Design of a wrist and operator interface for an agricultural manipulator : a thesis presented in partial fulfilment of the requirements for the degree of Master of Technology in Engineering and Automation at Massey University

Roadside mowing and tree pruning has always been a job that most people would consider as unpleasant. This project is concerned with the development of a system to make these tasks simpler, safer and more pleasant for the operator. 1.1 Software This project is involved with the design of a complex mechanical system, which could be done using a modern CAD package. To achieve this, research into what modelling package was best was necessary. Several contenders were considered. These include SolidWorks [1], Mechanical Desktop [2] and CADKEY [3]. CADKHY was disregarded early as it is not as expandable as the other two. Both SolidWorks and Mechanical Desktop have additional software packages that allow for motion, force and stress analysis. The major difference between SolidWorks and Mechanical Desktop, is that SolidWorks is a true three dimensional modelling package, whereas Mechanical Desktop is based on the two dimensional AutoCAD system with a three dimensional toolbox. The choice was finalised to SolidWorks as it handles three dimensional modelling more efficiently. Massey University also uses SolidWorks. This allowed the project to continue while studying at the Turitea campus. 1.2 Overview This project is involved with the development of a wrist mechanism and hydraulic control system for an agricultural manipulator. The manipulator is called the Hydra Trim and was developed by Pivot Engineering Ltd. Napier [4]. The wrist mechanism is an integral part of making the Hydra Trim a success. The hydraulic control requires not only the valves but also an interface between the operator and the valves

Digital hydraulic valving system

The design and development are reported of a digital hydraulic valving system that would accept direct digital inputs. Topics include: summary of contractual accomplishments, design and function description, valve parameters and calculations, conclusions, and recommendations. The electrical control circuit operating procedure is outlined in an appendix

Volume 2 – Conference: Wednesday, March 9

10. Internationales Fluidtechnisches Kolloquium:Group 1 | 2: Novel System Structures Group 3 | 5: Pumps Group 4: Thermal Behaviour Group 6: Industrial Hydraulic

Digital flight control actuation system study

Flight control actuators and feedback sensors suitable for use in a redundant digital flight control system were examined. The most appropriate design approach for an advanced digital flight control actuation system for development and use in a fly-by-wire system was selected. The concept which was selected consisted of a PM torque motor direct drive. The selected system is compatible with concurrent and independent development efforts on the computer system and the control law mechanizations

Development and optimization of a suspension system for lower limbs prostheses

Dissertação de mestrado integrado em Engenharia BiomédicaThe increasing rate of amputations reinforce the need to improve the prostheses currently on the market and develop new solutions, to provide a better quality of life for the amputees. The suspension systems have a fundamental role in adapting to the prosthesis and amputee’s rehabilitation. These systems guarantee a firm attachment between the residual limb and prosthesis. The suspension systems available in the currently market, do not provide the quality of life that the lower limb amputees deserve, since do not ensure the total safety and comfort enough to use the prosthesis in long term. These limitations are associated with the difficulties on donning and doffing the prosthesis. This dissertation proposes a novel approach to solve some of these limitations. The proposed suspension system was obtained following the Design methodology, to understand the amputees’ needs, define the statement-problem, create several alternative solutions, and prototyping and testing the selected solution. The new suspension system is a combination of a guiding and fixation mechanisms, that improves the donning and doffing of prosthesis and, consequently, increases the amputee’s satisfaction. Motion analysis, safety and functional tests were done to evaluate the performance of the prototype and ensure that the proposed solution is viable and follows all the requirements and specifications stablished. Due to some technical issues, it was not possible to test all the functionalities of the prototype of the suspension system. However, the proposed suspension system presented an effective fixation of the serrated pin. Additional tests are still needed to evaluate the proposed system with the intention of being tested on amputees. In short, the new suspension system is a good alternative system to improve the life quality of amputees with lower activity level on the daily basis. With this dissertation, were published abstract for the Regional HELIX'17 conference and a paper for the International Journal of Mechatronics and Applied Mechanics, and a paper for the ICEUBI 2017 conference

Design, simulation and experimental investigation of a novel reconfigurable assembly fixture for press brakes

A reconfigurable assembly fixture is a major and important component of a reconfigurable assembly system. It isrequired for the assembly of a variety of press brake models inorder to reduce the assembly time and overall production time.The stages and requirements for the design of an assembly fixtureand understanding of the assembly process for press brakemodels were used to design a reconfigurable assembly fixture.A detailed design analysis of parts of the fixture and the hydraulicsystem is considered and presented in this article. The stress anddisplacement analysis of the parts is executed using Solidworksexpress simulation. The parameters of the hydraulic componentswere determined from force requirements, and the hydraulic system was modelled physically using Matlab Simscape hydraulics.The response of the hydraulic system was obtained for eachactuator in the system in order to depict the output of the actuators from the spool displacement of the valves. Stress analysisconducted on parts of the fixture showed that it can withstandmaximum stresses that are lesser than the yield strength of thematerial used for the part. It was also established that synchronization of hydraulic actuators can best be achieved by the use of asine input to the electrohydraulic valve. An experimental investigation was done using FESTO hydraulic test bench in order toobserve the synchronized extension and retraction of the hydraulic actuators. The simulation of the hydraulic system, electricsystem and the programmable logic controller was prepared using automation studio. The design is envisaged to provide the industries with relevant information on accurate location and gripping of press brake frames rather than turning and repositioning of the frame in order to fit other parts during assembly. The article provides relevant information on the design analysis of a reconfigurable assembly fixture for press brakes which is novel because articles on reconfigurable assembly fixtures have not considered its application to press brake assembly

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

Design of aircraft turbine fan drive gear transmission system

The following basic types of gear reduction concepts were studied as being feasible power train systems for a low-bypass-ratio, single-spool, geared turbofan engine for general aircraft use: (1) single-stage external-internal reduction, (2) gears (offset shafting), (3) multiple compound idler gear system (concentric shafting), and (4) star gear planetary system with internal ring gear final output member (concentric shafting-counterrotation). In addition, studies were made of taking the accessories drive power off both the high-speed and low-speed shafting, using either face gears or spiral bevel gears. Both antifriction and sleeve-type bearings were considered for the external-internal and star-planet reduction concepts

Study of turboprop systems reliability and maintenance costs

The overall reliability and maintenance costs (R&MC's) of past and current turboprop systems were examined. Maintenance cost drivers were found to be scheduled overhaul (40%), lack of modularity particularly in the propeller and reduction gearbox, and lack of inherent durability (reliability) of some parts. Comparisons were made between the 501-D13/54H60 turboprop system and the widely used JT8D turbofan. It was found that the total maintenance cost per flight hour of the turboprop was 75% higher than that of the JT8D turbofan. Part of this difference was due to propeller and gearbox costs being higher than those of the fan and reverser, but most of the difference was in the engine core where the older technology turboprop core maintenance costs were nearly 70 percent higher than for the turbofan. The estimated maintenance cost of both the advanced turboprop and advanced turbofan were less than the JT8D. The conclusion was that an advanced turboprop and an advanced turbofan, using similar cores, will have very competitive maintenance costs per flight hour