GB2144599A

GB2144599A - Distinguishing different types of movement

Info

Publication number: GB2144599A
Application number: GB08418249A
Authority: GB
Inventors: Anthony Maurice Howard; Terence John Waterfield
Original assignee: Plessey Co Ltd
Current assignee: Plessey Co Ltd
Priority date: 1983-07-20
Filing date: 1984-07-18
Publication date: 1985-03-06
Also published as: GB8319642D0; GB8418249D0

Abstract

In a Doppler movement detector, which operates by means of reflecting radiation off a subject's hand onto a self-mixing Gunn diode 12, a logic circuit 20 determines whether the movement is random shaking or deliberate movement. The output of the logic circuit 20 can be used to activate a switch 26. The logic circuit is shown in detail (Fig. 3, not shown). <IMAGE>

Description

SPECIFICATION Remote switch The present invention relates to remote switches and more particularly to a switch which is operated by detection of movement.

The object of the present invention is to provide a remotely operated switch which can distinguish between random involuntary movements of a persons hand and those made deliberately in response to a stimulus.

The remote switch of the present invention finds particular application for persons suffering from cerebral palsy and thereby can be used in co-operation with a "POSSUM" communication teaching panel to effect the operation thereof.

According to the present invention there is provided a remote switch for detection of deliberate movements including a microwave source and detector unit, an amplification circuit connected to the output of the microwave detector and a logic unit connected to the amplifier to distinguish between random and a deliberate movement and to provide an output signal on detection of a deliberate movement.

Embodiments of the present invention will now be described with reference to the accompanying drawings in which, Figure 1 shows the remote switch unit according to the present invention and, Figure 2 shows in block diagrammatic form circuitry for the remote switch of Fig. 1, and Figure 3 shows a logic circuit for use in the circuit shown in Fig. 2.

Referring now to the drawings the remote switch unit 10 comprises a low power K-band Gunn diode oscillator 1 2 mounted in a sealed box 14. A foam window 1 6 allows passage of the microwave radiation and seals the unit against ingress of extraneous liquids and solids.

The output of the gunn diode 1 2 is connected to an amplifier unit 18 and a logic unit 20, the output of which operates a transistor 22 which may be used to energise a coil 24 and in turn a switch 26.

The K-band Gunn diode oscillator 1 2 operates in the self oscillating mixer mode which provides a narrow beam of radiation whose frequency may be modulated by movement with a component of velocity colinear with the beam. This change in frequency is detected by the oscillator 1 2 to give an output signal the frequency of which is proportional to colinear velocity component of the motion of the object. To enable differentiation between deliberate and random movements, the output signal from the oscillator is processed in a simple logic circuit 20 after amplification. On sensing a movement determined as deliberate, a relay 24 is activated to provide a switching signal to operate for example the "Possum" communication unit.

The output from the radar unit is a series of pulses whose pulse repeatition frequency corresponds to the doppler frequency shift of the tansmitted beam. Thus in the absence of a moving target within the beam, the output zero.

Referring now to the logic circuit shown in Fig. 3. In the quiescent state the outputs of IC1 and IC5a are low so that the Green LED is lit and the two red LEDs are extinguished.

Two counters IC3 and IC4 are also disabled.

The leading edge of the first singnal pulse from the output of the radar unit triggers both halves of IC1, and loads the two counters with the number set on the switches 1 6 and 1 7. IC1 b sets flip-flop IC2a to enable both counters. The output of IC1a remains high for approximately 2 seconds allowing the two counters to count the incoming pulses from the output of the radar unit. When the terminal count is reached TC of IC4 goes high resetting IC2a in hibiting the counters. At the same time IC5a is triggered to give an output for approximately 1 second to drive a Possum training machine. The red LEDs give a visual indication.

If the terminal count is not reached within the 2 second period, the counters are disabled as ICla returns to its quiescent state. Thus when the patient makes a deliberate movement, he causes a signal to be transmitted to the Possum training machine and any random involuntary movements, although detected, do not integrate to give the required count with the 2 second period. This, and the number loaded into the counters, have been selected for the particular patient for whom the equipment was designed.

The invention therefore provides a short range remotely operated switch which can distinguish between the random involuntary movements of a persons hand, and those made deliberately in response to a stimulus.

The unit is specifically designed around the needs of a person suffering from cerebral palsy to enable operation of a "Possum" communicator teaching panel.

(a) Remote operation.

(b) Range sufficient to avoid accidental damage by gross involuntary movements of subject, yet not so great as to react to unintentional nearby movements of other persons.

(c) Ability to distinguish between random involuntary motion and deliberate movement with a component of velocity towards or away from the unit.

(d) Adjustable sensitivity such that movements ranging from gross arm to subtle finger motion can be accommodated.

Other applications of the inventive concept include any which require distinction between random and deliberate movements to remotely operate a switch which can be used to operate other equipment.

It will be appreciated by one skilled in the art that variations and modifications can be made to the remote switch for example the time period in which the counters are operative can be altered depending on the requirements and use of the remote switch.

Claims

CLAIMS 1. A remote switch for detection of deliberate movements of an object comprising a microwave source and detector unit for emitting a beam of radiation, an amplification circuit connected to the output of the microwave source and detector unit, and a logic unit connected to the amplification circuit for distinguishing between random movements and deliberate movements and for providing an output signal indicative of deliberate movements. 2. A remote switch as claimed in claim 1 wherein the frequency of the beam of radiation emitted from the microwave source is modulated as a result of movement of the object, and wherein the detector unit detects the change in frequency and produces an output signal indicative of the movement of the object. 3. A remote switch as claimed in claim 1 or claim 2 wherein the microwave source and detector unit is a K-band Gunn diode oscillator operable in the self oscillating mixer mode. 4. A remote switch as claimed in any preceding claim wherein the output signal of the logic unit operates a switch of a device on sensing movement determined as deliberate. 5. A remote switch for detection of deliberate movements of an object substantially as hereinbefore described with reference to the accompanying drawings. CLAIMS

1. A remote switch comprising a microwave source, a detector for detecting changes in a transmitted beam from said source, counting means and switching means wherein said detector provides a pulse signal to said counting means the frequency of which pulse signal varies in dependance on doppler frequency shift of the transmitted signal, and said counting means is arranged to cause said switching means to operate when a predetermined number of pulses are received within a predetermined period and is arranged to recommence the count when said predetermined period expires before receipt of said predetermined number of pulses whereby pulses generated as a result of deliberate movement of an objective effect operation of the switching means and random movement of such an objective is ineffective.

2. A remote switch as claimed in claim 1 wherein said predetermined number is presettable by means of a plurality of switches.

3. A remote switch is claimed in claim 1 or claim 2 wherein said microwave source is a Gunn diode oscillator operating as a selfoscillating mixer.

4. A remote switch as claimed in any preceding claim wherein said switching means is an electronically controlled relay switch.

5. A remote switch as claimed in any preceding claim wherein a visual indication of the operation of the switching means is provided.

6. A remote switch as claimed in claim 5 wherein said visual indication of the operation of the switching means is provided by illuminating at least one light source.

7. A remote switch substantially as hereinbefore described with reference to the accompanying drawings.