AU2007216709A1 - Systems and Methods for Immobilization Using Selected Electrodes - Google Patents

Description

P/00/011 28/5/91 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Name of Applicant: Actual Inventors Address for service is: TASER International, Inc.

Magne H Nerheim Patrick W Smith WRAY ASSOCIATES Level 4, The Quadrant 1 William Street Perth, WA 6000 Attorney code: WR Invention Title: SYSTEMS AND METHODS FOR IMMOBILIZATION USING SELECTED ELECTRODES The following statement is a full description of this invention, including the best method of performing it known to me:- SYSTEMS AND METHODS FOR IMMOBILIZATION USING SELECTED ELECTRODES -4 FIELD OF THE INVENTION The present invention relates to systems and methods for reducing mobility in a person or 0 animal.

BACKGROUND ART The following discussion of the background art is intended to facilitate an understanding of the present invention only. The discussion is not an acknowledgment or admission that any of the material referred to was part of the common general knowledge in Australia at the priority date of the application.

Weapons that deliver electrified projectiles have been used for self defense and law enforcement. These weapons typically deliver a stimulus signal through a target where the target is a human being or an animal. One conventional class of such weapons includes conducted .0 energy weapons of the type described in U.S. Patents 3,803,463 and 4,253,132 to Cover. These weapons typically fire projectiles toward the target so that electrodes carried by the projectile make contact with the target, completing a circuit that delivers a stimulus signal via tether wires through the electrodes and through the target. Other conventional conducted energy weapons omit the projectiles and deliver a stimulus signal through electrodes placed in contact with the target when the target is in close proximity to the weapon.

The stimulus signal may include a series of relatively high voltage pulses known to cause pain in the target. At the time that the stimulus signal is delivered, a high impedance gap air or clothing) may exist between electrodes and the target's conductive tissue. Conventional stimulus signals include a relatively high voltage about 50,000 volts) signal to ionize a pathway across such a gap of up to 2 inches. Consequently, the stimulus signal may be conducted through the target's tissue without penetration of the projectile into the tissue.

In some conventional conducted energy weapons, a relatively higher energy waveform has been used. This waveform was developed from studies using anesthetized pigs to measure the muscular response of a mammalian subject to an energy weapon's stimulation. Devices using the higher energy waveform are called Electro-Muscular Disruption (EMD) devices and are of the type generally described in U.S. Patent Application 10/016,082 to Patrick Smith, filed December 12, 2001. An EMD waveform applied to an animal's skeletal muscle typically causes that skeletal muscle to violently contract. The EMD waveform apparently overrides the target's 2 nervous system's muscular control, causing involuntary lockup of the skeletal muscle, and may result in complete immobilization of the target.

Unfortunately, the relatively higher energy EMD waveform is generally produced from a higher power capability energy source. In one implementation, a handheld launch device includes 8 AA size (1.5 volt nominal) batteries, a large capacity capacitor, and transformers to 0 generate a 26-watt EMD output in a tethered projectile.

A two pulse waveform of the type described in U.S. Patent Application 10/447,447 to Magne Nerheim filed February 11, 2003, provides a relatively high voltage, lower amperage pulse (to form an arc through a gap as discussed above) followed by a relatively low voltage, higher amperage pulse (to stimulate the target). Effects on skeletal muscles may be achieved with 80% less power than used for the EMD waveform discussed above.

There exists a significant need for a more effective stimulus signal for use in conducted energy weapons to immobilize a human target without lasting injury or death. In the decade preceding this application, annually over 30,000 people died of bullet wounds in the United States. Further, thousands of police officers are injured as a result of confrontations with non .0 compliant members of the general public each year. Even larger numbers of these noncompliant subjects are injured in the process of being taken into police custody.

DISCLOSURE OF THE INVENTION In accordance with a first aspect of the present invention, there is provided a method for selecting a subset of electrodes from a plurality of electrodes, the subset for use in immobilizing a target, the method comprising: a step for recalling a stored sequence of entries, each entry identifying a respective subset of electrodes; a step for sequentially testing subsets in accordance with the sequence of entries; and a step for immobilizing the target via a current through a tested subset of electrodes.

Preferably, the method further comprises a step for propelling the plurality of electrodes toward the target.

Preferably, the method further comprises a step for propelling toward the target a means for providing the current.

In accordance with a second aspect of the present invention, there is provided an immobilization device comprising: a signal source that provides an immobilization signal; a plurality of electrodes; and a circuit that selectively couples each of a multiplicity of subsets of electrodes of the plurality of electrodes to the signal source for delivery of the immobilization signal via a selected S subset of electrodes.

