Estimation of Physiological Impedance from Neuromuscular Pulse Data

Area of Science:

• Forensic Science
• Electrical Engineering
• Biomedical Engineering

Background:

• Conducted Electrical Weapons (CEWs) use probes to deliver current, inducing muscle contractions.
• Variations in inter-probe resistance can affect CEW charge delivery.
• Newer CEW models feature feed-forward control circuits to maintain constant charge delivery.

Purpose of the Study:

• To explore the load limits of the charge metering system in newer CEW models.
• To evaluate the reliability of stored Pulse Log data for estimating load resistance.

Main Methods:

• Tested 10 units each of TASER X2, X26P, and X26P+ CEW models.
• Utilized non-inductive high-voltage resistor assemblies ranging from 50 Ω to 10 kΩ, shorted output, and open circuits.
• Downloaded Pulse Log data to record charge, stimulation, and arc voltages during standard discharge cycles.

Main Results:

• CEWs delivered an average charge of 65.4 µC at load resistances below 1 kΩ.
• At load resistances of 1 kΩ and above, the delivered charge decreased as resistance increased.
• Pulse Log data, analyzed via regression, predicted resistance with an average error of 53 Ω (0-1 kΩ) and 16% (1-10 kΩ).
• Muzzle arcing detection is possible using parameter variability and arc voltage.

Conclusions:

• TASER X2, X26P, and X26P+ models maintain consistent charge delivery (< 1 kΩ load).
• Metered charge decreases with increasing load resistance (≥ 1 kΩ).
• Stored Pulse Log data provides reliable and accurate forensic analysis of load resistance.