IntermediateTopic 60 of 102Manufacturing, Robotics & Systems
Trajectory planning
Generate smooth paths in joint or Cartesian space.
In depth
Planning generates smooth time-parameterised paths between waypoints in joint or Cartesian space: polynomial (cubic, quintic), trapezoidal velocity profiles, splines, and time-optimal algorithms respecting velocity, acceleration and jerk limits. Path vs trajectory distinction; blending through via points.
Key points
- Boundary conditions
- Jerk-limited S-curve
- Cartesian straight lines need IK each step
ExampleA pick-and-place move uses a trapezoidal velocity profile for fast, smooth motion.
Trajectory planning produces smooth and feasible paths that respect speed, acceleration and jerk limits, which protects both the robot and the product.
What is Trajectory planning?
Generate smooth paths in joint or Cartesian space.
Why is it important to understand trajectory planning?
Trajectory planning produces smooth and feasible paths that respect speed, acceleration and jerk limits, which protects both the robot and the product.
What is a joint space path?
A path defined by joint angles over time, which is simple to compute and avoids singularities but may not give a straight tool path.
Why limit jerk?
Sudden changes in acceleration excite vibration and wear the mechanism, so smooth profiles give longer life and better accuracy.
How is Trajectory planning used in practice?
Typical applications include generating a smooth path for a robot that moves between two picking points, planning a welding path with a constant speed through corners and avoiding excessive vibration by limiting jerk in a fast pick and place cycle.
What should I learn before Trajectory planning?
Study "Robot dynamics" first (topic 59 of 102 in Manufacturing, Robotics & Systems). It covers the groundwork this topic builds on.
What are the key points of Trajectory planning?
Boundary conditions. Jerk-limited S-curve. Cartesian straight lines need IK each step.
Can you give an example of Trajectory planning?
A pick-and-place move uses a trapezoidal velocity profile for fast, smooth motion.
What comes after Trajectory planning?
The next topic is "Robot actuators and drives", which builds directly on this one.
How difficult is Trajectory planning?
It is classed as Intermediate in Manufacturing, Robotics & Systems (topic 60 of 102). It is an intermediate topic. Work through the beginner topics in Manufacturing, Robotics & Systems first.