You are designing a jumping microrobot using an electrostati

You are designing a jumping microrobot using an electrostatic inchworm motor with efficiency 20%, power electronics with efficiency 30%, and a spring that converts approximately 90% of its stored energy into kinetic energy upon release. Assume the mass of the motor, mechanisms, sensors and electronics (without the battery) is 20 mg.

a) Find the smallest battery that you can buy on the internet. What is the mass and energy stored in this battery? Your power electronics will take care of the DC-DC conversion to get the voltages you need for the electrostatic actuators.

b) Assuming zero drag, what is the maximum distance that your robot can jump before recharging the battery?

Solution

a) The smallest commercially available battery is PGEB201212, an ultrathin rechargable Li ion battery. Its weight is 0.45 g and energy stored is 32.5 mWh assuming linear discharge rate till end-of-discharge cutoff voltage.

b) mass of system = 0.02+0.45 = 0.47 g

Total energy in battery = 32.5 mWh = 117 J

Kinetic energy available = 117x0.2x0.3x0.9 = 6.318 J

mgH = 6.318

H = 1.3703 m

This is the max height the microbot can jump before recharging is required (assuming linear discharge rate from rated volatge to end-of-discharge cutoff voltage).