A delta-robot is a nice design for a robot, because it allows to separate the motor from the moving parts. As a result, large and heavy motors with 800 Watt can be used and at the same time the construction remains lightweight and the robot can move very fast. Instead of building a delta robot in real hardware, a first prototype was created in Box2d which is a physics engine to simulate diverse robotics types in realtime.
The joints in the middle can move freely, only the links ontop have a builtin servo motor. But something is wrong with the parallel kinematics. If the endeffector is moved away from the middle to the left, the angle is no longer 90 degree, but the endeffector gets a little bit diagonal. This makes it hard to grasp an object. Has this effect a name, and can it be fixed with improvements in the parallel kinematics?