Ground Robotic Hand Applications for the Space Program study (GRASP)

This document reports on a NASA-STDP effort to address research interests of the NASA Kennedy Space Center (KSC) through a study entitled, Ground Robotic-Hand Applications for the Space Program (GRASP). The primary objective of the GRASP study was to identify beneficial applications of specialized end-effectors and robotic hand devices for automating any ground operations which are performed at the Kennedy Space Center. Thus, operations for expendable vehicles, the Space Shuttle and its components, and all payloads were included in the study. Typical benefits of automating operations, or augmenting human operators performing physical tasks, include: reduced costs; enhanced safety and reliability; and reduced processing turnaround time

Electromechanical Performance of HASEL Actuators: Fundamentals and Applications

Soft robotic systems are well-suited to unstructured, dynamic tasks and environments, but are currently limited by the soft actuators that power them. Most current soft actuators are based on pneumatics or shape-memory alloys, which have issues with efficiency, response speed, and portability. More recently, dielectric elastomer actuators (DEAs) have shown promise, but they have limited material selection, fabrication methods, and modes of actuation. As such, there remains a need for new types of high performance and well-rounded soft actuators. This dissertation focuses on the development and exploration of a new class of soft electrohydraulic actuators called hydraulically amplified self-healing electrostatic (HASEL) actuators. The first part of this dissertation (Chapter 2) presents of a subclass of HASEL actuators called Peano-HASELs that simultaneously introduce a breakthrough materials system based on thermoplastic films as well as a novel contractile mode of actuation. This approach enables industrially-amenable fabrication techniques, vastly expands the usable materials for actuator construction, and results in high performance actuators with fast linear contraction on activation. The second part of this dissertation (Chapter 3) elucidates the fundamentals of the electromechanical coupling that drives HASEL actuators. An analytical model is developed that accurately describes the quasi-static actuation behavior of Peano-HASEL actuators without relying on fitting parameters. Using this model, we identify a theory-driven approach to actuator design, including a roadmap for actuators with drastically improved specific energies. The final section of this dissertation (Chapter 4 and 5) looks towards more integrated and applied designs of HASEL actuators. First, a new type of articulating actuator is presented that integrates both compliant and rigid components. These spider-inspired electrohydraulic soft-actuated (SES) joints demonstrate high torque and high-speed actuation in an independently-addressable multi-joint limb, a bidirectional actuator, and a versatile gripper. Second, a biodegradable materials system is presented for high performance Peano-HASEL actuators that reduce environmental impact. Finally, a new method of capacitive self-sensing is presented that enables inexpensive and compact circuits that use only off-the-shelf and low voltage components. The results presented in this dissertation provide a framework for the development of high-performance actuators that may one day power the next generation of capable soft robots.</p

Concept Development of a Water Hydraulic Actuation System

European Union’s need of mining inside its borders generates a demand for innovative mining machinery. The objective of the ROBOMINERS project’s mining robot is to meet that demand. This kind of innovative mining machinery require innovative systems and procedures to solve different environmental, legislative and engineering challenges. This thesis lays down the foundations of water hydraulic systems and water hydraulic actuators for the actuation system development of the mining robot prototype. Since mineral oil is more commonly used in hydraulics, the use of water as a hydraulic fluid is examined. After the examination of water hydraulic systems and its components, the aim was moved towards hydraulic artificial muscles (HAMs). The possibilities and challenges of this kind of actuators were studied, as they will be utilised in the mining robot. One type of commercial off-the-shelf (COTS) HAM was tested to ensure the findings of these studies and to start the development of the mining robot’s actuating mechanisms. The study indicates that water hydraulic systems are a viable drivetrain option for the mining robot. In addition, 3 European suppliers of water hydraulic components were found. COTS components from these suppliers will help in the building process of the actuation system. Furthermore, findings and testing of the HAMs gave some base information for the use of this kind of actuators. It was found, that the Festo’s Fluidic Muscles should be suitable for the mining robot prototype, as they reach over 14 kN maximum force and allow 14 bars of overpressure. This thesis can also be used as an introduction to water hydraulic systems and water hydraulic actuators for the ROBOMINERS project group

Visual Servoing in Robotics

Visual servoing is a well-known approach to guide robots using visual information. Image processing, robotics, and control theory are combined in order to control the motion of a robot depending on the visual information extracted from the images captured by one or several cameras. With respect to vision issues, a number of issues are currently being addressed by ongoing research, such as the use of different types of image features (or different types of cameras such as RGBD cameras), image processing at high velocity, and convergence properties. As shown in this book, the use of new control schemes allows the system to behave more robustly, efficiently, or compliantly, with fewer delays. Related issues such as optimal and robust approaches, direct control, path tracking, or sensor fusion are also addressed. Additionally, we can currently find visual servoing systems being applied in a number of different domains. This book considers various aspects of visual servoing systems, such as the design of new strategies for their application to parallel robots, mobile manipulators, teleoperation, and the application of this type of control system in new areas

