PERHITUNGAN FAKTOR KALIBRASI SENSOR AKSELEROMETER MMA7361L PADA KETIGA SUMBU DENGAN MENGGUNAKAN SIMULATOR ST-3176-TC-10

Abstrak Akselerometer adalah sensor percepatan yang banyak dipakai sebagai komponen utama dalam pembuatan IMU (Inertial Measurement Unit). Akselerometer MMA7361L merupakan sensor percepatan dengan 2 pilihan tingkat sensitivitas, yaitu 800 mV/g dan 206 mV/g. Sensor akselerometer yang dijual belum terkalibrasi, sehingga sensor harus dikalibrasi sebelum digunakan. Kalibrasi akselerometer dipengaruhi oleh tegangan catu daya, sehingga diperlukan catu daya yang stabil dalam pemakaiannya. Faktor kalibrasi merupakan faktor pengali yang mengubah data ADC keluaran sensor menjadi nilai percepatan hasil pengukuran. Alat utama yang digunakan untuk melakukan kalibrasi sensor dan pengujian sensor adalah simulator gerak 3 sumbu ST-3176-TC-10. Hasil pengujian menunjukkan bahwa sensor dengan tipe yang sama mempunyai faktor kalibrasi yang berbeda-beda, sehingga setiap sensor harus dikalibrasi sebelum digunakan. Faktor kalibrasi suatu sensor tidak dapat digunakan untuk sensor yang lain meskipun tipenya sama

KALIBRASI SENSOR MULTIGAIN AKSELEROMETER DENGAN ACUAN PERCEPATAN GRAVITASI BUMI

Akselerometer merupakan salah satu sensor percepatan yang banyak dipakai dalam pembuatan IMU (Inertial Measurement Unit). Sensor akselerometer dijual di pasaran dalam keadaan belum terkalibrasi, sehingga tidak bias langsung digunakan. MMA7361L merupakan akselerometer dengan 2 pilihan tingkat sensitivitas, yaitu 1,5 g dan 6 g, sehingga penggabungan 2 unit sensor tersebut dapat digunakan dalam perancangan sensor multigain. Kalibrasi akselerometer dipengaruhi oleh tegangan catu daya, sehingga diperlukan catu daya yang stabil dalam pemakaiannya. Keluaran sensor pada saat tidak ada eksitasi dari luar disebut sebagai nilai offset sensor. Kalibrasi sensor multigrain dapat dilakukan secara bersamaan dengan membandingkan percepatan gravitasi bumi. Alat utama yang digunakan untuk melakukan kalibrasi sensor dan pengujian sensor adalah simulator gerak 3 sumbu ST-3176-TC-10. Hasil pengujian menunjukkan bahwa sensor dengan tipe yang sama mempunyai sensitivitas dan nilai offset yang berbedabeda. Sensor MMA7361L 1,5 g mempunyai nilai sensitivitas yang lebih tinggi dan nilai (Root Mean Square Error) RMSE yang lebih rendah jika dibandingkan dengan MMA7361L 6 g

KALIBRASI SENSOR MULTIGAIN AKSELEROMETER DENGAN ACUANPERCEPATAN GRAVITASI BUMI Cover

eprints.undip.ac.id/7182

Collaborative human-machine interfaces for mobile manipulators.

The use of mobile manipulators in service industries as both agents in physical Human Robot Interaction (pHRI) and for social interactions has been on the increase in recent times due to necessities like compensating for workforce shortages and enabling safer and more efficient operations amongst other reasons. Collaborative robots, or co-bots, are robots that are developed for use with human interaction through direct contact or close proximity in a shared space with the human users. The work presented in this dissertation focuses on the design, implementation and analysis of components for the next-generation collaborative human machine interfaces (CHMI) needed for mobile manipulator co-bots that can be used in various service industries. The particular components of these CHMI\u27s that are considered in this dissertation include: Robot Control: A Neuroadaptive Controller (NAC)-based admittance control strategy for pHRI applications with a co-bot. Robot state estimation: A novel methodology and placement strategy for using arrays of IMUs that can be embedded in robot skin for pose estimation in complex robot mechanisms. User perception of co-bot CHMI\u27s: Evaluation of human perceptions of usefulness and ease of use of a mobile manipulator co-bot in a nursing assistant application scenario. To facilitate advanced control for the Adaptive Robotic Nursing Assistant (ARNA) mobile manipulator co-bot that was designed and developed in our lab, we describe and evaluate an admittance control strategy that features a Neuroadaptive Controller (NAC). The NAC has been specifically formulated for pHRI applications such as patient walking. The controller continuously tunes weights of a neural network to cancel robot non-linearities, including drive train backlash, kinematic or dynamic coupling, variable patient pushing effort, or slope surfaces with unknown inclines. The advantage of our control strategy consists of Lyapunov stability guarantees during interaction, less need for parameter tuning and better performance across a variety of users and operating conditions. We conduct simulations and experiments with 10 users to confirm that the NAC outperforms a classic Proportional-Derivative (PD) joint controller in terms of resulting interaction jerk, user effort, and trajectory tracking error during patient walking. To tackle complex mechanisms of these next-gen robots wherein the use of encoder or other classic pose measuring device is not feasible, we present a study effects of design parameters on methods that use data from Inertial Measurement Units (IMU) in robot skins to provide robot state estimates. These parameters include number of sensors, their placement on the robot, as well as noise properties on the quality of robot pose estimation and its signal-to-noise Ratio (SNR). The results from that study facilitate the creation of robot skin, and in order to enable their use in complex robots, we propose a novel pose estimation method, the Generalized Common Mode Rejection (GCMR) algorithm, for estimation of joint angles in robot chains containing composite joints. The placement study and GCMR are demonstrated using both Gazebo simulation and experiments with a 3-DoF robotic arm containing 2 non-zero link lengths, 1 revolute joint and a 2-DoF composite joint. In addition to yielding insights on the predicted usage of co-bots, the design of control and sensing mechanisms in their CHMI benefits from evaluating the perception of the eventual users of these robots. With co-bots being only increasingly developed and used, there is a need for studies into these user perceptions using existing models that have been used in predicting usage of comparable technology. To this end, we use the Technology Acceptance Model (TAM) to evaluate the CHMI of the ARNA robot in a scenario via analysis of quantitative and questionnaire data collected during experiments with eventual uses. The results from the works conducted in this dissertation demonstrate insightful contributions to the realization of control and sensing systems that are part of CHMI\u27s for next generation co-bots

