Energy and time optimal trajectories in exploratory jumps of the spider Phidippus regius
Journal: Scientific Reports
Publication Date: 08 May, 2018
Jumping spiders inspire leap in micro robots
Jumping spiders get their name from their ability to perform highly athletic and precise jumps for the purposes of moving about in their environment and catching prey. Scientific measurement of jumping behaviour is challenging because the spiders are very small and the jumps are over in a fraction of a second. Now, researchers at the University of Manchester have been able to capture the action! The research is ground breaking in that it is the first in which a spider has been trained to jump between platforms of varying height and distance, with results recorded using ultra-high-speed, high-resolution cameras, and detailed leg geometry captured using 3D X-ray scanning. Results show that for close-range jumps associated with prey capture, the spider adopts shallower launch angles which use up more energy, but minimise flight time. For long-range jumps, the spider jumps at angles that minimise the energy consumption. It is remarkable that despite limited visual sensing and control capability the spider can compute and execute highly optimal motion trajectories. The work provides inspiration for a new class of agile micro robots that are currently unthinkable using today’s engineering technologies.
- The species of spider used for the study is Phidippus regius. Out of four spiders sourced for the study only one named Kim was successfully trained to jump. She was 15 mm long and weighed 0.15 g.
- Whilst Kim has four pairs of legs, she only uses the rear two pairs for jumping. The front two pairs are used for balance during take-off.
- Kim always attaches a silk line to the launch platform before taking-off. The reason for this is not clear, but it may act as a safety line in the event of a missed jump. Kim never missed landing in all the tasks she was set so we do not know if it works or not!
- In the absence of significant air resistance, the best launch angle of any ballistic object to achieve the longest jump on a horizontal surface, be it a spider or canon ball, is 45 degrees.
- The best angle to achieve the minimum time of flight depends on the total amount of energy you have available for the jump. Shallower jumps get you there quicker, but take more energy.
- Jumping as means of locomotion is very common in the insect world. Spiders are not the highest performance jumpers, but they are probably the most accurate – bad news for prey