ALMA - Articulated Locomotion and Manipulation for a Torque-Controllable Robot

Abstract

We present a motion planning and control framework for ALMA, a torque-controlled quadrupedal robot equipped with a six degrees of freedom robotic arm capable of performing dynamic locomotion while executing manipulation tasks. The online motion planning framework, together with a whole-body controller based on a hierarchical optimization algorithm, enable the system to walk, trot and pace while executing tasks such as fixed-position end-effector control, reactive human-robot collaboration and torso posture optimization to increase the arm's kinematic reachability. The torque controllability of the whole system enables the implementation of compliant behavior, allowing a user to safely interact with the robot in a very natural way. We verify our framework on the real robot by performing tasks such as opening a door and carrying a payload together with a human.

Terrain-Adaptive Planning and Control of Complex Motions for Walking Excavators

“…Typically, whole-body control is associated with torquecontrolled robots and there is rich literature covering the topic [19], [20], [2], [8], [9]. However, many existing machines do not feature actuators for high accuracy torque control (e.g.…”

“…Hence, the base tracking task is split into terrain adaptive posture tracking (roll, pitch and height that are influenced by FE joints) and 2D pose tracking (x, y and yaw influenced by Abduction/Adduction (AA) and steer joints). Exploiting the hierarchical task setup to achieve posture adaptation has been reported in [19]. We exploit hierarchical task setup to realize the terrain adaptive behavior.…”

An Optimization-Based Locomotion Controller for Quadruped Robots Leveraging Cartesian Impedance Control

“…In order to save energy, a third QP has to be added to minimize torque commands. Usually, those are the three fundamental QPs required by HQP controllers (Bellicoso et al, 2019 ). For walking gaits, if we separate swing legs and torso into different prioritized tasks, one more QP has to be solved.…”

Whole-Body MPC for a Dynamically Stable Mobile Manipulator

“…So far, the most remarkable robot capable of performing dynamic coordination of locomotion, manipulation and balancing on a statically unstable platform is Handle by Boston Dynamics [17], whose controller is not described in any publications. In [4], manipulation is performed with an arm on a quadrupedal robot. However, contact forces are considered as disturbances in the balancing planner.…”

“…In the robotics literature, there are works that have treated the manipulation problem for systems balancing on unstable platforms (e.g., [4], [5], [6]). However, current approaches do not take into account the full non-linear system dynamics in the planner.…”