Power Circuit Description

Motor Power Circuitry

The motor drives circuitry is powered with 120VAC from a standard wall socket this 120VAC is converted to 40VDC using a transformer and rectifier. Also the 120AC is converted to give us 12VDC through a PC power supply. This leaves us with useable 40VDC signal and a 12VDC signal. The motors each have a brake and armature coil that we need to control with circuitry

We can control the motors power using two different methods, a signal from the EMG circuit through a micro-controller or a teach pendant. There is a selector switch on the bottom of the teach pendant to select between the two methods of operation.

The teach pendant is constructed of a panel of 6 push button switches the top 5 are for each individual finger and the bottom one is for all fingers at the same time. There is also a switch to control the up and down motion of the hand located on right side of pendant. Each individual push button when activated sends 12VDC signal through it to energize a relay that turns the system either on or off. There is an individual relay for each of the 5 motors. When the all push button is activated it overrides the 5 individual buttons and sends power to all 5 on / off relays. The next 5 relays are the open / close these are activated using the side selector switch. You can operate the hand either up or down by this selector switch. When the switch is in either the up or down position it sends 12VDC to the appropriate side of the open / close relays. Which then activates the darlington pair circuit attached to motor drives.

When the pendant is in EMG mode the 12VDC from the power circuitry is fed back through a 9pin cable into the micro-controller circuitry when the micro-controller is triggered from the EMG circuit it allows this power to loop back and switch a relay that activates all 5 on / off relays in the power circuitry.  There is also two other lines that feed through the 9 pin cable these particular lines are fed from the micro controller and gives us the switching voltage for the open / close relays on the relay circuit.

When the motors are triggered from the relay circuitry two things happen, the brakes are energized and the forward motor coil or the reverse motor coil is energized. The brake coils are energized using a darlington pair circuit that when the motors switch they get activated with 12VDC.  The motors when activated are controlled with a variable voltage up to 30VDC.  This voltage is generated from the 40VDC transformer and regulated through 5 separate voltage regulators. This is sent to the motors through the open / close relays when there are switched either in the open or close positions.

There are also two limit switches per motor incorporated into the system. These are used to control how far the motor can operate safely.  The Switches are wired normally open and when closed break the connection to the brake and motor stopping the operation of system instantly.