GB2106756A - Remote control system using a radio link - Google Patents

Abstract

A motor 9 is controlled by a manually- operable controller 1 via a radio link 3,5. The radio link uses a separate frequency for each of a predetermined number of motor speeds. The frequencies used are sufficiently low that the link operates on an inductance effect with a maximum range of a fraction of a wavelength. <IMAGE>

Description

SPECIFICATION Remote control system using a radio link The present invention relates to a remote control system using a radio link particularly, but not exclusively, for use with travelling cranes.

In conventional travelling crane remote control systems using radio links, if it is desired to provide a large number of available speed steps, a separate frequency must be used for each speed and this makes it technically difficult to provide 20 or 30 frequency channels, without requiring very expensive equipment. Some remote control systems use UHFNHF radio frequencies and in these high frequencies is the ability to bounce of objects and therefore carry much further than low frequencies. In addition a disadvantage of using these frequencies is the close proximity of the frequencies allocated in the frequency spectrum and their use in mobile units e.g. taxis, cars and emergency services resulting in a considerable probability of interference and consequently a safety hazard.Furthermore as the system only provides control by such discrete speed steps, this means that the operating efficiency of the crane is limited, which is another disadvantage of the present control system.

An object of the present invention is to obviate or mitigate the above said disadvantages.

According to the present invention there is provided a remote control system comprising, a controller adapted to transmit control information relating to the desired movement of an electric motor., the controller having an adjustable control member having positions corresponding to off, select direction, reduce speed, maintain speed and increase speed, a receiver for recording the control information, and control means responsive to the receiver to control the electric motor, the control means including a voltage varying device, the output of which controls the speed of the motor, the output of the voltage varying device being determined by the positions selected on the control member.

Preferably the control member is a joystick and is manually adjustable.

Preferably also the remote control system uses radio telemetry, the frequency of the carrier used being around 300 KHZ and the wavelength being around 1000 metres.

Preferably also, there are at least three motions controllable by the remote control system, the controller having an auxiliary selector for determining movement of the particular electric motor selected.

Alternatively, there is provided a separate controllet for each movement or a single controller having a separate joystick for each movement.

Preferably also, the select direction and reduce speed position controls on the controller are combined in the same position.

Preferably also, there are four frequency channels used for each motion.

Preferably also, the control member is a joystick which is spring biased to the off position in the absence of a manually applied force.

Preferably also, the voltage varying device is a motorised potentiometer.

Preferably also, the output of the motorised potentiometer is processed in a signal processing means to provide the control signal to the electric motor, the signal processing means including a microprocessor and a memory device, the memory device containing a program executed under the control of the microprocessor for controlling the movement of the motor in a predetermined manner.

An embodiment of the present invention will now be described by way of example with reference to the accompanying drawings, in which: Figure lisa block diagram of the remote control system according to the present invention; Figure2 is a block diagram similar to Figure 1 with a single controller having an auxiliary selector.

Figure 3 is a schematic diagram of the positions of one control member of Figure 1 or Figure 2 in accordance with the present invention.

Referring now to the drawings, a controller 1 has control members 2a, 2b and 2c in the form of joysticks each of which are manually movable through a range of positions shown in detail in Figure 3. The output of each control member is connected to a transmitter 3, which transmits the information on a carrier frequency of around 300 Kz, giving a transmission wavelength of approximately 1000 metres. Therefore, the system actually works on an induction effect.

There is a single frequency corresponding to each position of the control member selected. That is for one motion 4 frequency channels are used plus the frequency for 'on' and another frequency for 'off'.

For three motions fourteen frequencies are required.

One of the carrier frequencies enables the system but if the range between the controller and receiver exceeds a predetermined distance, for example 60 feet, the induction signal would be insufficient to continue to enable the system.

Of course, should the controller be brought into range again the system would immediately be enabled again. In Figure 2, the controller may also include a crane motion selector switch 4 for selecting the particular crane motion desired, e.g. long-travel, cross-travel, hoist or lower.

Information relating to the control of each motion of an electric motor is transmitted on the frequency of the particular position selected. The control movements transmitted for each motion are those shown in Figure 3 and are select direction and reduce speed 1, hold speed 2, increase speed 3 and off4.

The transmitted control frequency is picked up by a receiverS tuned to that particular frequency. The movement control signal is then fed to a motorised potentiometer 6 which is then driven in response.

