Wedges and Control Robots

Control robots win by controlling where the opponent goes rather than by tearing it apart. They get under it, push it, pin it, grab it or lift it, and drive it into walls, hazards and pits. The simplest is the wedge. Wedges are often called boring, but they win a lot of matches. In Team Run Amok's 2016 study of a large beetleweight tournament, robots whose only weapon was a wedge won 65% of their matches on average, against 39% for spinners.[1] This page covers wedges, wedgelets and forks, pushers, grabbers and crushers. Lifters are covered on Flippers and Lifters, and the basics of wedge types are on Weapons.

Types

Fixed wedges

A fixed wedge is a ramp that is part of the chassis, or bolted solidly to it. It's strong, simple and also works as front armor. The catch is height: a fixed wedge has to sit a little above the floor so it doesn't catch on seams. On a wide wedge, the high spots of the floor decide how high the whole edge rides.[2]

Hinged wedges

A hinged or dragging wedge pivots so that its edge rests on the floor and follows bumps. It can get lower than a fixed wedge, but it may lift or bounce when it's hit, and it needs a strong hinge.

Wedgelets and forks

Wedgelets (also called forks or horns) are small, separate wedges, usually two or more across the front. They're lighter than a full wedge, each one can find its own low spot in the floor, and you can replace them one at a time.

Several hinged forks have a better chance of getting under a full-width wedge than one wide wedge does. BotKits' "wedge killer" drop forks for the D2 kit are a well-known example. BotKits suggests forks against wedges and drum or egg-beater spinners, and a full wedge against other weapons.[3]
Plastic wedgelets get cut up by thin horizontal spinner blades, which is why some builders use titanium ones.[4]
Forks give little protection against weapons, apart from low attacks.

See also BotKits' D2 Wolverine Kit (about $40 as of October 2026).

Pushers and plows

A pusher or plow relies on traction, power and driving to shove the opponent around. Many invertible 150 g robots are simple pushers. Pushing power comes from the drivetrain, so see Drive Systems and Wheels.

Grabbers, clampers and crushers

Grabbers or clampers get under the opponent (often with a lifter) and then close an arm or jaw to hold it, so they can carry it to a hazard. In insect classes these are usually servo-driven.
Crushers close a pointed beak or jaw to pin and puncture. NHRL's guide notes that crushers have to hold on for a long time, and need some luck to hit something vital.[5]
Pin and hold time limits apply to all of these (see below).

Lifters as control weapons

A lifter that just raises the opponent's wheels off the floor takes away its pushing and steering, so it's easy to steer into a wall or a pit. Many control robots are a wedge with a lifter or forks. See Flippers and Lifters.

Strengths and weaknesses

Strengths

Simple, cheap, tough and safe to test. A good first robot (see GettingStarted).
A good wedge deflects spinner hits and protects the wheels. Bending the wedge around the sides helps, and curving the ends down avoids leaving sharp corners for a spinner to bite ("spinner bait").[6]
Little to break between matches, so more time for driving practice.
Wins on control and engagement points when matches go to the judges.

Weaknesses

Little or no damage, so you rely on knockouts by hazards, pins and judges' decisions.
Heavily dependent on driving skill (see Driving Practice).
A lower wedge beats you, and uneven arena floors can make a low wedge catch or ride high.
Some events don't allow robots without an active weapon. For example, as of 2026 NHRL doesn't allow a wedge as a main robot, though teams use small wedges as part of a multibot.[7] Check your event's rules (see Rules).

Matchups

General guidelines only – see also Driving Practice.

Against vertical spinners and drums: keep the front pointed at them and get under the weapon. Strong forks or a hardened wedge help. A vert that is kept off the floor or can't get up to speed has trouble.
Against horizontal spinners: a low, strong wedge can get under the blade and tip them. Use metal wedgelets, not plastic.
Against other wedges: whoever is lower wins. Forks help, and so does attacking from the side instead of head-on.[8]
Against lifters and grabbers: don't let them get under you. Push them into walls before they get their forks under you.
Against hammers: get under and keep pushing, so the hammer can't line up its swing.

