Title: Planning of efficient trajectories in robotized assembly of aerostructures exploiting kinematic redundancy

Author of the experiment: Federica Storiale, Enrico Ferrentino, Pasquale Chiacchio

Description: Optimal trajectories are planned for the Fanuc M20iA/35M robot placed on a slide in the LABOR cell, simulating a sequence of operations on a fuselage. The planning is made through a dynamic programming algorithm that exploits the kinematic redundancy given by the slide to minimize the joint displacements and to maximize the stiffness at the working pose, while respecting joint position and velocity bounds and avoiding collisions. It is shown that a higher trajectory duration allows the robot to move its kinematic structure to achieve a stiffer posture without violating joint limits. Then, a comparison is made with a traditional approach based on the heuristics of fixing the slide in front of the holes to be drilled. In this case, time, stiffness and/or safety must be sacrificed for complex hole pattern geometries, while the dynamic programming solution allows for a faster, smoother, stiffer and safer movement of the whole kinematic chain along the desired paths.
More details in the paper F. Storiale, E. Ferrentino, P. Chiacchio, “Planning of efficient trajectories in robotized assembly of aerostructures exploiting kinematic redundancy”, Manufacturing Review, 8, 8, 2021, link.


Title: ROS-based robot-agnostic motion and interaction control

Author of the experiment: Giovanni Longobardi

Description: A ROS-based robot-agnostic software architecture is developed for heterogeneous and hyper-flexible worcells to deploy exactly the same control algorithm on different hardware and simulators. The video shows experiments for motion and interaction control on the Universal Robots' UR10 research robot, the Comau Smart-Six industrial robot and their digital twins. Trajectories are executed while interaction with the surrounding environment is handled through the acquisition of forces by means of different types of force/torque sensors mounted at the robot flange. The aim is to demonstrate that widely used algorithms for robot control can be made independent of the hardware architecture, with no need to recompile the code for each single robot, simplifying robot programming, increasing flexibility and reducing maintenance costs, without sacrificing performances.


Title: Redundancy resolution for energy minimization and obstacle avoidance with Franka Emika's Panda robot

Author of the experiment: Enrico Ferrentino, Federico Salvioli

Description: Globally-optimal trajectories along a pre-scribed path are planned for Franka Emika's Panda robot using dynamic programming. On a first trial, the square norm of joint velocities is minimized, to achieve indirect minimization of energy. In this case, the robotic arm collides with the wall on the side. On a second trial, a second objective function is added, corresponding to the distance from the obstacle, in a Pareto-optimal setup. The solution corresponding to the minimum norm of the objective vector is shown in the video. In this case, the robotic arm avoids the obstacle.
Source code here. More details in the paper Ferrentino, E.; Salvioli, F.; Chiacchio, P. Globally Optimal Redundancy Resolution with Dynamic Programming for Robot Planning: A ROS Implementation. Robotics 2021, 10, 42, link.


Title: Case study of constructive commissioning

Author of the experiment: Luigi Ferrara, Francesco Basile

Description: The virtual process in the video is made of three conveyors, each equipped with three retroflective sensors, transporting boxes from the left to the right. The process must be controlled to fulfil two specifications: (1) At most two robots can simultaneously work; (2) A robot can not grasp more than two boxes consecutively if one of the other robots has not grasped a box At this aim, a supervisor control architecture is adopted. First, the supervisor is designed either as an automaton (using Supremica) or a Petri net (using PetriBaR). Then, the toolbox SUP2PLC (available at the software section) is used to automatically generate the PLC code, starting from a supervisor model. Finally, the closed-loop system is simulated: a virtual PLC is instantiated with PLC-SIM (Step 7), and the code is run. I/O signals are exchanged with Factory I/O through TCP/IP. More details in the paper F. Basile, L. Ferrara (2020), From supervisory control to PLC code: a way to speed-up Constructive/Virtual Commissioning of Manufacturing Systems, 15th IFAC Workshop on Discrete Event Systems (WODES 2020)


Title: Execution of time-optimal trajectories with the Franka Emika's Panda robot

Author of the experiment: Enrico Ferrentino, Heitor Judiss Savino

Description: Time-optimal trajectories are planned with a dynamic programming algorithm that exploits kinematic redundancy to minimize trajectory tracking time. The trajectories are planned for Franka Emika's Panda robot by considering a dynamic model with friction together with joint velocity, acceleration, jerk, torque and torque rate bounds. The planned trajectories are executed on the real robot to assess feasibility and tracking accuracy. Feasibility is obtained through interpolation and smoothing of the planned joint position references, while the tracking error in the joint space is lower than 0.8 degrees. Two trajectories are planned corresponding to a straight line of 0.50 m and an ellipse-shaped line of 1.45 m. Execution times are 0.62 s and 1.70 s respectively.


Title: Decentralized multi-arm planning

Author of the experiment: Alessandro Marino & Jolanda Coppola

Description: A two-layer decentralized framework for kinematic control of cooperative and collaborative multi-robot systems is developed and tested. The motion of the system is specified at the workpiece level, by adopting a task-oriented formulation for cooperative tasks. The first layer computes the motion of the single arms in the system. In detail, the control unit of each robot computes the end-effector motion references in a decentralized fashion on the basis of the knowledge of the assigned cooperative task and the motion references computed by its neighbors. Then, in the second layer, each control unit computes the reference joint motion of the corresponding manipulator from the end-effector reference motion.

Setup: 2 Comau SmartSix robots installed at the Automatica Laboratory of University of Salerno.


Title: Cooperative drilling of aeronautic hybrid stacks

Author of the experiment: Alessandro Marino

Description: The proposed technology consists in a general robot architecture and a cooperative drilling process using only standard low-cost robots and off-the-shelf components. A first robot is in charge of drilling the hybrid stack, while a second manipulator ensures the right clamping force between the parts of the stack. Both robots are equipped with force control capabilities to control the generalized forces raising during the interaction with the stack. Thanks to the adoption of a fuzzy inference system, the tuning of the force controllers might be carried out by operators that have knowledge of the drilling process but not of control system technology.

Setup: 2 Comau SmartSix robots equipped with force/torque sensors installed at the Automatica Laboratory of University of Salerno.