The potentiometer output 7 is a voltage which varies between 0v and 1 2v, and also in polarity depending on the direction selected and is fed to a signal processing means in the form of a control card 8.

The control card processes the potentiometer output signal and sends a speed control signal to the motor 9 accordingly.

The method of operation of the remote control system is described as follows with particular referenceto Figure 1.

The desired motion is firstly selected using the appropriate joystick on the controller 1, i.e. longtravel. cross-travel, hoist or lower.

Initially, the joystick is at position 4, i.e. off. In order to initiate movement of the motor the operator moves the joystick in direction A or direction B to select the direction of movement for the particular crane motion desired.

When the joystick is moved from position 4 'off' to position 1 the 'directional' relay is selected but no movement occurs, when the joystick is moved from position 1 to position 2 the 'hold speed' relay is energised together with a directional relay; no movement occurs. When the joystick is moved from position 2 to position 3 the 'hold speed' relay drops out, the 'directional' relay is still energised and the 'increase speed' relay is energised. The motorised potentiometer 6 then begins to drive from 0v to 12 volts and the potentiometer output signal 7 is fed to the main control card 8. If the joystick is maintained at position 3 the potentiometer drives until the output voltage is 12v. When this occurs the power to the motorised potentiometer 9 is cut-off by a microswitch and full speed is held.When the joystick is moved from position 3 to position 2 the 'increase speed' relay drops out and the 'hold speed' relay is energised. If the motor is moving at full speed there is no change, however, if the motor 9 is moving at any speed between zero and full speed then this speed is maintained. When moving from position 2 to position 1 the 'hold speed' relay drops out and the potentiometer 6 starts to motor back to zero thus decreasing speed until motion stops and the brakes are applied. When the output 7 of the potentiometer is at zero volts, the control card 8 cuts power to the motion and applies the brakes. In the same manner movements may be controlled for other crane motions.

Several modifications may be made to the system hereinbefore described without departing from the scope of the invention.

For example, if the controller shown in Figure 2 is used the desired motion would firstly be selected using the selector switch 4, then the motion would be controlled by the joystick as described above.

For example, the control card 8 may be replaced by a control card 10 which contains a programmable memory 11 and a microprocessor 12. The microprocessor 12 controls the movement or motion of the electric motor 9 in accordance with a predetermined program stored in the memory executed under the control of the microprocessor 12 in response to the potentiometer output signal 7. This provides remote control of the motions of a travelling crane by the microprocessor-based infinitely variable speed control system (IVSC) disclosed in copending British Patent Application in the name of J. H. Carruthers and Co., Ltd.

Advantages of the present invention include; the use of a low carrier frequency is approved by the U.K. Health and Safety Executive and it has none of the disadvantages associated with UH FNHF fre- quencies; the ergonomics of the control system allied to the infinitely variable speed control system means that minimal operator training is required to develop the required skills; all the information necessary to effect control of the crane motion can be transmitted on 4 channels only; and the use of the remote control system together with the IVSC enables the crane to be operated safely and maximises the operating efficiency.

CLAIMS (Filed on 7 - 9 - 82) 1. A remote control system comprising: a controller adapted to transmit control information relating to the desired movement of an electric motor, the controller having an adjustable control member having positions corresponding to off, select direction, reduce speed, maintain speed and increase speed, a receiver for recording the control information, and control means responsive to the receiver to control the electric motor, the control means including a voltage varying device, the output of which controls the speed of the motor, the output of the voltage varying device being determined by the positions selected on the control member.

2. The system of claim 1, in which the control member is a manually-operable joystick.

3. The system of claim 1 or claim 2, in which the controller and receiver are connected by radio telemetry on a carrier frequency of 200-400 kHz.

4. The system of any preceding claim, in which there are at least three motions controllable by the remote control system, the controller having an auxiliary selector for determining movement of the particular electric motor selected.

5. The system of any preceding claim, in which the select direction and reduce speed position controls on the controller are combined in the same position.

6. The system of any preceding claim, in which four frequency channels are used for each motion.

7. The system of any preceding claim, in which the voltage varying device is a motorised potentiometer.

8. The system of claim 7, in which the outut of the motorised poteniometer is processed in a signal processing means to provide the control signal to the electric motor, the signal processing means including a microprocessor and a memory device, the memory device containing a program executed under the control ofthemicroprocessorforcontroll- ing the movement of the motor in a predetermined manner.

