An adaptive sensor foot for a bipedal and quadrupedal robot

Abstract

One key benefit of legged robots is their ability to act on the environment by applying forces in a noncontinuous 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 paper focuses on a sophisticated lower limb system for a multi-legged robot to demonstrate the advantages of actuated multi-point-contact feet. Indications for these advantages can be found in nature, where the mechanical and sensory interaction of the feet with the substrate enables highly flexible ways of locomotion in animals and helps to optimize traction. Multi-point-contact feet even enable the transition from quadrupedal to bipedal walking, a dexterous behavior of ape-like mammals. To prove the technical plausibility of the planned leg structure, a first prototype including a lower leg, an actuated ankle joint, an attached foot structure, and a set of sensors with their required electronics was developed and integrated. Due to its characteristics, the lower limb -as a subcomponent of a legged robotic system -will extend the robot's knowledge of its internal and the environmental states. The mechanical and electronic design of the foot structure is presented in this paper as the basis for a later development of a biologically inspired control scheme.

Plantar Tactile Feedback for Biped Balance and Locomotion on Unknown Terrain

“…[17][18][19][20] For bigger robot sizes (closer to human size and weight), resistive sensors are combined within the structural layers of the soles to increase the sensing range and endurance. 21,22 Likewise, other tactile sensing principles have been applied as the optical measurement of rubber deformation 23 or the high-speed pressure sensor grid 24 which can acquire the pressure shape of the foothold at a frequency of 1 kHz.…”

Real-Time Digital Signal Processing Based on FPGAs for Electronic Skin Implementation †

“…The development of the e-skin system starts by defining the system specifications, designing and fabricating the mechanical arrangement of the skin itself (i.e., sensing materials), together with the embedded digital system for tactile data processing. The different e-skin tasks are still in their infancy and far from being properly addressed even if many research groups are addressing the topic with different approaches at each level of the problem [3,4,5,6,7,8,9]. …”

Design and Experimental Development of a Pneumatic Stiffness Adjustable Foot System for Biped Robots Adaptable to Bumps on the Ground

“…Some robotic foot systems were designed by adding toe joints and elastic elements to the simple rigid flat foot [19][20][21][22][23]. Segmented to the heel part and toe part, human-like heel contact and toe contact were realized in bipedal robotic walking [20].…”

“…Segmented to the heel part and toe part, human-like heel contact and toe contact were realized in bipedal robotic walking [20]. These feet were able to dissipate energy from the heel strike with the elasticity of the heel [21,22], and to provide more traction using the toe pad at the push-off phase [23], but they could not adapt to rough terrain. Based on the concept of maintaining multi-point contact on uneven ground, a foot capable of providing stable contact on convex and concave surfaces was developed.…”