As a reasonably proficient juggler and a less than reasonably proficient roboticist: The only functional juggling robot at any scale is housed inside a case an

As a reasonably proficient juggler and a less than reasonably proficient roboticist: The only functional juggling robot at any scale is housed inside a case and doesn't use an arm, it can juggle at exactly one width, and doesn't use any form of complex reverse kinematics. There isn't any kind of "arm" on any scale that is currently capable of juggling (that I've seen anyway). Some get close, but the only videos are of slower forms where they get assistance from people or interact with people. That also entirely ignores the physics of the situation. To get a 1000kg car to move up the 8 or so meters from catch to head height, and then catch it again, the forces are enormous. You'd need to apply nearly 80K newtons of force over a second or so to slow the object down on the catch.