Preferably, the circuit: determines a respective test result in response to coupling each subset of the multiplicity 0 to the signal source; and selects the selected subset of electrodes in accordance with comparing the test result of the selected subset to a limit.

Preferably, the immobilization signal comprises a peak voltage less than an ionization voltage.

Preferably, the immobilization signal comprises: a stage for determining the respective test result; and a stage for immobilizing a target having tissue in series between at least two electrodes of the selected subset of electrodes.

Preferably, the device further comprises a launch device that propels the plurality of electrodes toward the target.

O.0 Preferably, the device further comprises a launch device that propels the signal source toward the target.

In accordance with a third aspect of the present invention, there is provided a projectile comprising an immobilization device in accordance with the second aspect of the present invention as hereinbefore described.

In accordance with a fourth aspect of the present invention, there is provided a system for immobilizing a target, the system comprising a launch device and a projectile in accordance with the third aspect of the present invention as hereinbefore described.

In accordance with a fifth aspect of the present invention, there is provided a method for selecting a subset of electrodes from a plurality of electrodes, the subset for use in immobilizing a target, the method comprising: recalling a stored sequence of entries, each entry identifying a respective subset of electrodes; sequentially testing subsets in accordance with the sequence of entries; and immobilizing the target via a current through a tested subset of electrodes.

Preferably, the method further comprises propelling the plurality of electrodes toward the target.

Preferably, the method further comprises propelling toward the target a means for providing the current.

S 5 Systems, devices, circuits and methods according to various aspects of the present 0 N invention seek to alleviate to some extent some or all of the problems discussed above by more effectively immobilizing a target, by reducing the risk of serious injury or death, and/or by immobilizing for a period of time with an expenditure of energy less than systems using r"- 0 conventional techniques.

BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the present invention will now be further described, by way of example, with reference to the accompanying drawings, wherein like designations denote like elements, of which: N .5 FIG. 1 is a functional block diagram of a system that uses a stimulus signal for immobilization according to various aspects of the present invention; FIG. 2 is a functional block diagram of an immobilization device used in the system of FIG. 1; FIG. 3 is a timing diagram for a stimulus signal provided by the immobilization device of !0 FIG. 2; and FIG. 4 is a functional flow diagram for a process performed by the immobilization device of FIG. 2.

BEST MODES FOR CARRYING OUT THE INVENTION A system according to various aspects of the present invention delivers a stimulus signal to an animal to immobilize the animal. Immobilization is suitably temporary, for example, to remove the animal from danger or to thwart actions by the animal such as for applying more permanent restraints on mobility. Electrodes may come into contact with the animal by the animal's own action motion of the animal toward an electrode), by propelling the electrode toward the animal electrodes being part of an electrified projectile), by deployment mechanisms, and/or by gravity. For example, system 100 of FIGs. 1-4 includes launch device 102 and cartridge 104. Cartridge 104 includes one or more projectiles 132, each having a waveform generator 136.

Launch device 102 includes power supply 112, aiming apparatus 114, propulsion apparatus 116, and waveform controller 122. Propulsion apparatus 116 includes propulsion activator 118 and propellant 120. In an alternate embodiment, propellant 120 is part of cartridge 104. Waveform controller 122 may be omitted with commensurate simplification of waveform generator 136, discussed below.

Any conventional materials and technology may be employed in the manufacture and

O

S operation of launch device 102. For example, power supply 112 may include one or more rechargeable batteries, aiming apparatus 114 may include a laser gun sight, propulsion activator 118 may include a mechanical trigger similar in some respects to the trigger of a hand gun, and Spropellant 120 may include compressed nitrogen gas. In one embodiment, launch device is 0 handheld and operable in a manner similar to a conventional hand gun. In operation, cartridge 104 is mounted on or in launch device 102, manual operation by the user causes the projectile I bearing electrodes to be propelled away from launch device 102 and toward a target an animal such as a human), and after the electrodes become electrically coupled to the target, a stimulus signal is delivered through a portion of the tissue of the target.

iN 5 Projectile 132 may be tethered to launch device 102 and suitable circuitry in launch device 102 (not shown) using any conventional technology for purposes of providing substitute or auxiliary power to power source 134; triggering, retriggering, or controlling waveform generator 136; activating, reactivating, or controlling deployment; and/or receiving signals at launch device 102 provided from electrodes 142 in cooperation with instrumentation in projectile 0 132 (not shown).

A waveform controller includes a wireless communication interface and a user interface.

