© 2018 by 21Geo, Thomas Dobroth

Efficient Robotic Walking

The limb systems on a walking robot do not work efficiently.  For the body of the robot to move forward and keep the body of the robot level, one of the limbs will have to be lifting the robot, and the other will need to be lowering.  The lifting limb must put energy in.  The other takes energy out.  Every step is also a pushup.  Because of the losses in the transmission system, it’s not possible to use regenerative techniques to minimize the losses.  Some robots have may use springs or put wheels under the legs to minimize the losses. 

The losses are proportional to the weight of the robot.  If the robot’s task is to ferry materials, then payload and battery life are direct trade-offs. 

A Better Way

21Geo has invented a leg joint that does not move the robot up as the limb moves.  It uses Precise Motion Technology to raise the leg in the middle of the stroke.  The result is a highly efficient way to walk.  The energy of the device in the animation below is similar to rolling. In fact, under some surfaces, it could be more efficient.  Once the device gets going it continues to move with very little energy. 

An additional benefit will likely be a more nimble robot.  With the prior version, the actuators have a load when not moving, requiring an even larger load to make a movement.  The new leg joint has no load while not moving – making it easier to move. 

The final animation shows one possible configuration for how the device would walk.  There could be many other possible configurations.  For example, there could only four legs or four legs with an additional joint.