Climbing and Walking Robots

With the advancement of technology, new exciting approaches enable us to render mobile robotic systems more versatile, robust and cost-efficient. Some researchers combine climbing and walking techniques with a modular approach, a reconfigurable approach, or a swarm approach to realize novel prototypes as flexible mobile robotic platforms featuring all necessary locomotion capabilities. The purpose of this book is to provide an overview of the latest wide-range achievements in climbing and walking robotic technology to researchers, scientists, and engineers throughout the world. Different aspects including control simulation, locomotion realization, methodology, and system integration are presented from the scientific and from the technical point of view. This book consists of two main parts, one dealing with walking robots, the second with climbing robots. The content is also grouped by theoretical research and applicative realization. Every chapter offers a considerable amount of interesting and useful information

Steady State and Dynamic Characteristics of Water Hydraulic Valves for Mining Robot

This master’s thesis was done on the mechatronics research group of Tampere University. The thesis is related to the robominers project in which a completely new water hydraulic mining robot is developed. The objectives of the thesis were to determine the maximum control frequency of two different water hydraulic on-off valves and to study the response of a water hydraulic pressure-reducing valve. To find answers to the research questions measurements were conducted in laboratory with three different test systems. One of the tested on-off valves was direct operated and the other tested valve was pilot operated. As expected according to the literature the maximum control frequency of the direct operated valve was higher than the maximum control frequency of the pilot operated valve. With the maximum on-off valve control frequencies determined in this thesis the actuators of the mining robot can be precisely controlled. The pressure-reducing valve was constructed of two direct-operated on-off valves, pressure sensor and two accumulators. The purpose of the two accumulators were to dampen the pressure peaks. The pressure-reducing valve was tested with different flows when keeping the target pressure constant. The pressure-reducing valve was tested also with different target pressures when keeping the flow constant. According to the measurements the performance of the pressure-reducing valve was good with pressures of 40 bar or above, but the pressure-reducing valve had poor performance with pressures 30 bar or less. The measurements of this thesis prove that the operation principle of the pressure-reducing valve works in practice and according to the measurements the pressure-reducing valve can now be used on the mining robot where pressure is reduced to 40 bars

Pneumatic Artificial Muscle Driven Trailing Edge Flaps For Active Rotors

This research focuses on the development of an active rotor system capable of primary control and vibration reduction for rotorcraft. The objective is to investigate the feasibility of a novel Trailing Edge Flap (TEF) actuation system driven by Pneumatic Artificial Muscles (PAMs). A significant design effort led to a series of experimental apparatuses which tested various aspects of the performance of the actuators themselves and of TEF systems driven by them. Analytical models were developed in parallel to predict the quasistatic and dynamic behavior of these systems. Initial testing of a prototype blade section with an integrated PAM driven TEF proved the viability of the concept through successful benchtop testing under simulated M = 0.3 loading and open jet wind tunnel tests under airspeeds up to M = 0.13. This prototype showed the ability of PAM actuators to generate significant flap deflections over the bandwidth of interest for primary control and vibration reduction on a rotorcraft. It also identified the importance of high pneumatic system mass flow rate for maintaining performance at higher operating frequencies. Research into the development and improvement of PAM actuators centered around a new manufacturing technique which was invented to directly address the weaknesses of previous designs. Detailed finite element model (FEM) analysis of the design allowed for the mitigation of stress concentrations, leading to increased strength. Tensile testing of the swaged actuators showed a factor of safety over 5, and burst pressure testing showed a factor of safety of 3. Over 120,000,000 load cycles were applied to the actuators without failure. Characterization testing before, during, and after the fatigue tests showed no reduction in PAM performance. Wind tunnel testing of a full scale Bell 407 blade retrofitted with a PAM TEF system showed excellent control authority. At the maximum wind tunnel test speed of M = 0.3 and a derated PAM operating pressure of 28 psi, 18.8° half-peak-to-peak flap deflections were achieved at 1/rev (7 Hz), and 17.1° of half-peak-to-peak flap deflection was still available at 5/rev (35 Hz). A quasistatic system model was developed which combined PAM forces, kinematics and flap aerodynamics to predict flap deflection amplitudes. This model agreed well with experimental data. Whirl testing of a sub-span whirl rig under full scale loading conditions showed the ability of PAM TEF systems to operate under full scale levels of centrifugal (CF), aerodynamic, and inertia loading. A commercial pneumatic rotary union was used to provide air in the rotating frame. Extrapolation of the results to 100% of CF acceleration predicts 15.4° of half-peak-to-peak flap deflection at 1/rev (7 Hz), and 7.7° of half-peak-to-peak flap deflection at 5/rev (35 Hz). A dynamic model was developed which successfully predicted the time domain behavior of the PAM actuators and PAM TEF system. This model includes control valve dynamics, frictional tubing losses, pressure dynamics, PAM forces, mechanism kinematics, aerodynamic hinge moments, system stiffness, damping, and inertia to solve for the rotational dynamics of the flap. Control system development led to a closed loop control system for PAM TEF systems capable of tracking complex, multi-sinusoid flap deflections representative of a combined primary control and vibration reduction flap actuation scheme. This research shows the promise that PAM actuators have as drivers for trailing edge flaps on active helicopter rotors. The robustness, ease of integration, control authority and tracking accuracy of these actuators have been established, thereby motivating further research

