Multiple Players/Users in Augmented Reality (AR)

Multiple Players/Users in Augmented Reality (AR)

In the previous lesson, we addressed an important problem among augmented reality users. How can we use the hand as an operator for augmented reality? We learned about solutions to implement this technology in mobile and how to use hand and finger movement as a tool for user interaction with the application. We also became acquainted with some practical SDKs for implementing this technology and understood their applications. In this lesson, we are going to look at another practical topic about how we can share augmented reality data and content with multiple users around the world and view their AR…
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Hand Tracking in Augmented Reality (AR)

Hand Tracking in Augmented Reality (AR)

In the previous lesson, we learned a new way to implement location-based augmented reality without using GPS. We learned how to position objects in augmented reality accurately and offline. In this video, we want to use a new and handy feature for augmented reality to increase the productivity of AR applications and provide practical freedom for the user. If you want to know how you can implement this, continue this lesson by watching the video version of the lesson at the link below: https://www.youtube.com/watch?v=zJq1gp0t_SU You can also watch more lessons about Virtual Reality (VR) and Augmented Reality (AR) in the…
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Location-based Augmented Reality (AR) without GPS

Location-based Augmented Reality (AR) without GPS

In the previous lesson, we learned about location-based augmented reality with GPS and how one or more geographic coordinates can be used as operators in the content displayed by augmented reality. We also talked about the challenges in this area and learned how to overcome them. In this lesson, we will learn about a new approach to implement location-based augmented reality. In this new method, the device does not need to be connected to any GPS satellites or even the Internet, and all calculations will be done offline. If you want to know how you can implement this, continue this…
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Training Modalities in Rehabilitation Robotics

Training Modalities in Rehabilitation Robotics

As we saw in the previous two lessons, rehabilitation robots can generally be categorized as upper-limb rehabilitation robots and lower-limb rehabilitation robots. No matter which part of the body they are targeting to rehabilitate, they can provide four different types of physical therapy that should be chosen based on the patient's needs. They are passive rehabilitation, active-assisted rehabilitation, active-resisted rehabilitation, and bilateral manipulation. Passive Rehabilitation Passive Rehabilitation can be used at the early stages of the impairment where the affected limb has no movement. In this type of therapy, the robot moves the affected limb of the patient through a…
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Lower-Extremity Rehabilitation Robots

Lower-Extremity Rehabilitation Robots

Previously, we learned about rehabilitation and the importance of robot-aided rehabilitation. We have also seen some of the upper-limb rehabilitation robots and how they operate. In this lesson, we will become familiarized with lower-limb rehabilitation robots that are helpful for patients with lower-extremity disorders. Lower-extremity exoskeleton robots can be designed to help the movement of a specific joint, or they are designed for gait rehabilitation. They can also serve as assistive devices to perform activities of daily living (ADL). Joint-specific Rehabilitation/Assistive Exoskeleton Robots Joint-specific rehabilitation/assistive exoskeleton robots are used for body joints rehabilitation and can be made to rehabilitate or…
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Homogeneous Transformation Matrices to Express Configurations in Robotics

Homogeneous Transformation Matrices to Express Configurations in Robotics

Up to this point, we have discussed orientations in robotics, and we have become familiarized with different representations to express orientations in robotics. In this lesson, we will start with configurations, and we will learn about homogeneous transformation matrices that are great tools to express configurations (both positions and orientations) in a compact matrix form. This lesson is part of the series of lessons on foundations necessary to express robot motions. For the full comprehension of the Fundamentals of Robot Motions and the necessary tools to represent the configurations, velocities, and forces causing the motion, please read the following lessons…
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Cayley-Rodrigues Parameters to Express Orientations in Robotics

Cayley-Rodrigues Parameters to Express Orientations in Robotics

In this lesson, we will become familiarized with another representation for orientations in robotics that is called Cayley-Rodrigues Parameters. Cayley-Rodrigues parameters provide local coordinates for SO(3). They are local coordinates because the representation is not singularity-free, and not all orientations can be expressed by them. However, they have properties that make them intriguing. This lesson is part of the series of lessons on foundations necessary to express robot motions. For the full comprehension of the Fundamentals of Robot Motions and the necessary tools to represent the configurations, velocities, and forces causing the motion, please read the following lessons (note that…
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Unit Quaternions to Express Orientations in Robotics

Unit Quaternions to Express Orientations in Robotics

In the lesson about the Exponential Coordinate Representation of the orientation, we saw that the logarithm could be numerically sensitive to small rotation angles ΞΈ because of the division by sinΞΈ. We also saw that all other three-parameter representations of SO(3), like Euler angles and roll-pitch-yaw angles, suffer from similar singularities in representation, and this means that the solution will not always exist for the inverse problem where we want to find a set of parameters for a given orientation. Therefore, an alternative representation of the orientation named Unit Quaternion is used that alleviates the singularity at the cost of…
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Other Explicit Representation for the Orientation in Robotics: Roll-Pitch-Yaw Angles

Other Explicit Representation for the Orientation in Robotics: Roll-Pitch-Yaw Angles

In the previous lesson, we learned about Euler Angles Representation which is one of the ways to explicitly represent an orientation. This lesson will continue with explicit ways to represent the orientation, and we will learn about Roll-Pitch-Yaw Angles. This lesson is part of the series of lessons on foundations necessary to express robot motions. For the full comprehension of the Fundamentals of Robot Motions and the necessary tools to represent the configurations, velocities, and forces causing the motion, please read the following lessons (note that more lessons will be added in the future): https://www.mecharithm.com/category/fundamentals-of-robotics/fundamentals-of-robot-motions/ Also, reading some lessons from the…
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Explicit Representation of the Orientation: Exponential Coordinates

Explicit Representation of the Orientation: Exponential Coordinates

In the previous lesson, we became familiar with rotation matrices, and we saw that the nine-dimensional space of rotation matrices subject to six constraints (three unit norm constraints and three orthogonality constraints) could be used to implicitly represent the three-dimensional space of orientations. There are also methods to express the orientation with a minimum number of parameters (three in three-dimensional space). Exponential coordinates that define an axis of rotation and the angle rotated about that axis, the three-parameter Euler angles, the three-parameter roll-pitch-yaw angles, the Cayley-Rodrigues parameters, and the unit quaternions (use four variables subject to one constraint) are some of…
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