GB1561661A - Data storage system - Google Patents

Description

(54) DATA STORAGE SYSTEM (71) We, HALL AUTOMATION LIMITED, a British Company, of Wiggenhall Industrial Estate, Watford, Hertfordshire, WED 1 8AP, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is performed to be particularly described in and by the following statement:- The present invention relates to a method and system for acquisition and storage of data, particularly for storing data for use in controlling automatic manipulating devices, sometimes known as "industrial robots".

At the present time, the data for controlling such devices is often recorded on magnetic tape which necessitates the use of electromechanical drives with their attendent disadvantages. Moreover, magnetic tape is not an ideal medium for the type of environment in which such equipment is often used.

It is an object of the present invention to provide a data storage method in which the use of magnetic tapes and an electromechanical tape drive may be avoided.

From one aspect the invention provides a method of handling data for controlling an automatic manipulating device, wherein said data is derived in or converted into digital form during a teaching phase of the manipulating device and is applied in real time to a microprocessor which selects specific data points from the real time data, and the specific data points from said microprocessor are fed to a memory device whose output is in turn employed to control the microprocessor so as to generate a microprocessor output including intermediate data between said specific data points and the output from said microprocessor is employed to control said manipulating device.

Preferably, the memory device is of a nonvolatile type.

From another aspect the invention provides a data storage system which supplies data to control an automatic manipulating device, said system comprising a microprocessor which outputs the control data and which is fed with selected data points from a storage device, said data points enabling the microprocessor to generate the control data in real time related to original real time data from which the data points were selected, this original data being derived during a teaching phase of the manipulating device.

Advantageously, the control data can be expressed in the form of cubic spline curves parametric in time, i.e. composite curves made up from a set of linked cubic equations in the parameter time. These cubic equations are linked such as to provide continuity of both slope and curvature at the junctions between adjacent cubic equations. Separate cubic equations are used to link between the adjacent significant points that have been stored after selection from the input data. The microprocessor can then be used to evaluate intermediate points on the cubic equation and thus reconstruct a reasonably accurate version of the original data, from only the selected significant points.This reconstruction which is effected in real time, enables recon struction of a very large amount of data from a small number of selected data points stored in the non-volatile memory; thus minimising the size of this memory and the speed at which data is stored and read from it.

The invention will now be further described by way of example, with reference to the accompanying drawing which is a block diagram of one embodiment of data storage system according to the invention.

Referring to the drawing, a manipulating device or industrial robot to be controlled is shown at 1. The control programme may be produced by taking the robot through a "teach" phase in which the workhead of the robot is manually manipulated through the motions required to carry out a specific task, these motions being converted into electrical voltages from which digital signals are derived to construct the control programme for use in subsequent operation of the robot.

The robot is capable of movement in up to six degrees of freedom and output voltages representing movement in these degrees of freedom are fed through a multiplexer 2 to an analogue-to-digital converter 3, whose output is fed to a microprocessor 4.

Since the data is derived in real time, irrespective of the length of the teaching phase, the microprocessor does not accumulate a back-log of data to be processed.

The movement in any of the degrees of freedom can be expressed as a curve when plotted against time and the microprocessor operates on the digital signals fed thereto to select significant points at approximately equal distances along the arc length of this curve, as well as areas of particular interest, such as turning points or points of inflexion, and discards the remainder of the input data.

Other algorithms can be used to decide on which points to select as significant. These selected points are then stored, together with their real times in the non-volatile memory device 5.

Once a programme has been stored in this way, for each degree of freedom, the output of the memory 5 can be employed for the subsequent control of the operation of the robot 1. Thus the microprocessor 4 uses the significant points and real times stored in the memory device 5 to compute a set of cubic spline equations passing through these significant points. It then calculates finely spaced points along the cubic equations between successive significant points in real time and this digital data is output and fed through a digital-to-analogue converter 7 whose output signals are applied through a distributor 8 and sample and hold amplifiers 9 to control the robot 1 in any of its six degrees of freedom.

The whole operation is synchronised to real time.

Since the converters 3 and 7 are not in use at the same time, they may largely share common circuitry.

Various modifications may be made to the system described. Thus, the input information may be derived directly in digital form, e.g.

from a shaft encoder.

The system may also be employed to control two or more machines independently and at the same time, e.g. one in the teaching mode and one in the operating mode.

Instead of the microprocessor operating on polynomials in the form of cubic equations, it may operate with polynomials in the form of quartic or even up to seventh order equations, or spline curves of nonpolynomical nature, such as those based on parametric equations relating radius of curvature to distance travelled along the arc length of the curve.

WHAT WE CLAIM IS: 1. A method of handling data for controlling an automatic manipulating device, wherein said data is derived in or converted into digital form during a teaching phase of the manipulating device and is applied in real time to a microprocessor which selects specific data points from the real time data, and the specific data points from said microprocessor are fed to a memory device whose output is in turn employed to control the microprocessor so as to generate a microprocessor output including intermediate data between said specific data points and the output from said microprocessor is employed'to control said manipulating device.

2. A method as claimed in claim 1, wherein the memory device is of a nonvolatile type.

3. A method as claimed in claim 1 or 2, wherein the control data is expressed in the form of cubic spline curves parametric in time, i.e. composite curves made up from a set of linked cubic equations in the parameter time.