The communication interface may include a radio or an infrared transceiver. The user interface may include a keypad and flat panel display. For example, waveform controller 122 forms and maintains a link by radio communication with waveform generator 136 for control and telemetry using conventional signaling and data communication protocols. Waveform controller 122 includes an operator interface capable of displaying status to the user of system 100 and capable of issuing controls commands, messages, or signals) to waveform generator 136 automatically or as desired by the user. Controls serve to control any aspect and/or collect data from any circuit of projectile 132. Controls may affect time and amplitude characteristics of the stimulus signal including overall start, restart, and stop functions. Telemetry may include feedback control of any function of waveform generator 136 or other instrumentation in projectile 132 implemented with conventional technology (not shown). Status may include any characteristics of the stimulus signal and stimulus signal delivery circuit.

Cartridge 104 includes projectile 132 having power source 134, waveform generator 136, and electrode deployment apparatus 138. Electrode deployment apparatus 138 includes deployment activator 140 and one or more electrodes 142. Power source 134 may include any conventional battery selected for relatively high energy output to volume ratio. Waveform generator 136 receives power from power source 134 and generates a stimulus signal according 6 r"- S5 to various aspects of the present invention. The stimulus signal is delivered into a circuit that is

O

N completed by a path through the target via electrodes 142. Power source 134, waveform generator 136, and electrodes 142 cooperate to form a stimulus signal delivery circuit that may further include one or more additional electrodes not deployed by deployment activator 142 O placed by impact of projectile 132).

0 Projectile 132 may include a body having compartments or other structures for mounting power source 134, a circuit assembly for waveform generator 136, and electrode deployment apparatus 138. The body may be formed in a conventional shape for ballistics a wetted aerodynamic form).

OAn electrode deployment apparatus includes any mechanism that moves electrodes from N 5 a stowed configuration to a deployed configuration. For example, in an embodiment where electrodes 142 are part of a projectile propelled through the atmosphere to the target, a stowed configuration provides aerodynamic stability for accurate travel of the projectile. A deployed configuration completes a stimulus signal delivery circuit directly via impaling the tissue or indirectly via an arc into the tissue. A separation of about 7 inches has been found to be more 0 effective than a separation of about 1.5 inches; and, longer separations may also be suitable such as an electrode in the thigh and another in the hand. When the electrodes are further apart, the stimulus signal apparently passes through more tissue, creating more effective stimulation.

According to various aspects of the present invention, deployment of electrodes is activated after contact is made by projectile 132 and the target. Contact may be determined by a change in orientation of the deployment activator; a change in position of the deployment activator with respect to the projectile body; a change in direction, velocity, or acceleration of the deployment activator; and/or a change in conductivity between electrodes 142 or electrodes placed by impact of projectile 132 and the target). A deployment activator 140 that detects impact by mechanical characteristics and deploys electrodes by the release or redirection of mechanical energy is preferred for low cost projectiles.

Deployment of electrodes, according to various aspects of the present invention, may be facilitated by behavior of the target. For example, one or more closely spaced electrodes at the front of the projectile may attach to a target to excite a painful reaction in the target. One or more electrodes may be exposed and suitably directed away from the target). Exposure may be either during flight or after impact. Pain in the target may be caused by the barb of the electrode stuck into the target's flesh or, if there are two closely space electrodes, delivery of a stimulus signal between the closely spaced electrodes. While these electrodes may be too close together for suitable immobilization, the stimulus signal may create sufficient pain and 7 disorientation. A typical response behavior to pain is to grab at the perceived cause of pain with the hands (or mouth, in the case of an animal) in an attempt to remove the electrodes. This so called "hand trap" approach uses this typical response behavior to implant the one or more exposed electrodes into the hand (or mouth) of the target. By grabbing at the projectile, the one or more exposed electrodes impale the target's hand (or mouth). The exposed electrodes in the hand (or mouth) of the target are generally well spaced apart from other electrodes so that stimulation between another electrode and an exposed electrode may allow suitable immobilization.

i In an alternate system embodiment, launch device 102, cartridge 104, and projectile 132 are omitted; and power source 134, waveform generator 136, and electrode deployment N 15 apparatus 138 are formed as an immobilization device 150 adapted for other conventional forms of placement on or in the vicinity of the target. In another alternate embodiment, deployment apparatus 138 is omitted and electrodes 142 are placed by target behavior and/or gravity.

Immobilization device 150 may be packaged using conventional technology for personal security planting in a human target's clothing or in an animal's hide for future activation), facility !0 security providing time for surveillance cameras, equipment shutdown, or emergency response), or military purposes land mine).

Projectile 132 may be lethal or non-lethal. In alternate embodiments, projectile 132 includes any conventional technology for administering deadly force.

