4 Dynamic take-off: high jumping power thanks to pneumatic drives Efficient landing: storing energy for the next jump In order to move as little mass as possible, all the components are optimally laid out, networked and controlled in the smallest possible space. The housing elements are cut out of foam. The kinematic system is made out of laser-sintered parts reinforced with carbon. As a result, the artificial animal weighs just seven kilograms with a height of around one metre, and it can jump up to 40 centimetres high and up to a distance of 80 centimetres. The take-off and flight phase Before the first jump, the elastic tendon is pneumatically pre- tensioned. The BionicKangaroo shifts its centre of gravity forwards and starts to tilt. As soon as a defined angle is reached at a corresponding angular velocity, the pneumatic cylinders are activated, the energy from the tendon is released and the kangaroo takes off. In order to jump as far as possible, the kangaroo pulls its legs forward during the flight phase. This creates torque at the hip, for which the artificial animal compensates with a movement of its tail. The top of the body thereby stays almost horizontal. The landing phase: energy for the next jump Upon landing, the tendon is tensioned again, thus converting the kinetic energy of the previous jump to potential energy. The energy is thereby stored in the system and can be called on for the second jump. The landing phase is the critical process for recovering the energy and is responsible for the kangaroo’s efficient jumping behaviour. During this phase the tail moves towards the ground and thus back to its starting position. Reduced energy consumption in the following jumps If the kangaroo continues jumping, it channels the stored energy directly into the next jump. The potential energy from the elastic tendon is used again at this point. The valves switch at the right moment and the next jump begins. In this way it takes several jumps one after the other. If the BionicKangaroo is supposed to come to a standstill, it must absorb as much energy as possible. To do so, the pneumatic actuators are switched accordingly and the tendon is actively tensioned again. Unique jumping behaviour: intelligent combination of installed components for stable and efficient jumping Shifting the centre of gravity forwards Pretensioning the elastic spring element Evaluation of the sensor values by the control system Pulling the legs forward and lifting the tail Landing and deflecting for the next jump Switching the valves on for take-off
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