Understanding-Machines - Robotics


In the long run, the Parallel kinematic manipulators have a good advantage over the serial manipulators. That due to their higher stiffness and large load carrying capacity. These advantages have increased the uses of parallel mechanisms in various applications. This thesis addresses the issues on stiffness estimation. Comparatively, we present a simple and comprehensive approach to estimate the stiffness of a 3PRS mechanism.


To begin with, the 3PRS consists of a mobile and a fixed platform joined by three identical limbs. The joints of each limb are – starting from the fixed platform – an actuated prismatic joint, a revolute joint and a spherical joint.

Like the name, the 3PRS manipulator has three identical limbs. And each limb has a prismatic revolute and spherical joint. In essence, to get the desired outcome through this research, we perform the kinematic with forward and inverse analysis, Jacobian, and singularity analysis.

Furthermore, we may use the Autodesk to design the CAD model of the proposed 3PRS mechanism. With the inverse kinematics, we derive an analytical model. A forward kinematic or an analytical and numerical analysis is performed to ensure the efficiency of the presented method.

Again, the results are compared with the presented CAD model. So, We also perform a Singularity analysis and three common types of singularities are discussed in this document. The results of the inverse and forward kinematics are obtained by writing a program in MATLAB ®.

Equally, the results are compared with the prototype CAD model and they are closely related. In brief, the stiffness model results obtained by numerical calculations are compared with the FEA of the CAD model. These results are a close match.


  • PKM Parallel Kinematic Manipulator
  • PRS Prismatic Revolute Spherical
  • CNC Computerized Numerical Control
  • RRR Revolute Revolute Revolute
  • SPS Spherical Prismatic Spherical
  • RPS Revolute Prismatic Spherical
  • UPU Universal Prismatic universal
  • PUU Prismatic Universal Universal
  • PSP Prismatic Spherical Prismatic
  • PRPaR Prismatic Revolute Prismatic and Revolute
  • CAD Computer Aided Design
  • FEA Finite Element Analysis


Moreover, the robots play an important part in manufacturing, that in automation. Today, the robots are flexible and are capable to execute a variety of tasks. They are faster, accurate and reliable. In addition, people prefer robots because of their precision. They also help to lower manufacturing cost and provide accuracy.


Similarly, Robots have many applications in the industry like the automobile industry.  Other applications include an automated production system. That is the pharmaceutical industry, process industry, packing industry and so on.

Likewise, the increasing dependence of industrial work on robotics is due to its cheaper manufacturing cost, efficiency, and accuracy. Applications are also dependent upon the type of links and joints. The actuators drive the links and joints in a robot manipulator. Parallel robots; on the other hand, have higher stiffness and precision as compared to the serial robots.

1.1 Robot Classification

In short, you can classify robots on the basis of various measures, they are:

  1. Degree of freedom
  2. Kinematic structure
  3. Work-space geometry
  4. Nature of Motion
  5. Control methods
  6. Accuracy and Repeat-ability

Identically, Kinematic is the most common and important property of the manipulators. We discuss it in detail:

1.1 Kinematic structure

Correspondingly, there are two main types of robots on the basis of Kinematics:

1. Serial robots
2. Parallel Robots

1.1.1 Serial Robots

Additionally, the serial robots are the serial manipulator. A series of links connect by joints that form an open kinematic chain. Their large work-space is the main advantage.

Also, they have a greater load because they carry actuators along each actuated joint. Inside the work-space, around six degrees of freedom. A robot manipulates an object to a desired position and orientation. We use the Kinematic analysis to develop the position and orientation of the end effector with reference to the fixed base.

1.1.1 Parallel Robots

Likely, the parallel robot also known as the parallel manipulator is well known for its higher accuracy and stiffness. In a parallel manipulators number of closed kinematic chains connect to the moving platform and fixed base. One of the joint in each limb is actuated. And the prismatic actuator, connected to the moving platform by passive revolute, spherical or a universal joint.

To Summarize:

Note: It is important that we understand how machines work. You can only beat the robotic revolution through creativity and innovation. You will need technology to supplement your creative ability.

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