Immobilization as discussed herein includes any restraint of voluntary motion by the target. For example, immobilization may include causing pain or interfering with normal muscle function. Immobilization need not include all motion or all muscles of the target. Preferably, involuntary muscle functions for circulation and respiration) are not disturbed. In variations where placement of electrodes is regional, loss of function of one or more skeletal muscles accomplishes suitable immobilization. In another embodiment, suitable intensity of pain is caused to upset the target's ability to complete a motor task, thereby incapacitating and disabling the target.

Alternate embodiments of launch device 102 may include or substitute conventionally available weapons firearms, grenade launchers, vehicle mounted artillery). Projectile 132 may be delivered via an explosive charge 120 gunpowder, black powder). Projectile 132 may alternatively be propelled via a discharge of compressed gas nitrogen or carbon dioxide) and/or a rapid release of pressure spring force, or force created by a chemical reaction such as a reaction of the type used in automobile air-bag deployment).

A waveform generator, according to various aspects of the present invention, may, in any order perform one or more of the following operations: select electrodes for use in a stimulus S signal delivery circuit, ionize air in a gap between the electrode and the target, provide an initial stimulus signal, provide alternate stimulus signals, and respond to operator input to control any of the aforementioned operations. In one embodiment, a large portion of these operations are 0 controlled by firmware performed by a processor to permit miniaturization of the waveform generator, reduce costs, and improve reliability. For example, waveform generator 200 of FIG. 2 may be used as waveform generator 136 discussed above. Waveform generator 200 includes low voltage power supply 204, high voltage power supply 206, switches 208, processor circuit 220, and transceiver 240.

I 5 The low voltage power supply receives a DC voltage from power source 134 and provides other DC voltages for operation of waveform generator 200. For example, low voltage power supply 204 may include a conventional switching power supply circuit LTC3401 marketed by Linear Technology) to receive 1.5 volts from a battery of source 134 and supply volts and 3.3 volts DC.

0 The high voltage power supply receives an unregulated DC voltage from a low voltage power supply and provides a pulsed, relatively high voltage waveform as stimulus signal VP.

For example, high voltage power supply 206 includes switching power supply 232, transformer 234, rectifier 236, and storage capacitor C12 all of conventional technology. In one embodiment, switching power supply 232 comprising a conventional circuit LTC 1871 marketed by Linear Technology) receives 5 volts DC from low voltage power supply 204 and provides a relatively low AC voltage for transformer 234. A feedback control signal into switching power supply 232 assures that the peak voltage of signal VP does not exceed a limit 500 volts). Transformer 234 steps up the relatively low AC voltage on its primary winding to a relatively high AC voltage on each of two secondary windings 500 volts). Rectifier 236 provides DC current for charging capacitor C12.

Switches 208 form stimulus signal VP across electrode(s) by conducting for a brief period of time to form each pulse; followed by opening. The discharge voltage available from capacitor C 12 decreases during the pulse duration. When switches 208 are open, capacitor C 12 may be recharged to provide the same discharge voltage for each pulse.

Processor circuit 220 includes a conventional programmable controller circuit having a microprocessor, memory, and analog to digital converter programmed according to various aspects of the present invention, to perform methods discussed below.

0 5 A projectile-based transceiver communicates with a waveform controller as discussed N above. For example, transceiver 240 includes a radio frequency about 450 MHz) transmitter and receiver adapted for data communication between projectile 132 and launch device 102 at any time. A communication link between waveform generator 136 and waveform controller 122 may be established in any suitable configuration of projectile 132 depending for 0 example on placement and design of radiators and pickups suitable for the communication link antennas or infrared devices). In one embodiment projectile 132 operates in four t"- I configurations: a stowed configuration, where aerodynamic fins and deployable electrodes S are in storage locations and orientations; an in flight configuration, where aerodynamic fins r- C are in position extended away from projectile 132; an impact configuration after contact with iN 5 the target; and an electrode deployed configuration.

A stimulus signal includes any signal delivered via electrodes to establish or maintain a stimulus signal delivery circuit through the target, and/or to immobilize the target. According to various aspects of the present invention, these purposes are accomplished with a signal having a plurality of stages. Each stage comprises a period of time during which one or more waveforms 0 are consecutively delivered via a waveform generator and electrodes coupled to the waveform generator. Stages from which a complete waveform, according to various aspects of the present invention may be constructed include in any order: a path formation stage for ionizing an air gap that may be in series with the electrode to the targets tissue; a path testing stage for measuring an electrical characteristic of the stimulus signal delivery circuit whether or not an air gap exists in series with the target's tissue); a strike stage for immobilizing the target; a hold stage for discouraging further motion by the target; and a rest stage for permitting limited mobility by the target to allow the target to catch a breath).

