Active Weapons

Combat robotics active weapon design focuses on maximizing kinetic energy transfer, weapon engagement ("bite"), and structural durability while managing gyroscopic forces and motor torque limits.

Tooth Geometry and Rake Angle

The profile of a spinner’s impact tooth dictates whether energy is transferred into puncturing, tearing, or launching an opponent.

• Positive Rake Angle (>0°): The tooth face slopes backward toward the direction of rotation. This geometry acts like an axe, digging deep into armor plates to tear material away. However, aggressive positive rake increases the risk of tooth fracture or snagging that can stall high-RPM motors.

• Neutral / Flat Rake (0°): The face aligns perpendicular to the cutting plane. It provides a reliable balance of punch resistance and broad surface contact.

• Negative Rake Angle (<0°): The face slopes forward. While it reduces penetration depth, negative rake increases tooth strength, redirects shock loads through the bulk of the weapon disk, and converts kinetic energy into massive blunt-force vertical launch rather than localized tearing.

• Relief Angle: Clearance behind the tooth tip must be sufficiently steep to avoid the rear profile rubbing against the opponent before the tooth makes full contact.

Engagement Dynamics (Weapon "Bite")

"Bite" is the distance the weapon tooth extends into an opponent's frame per revolution before impact:

Bite= (n⋅ω)/v_robot​​

where vrobot​ is closing velocity, n is the number of teeth, and ω is rotational speed (rev/s).

• Single-Tooth Disks: Deliver maximum bite per revolution by providing nearly 360∘ of weapon rotation between impacts. Requires an integrated counterweight.

• Multi-Tooth Disks (2–4 teeth): Naturally balanced and easier to manufacture, but bite is drastically reduced at high tip speeds, often resulting in superficial grinding rather than deep structural hits.

Single-Tooth Counterweighting

Single-tooth spinners maximize bite by using a counterweight lobe opposite the tooth. Because kinetic energy and centrifugal force depend on different geometric factors, geometry optimization is required. Utilizing CG estimation in CAD is essential to creating a balanced weapon geometry, in order to reduce vibration.