Horse Exoskeletons?

Question

Working on a society a society that was never centralized or peaceful enough to invest in rail and road networks, even as the rest of the world developed. They've imported camels, donkeys, and horses over the centuries, and I'm wondering if there might be some technology that could build on what they have as they're starting to modernize.

One thought I had was to just put wheels on both sides of the animals, allowing them to glide between gallops, like a bicycle; but I'm suspecting it might just be more weight for them to carry in a lot of circumstances, and if the road allowed this, why not just import cars? Wheels make more points of contact on the ground, which might help with distributing the weight they carry, but that's just what a cart does anyway.

Anyway, I saw some videos years ago about the military making mechanical exoskeletons to help soldiers carry more weight on them, which has me wondering if this kinda thing could be used on beasts of burden to carry things over uneven, unpaved terrain, allowing merchants to scale up how much merchandise they can move without scaling up how much feed they need or how much manure they need to clean. Maybe even just something simple that meant livestock wouldn't have to be put down whenever they broke a leg. Would present technology batteries even work for the distances between rest stops for donkey trains transport cargo? Would it even have a lower upfront cost than laying rails and carving tunnels?

Answer 1

There appear to be some misconceptions...

Let's look at ancient and medieval cargo transport. The cheapest method to move goods was by sea, by a huge margin. The second cheapest method was to move goods by rivers, significantly more expensive than by sea, but much cheaper than by land. The most expensive method was to move cargo by land, either in carts (pulled by horses, donkeys or oxen) or "self-propelled" cargo such as herds of goats or flocks of sheep.

Moving goods on the backs of animals (or people) is so marginal that it does not even rate a percentage point in the legal economy, because it is uneconomical. Let's look at horses - on average, a horse can safely carry 20% of its body weight or it can pull a cart or wagon up to 200% of its body weight. It is simply impractical to try to conduct regular, legal trade by loading goods on the back of horses instead of building a road and using a cart - any village without a road must effectively be completely self-sufficient and able to produce all of its own food, fuel for heating and cooking, building materials, tools etc since these cannot all be carried on the backs of horses or mules.

There are basically two use cases for loading goods on the backs of people or animals and thus avoiding developed roads. The first is (or was) exploration, especially prospecting for gold or other valuable metals or minerals. Ye olde prospector would load up with a limited amount of supplies and tools and go looking for a valuable strike. They and their pack animals would live off the land as much as they could, then intermittently return to town to resupply.

The second use case is smuggling. Whether it is high-tarriff luxury goods such as perfumes and precious metals or totally illegal goods such as opium and Stinger missiles, the smugglers resupply with food from sympathetic or intimidated communities along the way so they can devote their entire limited cargo capacity to their illegal payload. By staying off the roads they hope to avoid the enemies, including any "legal" authorities, that want to capture or kill them and seize their payload.

With that out of the way - in modern times there are extremely few villages or settlements that are supplied exclusively by pack animals because they just cannot carry enough. Even in the remote areas of Pakistan and Afghantistan, there will generally be a road, or a river, or a terrifying and sometimes hideously unsafe cable car that will be used for transport. If there is a state of conflict going on then it is quite possible that a settlement or region may be cut off temporarily because the single transport route in and out has been sabotaged or interdicted, but if there is no way in or out routinely then there is unlikely to be a settlement there. (Partial exceptions may exist for summer settlements as part of transhumance practices since the goats are self-propelled, but the winter settlement will need a reliable link.

Finally - let's talk about horses.

1. Horses have four gaits - the gallop is the fastest and it is the equivalent of sprinting for a human, and used for about the same proportion of the time.
2. Horses rely on contact with the ground for traction. Reducing the amount of weight that the horse can bring to bear on the ground is the equivalent of putting the spoilers on a Formula 1 car on upside down so they provide lift - suddenly they can't accelerate well, can't brake well and can't corner well. (A number of authors get this one wrong when they have characters running faster on low-G planets than they can on Earth - running may require less effort so a character can run for longer, but they will take longer to get up to speed and have trouble braking and cornering.)
3. There are all sorts of reasons why horses cannot recover from broken legs and it is extremely unlikely that an exoskeleton will help. Do a search on "Can horses recover from a broken leg" for a longer explanation.

In summary - there is no real replacement for using roads/rivers/railways/cable cars to conduct trade and other travel, but that is fine because there will not be any settlements that do not have at least one of those links anyway. The only people likely to be interested in putting exoskeletons on horses are likely to be smugglers, but the added logistics burden and sensor signature make them a bad idea in that application too.

Answer 2

Useable powered exoskeletons are something barely a century old. They are based on technology that must necessarily postdate a lot of other technology, including automated vehicles (necessarily, because the motors, energy distribution, joints, &c. have to be compact, strong, and resistant to a degree otherwise unattainable).
It would make more sense for your civilization to develop terrain-specific vehicles, rather than augment much more maintenance- heavy and cost-inefficient beasts of burden.

This point will be even more pronounced since you're talking about "present technology": it doesn't make sense to either have horses or horses powered by exoskeletons, instead of motorized vehicles adapted to your specific terrain.