An example of signal characteristics for each stage is described in FIG. 3. In FIG. 3, two stages of a stimulus signal are attributed to path management and three stages are attributed to target management. The waveform shape of each stage may have positive amplitude (as shown), inverse amplitude, or alternate between positive and inverse amplitudes in repetitions of the same stage. Path management stages include a path formation stage and a path testing stage as discussed above.

In the path formation stage, a waveform shape may include an initial peak (voltage or current), subsequent lesser peaks alternating in polarity, and a decaying amplitude tail. The initial peak voltage may exceed the ionization potential for an air gap of expected length about 50 Kvolts, preferably about 10 Kvolts). In one embodiment, the waveform shape is formed as a decaying oscillation from a conventional resonant circuit. One waveform shape having one or more peaks may be sufficient to ionize a path crossing a gap air). Repetition of applying such a waveform shape may follow a path testing stage (or monitoring concurrent with another stage) that concludes that ionization is needed and is to be attempted again prior attempt failed, or ionized air is disrupted).

In a path testing stage, a voltage waveform is sourced and impressed across a pair of 0 electrodes to determine whether the path has one or more electrical characteristics sufficient for entry into a path formation, strike, or hold stage. Path impedance may be determined by any conventional technique, for instance, monitoring an initial voltage and a final voltage across a capacitor that is coupled for a predetermined period of time to supply current into electrodes. In one embodiment, the shape of the voltage pulse is substantially rectangular having a peak amplitude of about 450 volts, and having a duration of about 10 microseconds. A path may be tested several times in succession to form an average test result, for instance from one to three voltage pulses, as discussed above. Testing of all combinations of electrodes may be accomplished in about one millisecond. Results of path testing may be used to select a pair of electrodes to use for a subsequent path formation, strike, or hold stage. Selection may be made .0 without completing tests on all possible pairs of electrodes, for instance, when electrode pairs are tested in a sequence from most preferred to least preferred.

In a strike stage, a voltage waveform is sourced and impressed across a pair of electrodes.

Typically this waveform is sufficient to interfere with voluntary control of the target's skeletal muscles, particularly the muscles of the thighs and/or calves. In another embodiment, use of the hands, feet, legs and arms are included in the effected immobilization. The pair may be as selected during a test stage; or as prepared for conduction by a path formation stage. According to various aspects of the present invention, the shape of the waveform used in a strike stage includes a pulse with decreasing amplitude a trapezoid shape). In one embodiment, the shape of the waveform is generated from a capacitor discharge between an initial voltage and a termination voltage.

The initial voltage may be a relatively high voltage for paths that include ionization to be maintained or a relatively low voltage for paths that do not include ionization. The initial voltage may correspond to a stimulus peak voltage (SPV) as in FIG. 3 at about a skeletal muscle nerve action potential). The SPV may be essentially the initial voltage for a fast rise time waveform. The SPV following ionization may be from about 3 Kvolts to about 6 Kvolts, preferably about 5 Kvolts. The SPV without ionization may be from about 100 to about 600 volts, preferably from about 350 volts to about 500 volts, most preferably about 400 volts.

The termination voltage may be determined to deliver a predetermined charge per pulse.

I Charge per pulse minimum may be designed to assure continuous muscle contraction as opposed to discontinuous muscle twitches. Continuous muscle contraction has been observed in human targets where charge per pulse is above about 15 microcoulombs. A minimum of about microcoulombs is used in one embodiment. A minimum of 85 microcoulombs is preferred, 0 though higher energy expenditure accompanies the higher minimum charge per pulse.

Charge per pulse maximum may be determined to avoid cardiac fibrillation in the target.

For human targets, fibrillation has been observed at 1355 microcoulombs per pulse and higher.

The value 1355 is an average observed over a relatively wide range of pulse repetition rates from about 5 to 50 pulses per second), over a relatively wide range of pulse durations consistent I 5 with variation in resistance of the target from about 10 to about 1000 microseconds), and over a relatively wide range of peak voltages per pulse from about 50 to about 1000 volts).

A maximum of 500 microcoulombs significantly reduces the risk of fibrillation while a lower maximum about 100 microcoulombs) is preferred to conserve energy expenditure.

Pulse duration is preferably dictated by delivery of charge as discussed above. Pulse 0 duration according to various aspects of the present invention is generally longer than conventional systems that use peak pulse voltages higher than the ionization potential of air.

Pulse duration may be in the range from about 20 to about 500 microseconds, preferably in the range from about 30 to about 200 microseconds, and most preferably in the range from about to about 100 microseconds.

By conserving energy expenditure per pulse, longer durations of immobilization may be effected and smaller, lighter power sources may be used in a projectile comprising a battery). In one embodiment, a AAAA size battery is included in a projectile to deliver about I watt of power during target management which may extend to about 10 minutes. In such an embodiment, a suitable range of charge per pulse may be from about 50 to about 150 microcoulombs.

