scholarly journals Hybrid Parallel Compliance Allows Robots to Operate With Sensorimotor Delays and Low Control Frequencies

2021 ◽  
Vol 8 ◽  
Author(s):  
Milad Shafiee Ashtiani ◽  
Alborz Aghamaleki Sarvestani ◽  
Alexander Badri-Spröwitz
Keyword(s):  
Computer Simulation ◽  
Nervous System ◽  
Quadruped Robot ◽  
Legged Robots ◽  
Passive Stiffness ◽  
Leg Length ◽  
Sensors And Actuators ◽  
Control Frequency ◽  
Drop Landing ◽  
High Control

Animals locomote robustly and agile, albeit significant sensorimotor delays of their nervous system and the harsh loading conditions resulting from repeated, high-frequent impacts. The engineered sensorimotor control in legged robots is implemented with high control frequencies, often in the kilohertz range. Consequently, robot sensors and actuators can be polled within a few milliseconds. However, especially at harsh impacts with unknown touch-down timing, controllers of legged robots can become unstable, while animals are seemingly not affected. We examine this discrepancy and suggest and implement a hybrid system consisting of a parallel compliant leg joint with varying amounts of passive stiffness and a virtual leg length controller. We present systematic experiments both in computer simulation and robot hardware. Our system shows previously unseen robustness, in the presence of sensorimotor delays up to 60 ms, or control frequencies as low as 20 Hz, for a drop landing task from 1.3 leg lengths high and with a compliance ratio (fraction of physical stiffness of the sum of virtual and physical stiffness) of 0.7. In computer simulations, we report successful drop-landings from 3.8 leg lengths (1.2 m) for a 2 kg quadruped robot with 100 Hz control frequency and a sensorimotor delay of 35 ms.

scholarly journals A Quadruped Robot with the Wooden Body for Static Locomotion in a Controlled Environment

2020 ◽  
Author(s):  
Muhammad Bilal Khan
Keyword(s):  
Inverse Kinematics ◽  
Degrees Of Freedom ◽  
Position Control ◽  
Low Cost ◽  
Control Design ◽  
Quadruped Robot ◽  
Legged Robots ◽  
Controlled Environment ◽  
Robot Design ◽  
Classroom Setting

We present the design and overall development of an eight degrees of freedom (DOF) based Bioinspired Quadruped Robot (BiQR). The robot is designed with a skeleton made of cedar wood. The wooden skeleton is based on exploring the potential of cedar wood to be a choice for legged robots’ design. With a total weight of 1.19 kg, the robot uses eight servo motors that run the position control. Relying on the inverse kinematics, the control design enables the robot to perform the walk gait-based locomotion in a controlled environment. The robot has two main aspects: 1) the initial wooden skeleton development of the robot showing it to be an acceptable choice for robot design, 2) the robot’s applicability as a low-cost legged platform to test the locomotion in a laboratory or a classroom setting.

scholarly journals Control Design and Validation for Floating Piston Electro-Pneumatic Gearbox Actuator

2020 ◽  
Vol 10 (10) ◽  
pp. 3514 ◽  
Author(s):  
Adam Szabo ◽  
Tamas Becsi ◽  
Peter Gaspar
Keyword(s):  
Piecewise Linear ◽  
Control Design ◽  
Continuous Control ◽  
Control Methods ◽  
Linear Quadratic ◽  
Modeling And Control ◽  
Control Frequency ◽  
Heavy Duty Vehicle ◽  
High Control ◽  
And Control

The paper presents the modeling and control design of a floating piston electro-pneumatic gearbox actuator and, moreover, the industrial validation of the controller system. As part of a heavy-duty vehicle, it needs to meet strict and contradictory requirements and units applying the system with different supply pressures in order to operate under various environmental conditions. Because of the high control frequency domain of the real system, post-modern control methods with high computational demands could not be used as they do not meet real-time requirements on automotive level. During the modeling phase, the essential simplifications are shown with the awareness of the trade-off between calculation speed and numerical accuracy to generate a multi-state piecewise-linear system. Two LTI control methods are introduced, i.e., a PD and an Linear-Quadratic Regulators (LQR) solution, in which the continuous control signals are transformed into discrete voltage solenoid commands for the valves. The validation of both the model and the control system are performed on a real physical implementation. The results show that both modeling and control design are suitable for the control tasks using floating piston cylinders and, moreover, these methods can be extended to electro-pneumatic cylinders with different layouts.

scholarly journals Gero Miesenböck: instructing the nervous system

2007 ◽  
Vol 177 (3) ◽  
pp. 374-375
Author(s):  
William A. Wells
Keyword(s):  
Nervous System ◽  
Neural Activity ◽  
Sensors And Actuators ◽  
Genetically Encoded Sensors ◽  
And Control ◽  
At Will

Gero Miesenböck uses light and genetically encoded sensors and actuators to observe and control neural activity. Having caused headless flies to fly at will, he is set to understand how the nervous system encodes behavior.

scholarly journals XBot: A Cross-Robot Software Framework for Real-Time Control

2021 ◽  
Author(s):  
Luca Muratore ◽  
Arturo Laurenzi ◽  
Nikos G. Tsagarakis
Keyword(s):  
Software Architecture ◽  
Real Time ◽  
Humanoid Robots ◽  
Robotic Systems ◽  
Real Time Control ◽  
Software Infrastructure ◽  
Robotic Arms ◽  
Time Control ◽  
Control Frequency ◽  
High Control

The widespread use of robotics in new application domains outside the industrial workplace settings requires robotic systems which demonstrate functionalities far beyond that of classical industrial robotic machines. The implementation of these capabilities inevitably increases the complexity of the robotic hardware, control a and software components. This chapter introduces the XBot software architecture for robotics, which is capable of Real-Time (RT) performance with minimum jitter at relatively high control frequency while demonstrating enhanced flexibility and abstraction features making it suitable for the control of robotic systems of diverse hardware embodiment and complexity. A key feature of the XBot is its cross-robot compatibility, which makes possible the use of the framework on different robots, without code modifications, based only on a set of configuration files. The design of the framework ensures easy interoperability and built-in integration with other existing software tools for robotics, such as ROS, YARP or OROCOS, thanks to a robot agnostic API called XBotInterface. The framework has been successfully used and validated as a software infrastructure for collaborative robotic arms as KUKA lbr iiwa/lwr 4+ and Franka Emika Panda, other than humanoid robots such as WALK-MAN and COMAN+, and quadruped centaur-like robots as CENTAURO.

WCPG: A Central Pattern Generator for Legged Robots Based on Workspace Intentions

2011 ◽  
Author(s):  
Victor Barasuol ◽  
Victor Juliano De Negri ◽  
Edson Roberto De Pieri
Keyword(s):  
Central Pattern Generator ◽  
Physical Meaning ◽  
Pattern Generator ◽  
Quadruped Robot ◽  
Legged Robots ◽  
Coupling Relationship ◽  
Simulation Results

In this paper it is proposed a central pattern generator (CPG) based on workspace intentions, where the parameters of modulation have physical meaning and the walking can be adapted to overcome irregular terrains by changing few parameters. The walking features are independently modulated since there is no coupling relationship among WCPG parameters. Simulation results are presented to demonstrate the WCPG performance for a simplified quadruped robot model in different terrains.

Sign in / Sign up

Export Citation Format

Share Document