Time to build some robots! I’ll start by rebuilding the RATS from THS, page 124. This is described as “stealthy ground-combat cybershells intended to supplement or replace human infantry.” The example given “is typical: an ovoid four-legged body, with two short manipulator arms, retractable sensor booms, and a protruding gun tube. The spines studding its torso detect air vibrations, while its clawed legs enable it to burrow through sand or soil easily. 6’long, 250 lbs”. It also costs $483,000.

RATS

My design is a bit different: It still is a simple, four-legged robot with two manipulator arms. But for combat, it also mounts three more arms: Two mount additional sensor equipment, the third one mounts a currently-unspecified weapon.

The Arms

I am not quite following normal procedures; instead, I’ll design the arms first then move onto the body.

Sensor Arms

For sensor arms, we first need an actual sensor. The basic sensor is .5lbs, $2,500, and we can modify it by applying advantages. The goal of the arm is to allow extended sensing (for example around corners). Thermograph vision is useful for that (+50% weight, +20% cost). Smelling and hearing are not necessary; removing both gives a discount of -50%/-50%. In sum, that’s 0.5lb and $1,750; volume is 0.01cf.

The arm itself doesn’t have to be powerful (there’s a limit of 6lbs*ST, which we’ll easily meet 1), and I’ll just use an ST4 arm (24lbs limit). That’s a base cost of 0.4lbs and $800. It doesn’t need any manipulator, so striker saves half weight and 80% of cost. I’ll also add Extendible (x2/x2) and Retractable (x1.5, x1.5). Final mass is 0.6lbs, $480, volume 0.012cf.

The arm in total has a mass of 1.1lbs, costs $2,555, and takes up a volume of 0.022cf in the body (since it’s retractable). Surface area is 1. Reach is half that, rounded down meaning it’s either 1 (if you apply the minimum reach after the doubling from extendible), or 2 (the other way around). Going to go with the second.

Weapon Arm

The first question is which weapon we want to mount. The list in Robots itself lists several, many of which aren’t available due to our tech decision, and many which either aren’t useful or are overpowered. THS instead shows two alternatives: the anti-materiel rifle (23lbs and 0.29lbs per shot, ST13, but 11d+1 damage), and the battle rifle (11lbs and 0.016/0.8lbs per shot, ST10, but only 6d although it mount a micromissile pod). There’s also the police grenade launcher from Robots, at 25lbs, which would be interesting. I’ll still prefer the other two. Which one, though? Why not both?

Specifically, let’s assume we’ll just produce a pod which can be changed in the field. The pod is 35lbs and has a volume of 0.7cf; per default it mounts a battle rifle, 500 shots (8lbs), and an additional 20 minimissiles. Note that you can trade off minimissiles and normal ammunition at 50 shots per missile. Cost is $2,056.20. For less subtlety and less flexibility, mount the AMR plus 40 shots (34.6lbs, $3,064.32; waste brings it to 35lbs). The modular socket costs $350.

To fire that weaponry, the arm needs an ST of 13. I’ll take ST 15 for 1.4lbs and $3,000 base. Striker and retractable brings this to 1.05lbs and $900. Oh, and we’ll also need a sensor package - Telescopic Zoom 5 (32x), Deafness, and No Smell/Taste sound good and give 0.25lbs and $2,500.

In total, that arm will be 36.3lbs, $3,750 (without a pod), and has a volume of 0.726cf. It also needs 0.075kW of power. It has an area of 5, and therefore a reach of 1.

Manipulator Arms

More easily, the manipulator arms are ST 15, retractable arms. They are 2.1lbs, $4,500, and 0.042cf, and need 0.075kW of power. To bring them to human size, I’ll add empty space to bring it to 0.2cf, solidly into reach 1.

The Body

The arms already defined require 1.17cf. What else do we mount?

Sensors

The main sensors mounted on the robot feature thermograph vision, 360° vision, normal hearing, and normal smell. I’ll also add a radar/laser locator and an imaging LIDAR. Total weight is 0.875lbs, cost is $3,500. That makes volume 0.0175cf and power drain 0.25kW. The latter seems kind of high - modern lidars in the hundred-metre range draw a tenth of that. But I’ll work with it.

Robot Brain

Oh, we should also mount a robot brain. A standard brain (10lbs, 0.2cf, $3,750) seems like a good base; compacting and hardening brings it to 15lbs, 0.3cf, and $37,500. It has Complexity 5. That’s the most expensive component yet. I could also give it more data storage, which (at TL10), is $1,000 and 5lbs per terabyte. My own harddrive was a tenth of the cost, a tenth of the weight, and has eight TB. Weeeeeell, nope. I’ll just say it’s sufficient.