Initial and termination voltages may be designed to deliver the charge per pulse in a pulse having a duration in a range from about 30 microseconds to about 210 microseconds for about 50 to 100 microcoulombs). A discharge duration sufficient to deliver a suitable charge per pulse depends in part on resistance between electrodes at the target. For example, a one RC time constant discharge of about 100 microseconds may correspond to a capacitance of about 1.75 microfarads and a resistance of about 60 ohms. An initial voltage of 100 volts discharged to volts may provide 87.5 microcoulombs from the 1.75 microfarad capacitor.

A termination voltage may be calculated to ensure delivery of a predetermined charge.

For example, an initial value may be observed corresponding to the voltage across a capacitor.

As the capacitor discharges delivering charge into the target, the observed value may decrease.

A termination value may be calculated based on the initial value and the desired charge to be 0 delivered per pulse. While discharging, the value may be monitored. When the termination 0 value is observed, further discharging may be limited (or discontinued) in any conventional manner. In an alternate embodiment, delivered current is integrated to provide a measure of IO charge delivered. The monitored measurement reaching a limit value may be used to limit (or ,I discontinue) further delivery of charge.

OPulse durations in alternate embodiments may be considerably longer than 100 IN 5 microseconds, for example, up to 1000 microseconds. Longer pulse durations increase a risk of cardiac fibrillation. In one embodiment, consecutive strike pulses alternate in polarity to dissipate charge which may collect in the target to adversely affect the target's heart.

During the strike stage, pulses are delivered at a rate of about 5 to about 50 pulses per second, preferably about 20 pulses per second. The strike stage continues from the rising edge !0 of the first pulse to the falling edge of the last pulse of the stage for from 1 to 5 seconds, preferably about 2 seconds.

In a hold stage, a voltage waveform is sourced and impressed across a pair of electrodes.

Typically this waveform is sufficient to discourage mobility and/or continue immobilization to an extent somewhat less than the strike stage. A hold stage generally demands less power than a strike stage. Use of hold stages intermixed between strike stages permit the immobilization effect to continue as a fixed power source is depleted battery power) for a time longer than if the strike stage were continued without hold stages. The stimulus signal of a hold stage may primarily interfere with voluntary control of the target's skeletal muscles as discussed above or primarily cause pain and/or disorientation. The pair of electrodes may be the same or different than used in a preceding path formation, path testing, or strike stage, preferably the same as an immediately preceding strike stage. According to various aspects of the present invention, the shape of the waveform used in a hold stage includes a pulse with decreasing amplitude a trapezoid shape) and initial voltage (SPV) as discussed above with reference to the strike stage.

The termination voltage may be determined to deliver a predetermined charge per pulse less than the pulse used in the strike stage from 30 to 100 microcoulombs). During the hold stage, pulses may be delivered at a rate of about 5 to 15 pulses per second, preferably about 10 pulses per second. The strike stage continues from the rising edge of the first pulse to the falling edge of the last pulse of the stage for from about 20 to about 40 seconds about 28 seconds).

13 r'- A rest stage is a stage intended to improve the personal safety of the target and/or the N operator of the system. In one embodiment, the rest stage does not include any stimulus signal.

Consequently, use of a rest stage conserves battery power in a manner similar to that discussed above with reference to the hold stage. Safety of a target may be improved by reducing the 0 likelihood that the target enters a relatively high risk physical or emotional condition. High risk 0 physical conditions include risk of loss of involuntary muscle control for circulation or respiration), risk of convulsions, spasms, or fits associated with a nervous disorder 0 epilepsy, or narcotics overdose). High risk emotional conditions include risk of irrational behavior such as behavior springing from a fear of immediate death or suicidal behavior. Use of a rest stage may reduce a risk of damage to the long term health of the target minimize scar N 5 tissue formation and/or unwarranted trauma). A rest stage may continue for from 1 to 5 seconds, preferably 2 seconds.

In one embodiment, a strike stage is followed by a repeating series of alternating hold stages and rest stages.

In any of the deployed electrode configurations discussed above, the stimulation signal .0 may be switched between various electrodes so that not all electrodes are active at any particular time. Accordingly, a method for applying a stimulus signal to a plurality of electrodes includes, in any order: selecting a pair of electrodes; applying the stimulus signal to the selected pair; monitoring the energy (or charge) delivered into the target; if the delivered energy (or charge) is less than a limit, conclude that at least one of the selected electrodes is not sufficiently coupled to the target to form a stimulus signal delivery circuit; and repeating the selecting, applying, and monitoring until a predetermined total stimulus (energy and/or charge) is delivered. A microprocessor performing such a method may identify suitable electrodes in less than a millisecond such that the time to select the electrodes is not perceived by the target.