Actuators and sensors for application in agricultural robots: A review

In recent years, with the rapid development of science and technology, agricultural robots have gradually begun to replace humans, to complete various agricultural operations, changing traditional agricultural production methods. Not only is the labor input reduced, but also the production efficiency can be improved, which invariably contributes to the development of smart agriculture. This paper reviews the core technologies used for agricultural robots in non-structural environments. In addition, we review the technological progress of drive systems, control strategies, end-effectors, robotic arms, environmental perception, and other related systems. This research shows that in a non-structured agricultural environment, using cameras and light detection and ranging (LiDAR), as well as ultrasonic and satellite navigation equipment, and by integrating sensing, transmission, control, and operation, different types of actuators can be innovatively designed and developed to drive the advance of agricultural robots, to meet the delicate and complex requirements of agricultural products as operational objects, such that better productivity and standardization of agriculture can be achieved. In summary, agricultural production is developing toward a data-driven, standardized, and unmanned approach, with smart agriculture supported by actuator-driven-based agricultural robots. This paper concludes with a summary of the main existing technologies and challenges in the development of actuators for applications in agricultural robots, and the outlook regarding the primary development directions of agricultural robots in the near future

Thermal Robotic Arm Controlled Spraying via Robotic Arm and Vision System

The Tribology Surface Engineering industry is a worldwide multi billion euro industry with significant health and safety risks. The thermal spraying sector of this industry employs the technique of applying molten surface coating material to a substrate via a thermal spray process which is implemented either by manual spraying or pre-programmed robotic systems. The development of autonomous robotic systems for thermal spraying surface coating would significantly improve production and profitability over pre-programmed systems and improve health and safety over manual spraying. The aim of this research was to investigate and develop through software simulation, physical modelling and testing the development of robotic subsystems that are required to provide autonomous robotic control for the thermal spraying process. Computer based modelling programs were developed to investigate the control strategy identified for the thermal spaying process. The algorithms included fifth order polynomial trajectories and the complete dynamic model where gravitational, inertia, centrifugal and coriolis torques are considered. Tests provide detail of the load torques that must be driven by the robot electric actuator for various structural changes to the thermal spraying robot and for variations in trajectory boundary conditions during thermal spraying. The non-linear and coupled forward and inverse kinematic equations of a five axis articulated robot with continuous rotation joints were developed and tested via computer based modelling and miniature physical robot modelling. Both the computer based modelling and physical model confirmed the closed form kinematic solutions. A solution to running cables through the continuous rotation joints for power and data is present which uses polytetrafloraethylene (PTFE) electroless nickel. This material was identified during the literature review of surface coating materials. It has excellent wear, friction and conductivity properties. Physical tests on a slip ring and brushes test rig using electroless nickel are presented which confirm the viability of using PTFE electroless nickel as a slip ring. Measurement of the substrate during thermal spraying so as to autonomously control the thermal spaying robot is a significant challenge. This research presents solutions for the measurement of the substrate using a low cost camera system and lasers in a single wavelength environment. Tests were carried out which resulted in the removal of a butane flame obscuring a test piece requiring measurement from the camera image so that substrate measurements can be made using image processing and analysis techniques such as canny edge detection and centroid measurements. Test results for the low cost vision system provide depth measure errors of ±0.6 % and structural measurements such as area and perimeter in the range -5% to -7.5%. These results confirm the efficacy of this novel flame removal technique

Feasibility study of electromechanical cylinder drivetrain for offshore mechatronic systems

Currently, there is an increasing focus on the environmental impact and energy consumption of the oil and gas industry. In offshore drilling equipment, electric motors tend to replace traditionally used hydraulic motors, especially in rotational motion control applications. However, force densities available from linear hydraulic actuators are still typically higher than those of electric actuators. Therefore, usually the remaining source of hydraulic power is thereby the hydraulic cylinder. This paper presents a feasibility study on the implementation of an electromechanical cylinder drivetrain on an offshore vertical pipe handling machine. The scope of this paper is to investigate the feasibility of a commercial off-the-shelf drivetrain. With a focus on the motion performance, numerical modeling and simulation are used when sizing and selecting the components of the considered electromechanical cylinder drivetrain. The simulation results are analyzed and discussed together with a literature study regarding advantages and disadvantages of the proposed solution considering the design criteria of offshore drilling equipment. It is concluded that the selected drivetrain can only satisfy the static motion requirements since the required transmitted power is higher than the recommended permissible power of the transmission screw. Consequently, based on the recommendation of the manufacturer, avoidance of overheating cannot be guaranteed for the drivetrain combinations considered for the case study presented in this paper. Hence, to avoid overheating, the average speed of the motion cycle must be decreased. Alternatively, external cooling or temperature monitoring and control system that prevents overheating could be implemented