6,083 research outputs found
Inertial sensor-based knee flexion/extension angle estimation
A new method for estimating knee joint flexion/extension angles from segment acceleration and angular velocity data is described. The approach uses a combination of Kalman filters and biomechanical constraints based on anatomical knowledge. In contrast to many recently published methods, the proposed approach does not make use of the earthās magnetic field and hence is insensitive to the complex field distortions commonly found in modern buildings. The method was validated experimentally by calculating knee angle from measurements taken from two IMUs placed on adjacent body segments. In contrast to many previous studies which have validated their approach during relatively slow activities or over short durations, the performance of the algorithm was evaluated during both walking and running over 5 minute periods. Seven healthy subjects were tested at various speeds from 1 to 5 miles/hour. Errors were estimated by comparing the results against data obtained simultaneously from a 10 camera motion tracking system (Qualysis). The average measurement error ranged from 0.7 degrees for slow walking (1 mph) to 3.4 degrees for running (5mph). The joint constraint used in the IMU analysis was derived from the Qualysis data. Limitations of the method, its clinical application and its possible extension are discussed
Preparation of NiO catalyst on FeCrAI substrate using various techniques at higher oxidation process
The cheap nickel oxide (NiO) is a potential catalyst candidate to replace the
expensive available platinum group metals (PGM). However, the current methods to
adhere the NiO powder on the metallic substrates are complicated. Therefore, this
work explored the development of nickel oxide using nickel (Ni) on FeCrAl
substrate through the combination of nickel electroplating and oxidation process for
catalytic converter application. The approach was started with assessment of various
nickel electroplating process based on the weight gain during oxidation. Then, the
next experiment used the best process in which the pre-treatment using the solution
of SiC and/or Al2O3 in methanol. The specimens then were carried out to short term
oxidation process using thermo gravimetric analysis (TGA) at 1000
o
C. Meanwhile,
the long term oxidation process was conducted using an automatic furnace at 900,
1000 and 1100
o
C. The atomic force microscopy (AFM) was used for surface
analysis in nanometer range scale. Meanwhile, roughness test was used for roughness
measurement analysis in micrometer range scale. The scanning electron microscope
(SEM) attached with energy dispersive X-ray (EDX) were used for surface and cross
section morphology analysis. The specimen of FeCrAl treated using ultrasonic prior
to nickel electroplating showed the lowest weight gain during oxidation. The surface
area of specimens increased after ultrasonic treatment. The electroplating process
improved the high temperature oxidation resistance. In short term oxidation process
indicated that the ultrasonic with SiC provided the lower parabolic rate constant (kp)
and the Al2O3 and NiO layers were also occurred. The Ni layer was totally
disappeared and converted to NiO layer on FeCrAl surface after long term oxidation
process. From this work, the ultrasonic treatment prior to nickel electroplating was
the best method to adhere NiO on FeCrAl substrate
Towards IMU-based Full-body Motion Estimation of Rough Terrain Mobile Manipulators
For navigation or pose estimation, strap-down Micro-Electro-Mechanical System (MEMS) Inertial Measurement Units (IMU) are widely used in all types of mobile devices and applications, from mobile phones to cars and heavy-duty Mobile Working Machines (MWM). This thesis is a summary of work focus on the utilization of IMUs for state estimation of MWM. Inertial sensor-based technology oļ¬ers an alternative to the traditional solution, since it can signiļ¬cantly decrease the system cost and improve its robustness.
For covering the research topic of whole-body estimation with IMUs, ļ¬ve publications focus on the development of novel algorithms, which use sensor fusion or rotary IMU theory to estimate or calculate the states of MWM. The test-platforms are also described in detail.
First, we used low-cost IMUs installed on the surface of a hydraulic arm to estimate the joint state. These robotic arms are installed on a ļ¬oating base, and the joints of the arms rotate in a two-dimensional (2D) plane. The novel algorithm uses an Extended Kalman Filter (EKF) to fuse the output of the gyroscopes and the accelerometers, with gravity as the reference. Second, a rotary gyroscope is mounted on a grasper of a crane, and the rotary gyroscope theory is implemented to decrease the drift of the angular velocity measurement. Third, low-cost IMUs are attached to the wheels and the bogie test bed, and the realization of IMU-based wheel odometry is investigated. Additionally, the rotary gyroscope provides information about the roll and yaw attitude for the test bed. Finally, we used an industry grade IMU fuse with the output of wheel odometry to estimate the position and attitude of the base for an MWM moving on slippery ground.
One of the main aims of this research study is to estimate the states of an MWM only using IMU sensors. The research achievements indicate this approach is promising. However, the observability of IMU in the yaw direction of the navigation frame is limited so it is diļ¬cult to estimate the yaw angle of the rotation plane for the robotic arm when only using IMUs, to ensure the long-term reliable yaw angle and position of the vehicle base, external information might also be needed. When applying the rotary IMU theory, minimization of the power supply for the rotation device is still a challenge.
This research study demonstrates that IMUs can be low-cost and reliable replacements for traditional sensors in joint angle measurement and in the wheel rotation angle for vehicles, among other applications. An IMU can also provide a robust state for a vehicle base in a challenging environment. These achievements will beneļ¬t future developments of MWMs in remote control and autonomous operations
Human-activity-centered measurement system:challenges from laboratory to the real environment in assistive gait wearable robotics
Assistive gait wearable robots (AGWR) have shown a great advancement in developing intelligent devices to assist human in their activities of daily living (ADLs). The rapid technological advancement in sensory technology, actuators, materials and computational intelligence has sped up this development process towards more practical and smart AGWR. However, most assistive gait wearable robots are still confined to be controlled, assessed indoor and within laboratory environments, limiting any potential to provide a real assistance and rehabilitation required to humans in the real environments. The gait assessment parameters play an important role not only in evaluating the patient progress and assistive device performance but also in controlling smart self-adaptable AGWR in real-time. The self-adaptable wearable robots must interactively conform to the changing environments and between users to provide optimal functionality and comfort. This paper discusses the performance parameters, such as comfortability, safety, adaptability, and energy consumption, which are required for the development of an intelligent AGWR for outdoor environments. The challenges to measuring the parameters using current systems for data collection and analysis using vision capture and wearable sensors are presented and discussed
3DTouch: A wearable 3D input device with an optical sensor and a 9-DOF inertial measurement unit
We present 3DTouch, a novel 3D wearable input device worn on the fingertip
for 3D manipulation tasks. 3DTouch is designed to fill the missing gap of a 3D
input device that is self-contained, mobile, and universally working across
various 3D platforms. This paper presents a low-cost solution to designing and
implementing such a device. Our approach relies on relative positioning
technique using an optical laser sensor and a 9-DOF inertial measurement unit.
3DTouch is self-contained, and designed to universally work on various 3D
platforms. The device employs touch input for the benefits of passive haptic
feedback, and movement stability. On the other hand, with touch interaction,
3DTouch is conceptually less fatiguing to use over many hours than 3D spatial
input devices. We propose a set of 3D interaction techniques including
selection, translation, and rotation using 3DTouch. An evaluation also
demonstrates the device's tracking accuracy of 1.10 mm and 2.33 degrees for
subtle touch interaction in 3D space. Modular solutions like 3DTouch opens up a
whole new design space for interaction techniques to further develop on.Comment: 8 pages, 7 figure
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