A waveform generator, according to various aspects of the present invention may perform a method for delivering a stimulus signal that includes selecting a path, preparing the path for the stimulus signal, and repeatedly providing the stimulus signal for a sequence of effects including in any order: a comparatively highly immobilizing effect a strike stage as discussed above), a comparatively lower immobilizing effect a hold stage as discussed above), and a comparatively lowest immobilizing effect a rest stage as discussed above).

For example, method 400 of FIG. 4 is embodied as instructions stored in a memory device stored and/or conveyed by any conventional disk media and/or semiconductor circuit) and installed to be performed by a processor in read only memory of processor circuit 220).

Method 400 begins with a path testing stage as discussed above comprising a loop (402-

O

S 408) for determining an acceptable or preferred electrode pair. Because the projectile may include numerous electrodes, any subset of electrodes may be selected for application of a stimulus signal. Data stored in a memory accessible to the processor of circuit 220 may include 0 a list of electrode subsets pairs), preferably an ordered list from most preferred for 0 maximum immobilization effect to least preferred. In one embodiment, the ordered list indicates one preference for one subset of electrodes to be used in all stages discussed above. In another D embodiment, the list is ordered to convey a preference for a respective electrode subset for each iN of more than one stage. Method 400 uses one list to express suitable electrode preferences.

Alternate embodiments include more than one list and/or more than one loop (402-408) a N 5 list and/or loop for each stage). In another alternate embodiment a list includes duplicate entries of the same subset so that the subset is tested before and after intervening test or stimulus signals.

According to method 400, after path management, processor 220 performs target management. Path management may include path formation, as discussed above. Target 0 management may be interrupted to perform path management as discussed below (434). For target management, processor 220 provides the stimulus signal in a sequence of stages as discussed above. In one embodiment a sequence of stages is effected by performing a loop (424- 444).

For each (424) stage of a predefined stage sequence, a loop (426-442) is performed to provide a suitable stimulus signal. Prior to entry of the inner loop (426-442), a stage is identified. The stage sequence may include one strike stage, followed by alternating hold and rest stages as discussed above.

For the duration of the identified stage (426), processor 220 charges capacitors (428) C12 used for signal VP) until charge sufficient for delivery 100 microcoulombs) is available or charging is interrupted by a demand to provide a pulse operator command via transceiver 240, a result of electrode testing, or lapse of a timer). Processor 220 then forms a pulse a strike stage pulse or hold stage pulse) at the value of SPV set as discussed above (422 or 414). Processor 220 meters delivery of charge (432), in one embodiment, by observing the voltage VC) of the storage capacitors decrease (436) until such voltage is at or beyond a limit voltage about 228 volts). The selection of a suitable limit voltage may follow the well known relationship: AQ CAV where Q is charge in coulombs; C is capacitance in farads; and V is voltage across the capacitor in volts.

During metering of charge delivery, processor 220 may detect (434) that the path in use for the identified stage has failed. On failure, processor 220 quits the identified stage, quits the identified stage sequence, and returns (402) to path testing as discussed above.

When the quantity of charge suitable for the identified stage has been delivered (436), the pulse signal VP) is ended (440). The voltage supplied after the pulse is ended may be zero 0 open circuit at least one of the identified electrodes) or a nominal voltage sufficient to maintain ionization).

If the identified stage is not complete, then processing continues at the top of the inner loop (426). The identified stage may not be complete when a duration of the stage has not lapsed; or a predetermined quantity of pulses has not been delivered. Otherwise, processor 220 identifies (444) the next stage in the sequence of stages and processing continues in the outer loop (424). The outer loop may repeat a stage sequence (as shown) until the power source for waveform generator is fully depleted.

For each (402) listed electrode subset, processor 220 applies (404) a test voltage across an identified electrode subset. In one embodiment, processor 220 applies a comparatively low !0 test voltage about 500 volts) to determine an impedance of the stimulus signal delivery circuit that includes the identified electrodes. Impedance may be determined by evaluating current, charge, or voltage. For instance, processor 220 may observe a change in voltage of a signal VC) corresponding to the voltage across the a capacitor C12) used to supply the test voltage. If observed change in voltage peak or average absolute value) exceeds a limit, the identified electrodes are deemed suitable and the stimulus peak voltage is set to 450 volts. Otherwise, if not at the end of the list, another subset is identified (408) and the loop continues (402).

