iStruct Demonstrator


iStruct Demonstrator
The four-legged robot in DFKI's artificial crater environment (Source: Daniel Kühn, DFKI GmbH)
Contact person:
Dipl.-Inf. Daniel Kühn

Technical Details

Size: 66cm x 43cm x 75cm (standard position)
Weight: 18 Kg
Power supply: 44,4V / 2.5Ah (Lithium Polymer)
Actuation/ Engine: 8 * 48V RoboDrive motors with a 1:50 HarmonicDrive gear, 8 * 48V RoboDrive motors with a 1:80 HarmonicDrive gear, 4 BLDC Faulhaber-2250 motors as well as 6 BLDC Faulhaber 2444 Motors
Sensors:
Joints: Positions (absolute and relative), speed, current, supply voltage, temperature; Foot: 49 pressure sensors, a three axis acceleration sensor, one distance sensor, three absolute position sensors, one temperature sensor, and one 6DoF force-torque sensor; Spine: 2x6 Positions sensors (absolute and relative), 6x1DoF force sensors; Body: Inertial Measurement Unit, battery voltage

Organisational Details

Application Field: Space Robotics

System description

CAD sketch of the spine in the context of the currently developed ape-like demonstrator (Source: Frank Beinersdorf, DFKI GmbH)
Bioinspired functionality - Developmental steps of the lower leg design (Source: Felix Bernhard und Kristin Fondahl, DFKI GmbH)

One key benefit of legged robots is their ability to act on the environment by applying forces in a noncontiguous way in innumerous directions and magnitudes within their designed workspace. Most multi-legged robots are equipped with single-point-contact feet for the sake of simplicity in design and control.

This project focuses on a sophisticated lower limb system for a multi-legged robot to demonstrate the advantages of actuated multi-point-contact feet. The employed sensors include the pressure sensor array of 43 individual FSR-sensors, six additional FSR-sensors are located on exposed parts used for collision detection, a 6-axis Force/Torque-sensor, a distance sensor in the heel to anticipate the heel strike, a digital 3-axis accelerometer to perceive the orientation of the foot structure, two temperature sensors to compensate for the temperature influences in the involved electronics, and digital magnetic angular encoders to monitor every moving axes of the foot and ankle structure.

In addition, to increase the mobility towards a so-called multi-locomotion system, the rigid connection between the front and rear body will be replaced by an actuated spinal column. The mechanism is a 6-DoF parallel kinematic mechanism. The struts in the spine are arranged in such a way that only compression and tension forces occur. Hence, a single axis load cell can be integrated in line with each strut. Due to the embedded electronic in the spine the overall structure can be used as a 6-axes force-torque sensor.

iStruct: Walking

The video shows the walking pattern of the iStruct Demonstrator. Besides different walking directions a smooth transition between the respective directions is realized.

iStruct: Balancing

The robot shifts its center of mass in realtime, based on the slope it is walking on.

More Images

Lateral view on the developed ape-like robot with articial spine and sensor feet (Photo: Daniel Kühn, DFKI GmbH)
Lateral view on the developed ape-like robot with arti cial spine and sensor feet (Photo: Daniel Kühn, DFKI GmbH)
Close up picture of the ankle joint mechanism and sensor foot (Photo: Daniel Kühn, DFKI GmbH)
Close up picture of the ankle joint mechanism and sensor foot (Photo: Daniel Kühn, DFKI GmbH)
Actuation mechanism and rods within the spine (close-up / top view) (Photo: Daniel Kühn, DFKI GmbH)
Actuation mechanism and rods within the spine (close-up / top view) (Photo: Daniel Kühn, DFKI GmbH)
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© DFKI GmbH
last updated 24.04.2014
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