Quadruped pronking on compliant terrains using a reaction wheel

Abstract

While legged locomotion is a rapidly advancing area in robotics, several issues regarding the performance of such robots on deformable ground are still open. In this paper, we generate a pronking gait on a quadruped robot using a controller, which takes into account the effects of ground deformation. The controller, initially developed for monopods, is modified appropriately to operate for quadrupeds. The robot uses a reaction wheel to retain a desired body pitch. The dynamic models of leg motor drivetrains and of the reaction wheel are incorporated and their importance in the design of legged robots is highlighted. Simulation results show good performance in reaching commanded apex heights and forward velocities when traversing various deformable terrains, demonstrating that the developed controller is quite promising.

Towards Jumping Locomotion for Quadruped Robots on the Moon

“…The use of a tail was explored with the 2.5 kg Jeorba hopper [14] and the 1.25 kg Cheetah-Cub [15]. A reaction wheel was proposed during a simulation study to stabilize the pronking motion of a 10 kg quadruped on compliant terrain [16]. However, these systems are not capable of carrying a significant payload, which makes them of limited use in the proposed application.…”

Pronking and bounding allow a fast escape across a grassland populated by scattered obstacles

“…It has been recognized that quadrupeds are the animals that run faster [ 21 ] and are able to move steadily on rough ground [ 24 ], therefore there is a special interest in reproducing their gaits. A great effort is devoted to optimizing the leg control in order to reproduce a rich variety of motions [ 29 , 32 , 40 ]. Although for our model bounding can be considered almost equivalent to pronking, this is not exactly the case for robot design.…”

“…Moreover, in pronking gait, pitch and roll of the animal body are minimal and therefore the model of a pronking robot does not need a control of rigid body effects, at variance with the case of a robot moving with a bounding gait [ 27 , 39 ]. Robots used for exploration need to be able to move in uneven terrain, a recognized specialty of quadrupeds, nevertheless only recently experiments using legged robots have started to test their performances on irregular environments [ 24 , 25 , 28 , 31 , 32 ], and to simulate their performances under reduced gravity conditions of interest for planetary exploration [ 41 ]. Most research works analysed only the motion on flat or slightly uneven terrain where the performances of wheeled rover robots are definitely superior [ 29 ].…”

“…Pronking is one of the most-studied gaits, as it allows for obtaining a fast and stable motion with a limited number of control parameters, due to the fact that all the legs are parallel and move in phase [18,[24][25][26][27]. In the case of movement in an uneven environment [28][29][30][31][32], pronking can be a particularly effective gait to manage the problem of over-passing obstacles [19,31]. The results of our work could pave the way for further applications of pronking as a favourite choice for the development of robots that have to move in a terrain with randomly distributed natural boundaries.…”

Orientation Control System: Enhancing Aerial Maneuvers for Quadruped Robots

“…Changing the angular velocity of a rotating mass attached to the trunk generates a torque that can reorient the robot. This device was first applied for spacecraft orientation [ 15 ], and only sporadically investigated in legged locomotion for controlling pitch orientation, both for bipeds [ 16 , 17 ] and quadrupeds [ 18 , 19 ]. Compared with tails, flywheels do not have position limits, and, since their rotational axes pass through the CoM, angular momentum results in holonomic [ 20 ].…”