A modification of the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif"><mml:mrow><mml:mi mathvariant="italic">α</mml:mi><mml:mtext>BB</mml:mtext></mml:mrow></mml:math> method for box-constrained optimization and an application to inverse kinematics