4. A method as claimed in claim 1 or 2, wherein the control data operates with polynomials in the form of quartic or up to seventh order equations.

5. A method as claimed in claim 1 or 2, wherein the control data operates with spline curves of non-polynomical nature.

6. A method of acquisition and storage of data substantially as hereinbefore described with reference to the accompanying drawing.

7. A data storage system which supplies data to control an automatic manipulating device, said system comprising a microprocessor which outputs the control data and which is fed with selected data points from a storage device, said data points enabling the microprocessor to generate the control data in real time related to original real time data from which the data points were selected, this original data being derived during a teaching phase of the manipulating device.

8. A system as claimed in claim 7, wherein the input to the microprocessor is in digital form derived from an analogue to digital converter or directly from a digital shaft encoder.

9. A system as claimed in claim 7 or 8, wherein the output of the storage device is fed through a digital to analogue converter whose output signals are applied through a distributor device to control said manipulating device.

10. A system as claimed in claim 7, 8 or 9, wherein the storage device is a non-volatile memory.

11. A system as claimed in claims 8 and and 9, wherein said analogue to digital converter and digital to analogue converter share common circuitry.

12. A system as claimed in any of claims 7 to 11, wherein said system is employed to control independently a plurality of said manipulating devices.

13. A data storage system substantially as hereinbefore described with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (13)

**WARNING** start of CLMS field may overlap end of DESC **. Since the data is derived in real time, irrespective of the length of the teaching phase, the microprocessor does not accumulate a back-log of data to be processed. The movement in any of the degrees of freedom can be expressed as a curve when plotted against time and the microprocessor operates on the digital signals fed thereto to select significant points at approximately equal distances along the arc length of this curve, as well as areas of particular interest, such as turning points or points of inflexion, and discards the remainder of the input data. Other algorithms can be used to decide on which points to select as significant. These selected points are then stored, together with their real times in the non-volatile memory device 5. Once a programme has been stored in this way, for each degree of freedom, the output of the memory 5 can be employed for the subsequent control of the operation of the robot 1. Thus the microprocessor 4 uses the significant points and real times stored in the memory device 5 to compute a set of cubic spline equations passing through these significant points. It then calculates finely spaced points along the cubic equations between successive significant points in real time and this digital data is output and fed through a digital-to-analogue converter 7 whose output signals are applied through a distributor 8 and sample and hold amplifiers 9 to control the robot 1 in any of its six degrees of freedom. The whole operation is synchronised to real time. Since the converters 3 and 7 are not in use at the same time, they may largely share common circuitry. Various modifications may be made to the system described. Thus, the input information may be derived directly in digital form, e.g. from a shaft encoder. The system may also be employed to control two or more machines independently and at the same time, e.g. one in the teaching mode and one in the operating mode. Instead of the microprocessor operating on polynomials in the form of cubic equations, it may operate with polynomials in the form of quartic or even up to seventh order equations, or spline curves of nonpolynomical nature, such as those based on parametric equations relating radius of curvature to distance travelled along the arc length of the curve. WHAT WE CLAIM IS:

1. A method of handling data for controlling an automatic manipulating device, wherein said data is derived in or converted into digital form during a teaching phase of the manipulating device and is applied in real time to a microprocessor which selects specific data points from the real time data, and the specific data points from said microprocessor are fed to a memory device whose output is in turn employed to control the microprocessor so as to generate a microprocessor output including intermediate data between said specific data points and the output from said microprocessor is employed'to control said manipulating device.

2. A method as claimed in claim 1, wherein the memory device is of a nonvolatile type.

3. A method as claimed in claim 1 or 2, wherein the control data is expressed in the form of cubic spline curves parametric in time, i.e. composite curves made up from a set of linked cubic equations in the parameter time.

4. A method as claimed in claim 1 or 2, wherein the control data operates with polynomials in the form of quartic or up to seventh order equations.

5. A method as claimed in claim 1 or 2, wherein the control data operates with spline curves of non-polynomical nature.

6. A method of acquisition and storage of data substantially as hereinbefore described with reference to the accompanying drawing.

7. A data storage system which supplies data to control an automatic manipulating device, said system comprising a microprocessor which outputs the control data and which is fed with selected data points from a storage device, said data points enabling the microprocessor to generate the control data in real time related to original real time data from which the data points were selected, this original data being derived during a teaching phase of the manipulating device.

8. A system as claimed in claim 7, wherein the input to the microprocessor is in digital form derived from an analogue to digital converter or directly from a digital shaft encoder.

9. A system as claimed in claim 7 or 8, wherein the output of the storage device is fed through a digital to analogue converter whose output signals are applied through a distributor device to control said manipulating device.

10. A system as claimed in claim 7, 8 or 9, wherein the storage device is a non-volatile memory.

11. A system as claimed in claims 8 and and 9, wherein said analogue to digital converter and digital to analogue converter share common circuitry.

12. A system as claimed in any of claims 7 to 11, wherein said system is employed to control independently a plurality of said manipulating devices.

13. A data storage system substantially as hereinbefore described with reference to the accompanying drawing.