“The future depends on what you do today.”
Gandhi
Dorsiflexor
The Dorsiflexor integrates a linear actuator to passively induce dorsiflexion by applying a controlled linear force to the foot. It assists the user with a passive dorsiflexion stretch. Never exceeding the desired angle. It is a completely, controlled and safe way to stretch the gastrocnemius, soleus and associated fascia.
How they work
A Linear actuator lies parallel to the foot. At the end of the actuator’s rod is an end effector which pushes on a wedge. When the rod extends the footplate lowers. The footplate raises when it retracts. The wedge is the exact size of the dorsiflexion angle wanted. Because they linear actuator is parallel to the foot, it never flexes the foot more than the angle of the wedge itself.
Hardware
The actuator is driven by a microcontroller. There are four buttons to control it. Including the stop button, there are:
Extend and Retract buttons
The extend and retract buttons allow for the exact, manual positioning of the end effector on the wedge. So the dorsiflexion can be done gradually and stay at the exact angle wanted.
Randomise
The randomise button removes the manual extend/retract buttons’ function. Then it constantly generates distances at random that the actuator should go to, in order to move the wedge up and down. This brings about the constant, fluid extension and dorsiflection movement of the foot. Moving back and forth allowing the continuous variation for the foot’s dorsiflexion and extension angle.
The distance that the actuator’s rod moves is determined by a distance sensor (in this case an ultrasonic one). The sensor reads the end effector's distance and activates the actuator accordingly. [I chose to do it this way instead of by calculating the motor’s rotations to obtain distance travelled back and forth…mainly because that would have done my head in.]
2 different angled wedges
Without wedges
With wedges
Conclusion and considerations
• Great potential! Especially if the person's bodyweight is insufficient to work against very high tone
• As you can see on the video of this first prototype, the end effector was too tall and thin... Causing it to be unstable when extreme foot pressure was applied. Easily remedied by making it shorter.