Communication

A standard communicator is 0.25lbs and $125. We’ll add the Bullhorn option, and add a medium-range radio (5,000 miles seem pretty fine). Jamming is almost a certainty in combat, so to counteract this, we’ll give it a lasercom (which alone masses 2.5lbs and costs $1,250). And if it doesn’t have line-of-sight, there’s a backup extension cable for the cablejack of 100 yards. An IFF completes that package, for a total of 3.275lbs, $1,575, and 0.0655cf.

Drivetrain

Now it gets even more interesting! The main choice now becomes how much power we want to put into the drivetrain. And that depends on the final weight, which we don’t yet know (current weight is about 40-45lbs). Let’s figure a total of 100-150lbs for other components (that’d be 2-3cf). That’d be an area of 10-13 and therefore structural mass of 52lbs. Armouring it to 200DR is another ~150lbs, for a total estimated mass of about 350lbs. 1KW then gives move 14.3; 0.5KW move 10.1. The latter is about as fast as a world-class sprinting human; that seems fine.

Therefore, the drivetrain is 15lbs, 0.3cf, and $750 (it also requires 0.5KW). Since that’s actually not that much, I’ll double it - 30lbs, 0.6cf, $1500, and 1KW. I’ll probably only install a 0.5KW powerplant, but some batteries would allow high-speed sprinting, which seems nice.

Payload and Accessories

What else can we mount? There’s cargo spaces (including a hangar bay; that would be nice for deploying small recon drones). Actually, I’ll mount the cargo space as a modular socket - so that’s replaceable. It still is 1cf and can mass up to 50lbs.

Other components are three flashlights (one for the body, one each for the sensor arms; the latter should be included in the arm but that won’t make much of a difference) for a total of 6lbs, 0.12cf, and $60. I’ll also add the Inertial Compass system (1lbs, 0.02cf, $250), but will ignore the GPS - 1lbs? Those are built into each smartphone (so are inertial systems, but the accuracy of the Robots one is higher)! Another sign of technology moving forward since 1995.

Power

First question - how much power do we need? Up to 1KW for the legs, 0.265 for arms and 0.25 for the communicator. I’ll be rounding down to 1.5KW (we won’t always use all arms at once, and legs are fine with 0.5KW).

Now, what can we fuel this with? A gasoline engine is 10lbs, and requires 0.04 gallons per hour; a self-sealing tank good for 25 hours is 8lbs and 0.15cf. An MHD turbine masses slightly less (8lbs), and it can run on just half a gallon for the same time; this is 0.75lbs and 0.075cf (but the turbine is a bit more expensive at $500). In principle, there’s also nuclear power units but (a) they don’t seem to quite fit with the concept, and (b) they cost $20,000 (!).

So, I’ll be mounting a single MHD turbine, but I’ll upgrade it to 1.5KW (it’s cheap): 12lbs, $500, 0.24cf. I’ll also use even more fuel: The 1-gallon tank can propel it for 50 hours at maximum power use, and is 1.5lbs, $40, and 0.15cf. If you want more endurance, fill the modular cargo slot with more tanks, for a maximum of almost two weeks.

The Drivetrain

Now that we have all of the components, how does the body look like? In total, the robot is now at 132.35lbs, $61,285, and 3.083cf. That includes all arms, which are mounted in the body and retractable. We only lack one more component: The drivetrain!

At the moment, this is a total of 30lbs, $1500, and 0.6cf. Since it’s four legs, each of those has 7.5lbs and 0.15cf. However, the whole drivetrain has to be 60% of the body’s volume (1.8498cf). We could move components into the legs, but fuel tanks seem kind of silly, so I’ll just add empty space to bring it to 1.85cf. That brings our whole robot to 4.933cf volume.

Structure and Surface Features

What are the surface areas? We already computed them for the arms (sensor arm: 1, weapon arm 5, manipulator arm 2.5); the body has an area of 18. Total is 30.

Our frame will be extra-heavy, massing 60lbs and costing $15,000. Hit points are 12 (sensor arm), 60 (weapon arm), and 30 (manipulator arm) - the extra-heavy option really pays of here. Similarly for the body - hit points are 108.

Our armour goal, as previously mentioned, is 200DR; at the total area of 30, every point laminate armour DR costs 1.2lbs and $120. Turns out I greatly underestimated total required area - DR of 200 would be 240lbs and $24,000.

