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Transforms

Modified 2018-10-23 by Theo Guerin

This unit focuses on transforms in robotics. In our experience, a significant fraction of effort in robotics programming is spent making sure transforms are correct. If you have an incorrect transform between a sensor and the robot’s body, it is much harder to use the sensor information. Inaccurate transforms directly translates to less precise information from the sensor. A useful reference on this topic is [23].

The process of finding a transform between the robot’s body and a sensor is called extrinsic calibration.

In this assignment we will practice using transformation matrices to compute the location of points in different coordinate systems as well as methods for performing extrinsic calibration. This topic is closely related to graphics, which uses the full power of a transformation matrix to shear, reproject etc. In robotics, the main activity is translation and rotation of rigid bodies. For example, after driving forward at 2 meters per second for 1 second, we want to estimate the robot’s new position. Or for example, after yawing at 10 degrees per second for 5 seconds, we want to find the robot’s updated rotation in the global space.