Arm using a two-joint module

Abstract

A robotic arm includes at least two two-joint modules and at least a first link. Each two-joint module includes a housing, a pair of hollow rotary actuator assemblies and a pair of motor drives. Each actuator assembly has an axis and a hollow shaft and the axes are arranged at an angle to each other. The pair of hollow rotary actuator assemblies are arranged such that a back end of the actuator assemblies is inside the housing and a front end of the actuator assemblies extends outwardly of the housing, and attached to the housing such that cables can be fed from the outside of one of the actuator assemblies to the inside thereof and to the inside of the other actuator assemblies to the outside thereof. The pair of motor drives are operably attached to the actuator assemblies and the motor drives are outside the housing.

What is claimed is: 
     
         1 . A robotic arm comprising:
 at least two two-joint modules wherein each two-joint module includes:
 a housing; 
 a pair of hollow rotary actuator assemblies each having an axis and a hollow shaft and the axes being arranged at an angle to each other and the pair of hollow rotary actuator assemblies being arranged such that a back end of each of the hollow rotary actuator assemblies is inside the housing and a front end of each of the hollow rotary actuator assemblies extends outwardly of the housing, and attached to the housing body such that the cables can be fed from the outside of one of the pair of hollow rotary actuator assemblies to the inside thereof and to the inside of the other of the pair of hollow rotary actuator assemblies to the outside thereof; and 
 a pair of motor drives operably attached to the pair of hollow rotary actuator assemblies and the motor drives being outside the housing; and 
   at least a first link.   
     
     
         2 . The robotic arm of  claim 1  further including a third two-joint module and a second link, and the two-joint modules are a shoulder module, an elbow module and a wrist module and shoulder module and the elbow module are operably attached to opposing ends of the first link and the elbow module and the wrist module are attached to opposing ends of the second link. 
     
     
         3 . The robotic arm of  claim 1  wherein each the axes of the pair of hollow rotary actuator assemblies are arranged orthogonally. 
     
     
         4 . The robotic arm of  claim 3  wherein each hollow rotary actuator assembly is a combo actuator. 
     
     
         5 . The robotic arm of  claim 4  wherein each hollow rotary actuator assembly includes a brushless DC servo motor having a hollow central portion, an encoder having a hollow central portion, a brake having a hollow central portion and an encoder having a hollow central portion. 
     
     
         6 . The robotic arm of  claim 1  wherein housing of each two-joint module includes a housing body and a housing cover releasably attachable to the housing body. 
     
     
         7 . The robotic arm of  claim 6  wherein each housing body includes a pair of generally cylindrical compartments for housing the pair of hollow rotary actuator assemblies. 
     
     
         8 . The robotic arm of  claim 7  wherein each housing body further includes center compartment between the two generally cylindrical compartments. 
     
     
         9 . The robotic arm of  claim 1  wherein the axes of the pair of hollow rotary actuator assemblies are arranged at an obtuse angle therebetween. 
     
     
         10 . The robotic arm of  claim 1  wherein the power, speed and torque of the pair of the hollow rotary actuator assemblies is the same. 
     
     
         11 . The robotic arm of  claim 1  wherein the power, speed and torque of the pair of the hollow rotary actuator assemblies is different. 
     
     
         12 . The robotic arm of  claim 1  wherein the first link is a shoulder link. 
     
     
         13 . The robotic arm of  claim 12  wherein the shoulder link includes a body and a hollow cover and having a first port and a second port. 
     
     
         14 . The robotic arm of  claim 13  wherein the first port and the second port of the shoulder link are generally in the same plane. 
     
     
         15 . The robotic arm of  claim 14  wherein the at least two two-joint modules are three two-joint modules being a shoulder module, an elbow module and a wrist module and further including a second link being a wrist link and wherein the shoulder module is attached at one end of the shoulder link and the elbow module is attached at the other end thereof and the elbow module is attached a one end of the wrist link and the wrist module is attached at the other end thereof. 
     
     
         16 . The robotic arm of  claim 15  where in the wrist link has a first and second port that are generally orthogonal to each other. 
     
     
         17 . The robotic arm of  claim 1  further a motor drive operably attached to each of the hollow rotary actuator assemblies and the motor drives being outside the housing.