Motion encoder

A motion encoder comprising:

• a joint, the joint comprising:
• a first part;
• and
• a second part, the first part being movably mounted with respect to the second part to change the joint between a first joint condition and a second joint condition;
• a first image capture device (ICD) comprising an array of light sensing elements arranged to generate images;
• a processing unit;
• and
• a pattern surface, the pattern surface defining or being arranged to define a pattern which moves relative to the first ICD between a first pattern position and a second pattern position as the joint changes between the first joint condition and a second joint condition, the pattern comprising pattern features,
• wherein:
• the first ICD has a field of view encompassing the first pattern position and the second pattern position such that the pattern features are visible to the first ICD in both the first pattern position and the second pattern position;
• the processing unit is communicatively coupled to the first ICD to receive the images from the first ICD, the processing unit being configured to determine how image features corresponding to the pattern features transform between the received images to quantify the position and/or movement of the first part relative to the first ICD;
• and
• the processing unit is configured to select image features to define the pattern features and to determine how the image features transform between the received images to quantify the position and/or movement of the first part relative to the first ICD.

A motion encoder comprising:

• a joint, the joint comprising:
• a first part;
• and
• a second part, the first part being movably mounted with respect to the second part to change the joint between a first joint condition and a second joint condition;
• a first image capture device (ICD) comprising an array of light sensing elements arranged to generate images;
• a processing unit;
• and
• a pattern surface, the pattern surface defining or being arranged to define a pattern which moves relative to the first ICD between a first pattern position and a second pattern position as the joint changes between the first joint condition and a second joint condition, the pattern comprising pattern features,
• wherein:
• the first ICD has a field of view encompassing the first pattern position and the second pattern position such that the pattern features are visible to the first ICD in both the first pattern position and the second pattern position;
• wherein the second part is movably mounted with respect to the first part to change the joint to a third joint condition and the pattern moves relative to the first ICD to a third pattern position as the joint changes between the first and/or second joint condition and the third joint condition, the third pattern position being at least partially outside the field of view of the first ICD, wherein the processing unit is configured to:
• determine that the pattern is moving to the third pattern position;
• select new image features having a known spatial relationship with respect to the image pattern features to replace the image pattern features;
• and
• determine how the new image features transform between the received images to quantify the position and/or movement of the first part relative to the first ICD;
• and
• the processing unit is communicatively coupled to the first ICD to receive the images from the first ICD, the processing unit being configured to determine how image features corresponding to the pattern features transform between the received images to quantify the position and/or movement of the first part relative to the first ICD.