阅读说明：本技术 一种多自由度球形电机驱动控制装置 (Multi-freedom-degree spherical motor driving control device ) 是由 王秀芹 张锐 李国丽 于 2020-12-29 设计创作，主要内容包括：本发明是一种多自由度球形电机驱动控制装置,包括：电源,与驱动模块和触摸屏连接,为驱动模块和触摸屏提供直流电压信号；具有外接蓝牙模块的主控制器与位置传感器以及触摸屏连接,通过蓝牙模块得到并输出多自由度球形电机输出轴的位置信息,从而输出控制力矩值以及多自由度球形电机所有定子线圈需要的电流值信息；驱动模块与主控制器连接,接收并输出所有定子线圈需要的电流值信息,驱动多自由度球形电机运动；触摸屏与主控制器连接,接收并显示多自由度球形电机输出轴位置信息、控制力矩信息以及多自由度球形电机所有定子线圈需要的电流值信息。本发明在驱动模块中采用优化算法,并使用小体积主控制器,使装置成本降低、动态响应速度提高。(The invention relates to a multi-degree-of-freedom spherical motor driving control device, which comprises: the power supply is connected with the driving module and the touch screen and provides direct-current voltage signals for the driving module and the touch screen; the main controller with an external Bluetooth module is connected with the position sensor and the touch screen, and the position information of the output shaft of the multi-degree-of-freedom spherical motor is obtained and output through the Bluetooth module, so that the control torque value and the current value information required by all stator coils of the multi-degree-of-freedom spherical motor are output; the driving module is connected with the main controller, receives and outputs current value information required by all stator coils, and drives the multi-freedom-degree spherical motor to move; the touch screen is connected with the main controller, and receives and displays the position information of the output shaft of the multi-freedom-degree spherical motor, the control moment information and the current value information required by all stator coils of the multi-freedom-degree spherical motor. The invention adopts an optimization algorithm in the driving module and uses a small-volume main controller, thereby reducing the cost of the device and improving the dynamic response speed.)

1. The utility model provides a spherical motor drive control device of multi freedom which characterized in that mainly includes power, main control unit, drive module and touch-sensitive screen, wherein:

the power supply is connected with the driving module and the touch screen and provides direct-current voltage signals for the driving module and the touch screen;

the main controller is provided with an external Bluetooth module, is connected with the position sensor and the touch screen, and obtains and outputs position information of an output shaft of the multi-degree-of-freedom spherical motor through the Bluetooth module so as to output a control torque value and current value information required by all stator coils of the multi-degree-of-freedom spherical motor;

the driving module is connected with the main controller, receives and outputs current value information required by all the stator coils and drives the multi-freedom-degree spherical motor to move;

and the touch screen is connected with the main controller and is used for receiving and displaying the position information of the output shaft of the multi-freedom-degree spherical motor, the control moment information and the current value information required by all stator coils of the multi-freedom-degree spherical motor.

2. The utility model provides a spherical motor drive control device of multi freedom which characterized in that mainly includes power, main control unit, drive module and touch-sensitive screen, wherein:

the power supply is connected with the driving module and the touch screen and provides direct-current voltage signals for the driving module and the touch screen;

the device comprises a main controller with an external Bluetooth module, a position sensor and a touch screen, wherein the main controller is connected with the position sensor and the touch screen, obtains and outputs position information of an output shaft of the multi-freedom-degree spherical motor through the Bluetooth module, and obtains and outputs current value information required by all stator coils of the multi-freedom-degree spherical motor through the touch screen;

the driving module is connected with the main controller, receives and outputs current value information required by all the stator coils and drives the multi-freedom-degree spherical motor to move;

the touch screen is connected with the main controller and used for receiving and displaying the position information of the output shaft of the multi-freedom-degree spherical motor; and outputting current value information of all stator coils by a user through a touch screen, wherein the current value information is the magnitude, the direction and the on-off state of current.

3. The multi-degree-of-freedom spherical motor drive control device according to claim 1 or 2, wherein the master controller communicates with the touch screen through a ModBus communication protocol.

4. The multi-degree-of-freedom spherical motor drive control device according to claim 1 or 2, wherein the main controller obtains data of the position sensor through the bluetooth module in a wireless communication mode and decodes the data to obtain corresponding position, speed and acceleration values.

5. The multi-degree-of-freedom spherical motor driving control device as claimed in claim 1, wherein the main controller obtains the control torque of the multi-degree-of-freedom spherical motor according to the position information of the output shaft of the multi-degree-of-freedom spherical motor sent by the position sensor.

6. The driving control device of the multi-degree-of-freedom spherical motor according to claim 1, wherein the main controller obtains a current matrix required by all stator coils of the multi-degree-of-freedom spherical motor according to the control torque characteristic matrix of the multi-degree-of-freedom spherical motor.

7. The multi-degree-of-freedom spherical motor drive control device according to claim 1 or 2, wherein the current value information is packaged into a data packet with the same protocol as that of the drive module, the data packet is sent to the drive module through a serial port (1) on the main controller, and the drive module outputs a corresponding current value to a stator coil of the multi-degree-of-freedom spherical motor.

8. The multi-degree-of-freedom spherical motor drive control device according to claim 1 or 2, wherein the main controller receives and analyzes the data packet transmitted by the position sensor to obtain the position information of the output shaft of the multi-degree-of-freedom spherical motor.

9. The multi-degree-of-freedom spherical motor drive control device according to claim 1 or 2, wherein the connection and disconnection between the bluetooth module and the position sensor are controlled by a Key _ up button on the main controller.

10. The multi-degree-of-freedom spherical motor drive control device according to claim 1 or 2, wherein the sending of the instruction for calibrating the position sensor is controlled by a Key _0 Key on the master controller; and whether the current information is sent to a driving module is controlled through a Key _1 Key on the main controller.

Technical Field

The invention belongs to the technical field of multi-degree-of-freedom spherical motors, and particularly relates to a multi-degree-of-freedom spherical motor driving control device.

Background

With the development of modern manufacturing industry, electromechanical devices such as industrial robots and mechanical arms capable of realizing multi-degree-of-freedom motion in three-dimensional space are widely applied to various industrial productions. The traditional multi-degree-of-freedom mechanical transmission device is usually composed of a plurality of single-shaft motors, and the multi-degree-of-freedom spherical motor can realize multi-degree-of-freedom motion on one motor, so that the volume of the whole electromechanical equipment is reduced, the transmission efficiency is increased, the dynamic response speed is improved, and the multi-degree-of-freedom mechanical transmission device can be applied to more complex occasions. For the motor to move, it is necessary to make the stator coil flow current to interact with the permanent magnet to generate electromagnetic torque to drive the rotor to move. The driving and controlling technology of the traditional single-shaft motor is relatively mature, but along with the improvement of the degree of freedom, the number of stator coils of the multi-degree-of-freedom spherical motor and the structure of a rotor can be correspondingly changed to realize the multi-degree-of-freedom motion, so that great difficulty is brought to the driving control of the multi-degree-of-freedom spherical motor. A set of driving control device with simple structure and excellent performance is a foundation and a precondition for realizing the industrial application of the multi-freedom spherical motor.

In order to solve the above problems, in recent years, a drive control device for a multi-degree-of-freedom spherical motor has been proposed. Compared with the common motor drive control, the drive control device of the multi-freedom spherical motor mainly has the following advantages: (1) the output current range is large, and the control precision is high. (2) Can be controlled on line in real time, and can meet the requirement of multi-channel output. (3) The current with positive and negative polarities can be output, and the output power is high.

At present, a plurality of multi-degree-of-freedom spherical motor driving control devices are proposed in the prior art. It includes: the device comprises a master control station, a control module, a driving module, a position sensor and a controlled multi-degree-of-freedom spherical motor, wherein the master control station uses a computer. However, the drive control device still has a further improved space in the selection of the drive module and the upper computer.

In summary, the disadvantages of the prior art are as follows: the driving module has simple algorithm and slow dynamic response. The host computer uses a computer, has overlarge volume and is difficult to compare with a common motor drive control device. The driving current solving speed is slow.

Disclosure of Invention

In order to solve the technical problems in the prior art, the invention aims to provide the multi-degree-of-freedom spherical motor driving control device which is simple in structure, high in dynamic response speed and high in current solving speed.

In order to achieve the above object, a first aspect of the present invention provides a multi-degree-of-freedom spherical motor driving control device, which is implemented by the following technical solution, and mainly includes a power supply, a main controller, a driving module, and a touch screen, wherein:

the power supply is connected with the driving module and the touch screen and provides direct-current voltage signals for the driving module and the touch screen;

the main controller is provided with an external Bluetooth module, is connected with the position sensor and the touch screen, and obtains and outputs position information of an output shaft of the multi-degree-of-freedom spherical motor through the Bluetooth module so as to output a control torque value and current value information required by all stator coils of the multi-degree-of-freedom spherical motor;

the driving module is connected with the main controller, receives and outputs current value information required by all the stator coils and drives the multi-freedom-degree spherical motor to move;

and the touch screen is connected with the main controller and is used for receiving and displaying the position information of the output shaft of the multi-freedom-degree spherical motor, the control moment information and the current value information required by all stator coils of the multi-freedom-degree spherical motor.

In order to achieve the above object, a second aspect of the present invention provides a multi-degree-of-freedom spherical motor driving control device, which is implemented by the following technical solution, and mainly includes a power supply, a main controller, a driving module, and a touch screen, wherein:

the power supply is connected with the driving module and the touch screen and provides direct-current voltage signals for the driving module and the touch screen;

the device comprises a main controller with an external Bluetooth module, a position sensor and a touch screen, wherein the main controller is connected with the position sensor and the touch screen, obtains and outputs position information of an output shaft of the multi-freedom-degree spherical motor through the Bluetooth module, and obtains and outputs current value information required by all stator coils of the multi-freedom-degree spherical motor through the touch screen;

the driving module is connected with the main controller, receives and outputs current value information required by all the stator coils and drives the multi-freedom-degree spherical motor to move;

the touch screen is connected with the main controller and used for receiving and displaying the position information of the output shaft of the multi-freedom-degree spherical motor; a user can output current value information of all stator coils through the touch screen, wherein the current value information is the size, the direction and the on-off state of current.

Preferably, the main controller communicates with the touch screen through a ModBus communication protocol.

Preferably, the main controller obtains data of the position sensor through the bluetooth module in a wireless communication mode and decodes the data to obtain corresponding position, speed and acceleration values.

Preferably, the main controller obtains the control torque of the multi-degree-of-freedom spherical motor according to the position information of the output shaft of the multi-degree-of-freedom spherical motor sent by the position sensor.

Preferably, the main controller obtains current matrixes required by all stator coils of the multi-degree-of-freedom spherical motor according to the control torque characteristic matrix of the multi-degree-of-freedom spherical motor.

Preferably, the current value information is packaged into a data packet with the same protocol as that of the driving module, the data packet is sent to the driving module through a serial port 1 on the main controller, and the driving module outputs a corresponding current value to the stator coil of the multi-degree-of-freedom spherical motor.

Preferably, the main controller receives and analyzes the data packet sent by the position sensor to obtain the position information of the output shaft of the multi-degree-of-freedom spherical motor.

Preferably, the Key _ up Key on the main controller is used for controlling the connection and disconnection between the Bluetooth module and the position sensor.

Preferably, the sending of the instruction for calibrating the position sensor is controlled by a Key _0 Key on the main controller; and whether the current information is sent to a driving module is controlled through a Key _1 Key on the main controller.

The invention has the beneficial effects that: compared with other multi-degree-of-freedom spherical motor driving control devices, the multi-degree-of-freedom spherical motor driving control device provided by the invention uses the small-volume main controller, and has the characteristics of low cost, simple structure, high dynamic response speed, high current solving speed and the like. Meanwhile, the invention adopts an optimization algorithm in the driving module, so that the current response time of the stator coil is greatly reduced, and the fluctuation of the current change stage is reduced. Creating conditions for the industrial application of the multi-degree-of-freedom spherical motor.

Drawings

FIG. 1 is a schematic structural diagram of a system scheme 1 of a multi-degree-of-freedom spherical motor driving control device of the invention;

FIG. 2 is a schematic structural diagram of a system scheme 2 of a multi-degree-of-freedom spherical motor driving control device according to the invention;

FIG. 3 is a schematic diagram of the functional principle of the main controller in use in the present invention;

FIG. 4 is a schematic diagram of the operation of a multi-degree-of-freedom spherical motor driving control device according to the present invention;

FIG. 5a is a graph of voltage changes at two ends of a single stator coil of a multi-degree-of-freedom spherical motor obtained by a PI control algorithm in the prior art;

FIG. 5b is a graph of voltage changes at two ends of a single stator coil of a multi-degree-of-freedom spherical motor obtained by a prior art incremental PID control algorithm;

FIG. 5c is a graph of voltage changes at two ends of a single stator coil of a multi-degree-of-freedom spherical motor obtained by a prior art integral separation PID control algorithm;

FIG. 5d is a graph of voltage changes at two ends of a single stator coil of the multi-degree-of-freedom spherical motor obtained by the improved PID control algorithm.

Detailed Description

Other aspects, features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which form a part of this specification, and which illustrate, by way of example, the principles of the invention.

The invention mainly designs a drive control device for a multi-degree-of-freedom spherical motor. The device replaces current PC master control station and control module with main control unit and touch-sensitive screen, and the main control unit adopts the STM32F407 treater.

Referring to fig. 1, a first aspect of the present invention is to provide a solution 1 for a multi-degree-of-freedom spherical motor driving control apparatus, which mainly includes a power supply, a main controller, a driving module, and a touch screen, wherein:

the power supply is connected with the driving module and the touch screen and provides direct-current voltage signals for the driving module and the touch screen;

the main controller is provided with an external Bluetooth module, is connected with the position sensor and the touch screen, and obtains and outputs position information of an output shaft of the multi-degree-of-freedom spherical motor through the Bluetooth module so as to output a control torque value and current value information required by all stator coils of the multi-degree-of-freedom spherical motor;

the driving module is connected with the main controller, receives and outputs current value information required by all the stator coils and drives the multi-freedom-degree spherical motor to move;

and the touch screen is connected with the main controller and is used for receiving and displaying the position information of the output shaft of the multi-freedom-degree spherical motor, the control moment information and the current value information required by all stator coils of the multi-freedom-degree spherical motor.

Specifically, the main controller communicates with the touch screen through a ModBus communication protocol.

Specifically, the main controller obtains data of the position sensor through the Bluetooth module in a wireless communication mode and decodes the data to obtain corresponding position, speed and acceleration values.

Specifically, the main controller obtains the control torque of the multi-freedom-degree spherical motor according to the position information of the output shaft of the multi-freedom-degree spherical motor sent by the position sensor.

Specifically, the main controller obtains current matrixes needed by all stator coils of the multi-degree-of-freedom spherical motor according to the control torque characteristic matrix of the multi-degree-of-freedom spherical motor.

Specifically, the current value information is packaged into a data packet with the same protocol as that of the driving module, the data packet is sent to the driving module through a serial port 1 on the main controller, and the driving module outputs a corresponding current value to the stator coil of the multi-freedom-degree spherical motor.

Specifically, the main controller receives and analyzes a data packet sent by the position sensor to obtain the position information of the output shaft of the multi-degree-of-freedom spherical motor.

Specifically, the connection and disconnection between the Bluetooth module and the position sensor are controlled through a Key _ up Key on the main controller.

Specifically, the Key _0 Key on the main controller controls the sending of an instruction for calibrating the position sensor; and whether the current information is sent to a driving module is controlled through a Key _1 Key on the main controller.

Referring to fig. 2, a scheme 2 of a multi-degree-of-freedom spherical motor driving control device according to a second aspect of the present invention is shown, in which a main controller obtains and outputs position information of an output shaft of a multi-degree-of-freedom spherical motor through a bluetooth module, and a touch screen receives and displays the position information. A user inputs current value information required by all stator coils in a touch screen interface and outputs the current value information to the main controller, the main controller sends the current value information to the driving module through the serial port 1, and the driving module outputs corresponding current values to the stator coils of the multi-freedom-degree spherical motor.

With reference to fig. 2, a second aspect of the present invention is further introduced, in which a technical solution of a multi-degree-of-freedom spherical motor driving control device mainly includes a power supply, a main controller, a driving module, and a touch screen, wherein:

the power supply is connected with the driving module and the touch screen and provides direct-current voltage signals for the driving module and the touch screen;

the device comprises a main controller with an external Bluetooth module, a position sensor and a touch screen, wherein the main controller is connected with the position sensor and the touch screen, obtains and outputs position information of an output shaft of the multi-freedom-degree spherical motor through the Bluetooth module, and obtains and outputs current value information required by all stator coils of the multi-freedom-degree spherical motor through the touch screen;

the driving module is connected with the main controller, receives and outputs current value information required by all the stator coils and drives the multi-freedom-degree spherical motor to move;

the touch screen is connected with the main controller and used for receiving and displaying the position information of the output shaft of the multi-freedom-degree spherical motor; a user can output current value information of all stator coils through the touch screen, wherein the current value information is the size, the direction and the on-off state of current.

