage during the charging process.

Detailed Description of the Invention

As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting but merely as a basis for claims. It should be understood that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the invention is to cover all modifications, equivalents and alternatives falling within the scope of the present invention as defined by the appended claims. As used throughout this application, the word "may" is used in a permissive sense (i.e. , meaning having the potential to), rather than the mandatory sense (i.e., meaning must). Similarly, the words "include," "including," and "includes" mean including, but not limited to. Further, the words "a" or "an" mean "at least one” and the word "plurality" means one or more, unless otherwise mentioned. Where the abbreviations or technical terms are used, these indicate the commonly accepted meanings as known in the technical field. For ease of reference, common reference numerals will be used throughout the figures when referring to the same or similar features common to the figures. The present invention will now be described with reference to Figures 1 6

The present invention relates to a charging system (100) for an unmanned aerial vehicle (UAV) (101 ), comprising:

an on board system (102) and an on ground system (103);

wherein the on board system (102) comprises the UAV (101 ) having a power source (104), a polarity modulator circuit (105) and at least two skids (106) mounted with a contact pin (107);

characterized in that:

the polarity modulator circuit (105) comprises a plurality of diode bridge rectifier (108) to modulate the polarity signal for suitable charging; each of the diode bridge rectifier (108) having two input terminals (109) and two output terminals (1 10);

wherein each of the input terminal (109) connected to each of the contact pin (107); the two output terminals (1 10) connected to the main terminal of the power source (104);

the on ground system (103) comprises a charging platform (1 1 1 ) having a plurality of square plates (1 12) connected to a power supply (1 13); wherein each of the neighbouring square plate (1 12) comprises opposite polarity for allowing the contact pins (107) to contact with different polarities.

In a preferred embodiment of the present invention, the polarity modulator circuit (105) comprises a current indicator (1 14) for indicating current flow in charging process.

In a preferred embodiment of the present invention, the square plates (1 12) comprises a conduction material for transmitting charging current and voltage to the power source (104).

In a preferred embodiment of the present invention, the power supply (1 13) comprises a solar panel (1 15) to supply solar power for outdoor charging or a DC adaptor (1 16) to supply DC power for indoor charging.

The present invention also provides a method for charging UAV (101 ), comprising the steps of:

landing of the UAV (101 ) on the charging platform (1 1 1 );

transferring the polarity signal from the contact pins (107) to polarity modulator circuit (105);

modulating the polarity signal before start charging;

transferring the modulated polarity signal to the contact pins (107); supplying charging voltage to the main terminal of the power source

(104);

adjusting the voltage of the power source (104) to the maximum charging voltage level;

initiating of the charging process. Below is an example of a charging system of UAV from which the advantages of the present invention may be more readily understood. It is to be understood that the following example is for illustrative purpose only and should not be construed to limit the present invention in any way.

Examples

Figure 1 shows a block diagram of a charging system (100) for an UAV (101 ) wherein comprises an on board system (102) and an on ground system (103). Said on board system (102) comprises UAV (101 ) having a power source (104) such as battery cells, a polarity modulator circuit (105) for modulating charging polarity and a contact pin (107) mounted on each of a skid (106) of UAV (101 ). On the other hand, the on ground system (103) comprises charging platform (1 1 1 ) connected to DC or solar power supply (1 13).

An overall connection of the polarity modulator circuit (105) in the on board system (102) is shown in Figure 2. Said circuit (105) comprises plurality diode bridge rectifiers (108) for modulating the polarity signal. Basically, the diode bridge rectifiers (108) work as a one-way valve for allowing positive or negative polarity signal to flow through while blocking regular current. Each of the diode bridge rectifier (108) comprises two input terminals (109) and two output terminals (1 10); wherein each of the input terminals (109) are connected to a contact pins (107) for covering all the probability of polarity alterations; whereas, another two of the output terminals (1 10) are connected to the main terminals of the power source (104) of the UAV (101 ). When the input terminals (109) of the diode bridge rectifier (108) receive positive or negative polarity signal, then the diodes in the input terminals will act as forward bias for reducing the potential barrier to establish the easy flow of the current. When conducting the current more than the threshold level of the diodes, the other two diodes in the output terminals (1 10) will act as reverse bias for providing high resistive path to the flow of current and the load current will start to flow through the forward bias. The number of the diode bridge rectifier (108) is adjustable with the change of number of the contact pin (107). Said circuit (105) also comprises a current indicator (1 14) to indicate current flow during the UAV (101 ) charging process.

Figure 3 shows the charging platform (1 1 1 ) comprises plurality of square plates (1 12) made of conduction material wherein having consecutive positive and negative polarity for allowing contact pins (107) to contact with different polarities during randomly landing of UAV (101 ) on the charging platform (1 1 1 ). Said charging platform (1 1 1 ) can be energized by two options of power supply (1 13). For example, solar panel (1 15) for outdoor charging or DC adaptor (1 16) can be used for indoor charging.

Figure 4 shows randomly landing of UAV (101 ) on the charging platform (1 1 1 ). When the contact pins (107) touch the charging platform (1 1 1 ) that comprises consecutive positive and negative polarity, the polarity signal start to flow through the contact pins (107). Consequently, said polarity signal will be transferred to the polarity modulator circuit (105) for modifying before charging. After that, the modulated polarity signal will be received by the contact pins (107) to provide suitable charging voltage to the power source (104). The voltage level of the power source (104) will be adjusted to the maximum charging voltage level due to low charging current is provided to the charging platform (1 1 1 ) may cause voltage drop of the forward diodes. The charging current and voltage during charging process are shown in Figure 5 and Figure 6, respectively. The charging process can be initiated automatically without human intervention.

The charging system (100) configuration in present invention is developed to overcome the misalignment conditions due to landing error. By implementing said charging system (100), the UAV (101 ) can land in any angles and orientations on the charging platform (1 1 1 ) that comprises consecutive positive and negative polarity due to the polarity modulator circuit (105) will modulate the polarity signal for providing suitable charging to the power source (104). Besides, the UAV (101 ) does not need to undock from the landing platform and can quickly take off unhindered after the charging is completed. Furthermore, said polarity modulator circuit (105) is optimized to reduce the weight of charging components and thus reduce the complexity and cost as well.

Although the present invention has been described with reference to specific embodiments, also shown in the appended figures, it will be apparent for those skilled in the art that many variations and modifications can be done within the scope of the invention as described in the specification and defined in the following claims.

Description of the reference numerals used in the accompanying drawings according to the present invention: