From: veritasium
A new tiny robot, weighing less than a tennis ball [00:00:00], holds the world record for jumping, reaching heights of 31 meters [00:00:16] – equivalent to a 10-story building [00:00:19] or from the Statue of Liberty’s feet to eye level [00:00:24]. This significantly surpasses the previous record of 3.7 meters [00:00:11].
Defining a Jump
For something to qualify as a jump, it must meet two criteria [00:00:30]:
- Motion must be created by pushing off the ground [00:00:35] (e.g., quad-copters pushing off air do not count [00:00:38]).
- No mass can be lost during the process [00:00:43] (e.g., rockets ejecting fuel or arrows launched from a bow do not count [00:00:45]).
Inspiration from the Animal Kingdom
Many animals, from sand fleas to kangaroos, execute jumps by launching their bodies into the air with a single muscle stroke [00:01:02]. The height of the jump is determined by the energy delivered in that single stroke [00:01:08]. The Galago, or Bush Baby, is considered the best jumper in the animal kingdom, dedicating 30% of its muscle mass to jumping [00:01:23], allowing it to leap over two meters from a standstill [00:01:31]. This is due to having more jumping muscles, not necessarily better ones [00:01:39].
How the Robot Jumps
The robot’s main structure consists of four pieces of carbon fiber held together by elastic bands, forming a spring that stores energy [00:03:57]. A small motor at the top of the robot winds a string connected to the bottom, compressing the structure and storing energy in the carbon fiber and rubber bands [00:04:08]. After about 90 seconds of compression [00:04:24], a trigger releases a latch, unspooling the string and releasing the stored energy [00:04:39]. This propels the jumper from a standstill to over 100 kilometers per hour in just nine milliseconds [00:04:55], experiencing an acceleration of over 300 g’s [00:05:12].
Key Design Features
This robot’s ability to jump nearly 10 times higher than the previous record holder [00:05:27] is attributed to three special design features:
Lightweight Construction
The jumper weighs only 30 grams [00:05:35], achieved through a tiny motor and battery, and a structure made entirely of lightweight carbon fiber and rubber that doubles as the spring [00:05:39]. Natural latex rubber can store 7,000 joules per kilogram, more energy per unit mass than almost any other elastic material [00:05:48].
Optimized Spring Design
The spring’s design is crucial for its performance [00:06:02].
- Early designs using only rubber bands with hinged aluminum rods showed a force profile that peaked and then decreased upon compression [00:06:06].
- Another design with only carbon fiber slats required significant initial force, which then increased linearly with compression [00:06:20].
- The ultimate design is a hybrid of these two, creating a force profile that is almost flat over the entire range of compression [00:06:30]. This allows it to store double the energy of a typical spring where force is proportional to displacement [00:06:45], making it potentially the most efficient spring ever made [00:06:52].
Work Multiplication
The robot’s primary advantage comes from work multiplication [00:07:39]. Unlike animals, which use a single muscle stroke, engineered jumpers can store energy from many strokes (or motor revolutions) [00:07:42]. This allows the motor to be small, as it doesn’t need to deliver all energy at once but builds it up gradually over several minutes [00:07:55]. This process is enabled by a latch that prevents the spring from unspooling until full compression is reached [00:08:10].
While some biological organisms, like the sand flea [00:08:21] and the slingshot spider [00:09:29], utilize latches or external elements to store energy over multiple “strokes,” no organism has developed internal work multiplication for a jump from a standstill [00:09:01]. Historically, engineered jumping aimed to mimic biology [00:10:09], but work multiplication provides a unique advantage by shifting the limiting factor from motor power to spring power [00:10:11].
Potential Applications and Future Developments
This jumping robot concept holds significant potential applications for jumping robots, particularly for exploring other worlds where the atmosphere is thin or non-existent [00:02:50].
- On the Moon, with one-sixth of Earth’s gravity, this robot could leap 125 meters high and half a kilometer forward [00:02:58].
- Jumpers could navigate challenging terrains like steep cliffs and deep craters, acting as sample-fetchers for rovers [00:03:07].
- With the ability to store kinetic energy back in the spring upon landing, the efficiency could be near perfect [00:03:16].
The development team is already building a fleet of jumping robots with advanced capabilities [00:03:26]:
- Some can right themselves after landing for immediate re-launch [00:03:30].
- Others are steerable, featuring three adjustable legs that allow directional launches [00:03:36].
Scaling and Air Resistance
The robot has nearly maximized the achievable height with its current spring design [00:10:29]. To jump even higher, future designs could focus on incorporating air resistance and aerodynamics [00:10:44]. Scaling the jumper up ten times isometrically could lead to a 15-20% higher jump [00:10:50]. This is because while the cross-sectional area (and thus drag force) increases by a hundred, the mass increases by a thousand, giving it significantly more inertia and reducing the effect of drag [00:11:05].
The broader concept of work multiplication could revolutionize robotics, allowing robots to store and release enormous amounts of energy over time, overcoming the portability limitations of small motors [00:11:25]. This innovation showcases the deep understanding of math and physics of jumping and energy storage required for such advanced engineering [00:11:57].