Specifically, the main controller communicates with the touch screen through a ModBus communication protocol.

Specifically, the main controller obtains data of the position sensor through the Bluetooth module in a wireless communication mode and decodes the data to obtain corresponding position, speed and acceleration values.

Specifically, the current value information is packaged into a data packet with the same protocol as that of the driving module, the data packet is sent to the driving module through a serial port 1 on the main controller, and the driving module outputs a corresponding current value to the stator coil of the multi-freedom-degree spherical motor.

Specifically, the main controller receives and analyzes a data packet sent by the position sensor to obtain the position information of the output shaft of the multi-degree-of-freedom spherical motor.

Specifically, the connection and disconnection between the Bluetooth module and the position sensor are controlled through a Key _ up Key on the main controller.

Specifically, the Key _0 Key on the main controller controls the sending of an instruction for calibrating the position sensor; and whether the current information is sent to a driving module is controlled through a Key _1 Key on the main controller.

Referring to fig. 1 and 2, the present invention will be further explained in detail: the multi-freedom-degree spherical motor control system is characterized in that a Bluetooth module is externally connected to the main controller, the Bluetooth module adopts an ATK-HC05 Bluetooth 2.0 module, receives position information sent by a position sensor in a wireless transmission mode, combines the position information set by the main controller, calculates a control torque value required by the multi-freedom-degree spherical motor through a drive control algorithm in the main controller, solves current value information required by all stator coils of the multi-freedom-degree spherical motor through a control torque characteristic matrix, sends the current value information to the drive module through a serial port 1, and energizes the stator coils of the multi-freedom-degree spherical motor after receiving a current instruction, so that the multi-freedom-degree spherical motor moves. The main controller uses the serial port 2 to carry out RS485 communication with the touch screen, and the touch screen displays real-time position information, control moment information, current value information and the like of the output shaft of the multi-freedom-degree spherical motor. The power supply is a direct current power supply and provides a direct current voltage signal. And calculating the current by using a driving control algorithm in the main controller.

Referring to fig. 1, fig. 2, fig. 3 and fig. 4, the working principle of the multi-degree-of-freedom spherical motor driving control device of the present invention in the whole system is described in detail as follows:

referring to fig. 3, the main controller of the present invention uses a functional schematic diagram to show: serial port 1, serial port 2, serial port 3, power supply port, LCD screen, RS485 interface, Key _ up button, Key _0 button, Key _1 button, LED, program download, ATK-HC 05. The Bluetooth module adopts an ATK-HC05 Bluetooth module, and the program downloading is carried out by using an ST-LINKV2 simulator. The power supply port supplies power by adopting a power adapter and outputs direct-current voltage.

Referring to fig. 4, the working schematic diagram of a multi-degree-of-freedom spherical motor driving control device of the present invention includes: the device comprises a user, a position sensor, a main controller, a touch screen, a driving module and a multi-degree-of-freedom spherical motor, and the working principle of the multi-degree-of-freedom spherical motor driving control device is described as follows: the user goes to operate touch-sensitive screen and main control unit, and the development board is external to have bluetooth module. The user can control the connection or disconnection of the Bluetooth module and the position sensor through a Key _ up Key on the main controller, the Key _0 Key sends an instruction for calibrating the position of the position sensor, and the Key _1 Key controls the current information to be sent to the driving module through the serial port 1, and an LCD screen on the main controller can display whether the instruction is sent successfully or not. Firstly, the driving module and the touch screen are powered through a direct current source. The touch screen supplies power to the starting-up display control interface, the main controller supplies power through a power supply port and then runs a program, the main controller is connected with the position sensor through the Bluetooth module, then receives a data packet sent by the position sensor through a serial port 3 on the main controller, and then analyzes the data packet to obtain the position information of the output shaft of the multi-freedom-degree spherical motor; and then obtaining a control torque through a control algorithm in the main controller, and finally solving current matrixes required by all stator coils. And packaging the obtained current matrix into a data packet with the same protocol as the driving module, and sending the data packet to the driving module through a serial port 1 on the main controller. The driving module outputs corresponding current values to the stator coils of the multi-freedom-degree spherical motor. The main controller uses the serial port 2 to carry out RS485 communication with the touch screen through a ModBus protocol, so that position information, control moment information, control current information and the like are displayed on the touch screen. And the Key _ up Key controls the connection between the Bluetooth module and the position sensor. The indicator lamp on the Bluetooth module is in flash twice every 2s, namely the connection is successful, the operation of a drive control algorithm in the main controller is in an active connection mode, the Key _ up is pressed down, the connection is disconnected, and the connection can be carried out again by pressing once again. The Key _0 controls the sending of a calibration instruction of the position sensor; the Key _1 controls the sending of current data; the LED0 is on, which indicates that the communication between the main controller and the driving module is normal and the current data is sent normally. The LED1 lights indicating that the master controller is communicating properly with the touch screen.

