In order to be a performance-enhanced, standalone system legged robots are desired to have an effective mechanism and lightweight control hardware. In the context, this paper shows how to design a biped robot adopting a field programmable gate array, or FPGA for short, as the motor controller. Additionally, the onboard electronic hardware system features a digital signal processor (DSP) as the main CPU. By using the FPGA in conjunction with PWM RC servomotors, a more flexible hardware system has been accomplished with the integrated, digital controller.

A small power biped robot is designed by the load sharing method of walking gait. Walking can be classified into one-foot and two-foot standing during the common speed smooth walking. In two-foot standing, the weight of robot can be distributed to all joints. However, in one-foot standing, it is burdened to one foot, especially to ankle joint. So bigger actuator or even the passive joint is considered at the ankle joint; but bigger actuator increases the weight of robot and passive joint does not control ankle. When the small power actuator is used at all joints, ankle joint is sometimes overloaded during walking and this makes walking impossible. This problem is solved using the appropriate walking gait, that is, it depresses or distributes the driving power of the ankle joint when the load is applied to the ankle, and drives the ankle joint before the load is applied. By this method, the small power biped robot can be implemented without overloading the ankle joint. Experiments are conducted to prove the proposed method.

An indirect adaptive control approach is developed in this paper for unknown robots using neural networks (NN). A key property of the proposed approach is that the actual joint angle values in the control law is replaced by the desired joint angle, angular speed and acceleration, and the bound on the NN reconstruction error is assumed to be unknown. Main theoretical results for designing such a neuro-adaptive controller are given, and the control performance of the proposed controller is verified with simulation studies.

The human-robot coordination with rotational motion is discussed and experimented. In order to deal with the rotational motion, a new force sensor is proposed to measure the force provided by the human operator in addition to the force sensor previously proposed for the compliant motion of the robot. The force sensor on the human-hand side interprets the desired motion of the human operator while the force sensor of the robot side defines the actual motion of the end-effector. The two motions then serve as the reference input and actual output of the feedback control system respectively. With the new force sensor, load distribution becomes a simple issue. It can be done by simply specifying a distribution factor which determines the ratio between the forces provided by the robot and the arm respectively. Experiment shows that the coordination scheme is effective for both the rotational and translational motions in the human-robot coordination.

Unknown load distribution between two coordinated industrial robots is studied using two different methods. In the first method, called the load estimation method, the parameters associated with the load are estimated using the information from two wrist force sensors. As a result, the load becomes known, and conventional methods can then be applied to distribute the force. In the second method, the force compensation method, one of the robots, called the leader, takes the major role of carrying the load. The load is compensated for by another robot called the follower until the leader can carry the load to follow a satisfactory trajectory. Simulation results which demonstrate the validity of the force compensation method are presented. >