Reaching and Grasping Flashcards
What are the components of reaching and grasp task?
Arm transport component and grip
component
How many degrees of freedom in the arm? Hand?
Arm: 7 DOF
Hand: 20 DOF
What are the three phases of reach-to-grasp trajectories?
Phase 1: Hand acceleration - reaching peak velocity
Phase 2: Hand deceleration - decelerating and fingers open to maximum aperture
Phase 3: Final closure of fingers - closing fingers to achieve degree of stability needed
What is Fitts Law
Inverse relationship between velocity of movement and precision (error)
T = a + b*log2(1+D/W)
Can a single corticospinal input activate multiple muscles?
Yes, and these muscles have synergistic actions.
What are the two feedback controls for development of force requirement?
Before grasp, visual input and expect motor requirements cause a feedforward controller to be activated to predict amount of force required (anticipatory parameter control)
After contact, a feedback controller, initialed by mechanical inputs from the fingertips is used to adjust the force requirement based on conditions found.
What are some biomechanical constraints at the peripheral apparatus? (2)
Soft tissue (ex. webbing) constrains the fingers.
Muscles with multiple tendons at different fingers activate the other fingers even if not required.
Constraint-Induced Movement Therapy (CIMT)
Unaffected limb is constrained, forcing the person to use their affected side to perform a number of different tasks.
Used to rehab motor deficits for upper limb functional disabilities.
What are 3 types of FES for Hand/Arm control?
- Freehand
- Handmaster
- Bionic glove
Freehand
- Enabled palmer grasp for holding larger objects, lateral grasp for smaller
- Used joystick on wrist/shoulder to control
- Disadvantage was required more surgery if system broke
(1997-2002)
Handmaster system
-Hinged wrist-forearm splint with a stimulator box electrically connected to the splint via a cable; electrodes stimulate key muscle points
-Disadvantage: rigid splint prevents optimal electrode placement
Bionic Glove
-Developed by UofA
-The Glove senses wrist movement, and electrically stimulates different muscles in the forearm, causing the paralyzed thumb and fingers to form a pinch grip
What is the ReJoyce?
Rehabilitation Joystick for Computerized Exercise.
- Stick with handle and different features (squeeze, twist, key, coin, peg, doorknob, handles, gripper). We used it at Glenrose. Games mimic activities of daily living.
What techniques to rehabilitation robotics use? (5)
Active assisted exercise, active constrained exercise, active resistive exercise, passive exercise, adaptive exercise.
Examples of rehab robotics (3)
- MIT-Manus: hand stuck to a joystick, patients (hand exoskeleton) perform movements while playing interactive videogames
- Bi-Manu Track: robotic arm trainer for both arms strapped in and you hold handles.
- MIME: two forearm-elbow-arm exoskeletons
Factors that affect motor recovery (4)
- Early intervention
- Task-Orientated training
- Amount and scheduling of practice
- Degree of participation (compliance and motivation)
Describe the MIT-Manus
Arm strapped to a handle, allows motion in horizontal plane with 2 DOF. Patients perform movements while playing video games, measures motor behaviors.
Describe the Bi-Manu Track
A robotic arm trainer where both arms are strapped in with two joysticks. Works on practicing bilateral elbow pro-supination and wrist flexion-extension. Each only give 1 df for each action
Describe the MIME
Mirror Image Motion Enabler.
Works via two forearm-elbow-arm exoskeletal orthoses that are linked to produce elbow flexion/extension and forearm pronation/supination.
They work in a Master-Slave configuration, where the good arm is placed in the master exoskeleton and the weakened arm is placed in the slave. The weakened arm reproduces the movement of the master by either body-powered or servomotor positioning.
Force Enslavement
When one finger is asked to produce force, activity in other fingers will also produce a force (not asked)
Eigenpostures
Hand actions have common patterns, but for different tasks