So, back to the drawing board. A 60° slope for the body from the front increases effective volume to 3.85375; total leg volume then becomes 2.31cf. This gives a total volume of 6.16375cf, area of 21 (total is 33) and therefore structural mass of 66lbs and costs $16,500. Body HP, by the way, becomes 126.

Now, we’ll mount laminate armour worth 100DR: 132lbs, $13,200. From the front, that’s an effective DR 200.

What else? I dislike the chameleon systems, but an infrared cloak is extremely useful, and so would be radiation shielding. Also, sealing. That’s 16.5lbs, $2,475 for the infrared cloak, 16.5lbs and $165 for radiation shielding, and another $330 for sealing. Actually, let’s replace the IR cloak with IR/Stealth: 33lbs, $4950.

What else? Surface sensors would be nice, but $9,900 seem a bit high. I’ll leave them off.

Statistics

So, where does that leave us?

  • Design Weight: That’s 359.85lbs unloaded, and 409.85 loaded (0.205t).
  • Volume and Size: Total volume is 6.16cf; longest dimension is about 1.7 metres.
  • Price: The robot costs $97,930. That does not include the weapons pod.
  • Attributes: Body ST is 64; arm STs can be found above but are 15 for the manipulators. DX is 10; IQ 8. HT is 12.
  • Ground Speed: 1KW drivetrain divided by 0.205t and multiplied by the speed factor gives 13.25y/s as speed. That is slightly better than human world-class sprinter speeds. Luckily we over-provisioned the power system! Loaded, it cannot float; unloaded it does. In that case, it can swim at 3y/s.

Another attribute is required maintenance: Robots doesn’t include that, but Vehicles does (at 20,000/sqrt(cost)). This means a maintenance interval of 63 hours for our robot: Every 63 operating hours, it needs four hours of maintenance. This means a human mechanic could keep five robots operating continuously; if we assume maintenance being more automated, this could rise to maybe fifty.

Another Brain

But wait! THS has different computers. The closest equivalent to the 10lbs standard PC would be a 10lbs microframe, at $15,000 vs $10,000; plus the latter is already hardened. The THS one also has a higher complexity: 7 vs 5. Rebuilding the robot brain, we can mount a normal-sized microframe (10lbs, $10,000, 0.2lbs); with a DX+3 booster it’s $30,000. Since really exchanging that component would require me to recompute volume, armour etc, I’ll just leave it be.

This changes statistics: Cost is only $90,430 (without software), IQ is 10, and DX is 14.

Software

What kind of software should this mount? We’ll probably want Ambidexterity (C2, $10,000), Combat Reflexes (C4, $15,000), a Personality Simulation (limited, C4 and $8,000), and a Datalink (C1, $800). I’m ignoring the encryption program: That seems like it should be standard anyway.

As for skills, there’s Guns (long-arm, subsuming the others as from the pyramid article), Soldier, Land Navigation, Tactics, Stealth, Electronic Ops (Comms), Camouflage, and Forward Observer. I’ll buy Guns, Soldier, and Tactics to 4CP (C4), $2,000 each. The others, I’ll buy at 2CP (C3, $1,000 each); note that I’m ignoring that physical skills are more expensive. That’s a total of $11,000.

This gives Guns-16, Soldier-10, Land Navigation-10 (although the inertial compass and GPS make this quite a bit higher in practice), Tactics-10, Stealth-14, Electronic Ops (Comms)-10, Camouflage-11, and Forward Observer-10.

Note that the software will probably be cheaper since the military probably doesn’t pay by license but pays for the development.

And there we go - that’s the robot!

Summary

Compared to the RATS from THS, it is superior in almost every way: Far more heavily armoured (200DR vs 60DR), more and higher-powered weapons (usually a battle rifle and minimissiles vs a PDW and micro-missiles), and it only costs a quarter. On the other hand, the THS RATS can tunnel, has melee claws, and masses only half. Still, I’d definitely prefer the former.

Note that I might have redesigned it to mount a heavier weapon on the arm; the 15mm chaingun from Vehicles (p. 43, 16d, 51lbs and ROF of 20) would’ve made an excellent (extremely heavy) support weapon.

Despite their speed, they will probably be transported by another vehicle (which would also contain more fuel and ammunition), clamped to the outside. They are far more efficient to transport using spacecraft: You can fit 80 robots into the space occupied by one bunkroom (four people); mass-equivalency is 5 robots per bunkroom but does not include any equipment for the humans.

On a more meta-note, this took me quite some time to implement (probably about 3-6 hours). Part of it is my own inexperience, of course; I could probably achieve a far higher speed by writing a small program for that system. Might actually do that.

  1. Note that this does not include armour which would make this quite a bit more weight. ↩