Robot crash protector

Abstract

A robotic crash protector device is configured for heavy payload applications. The device includes a housing, a piston and an actuator movably mounted within the housing, a cam member secured within the housing in fixed relation to the housing's base, and a switch. The cam member includes a cam surface with some portions being closer to the housing's base than other portions. The actuator includes bearing members that are configured to, responsive to a rotational force imparted to the actuator, move along the cam surface and thereby collectively displace the piston. The switch detects this displacement and indicates a crash. When moving along the cam surface, the bearing members are each configured to engage the surface along a line of contact, rather than at a single point. With forces imparted to each bearing member and the cam surface distributed across a line, the components better endure heavy payload applications.

1 . A robotic crash protector device adapted to be interposed between a robot arm and a robotic tool, and operative to detect a crash, comprising:
 a housing having a central axis and a base;   a piston movably mounted within the housing;   a cam member secured within the housing in fixed relation to the base and including a cam surface oriented towards the piston, some portions of the cam surface being closer to the base than other portions of the cam surface;   an actuator movably mounted in the housing and including a plurality of bearing members that are configured to, responsive to a rotational force imparted to the actuator about said central axis, move along the cam surface and thereby collectively displace the piston, each bearing member configured to engage the cam surface along a line of contact when moving along the cam surface; and   a switch configured to detect displacement of the piston and, responsive thereto, to indicate a crash.   
     
     
         2 . The robotic crash protector device of  claim 1 , wherein each bearing member is configured to engage the cam surface along a line of contact that is transverse to a direction in which the bearing member moves along the cam surface. 
     
     
         3 . The robotic crash protector device of  claim 1 , wherein said plurality of bearing members each include a half-cylindrical outer surface having a flat side and a curved side, the length of the curved side engaging the cam surface along a line of contact. 
     
     
         4 . The robotic crash protector device of  claim 1 , wherein said plurality of bearing members are configured to move along the cam surface by sliding along the cam surface. 
     
     
         5 . The robotic crash protector device of  claim 1 , wherein said plurality of bearing members each include a substantially cylindrical outer surface, the length of which engages the cam surface along a line of contact. 
     
     
         6 . The robotic crash protector device of  claim 1 , wherein said plurality of bearing members are configured to move along the cam surface by rolling along the cam surface. 
     
     
         7 . The robotic crash protector device of  claim 1 , wherein said plurality of bearing members comprise a plurality of spherical bearings. 
     
     
         8 . The robotic crash protector device of  claim 1 , wherein said plurality of bearing members each include an outer raceway that engages the cam surface along a line of contact, an inner raceway concentric with the outer raceway, and one or more anti-friction features disposed between the outer raceway and the inner raceway. 
     
     
         9 . The robotic crash protector device of  claim 1 , wherein said plurality of bearing members each include one or more spring loaded members configured to maintain an outer surface of that bearing member in alignment with the cam surface. 
     
     
         10 . The robotic crash protector device of  claim 1 , wherein portions of the cam surface that are closest to the base comprise crests and portions of the cam surface that are furthest from the base comprise troughs, and wherein said troughs and crests comprise flat surfaces that are substantially perpendicular to the central axis of the housing. 
     
     
         11 . The robotic crash protector device of  claim 10 , wherein portions of the cam surface between any given trough and crest form a gradual transition between that trough and crest by transitioning from an approximately convex surface proximal to the trough, to an approximately concave surface proximal to the crest. 
     
     
         12 . The robotic crash protector device of  claim 10 , wherein portions of the cam surface between any given trough and crest cant radially inward toward the central axis of the housing. 
     
     
         13 . The robotic crash protector device of  claim 1 , wherein the piston is biased in a direction away from the base, and the plurality of bearing members engage those portions of the cam surface that are furthest away from the base when no forces are imparted to the actuator. 
     
     
         14 . The robotic crash protector device of  claim 13 , wherein the housing includes a cap rigidly fixed thereto, and wherein the cam member is secured to the cap, the cap and the cam member configured to arrest movement of the actuator in a direction away from the base. 
     
     
         15 . The robotic crash protector device of  claim 13 , wherein the housing contains a cavity, and wherein the piston forms a chamber in the cavity and is biased in a direction away from the base by compressed gas or fluid in the chamber. 
     
     
         16 . The robotic crash protector device of  claim 13 , wherein the plurality of bearing members are configured to, responsive to a rotational force imparted to the actuator about said central axis, move along those portions of the cam surface that are closer to the base and thereby collectively displace the piston in a direction toward the base. 
     
     
         17 . The robotic crash protector device of  claim 1 , further comprising a contact surface member interposed between the piston and the actuator that is configured to transfer movement of the actuator into movement of the piston. 
     
     
         18 . A robotic crash protector device adapted to be interposed between a robot arm and a robotic tool, and operative to detect a crash, comprising:
 a housing having a central axis and a base;   a piston movably mounted within the housing;   a cam member secured within the housing in fixed relation to the base and including a cam surface oriented towards the piston, some portions of the cam surface being closer to the base than other portions of the cam surface;   an actuator including bearing means for engaging the cam surface along a line of contact, responsive to a rotational force imparted to said means about said central axis, to thereby displace the piston;   switching means for detecting displacement of the piston and, responsive thereto, indicating a crash.   
     
     
         19 . An actuator movably mounted in the housing of a robotic crash protector device that is interposed between a robot arm and a robotic tool, the actuator comprising a plurality of bearing members that are configured to, responsive to a rotational force imparted to the actuator about a central axis of the housing, move along a cam surface of a cam member secured within the housing and thereby collectively displace a piston movably mounted within the housing, each bearing member configured to engage the cam surface along a line of contact when moving along the cam surface. 
     
     
         20 . The actuator of  claim 19 , wherein each bearing member is configured to engage the cam surface along a line of contact that is transverse to a direction in which the bearing member moves along the cam surface.