Introduction to Robotics: Mechanics and Control

Citation

Craig, J. J. (2022). Introduction to Robotics: Mechanics and Control (4th ed.). Pearson.

Chapter Summary

The book has thirteen chapters. The publisher describes it as blending traditional mechanical engineering material with computer science and control-theoretic concepts, covering rigid-body transformations, forward and inverse positional kinematics, velocities and Jacobians of linkages, dynamics, linear and nonlinear control, force control, mechanical design and robot programming. It is aimed at senior-year undergraduate and first-year graduate courses in robotics, and the publisher says the 4th edition keeps a balance of application and theory, with an emphasis on the computational aspects of problems and a simple, intuitive presentation. The book has been in print since 1986.

Chapters 1–2: Introduction; Spatial Transformations

The first chapter introduces the field. Chapter 2 treats spatial transformations, the rigid-body description of position and orientation on which the kinematics chapters depend.

Chapters 3–4: Forward Kinematics; Inverse Kinematics

These two chapters cover the positional kinematics of manipulators: computing where the end of a linkage is from its joint values, and the inverse problem of finding joint values for a desired position.

Chapters 5–6: Velocities, Static Forces, and Jacobians; Dynamics

Chapter 5 extends kinematics to velocities and static forces through the Jacobian. Chapter 6 treats the dynamics of manipulators.

Chapters 7–8: Trajectory Planning; Mechanical Design of Robots

Chapter 7 deals with planning the motion of a manipulator through time. Chapter 8 covers the mechanical design of robots.

Chapters 9–11: Linear Control; Non-Linear Control; Force Control

Three chapters on controlling manipulators, from linear and nonlinear position control to force control.

Chapters 12–13: Programming Languages and Systems; Simulation and Off-Line Programming

The last two chapters concern the software side: programming languages and systems for robots, and simulation and off-line programming.

Key Concepts

Chapters 1–4: Description and kinematics

• Spatial transformations: describing the position and orientation of rigid bodies and relating one frame to another.
• Forward and inverse kinematics: mapping joint variables to end position, and the reverse.

Chapters 5–8: Motion, forces and design

• Jacobians: relating joint velocities to end velocities and, in the static case, forces.
• Manipulator dynamics: the equations governing the motion of a linkage under applied torques.
• Trajectory planning: specifying a path with time dependence for the manipulator to follow.

Chapters 9–13: Control and software

• Linear and non-linear control of manipulators.
• Force control: methodologies for controlling contact forces.
• Off-line programming and simulation: preparing and testing robot programs without the robot.

Critical Analysis

Strengths

• A clear progression. The chapter order follows the usual logic of the subject: description, kinematics, velocities and statics, dynamics, trajectories, design, control and programming. Each part can be studied in turn.
• Balance of mechanics and control. The publisher stresses the blend of mechanical engineering with computer science and control theory, with three control chapters and two programming chapters alongside the mechanics.
• Computation emphasised. The 4th edition keeps its emphasis on computational aspects, which suits readers who plan to implement kinematics and dynamics in software.
• Established text. The publisher notes its original publication in 1986, so the book has a long record as a university course text.

Limitations

• Depends on outside background. The book treats control in three chapters; readers without a prior course in control systems will need a separate source for the underlying theory.
• Focused on manipulators. The chapter list is organised around robot manipulators and their programming; mobile robots, vision and learning-based methods do not appear in the table of contents.
• Several editions in circulation. Pearson lists different 4th-edition and Global Edition products, so check the edition when matching assignments to chapters.

Where It Fits in the Course

In this signals, systems and control course, Craig is the application book for robotics. It sits after the foundations: Oppenheim and Willsky's Signals and Systems, Sadiku's primer and Downey's Think DSP cover signals and systems, and Nise's Control Systems Engineering is an applied introduction to modeling, analysing and designing feedback systems, using MATLAB and Simulink. Åström and Murray's Feedback Systems is a modern introduction to feedback, modeling, stability, state space and robustness across physical, biological and information systems.

Craig builds on that control background in Chapters 9–11, so the sensible order is a first control course such as Nise or Åström and Murray, then Craig for the robot-specific mechanics and control. Readers whose interest is mostly mechanics can read Chapters 1–8 first, which depend on linear algebra and rigid-body dynamics more than on control theory. Readers who want the signals and systems tools behind later control work can start from the foundations listed above, and then return to Craig for a concrete engineering application of them.

How to Use This Book

The book is for senior undergraduates and first-year graduate students in mechanical, electrical or computer engineering who are taking a robotics course. Linear algebra, rigid-body dynamics and an introductory control course are the useful background.

A practical plan:

• Core: Chapters 1–6, in order. Chapters 2–4 supply the transformations and kinematics that everything else uses; Chapters 5 and 6 add velocities, statics and dynamics.
• Next: Chapter 7 on trajectory planning, then Chapters 9–10 for control of manipulators.
• Optional by interest: Chapter 8 for mechanical design, Chapter 11 for force control, and Chapters 12–13 for programming and simulation.

Implement forward and inverse kinematics for a simple arm in code as early as possible, since the book emphasises computation. Use the chapters on control alongside a dedicated control textbook, and treat the mechanics chapters and the control chapters as two blocks that can be revisited separately.

For a one-semester course, the usual shape is Chapters 1–7 for the mechanics, one or two of the control chapters, and a short look at programming. Students working alone can stop after Chapter 6 and still have the core of manipulator kinematics and dynamics; the remaining chapters then serve as a second pass once the mechanics is secure. The same ordering suits readers who come from a computer science background: start with the spatial transformations in Chapter 2, implement them, and bring in the dynamics only when the kinematic code is working.