System and method for remote control of unmanned vehicles

1. A first device comprising:

a first processing unit, wherein the first processing unit is adapted to determine a first status of a first connection between the first processing unit of the first device and a corresponding first processing unit of a second device; and

a second processing unit, wherein the second processing unit is adapted to determine a second status of a second connection between the second processing unit of the first device and a corresponding second processing unit of the second device, wherein the first processing unit is further adapted to:

receive the second status of the second connection from the second processing unit of the first device over a path between the first processing unit of the first device and the second processing unit of the first device; and

determine one or more actions to take with respect to a machine associated with the first device based on one or both of the first status and the second status.

2. The first device of claim 1 , wherein the first device is one or more of an e-stop controller or a hand held controller.

3. The first device of claim 1 , wherein the machine is a vehicle and the first device is an e-strop controller associated with the vehicle.

4. The first device of claim 1 , wherein the first processing unit and the second processing units are microcontrollers.

5. The first device of claim 1 , wherein determining the first status of the first connection comprises determining that the first connection has been severed.

6. The first device of claim 5 , wherein determining that the first connection has been severed comprises determining that a heartbeat signal has not been received by the first processing unit of the first device from the first processing unit of the second device for more than a threshold duration of time.

7. The first device of claim 1 , wherein the first status indicates whether the first connection has been severed and the second status indicates whether the second connection has been severed, and the first processing unit adapted to determine one or more actions to take with respect to the machine associated with the first device based on one or both of the first status and the second status comprises the first processing unit adapted to halt the machinery when both the first connection and the second connection have been severed.

8. The first device of claim 1 , wherein the first status indicates whether the first connection has been severed and the second status indicates whether the second connection has been severed, and the first processing unit adapted to determine one or more actions to take with respect to the machine associated with the first device based on one or both of the first status and the second status comprises the first processing unit adapted to halt the machinery when either the first connection and the second connection have been severed.

9. The first device of claim 1 , wherein the first connection and the second connection are wireless.

10. The first device of claim 9 , wherein the first connection and the second connection use different wireless frequencies or different wireless channels.

11. The first device of claim 1 , wherein the first device further comprises a safety relay and, and wherein the safety relay includes a first switch and a second switch.

12. The first device of claim 11 , wherein when the safety relay is in a closed state the first switch and the second switch are both closed, and when the safety relay is in an open state the first switch and the second switch are both open.

13. The first device of claim 12 , wherein the first processing unit is further adapted to:

send a first signal through the first switch of the safety relay to the second processing unit;

interrogate the second processing unit about the signal over the path between the first processing unit and the second processing unit; and

based on the interrogation, determine if the second processing unit received the first signal through the first switch.

14. The first device of claim 13 , wherein the first processing unit is further adapted to:

when the safety relay is in the open state and it is determined that the second processing unit received the first signal, determine that the safety relay has malfunctioned.

15. The first device of claim 13 , wherein the first processing unit is further adapted to:

when the safety relay is in the closed state and it is determined that the second processing unit received the first signal, determine that the safety relay has not malfunctioned.

16. The first device of claim 12 , wherein the second processing unit is further adapted to:

send a second signal through the second switch of the safety relay to the first processing unit;

interrogate the first processing unit about the signal over the path between the first processing unit and the second processing unit; and

based on the interrogation, determine if the first processing unit received the second signal through the second switch.

17. The first device of claim 15 , wherein the second processing unit is further adapted to:

when the safety relay is in the open state and it is determined that the first processing unit received the first signal, determine that the safety relay has malfunctioned.

18. The first device of claim 13 , wherein the first processing unit is further adapted to:

when the safety relay is in the open state and it is determined that the second processing unit received the first signal, determine that the safety relay has not malfunctioned.

19. The first device of claim 12 , wherein the first switch and the second switch are mechanically linked.