In another embodiment, processor 220 applies a comparatively low test voltage about 500 volts) with delivery of a suitable charge from about 20 to about microcoulombs) to attract movement of the target toward an electrode. For example, movement may result in impaling the target's hand on a rear facing electrode thereby establishing a preferred circuit through a relatively long path through the target's tissue. In one embodiment, the rear facing electrode is close in proximity to electrodes of the subset and is also a member of the subset. Alternatively, the rear facing electrode may be relatively distant from other electrodes of the set and/or not a member of the subset.

The test signal used in one embodiment has a pulse amplitude and a pulse width within the ranges used for stimulus signals discussed herein. One or more pulses constitute a test of one subset. In alternate embodiments, the test signal is continuously applied during the test of a 16 subset and test duration for each subset corresponds to the pulse width within the range used for stimulus signals discussed herein.

-If at the end of the list no pair is found acceptable, processor 220 identifies a pair of electrodes for a path formation stage as discussed above. Processor 220 applies (412) an ionization voltage to the electrodes in any conventional manner. Presuming ionization occurred, 0 subsequent strike stages and hold stages may use a stimulus peak voltage to maintain ionization.

Consequently, SPV is set (414) to 3 Kvolts.

The invention as hereinbefore described may provide benefits such as improvements in cost, reliability, range, and effectiveness for conducted energy weapons. It may also provide benefits in applications for conducted energy weapons in law enforcement and providing increased self defence to individuals.

The foregoing description discusses preferred embodiments of the present invention which may be changed or modified without departing from the scope of the present invention as defined in the claims. While for the sake of clarity of description, several specific embodiments of the invention have been described, the scope of the invention is intended to be measured by :0 the claims as set forth below.

Modifications and variations such as would be apparent to a skilled addressee are deemed to be within the scope of the present invention.

Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Furthermore, throughout the specification, unless the context requires otherwise, the word "include" or variations such as "includes" or "including", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Claims (21)

1. A method for selecting a subset of electrodes from a plurality of electrodes, the subset for use in immobilizing a target, the method comprising: O a step for recalling a stored sequence of entries, each entry identifying a respective 0 subset of electrodes; a step for sequentially testing subsets in accordance with the sequence of entries; and a step for immobilizing the target via a current through a tested subset of electrodes. S

2. The method of claim 1, further comprising propelling the plurality of electrodes toward the O target. O N 5

3. The method of claim 1 or 2, further comprising propelling toward the target a means for providing the current.

4. An immobilization device comprising: a signal source that provides an immobilization signal; a plurality of electrodes; and .0 a circuit that selectively couples each of a multiplicity of subsets of electrodes of the plurality of electrodes to the signal source for delivery of the immobilization signal via a selected subset of electrodes.

The device of claim 4, wherein the circuit: determines a respective test result in response to coupling each subset of the multiplicity to the signal source; and selects the selected subset of electrodes in accordance with comparing the test result of the selected subset to a limit.

6. The device of claim 4 or 5, wherein the immobilization signal comprises a peak voltage less than an ionization voltage.

7. The device of claim 4 or 5, wherein the immobilization signal comprises: a stage for determining the respective test result; and a stage for immobilizing a target having tissue in series between at least two electrodes of the selected subset of electrodes.

8. The device of any one of claims 4 to 7, further comprising a launch device that propels the plurality of electrodes toward the target.

9. The device of any one of claims 4 to 8, further comprising a launch device that propels the signal source toward the target.

A projectile comprising the device of any one of claims 4 to 9. 18

11. A system for immobilizing a target, the system comprising a launch device and the projectile of claim

12. A method for selecting a subset of electrodes from a plurality of electrodes, the subset for use in immobilizing a target, the method comprising: recalling a stored sequence of entries, each entry identifying a respective subset of 0 electrodes; sequentially testing subsets in accordance with the sequence of entries; and immobilizing the target via a current through a tested subset of electrodes.

13. The method of claim 12, further comprising propelling the plurality of electrodes toward the target. I 5

14. The method of claim 12 or 13, further comprising propelling toward the target a means for providing the current.

An immobilization device substantially as hereinbefore described with reference to the accompanying drawings.

16. A method for selecting a subset of electrodes substantially as hereinbefore described with .0 reference to the accompanying drawings.

17. A projectile substantially as hereinbefore described with reference to the accompanying drawings.

18. A system for immobilizing a target substantially as hereinbefore described with reference to the accompanying drawings.

19. An immobilization device that selects a subset of electrodes substantially as hereinbefore described with reference to the accompanying drawings.

A projectile that selects a subset of electrodes substantially as hereinbefore described with reference to the accompanying drawings.

21. A system that selects a subset of electrodes substantially as hereinbefore described with reference to the accompanying drawings.