9. A remote control system, substantially as herein described with reference to the drawings.

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

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. signal and sends a speed control signal to the motor 9 accordingly. The method of operation of the remote control system is described as follows with particular referenceto Figure 1. The desired motion is firstly selected using the appropriate joystick on the controller 1, i.e. longtravel. cross-travel, hoist or lower. Initially, the joystick is at position 4, i.e. off. In order to initiate movement of the motor the operator moves the joystick in direction A or direction B to select the direction of movement for the particular crane motion desired. When the joystick is moved from position 4 'off' to position 1 the 'directional' relay is selected but no movement occurs, when the joystick is moved from position 1 to position 2 the 'hold speed' relay is energised together with a directional relay; no movement occurs. When the joystick is moved from position 2 to position 3 the 'hold speed' relay drops out, the 'directional' relay is still energised and the 'increase speed' relay is energised. The motorised potentiometer 6 then begins to drive from 0v to 12 volts and the potentiometer output signal 7 is fed to the main control card 8. If the joystick is maintained at position 3 the potentiometer drives until the output voltage is 12v. When this occurs the power to the motorised potentiometer 9 is cut-off by a microswitch and full speed is held.When the joystick is moved from position 3 to position 2 the 'increase speed' relay drops out and the 'hold speed' relay is energised. If the motor is moving at full speed there is no change, however, if the motor 9 is moving at any speed between zero and full speed then this speed is maintained. When moving from position 2 to position 1 the 'hold speed' relay drops out and the potentiometer 6 starts to motor back to zero thus decreasing speed until motion stops and the brakes are applied. When the output 7 of the potentiometer is at zero volts, the control card 8 cuts power to the motion and applies the brakes. In the same manner movements may be controlled for other crane motions. Several modifications may be made to the system hereinbefore described without departing from the scope of the invention. For example, if the controller shown in Figure 2 is used the desired motion would firstly be selected using the selector switch 4, then the motion would be controlled by the joystick as described above. For example, the control card 8 may be replaced by a control card 10 which contains a programmable memory 11 and a microprocessor 12. The microprocessor 12 controls the movement or motion of the electric motor 9 in accordance with a predetermined program stored in the memory executed under the control of the microprocessor 12 in response to the potentiometer output signal 7. This provides remote control of the motions of a travelling crane by the microprocessor-based infinitely variable speed control system (IVSC) disclosed in copending British Patent Application in the name of J. H. Carruthers and Co., Ltd. Advantages of the present invention include; the use of a low carrier frequency is approved by the U.K. Health and Safety Executive and it has none of the disadvantages associated with UH FNHF fre- quencies; the ergonomics of the control system allied to the infinitely variable speed control system means that minimal operator training is required to develop the required skills; all the information necessary to effect control of the crane motion can be transmitted on 4 channels only; and the use of the remote control system together with the IVSC enables the crane to be operated safely and maximises the operating efficiency. CLAIMS (Filed on 7 - 9 - 82)

1. A remote control system comprising: a controller adapted to transmit control information relating to the desired movement of an electric motor, the controller having an adjustable control member having positions corresponding to off, select direction, reduce speed, maintain speed and increase speed, a receiver for recording the control information, and control means responsive to the receiver to control the electric motor, the control means including a voltage varying device, the output of which controls the speed of the motor, the output of the voltage varying device being determined by the positions selected on the control member.

2. The system of claim 1, in which the control member is a manually-operable joystick.

3. The system of claim 1 or claim 2, in which the controller and receiver are connected by radio telemetry on a carrier frequency of 200-400 kHz.

4. The system of any preceding claim, in which there are at least three motions controllable by the remote control system, the controller having an auxiliary selector for determining movement of the particular electric motor selected.

5. The system of any preceding claim, in which the select direction and reduce speed position controls on the controller are combined in the same position.

6. The system of any preceding claim, in which four frequency channels are used for each motion.

7. The system of any preceding claim, in which the voltage varying device is a motorised potentiometer.

8. The system of claim 7, in which the outut of the motorised poteniometer is processed in a signal processing means to provide the control signal to the electric motor, the signal processing means including a microprocessor and a memory device, the memory device containing a program executed under the control ofthemicroprocessorforcontroll- ing the movement of the motor in a predetermined manner.

9. A remote control system, substantially as herein described with reference to the drawings.