Design considerations

Getting under first

Edge: thin, hard and straight. Titanium, hardened steel and AR500 are common at 3 lb, and TPU and other plastics in lighter classes (see Armor and Materials and 3D Printing).
Ground clearance: know your arena. For one steel-floored beetleweight arena, the local organizer suggested that 1/8 to 1/4 inch clearance is fine for a four-wheel robot.[9]
Wedge angle: a steeper wedge deflects hits better and a shallower wedge gets under more easily. Ask Aaron's design archive covers the trade-off in detail.[10]
Interchangeable front ends: many robots swap between a full wedge and forks to suit the opponent. Under SPARC rules, swappable weapons must fit a common drive platform that drives properly with any of them installed.[11]

The wedgelet arms race

Wedgelets have been getting longer as builders try to reach under each other first. As of October 2026, the standard SPARC Robot Construction Specifications (v1.7) have no rule on wedge or wedgelet size or length.[12] Individual events can set their own limits, so read the event rules. Long, thin wedgelets also bend and snap, and a bent fork that drags on the floor can leave you stuck. Bring spares.

Pushing power

A pusher's real weapon is its drivetrain: traction, torque and gearing. See Drive Systems and Team Run Amok's optimum gearing guide. Too much speed doesn't help in a small arena.

Buying a wedge

Ready-made wedges and forks save a lot of fabrication. As of October 2026, examples include Repeat Robotics' antweight titanium wedge (about $35) and beetleweight titanium wedge (about $45), and the BotKits D2 Wolverine kit above. Check they fit your chassis before you order. See Suppliers.

How they win

Knockouts, pits and pins

Under the standard SPARC Match Rules:[13]

Pits and push-outs: the first robot to enter an elimination zone loses. If you push the opponent in but get stuck with it, it counts as both robots entering, and both are returned to the arena.
Pins: a stationary pin is limited to 5 seconds, and an active pin (moving, sawing and so on) to 10 seconds. After that you must fully release the opponent. Refusing when the referee asks forfeits the match.
Wall stucks: under the standard "modified single un-stick" rule, a robot that you push into a stuck position gets no un-stick. Pinning an opponent on a wall or hazard until it's counted out is a legitimate win.
Knockouts: a robot that can't show controlled movement in a straight line within 10 seconds is counted out. But the count stops while you keep attacking, so back off when the opponent is stuck.

Judges' decisions

Many control robot matches go to the judges. The SPARC Judging Guidelines (v1.3) offer events two scoring systems:[14]

Damage, Control and Aggression (17 points per judge: 5 aggression, 6 control, 6 damage). Control covers using your robot or the arena against the opponent without your weapon doing the damage. Examples include guiding the opponent into hazards, walls or the floor, flipping it, and stopping its weapon. A wedge or rammer that stops a spinner from ever getting up to speed is given as an example of a 6–0 control score. Aggression needs translational movement toward the opponent. Sitting and waiting doesn't count.
Damage and Engagement (4 damage points, 5 engagement points). Engagement rewards attacking, pinning, chasing, getting the opponent stuck or high-centered, and inverting it when that affects its fighting. Sitting and waiting or running away count against you. Being slow doesn't count against you.
Damage scoring for wedges: in the Damage and Engagement criteria, the wedges, plows and forks on a robot with a powered weapon count as structure or armor. On a robot without a powered weapon, whatever it attacks with counts as its weapon, so a destroyed wedge on a pusher counts as weapon damage.

For tips on driving with the judges in mind, see Driving Practice.

Safety

Wedges are passive, but the edge can be sharp. Deburr it, and cover it in the pits.
Grabbers, clampers and crushers are moving weapons. SPARC requires a clearly visible lock whenever the robot is outside the arena.[15] Keep fingers out of the jaws.
SPARC forbids weapons and defenses designed to entangle, such as nets, tape, string and some soft rubber or plastic parts.[16] Don't hang loose flaps or skirts off a wedge.
Every robot needs a working failsafe and power switch. See Failsafes, Switches and Safety.

Famous examples

Algos – a top-ranked beetleweight wedge. Ask Aaron recommends copying its wedge, which wraps around the sides and has turned-down ends.[17]
BotKits D2 – a beetleweight wedge kit with a machined titanium wedge. BotKits says D2 kits won three northwest US events in 2015, and the kit is still a popular base for forks and wedgelets (see Kits).[18]
Red Devil and Bite Force – BattleBots heavyweights listed as grapplers.
Quantum (Team Robo Challenge) – a BattleBots crusher.

Designs you can print

From the list on 3D Printing (links checked October 2026):

150 g: Microdot (Team Panic's triple wedge), emancarrillo's 150g Fork Wedge, and Maximilian Mehner's modular 4WD Attesa wedge/fork robot.
150 g grabbers and crushers: Graboid, Squeezy and emancarrillo's 150g Crusher.
1 lb: Duckling (full parts list and build guide), Banana Split (beginner) and the Basic Wedge (Blue Dream) plastic ant with several fork options.
3 lb: the Wallieonline Beetleweight Wedge, with a parts list.