The invention discloses a touch screen control interface for multi-degree-of-freedom spherical motor drive control, which comprises: the power-on interface, the position and torque information display interface, the current display interface and the coil electrifying interface are four interfaces. And different keys are selected to be pressed in the starting-up interface, and the corresponding display interface can be jumped to. The position and torque display interface may display in real time the rotational angles in the three degrees of freedom and the corresponding torque values in the three degrees of freedom. The current display interface can display the current values of the 24 stator coils in real time. The coil energizing interface can input the current value of any coil in the 24 stator coils.

Referring to fig. 5a to 5d, four graphs of voltage changes at two ends of a single stator coil of a multi-degree-of-freedom spherical motor obtained by a PI control algorithm, an incremental PID control algorithm, an integral separation PID control algorithm and an improved PID control algorithm according to the present invention are shown, and a comparative description of advantageous technical effects brought by the improved algorithm according to the present invention is introduced below with respect to a low dynamic response speed of a driving module: as shown in fig. 5 a-5 d, the left lower line in the graph represents the initial value of the voltage across the single stator coil of the multi-degree-of-freedom spherical motor, and the right higher line represents the set value of the voltage across the single stator coil. Given the same initial and set values, the abscissa represents time, the ordinate represents voltage value, and the time between two dashed segments represents the time of change of the voltage across the stator coil. And enabling the voltages at the two ends of the stator coil to reach the same set value.

Among the above four algorithms, the PI control algorithm of fig. 5a, the incremental PID control algorithm of fig. 5b, and the integral-separate PID control algorithm of fig. 5c, which respectively obtain respective graphs of voltage changes across the stator coil, each graph showing that the time taken for the voltage across the stator coil to rise for the algorithm is substantially uniform, while fig. 5d shows that the graph of voltage changes across the stator coil is obtained using the improved PID control algorithm of the present invention, and the graph of fig. 5d shows that the time taken for the voltage changes across the stator coil is shorter than that obtained by the PI control algorithm, the incremental PID control algorithm, and the integral-separate PID control algorithm of the related art. Referring to fig. 5a, the curve between two broken lines gradually increases in a step shape, the curve between two broken lines in fig. 5b and 5c has no obvious step shape, but the curve rises too gently, and the curve between two broken lines in fig. 5d rises to a very high value in a very short time. In summary, the superiority of the improved PID control algorithm is reflected.

In a typical PID control, the introduction of an integration element, i.e. the introduction of I, is mainly to eliminate static errors and improve control accuracy. However, when the system is started or stopped or the set value is changed greatly, the system output will have large deviation in a short time, which will cause integral accumulation and large error of the system. For the control of a multi-degree-of-freedom spherical motor, when an output shaft moves from one position to another position, currents with different magnitudes need to be supplied to a plurality of stator coils in a short time. Larger errors and longer adjustment times can affect the time control effect. The improved PID control algorithm can prevent the control quantity from staying in a saturation area for a long time, and has a better control effect when the system changes the set value greatly.

According to the algorithm and the comparison graph, after the improved PID control algorithm is used, the current response speed of the stator coil is greatly improved, and the motion control of the multi-freedom spherical motor is facilitated.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.