Discrete and Rhythmic Motion

Advance Machine LearningJacobs University, Bremen

Presented By: Dev Bahadur Poudel

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Discrete Movement

• Target Oriented• Have fixed start and end points• Reaching, grasping, kicking• Examples– Taking book from the shelf– Opening the door– Kicking a football

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Discrete Movement

• Modeled by dynamical system and it’s differential equations

• Path of motion is the trajectory between start and end point

• Solution of differential equation gives the trajectory

• Motion stops when the target point is reached• End point can be a fixed attractor

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Rhythmic Motion

• Walking, Swimming, Chewing• Periodic Motion• Spinal cord produces Central Pattern

Generators for rhythmic motion• While walking left and right legs produce

rhythmic motion

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Rhythmic Movement

• CPG of rhythmic movement is dynamical system

• The solution of the differential equation of the CPG is periodic attractor

• Frequency of the period determines the motion speed

• Walking is converted to running when the frequency of walking rhythm is increased

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Combination of Discrete and Rhythmic motion

• Running and kicking football– Running is rhythmic and kicking is discrete

• Human walking and taking book from shelf– Walking is rhythmic reaching book is discrete

• Movement can be switched• Coupling between different CPGs to make

coordinated motion

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Rhythmic motion coupling of knees

Step 1: both knee angle approx zero

Step 2: left knee angle increase right knee angle remains same

Step 3: left knee angle reaches maximum

Step 4: left knee angle approx zero and right knee angle starts to increase

Step 5: right knee angle reaches to maximum angle left knee angle approx zero

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Rhythmic motion analysis video

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Thank you!