On Increasing the Automation Level of Heavy-Duty Hydraulic Manipulators with Condition Monitoring of the Hydraulic System and Energy-Optimised Redundancy Resolution

Hydraulic manipulators on mobile machines are predominantly used for excavation and lifting applications at construction sites and for heavy-duty material handling in the forest industry due to their superior power-density and rugged nature. These manipulators are conventionally open-loop controlled by human operators who are sufficiently skilled to operate the machines. However, in the footsteps of pioneering original equipment manufacturers (OEMs) and to keep up with the intensifying demand for innovation, more and more mobile machine OEMs have a major interest in significantly increasing the automation level of their hydraulic manipulators and improving the operation of manipulators. In this thesis, robotic software-based functionalities in the form of modelbased condition monitoring and energy-optimal redundancy resolution which facilitate increased automation level of hydraulic manipulators are proposed.A condition monitoring system generally consists of software modules and sensors which co-operate harmonically and monitor the hydraulic system’s health in real-time based on an indirect measure of this system’s health. The premise is that when this condition monitoring system recognises that the system’s health has deteriorated past a given threshold (in other words, when a minor fault is detected, such as a slowly increasing internal leakage of the hydraulic cylinder), the condition monitoring module issues an alarm to warn the system operator of the malfunction, and the module could ideally diagnose the fault cause. In addition, when faced with severe faults, such as an external leakage or an abruptly increasing internal leakage in the hydraulic system, an alarm from the condition monitoring system ensures that the machine is quickly halted to prevent any further damage to the machine or its surroundings.The basic requirement in the design of such a condition monitoring system is to make sure that this system is robust and fault-sensitive. These properties are difficult to achieve in complex mobile hydraulic systems on hydraulic manipulators due to the modelling uncertainties affecting these systems. The modelling uncertainties affecting mobile hydraulic systems are specific compared with many other types of systems and are large because of the hydraulic system complexities, nonlinearities, discontinuities and inherently time-varying parameters. A feasible solution to this modelling uncertainty problem would be to either attenuate the effect of modelling errors on the performance of model-based condition monitoring or to develop improved non-model-based methods with increased fault-sensitivity. In this research work, the former model-based approach is taken. Adaptation of the model residual thresholds based on system operating points and reliable, load-independent system models are proposed as integral parts of the condition monitoring solution to the modelling uncertainty problem. These proposed solutions make the realisation of condition monitoring solutions more difficult on heavy-duty hydraulic manipulators compared with fixed-load manipulators, for example. These solutions are covered in detail in a subset of the research publications appended to this thesis.There is wide-spread interest from hydraulic manipulator OEMs in increasing the automation level of their hydraulic manipulators. Most often, this interest is related to semi-automation of repetitive work cycles to improve work productivity and operator workload circumstances. This robotic semi-automated approach involves resolving the kinematic redundancy of hydraulic manipulators to obtain motion references for the joint controller to enable desirable closed-loop controlled motions. Because conventional redundancy resolutions are usually sub-optimal at the hydraulic system level, a hydraulic energy-optimised, global redundancy resolution is proposed in this thesis for the first time. Kinematic redundancy is resolved energy optimally from the standpoint of the hydraulic system along a prescribed path for a typical 3-degrees-of-freedom (3-DOF) and 4-DOF hydraulic manipulator. Joint motions are also constrained based on the actuators’ position, velocity and acceleration bounds in hydraulic manipulators in the proposed solution. This kinematic redundancy resolution topic is discussed in the last two research papers. Overall, both designed manipulator features, condition monitoring and energy-optimised redundancy resolution, are believed to be essential for increasing the automation of hydraulic manipulators