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Balance

During joint control (choregraphe timeline for example), motion can be stabilized by Whole Body balancer. Consequently, initial motion is modified to the closest motion which respect balance and/or foot state.

Whole Body balancer have to be activated to use the following function (api wbEnable).

Foot State

This api sets the foot state:

• Fixed. The 6 cartesian degrees of freedom are constrained. The foot are completely fixed.
• Plane. It constrained the foot in the plane. The following cartesian axis are constrained (Z, WX, WY). Foot can move in X, Y et WZ axis.
• Free. The foot can move in all the cartesian axis.

            # Example showing how to fix the feet. 
            stateName = "Fixed" 
            supportLeg = "Legs" 
            proxy.wbFootState(stateName, supportLeg) 
          

Note:	Use choregraphe box "Keep Balance"!

Balance Constraint

Balance can be activated/disactivated. Support polygon depends of support leg: Legs (both feet), LLeg or RLeg.

            # Example showing how to Constraint Balance Motion. 
            isEnable   = True 
            supportLeg = "Legs" 
            proxy.wbEnableBalanceConstraint(isEnable, supportLeg)
          

At last, Foot have to be constrained. The following combination are allowed:

          # wbEnableBalanceConstraint(True, "Legs") with:
          # - wbFootState("Fixed", "Legs")
          # - wbFootState("Fixed", "LLeg") and wbFootState("Plane", "RLeg")
          # - wbFootState("Fixed", "RLeg") and wbFootState("Plane", "LLeg")
          
          # wbEnableBalanceConstraint(True, "LLeg") with:
          # - wbFootState("Fixed", "Legs")
          # - wbFootState("Fixed", "LLeg") and wbFootState("Fixed", "RLeg")
          # - wbFootState("Fixed", "LLeg") and wbFootState("Plane", "RLeg")
          # - wbFootState("Fixed", "LLeg") and wbFootState("Free" , "RLeg")

          # wbEnableBalanceConstraint(True, "RLeg") with:
          # - wbFootState("Fixed", "Legs")
          # - wbFootState("Fixed", "RLeg") and wbFootState("Fixed", "LLeg")
          # - wbFootState("Fixed", "RLeg") and wbFootState("Plane", "LLeg")
          # - wbFootState("Fixed", "RLeg") and wbFootState("Free" , "LLeg")
          

Warning:	When asked, if COM is not inside the desired support polygon, this constraint is not activated.

Examples

          # Example of a whole body FootState
          # Warning: Needs a PoseInit before executing
          #          Whole body balancer must be disactivated at the end of the script
          # Example available: path/to/aldebaran-sdk/modules/src/examples/
          #                    python/motion_wbFootState.py
          
          # Activate Whole Body Balancer.
          isEnabled  = True
          proxy.wbEnable(isEnabled)

          # Legs are constrained in a plane 
          stateName  = "Plane" 
          supportLeg = "Legs" 
          proxy.wbFootState(stateName, supportLeg) 
          
          # HipYawPitch angleInterpolation
          # Without Whole Body balancer, foot will not be kept plane.
          names      = "LHipYawPitch" 
          angleLists = [-45.0, 10.0, 0.0]
          timeLists  = [3.0, 6.0, 9.0] 
          isAbsolute = True 
          angleLists = [angle*math.pi/180.0 for angle in angleLists]
          proxy.angleInterpolation(names, angleLists, timeLists, isAbsolute) 
          
          # Disactivate Whole Body Balancer.
          isEnabled  = False 
          proxy.wbEnable(isEnabled)
        

            # Example of a whole body Enable Balance Constraint
            # Warning: Needs a PoseInit before executing
            #          Whole body balancer must be disactivated at the end of the script
            # Example available: path/to/aldebaran-sdk/modules/src/examples/
            #                    python/motion_wbEnableBalanceConstraint.py
            
            # Activate Whole Body Balancer.
            isEnabled  = True
            proxy.wbEnable(isEnabled)

            # Legs are constrained in a plane 
            stateName  = "Fixed" 
            supportLeg = "Legs" 
            proxy.wbFootState(stateName, supportLeg) 
            
            # Constraint Balance Motion. 
            isEnable   = True 
            supportLeg = "Legs" 
            proxy.wbEnableBalanceConstraint(isEnable, supportLeg) 
            
            # KneePitch angleInterpolation
            # Without Whole Body balancer, foot will fall down.
            names      = ["LKneePitch", "RKneePitch"] 
            angleLists = [ [0.0, 40.0*math.pi/180.0], [0.0, 40.0*math.pi/180.0]]
            timeLists  = [ [5.0, 10.0], [5.0, 10.0]] 
            isAbsolute = True 
            proxy.angleInterpolation(names, angleLists, timeLists, isAbsolute) 
            
            # Disactivate Whole Body Balancer.
            isEnabled  = False 
            proxy.wbEnable(isEnabled)
          

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