Efficient motion generation for a six-legged robot walking on irregular terrain via integrated foothold selection and optimization-based whole-body planning

Abstract

SUMMARYIn this paper, an efficient motion planning method is proposed for a six-legged robot walking on irregular terrain. The method provides the robot with fast-generated free-gait motions to traverse the terrain with medium irregularities. We first of all introduce our six-legged robot with legs in parallel mechanism. After that, we decompose the motion planning problem into two main steps: first is the foothold selection based on a local footstep cost map, in which both terrain features and the robot mobility are considered; second is a whole-body configuration planner which casts the problem into a general convex optimization problem. Such decomposition reduces the complexity of the motion planning problem. Along with the two-step planner, discussions are also given in terms of the robot-environmental relationship, convexity of constraints and robot rotation integration. Both simulations and experiments are carried out on typical irregular terrains. The results demonstrate effectiveness of the planning method.

Mechanism, Actuation, Perception, and Control of Highly Dynamic Multilegged Robots: A Review

“…For example, ANYmal [3] and HyQ2Max [15] quadruped robots have pure serial leg mechanisms. PKMs are typically used for the leg structures of high-payload mobile robots [7,8]. The serial-parallel hybrid mechanism has greater rigidity than the SKM with the same DOF and a larger workspace than the PKM with the same DOF [36].…”

“…It is now widely acknowledged that robotic technologies at that time were far from sufficient for carrying out complex rescue operations [5]. Recently, supported by the National Basic Research Program of China (973 Program), a series of hexapod robots with parallel legs were developed by Shanghai Jiao Tong University (SJTU) for firefighting, transportation, and detection in disaster environments, such as nuclear accidents [6][7][8]. The payloads of these hexapod robots can reach up to 500 kg.…”

“…In fact, robustness and safety are the key considerations for legged robots in outdoor environments, easily outweighing agility and autonomy. In practice, it is very difficult for current legged robots to be used in real applications in outdoor environments [11]; actually, only a few legged robots take into account the requirements of a specific application, such as nuclear disaster relief (e.g., SJTU hexapod robots [6][7][8]) or inspection of gas and oil sites (e.g., ANYmal [3] and its previous version). In addition, the performances of legged robots are related to many factors, including their mechanisms and actuation, perception, and control methods.…”

Quickly Obtaining Range of Articulated Rotating Speed for Electrically Driven Large-Load-Ratio Six-Legged Robot Based on Maximum Walking Speed Method

“…Hence, the rotation angles of the leg i are solved for the abductor joint, hip joint, and knee joint, when the position matrix 0 P (i) F has been acquired. According to (13) and (14), the mathematical expressions are written as follows. Meanwhile, the rotation angle θ i of abductor joint can be obtained.…”

“…Mendez-Monroy [13] used a pattern generator to maintain the balance of humanoid robot in the presence of strong disturbance. Tian and Gao [14] provided an efficient motion planning method for a six-legged robot to traverse the terrain with medium irregularities. Martinez et al [15] described a lower limb exoskeleton control approach for guiding leg movement.…”